Which of the following is not a colligative property?
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None required
Define colligative properties: depend on number of particles
Check each option against definition
Identify optical activity depends on structure not concentration
Confusing intensive and colligative properties
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Look for property that depends on molecular structure
None required
Define colligative properties: depend on number of particles
Check each option against definition
Identify optical activity depends on structure not concentration
Confusing intensive and colligative properties
After adding a non-volatile solute, freezing point decreases to -0.186Β°C. Calculate ΞT.
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ΞT = i x Kf x m.
Apply colligative property: ΞT = iKfm.
ΞT = (0.1) x (0.521 K kg/mol) = 0.0521.
Freezing point depression is directly proportional to solute molality.
Incorrectly calculating colligative properties due to formula errors.
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Carefully calculate using Vanβt Hoff factor and molality.
ΞT = i x Kf x m.
Apply colligative property: ΞT = iKfm.
ΞT = (0.1) x (0.521 K kg/mol) = 0.0521.
Freezing point depression is directly proportional to solute molality.
Incorrectly calculating colligative properties due to formula errors.
100 cmΒ³ of 1M CHβCOOH was mixed with 100 cmΒ³ of 2M CHβOH to form an ester. The change in the initial rate if each solution is diluted with an equal volume of water would be
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Rate = k Γ [CHβCOOH] Γ [CHβOH].
Rate = k Γ [CHβCOOH] Γ [CHβOH]. Dilution halves concentrations, reducing the rate by a factor of 1/4.
Rate reduction = (1/2 Γ 1/2) = 1/4 (0.25 times the original rate).
Final result: Rate decreases to 0.25 times.
Miscalculating rate reduction factor.
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Relate rate changes to dilution effect on reactant concentrations.
Rate = k Γ [CHβCOOH] Γ [CHβOH].
Rate = k Γ [CHβCOOH] Γ [CHβOH]. Dilution halves concentrations, reducing the rate by a factor of 1/4.
Rate reduction = (1/2 Γ 1/2) = 1/4 (0.25 times the original rate).
Final result: Rate decreases to 0.25 times.
Miscalculating rate reduction factor.
How many Coulombs of electricity are required for the oxidation of one mole of water to dioxygen?
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4 moles of electrons β 1 mole Oβ: 4 Γ 96,500 C.
Reaction: HβO β Oβ + 4HβΊ + 4eβ». Each mole of Oβ requires 4 moles of electrons.
Charge = 4 Γ Faraday constant (96,500 C) = 1.93 Γ 10β΅ C.
Final result: Charge required = 1.93 Γ 10β΅ C.
Miscalculating charge by ignoring Faraday's laws.
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Relate oxidation to Faradayβs laws of electrolysis.
4 moles of electrons β 1 mole Oβ: 4 Γ 96,500 C.
Reaction: HβO β Oβ + 4HβΊ + 4eβ». Each mole of Oβ requires 4 moles of electrons.
Charge = 4 Γ Faraday constant (96,500 C) = 1.93 Γ 10β΅ C.
Final result: Charge required = 1.93 Γ 10β΅ C.
Miscalculating charge by ignoring Faraday's laws.
Half-life period of a first-order reaction is 10 min. Starting with initial concentration of 12 M, the rate after 20 min is
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Rate = k Γ [A], k = 0.693/tβ/β.
Use first-order kinetics: k = 0.693/tβ/β.
Rate = k Γ [A]. Substituting k = 0.693/10 and [A] = 3 M (half of initial).
Final result: Rate = 0.0693 Γ 3 M/min.
Miscalculating k or using incorrect half-life formula.
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Use first-order reaction rate equation and calculate time elapsed.
Rate = k Γ [A], k = 0.693/tβ/β.
Use first-order kinetics: k = 0.693/tβ/β.
Rate = k Γ [A]. Substituting k = 0.693/10 and [A] = 3 M (half of initial).
Final result: Rate = 0.0693 Γ 3 M/min.
Miscalculating k or using incorrect half-life formula.
Which aqueous solution has the highest freezing point?
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ΞTf = i x Kf x m.
Freezing point depression depends on molality (m) and vanβt Hoff factor (i).
i (Sucrose) = 1, i (NaCl) = 2, i (NaβSOβ) = 3. Freezing point decreases with i.
Final result: Solution with 0.01 M NaCl has the highest freezing point.
Confusing freezing point depression with molarity alone.
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Relate freezing point depression to vanβt Hoff factor and molality.
ΞTf = i x Kf x m.
Freezing point depression depends on molality (m) and vanβt Hoff factor (i).
i (Sucrose) = 1, i (NaCl) = 2, i (NaβSOβ) = 3. Freezing point decreases with i.
Final result: Solution with 0.01 M NaCl has the highest freezing point.
Confusing freezing point depression with molarity alone.
In a first-order reaction, the concentration of the reactant is reduced to 12.5% in one hour. When was it half completed?
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t_half = 60 min / 3 = 20 min.
For a first-order reaction, 12.5% = (1/8) of the original concentration, meaning 3 half-lives.
Given total time = 60 min, divide it into 3 half-lives: t_half = 60 min / 3 = 20 min.
Final result: Half-life of reaction = 20 min.
Misinterpreting reaction order or fraction left after given time.
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Relate half-life and fraction of reactant remaining for first-order kinetics.
t_half = 60 min / 3 = 20 min.
For a first-order reaction, 12.5% = (1/8) of the original concentration, meaning 3 half-lives.
Given total time = 60 min, divide it into 3 half-lives: t_half = 60 min / 3 = 20 min.
Final result: Half-life of reaction = 20 min.
Misinterpreting reaction order or fraction left after given time.
For a chemical reaction, mA β xB, the rate law is r = k[A]Β². If the concentration of A is doubled, the reaction rate will be
π₯³ Wohoo! Correct answer
Rate = k[reactant]^order
Write rate equation r = k[A]Β²
Replace [A] with 2[A]
Simplify to get r = 4k[A]Β²
Forgetting to square the factor
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Consider exponent in rate law
Rate = k[reactant]^order
Write rate equation r = k[A]Β²
Replace [A] with 2[A]
Simplify to get r = 4k[A]Β²
Forgetting to square the factor
0.06% (w/v) aqueous solution of urea is isotonic with...
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Molality = moles/volume; Isotonic solutions: Same molarity.
Isotonic solutions: Same molarity, moles of solute.
Calculate molality: (0.06/60) = 0.001 mol; isotonic with 0.01 M glucose.
Final result: Isotonic with 0.01 M glucose.
Misinterpreting isotonicity due to incorrect molality calculation.
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Carefully compare molarity and isotonic conditions.
Molality = moles/volume; Isotonic solutions: Same molarity.
Isotonic solutions: Same molarity, moles of solute.
Calculate molality: (0.06/60) = 0.001 mol; isotonic with 0.01 M glucose.
Final result: Isotonic with 0.01 M glucose.
Misinterpreting isotonicity due to incorrect molality calculation.
The activation energy of a chemical reaction can be determined by
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k = Ae^(-Ea/RT)
Write Arrhenius equation
Use equation at two temperatures
Take ratio to solve for Ea
Confusing with collision theory
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Use rate constants at different temperatures
k = Ae^(-Ea/RT)
Write Arrhenius equation
Use equation at two temperatures
Take ratio to solve for Ea
Confusing with collision theory
3A β 2B rate of reaction + d[B]/dt is equal to
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Rate = -(coefficient of product/coefficient of reactant)(d[reactant]/dt)
Write balanced equation
Use stoichiometric relationship between A and B
Apply rate relation d[B]/dt = -(2/3)(d[A]/dt)
Not accounting for stoichiometry
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Consider stoichiometric coefficients
Rate = -(coefficient of product/coefficient of reactant)(d[reactant]/dt)
Write balanced equation
Use stoichiometric relationship between A and B
Apply rate relation d[B]/dt = -(2/3)(d[A]/dt)
Not accounting for stoichiometry
The amount of current in Faraday is required for the reduction of 1 mol of CrβOβΒ²β» ions to CrΒ³βΊ is
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1F = 96,500 coulombs
Write balanced reduction equation
Calculate oxidation state change
Multiply by number of chromium atoms
Not considering all Cr atoms
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Count electrons in half-reaction
1F = 96,500 coulombs
Write balanced reduction equation
Calculate oxidation state change
Multiply by number of chromium atoms
Not considering all Cr atoms
Osmotic pressure of the solution can be increased by
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Ο = CRT
Write van't Hoff equation Ο = CRT
Identify variables affecting Ο
Analyze direct relationship with T
Confusing concentration effects
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Look at variables in osmotic pressure equation
Ο = CRT
Write van't Hoff equation Ο = CRT
Identify variables affecting Ο
Analyze direct relationship with T
Confusing concentration effects
Which of the following is incorrect in a galvanic cell?
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Anode: oxidation (-eβ»)
Cathode: reduction (+eβ»)
List correct galvanic cell principles
Identify cathode gains electrons
Note anode loses electrons
Confusing anode and cathode processes
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Remember ANODE = OX, CATHODE = RED
Anode: oxidation (-eβ»)
Cathode: reduction (+eβ»)
List correct galvanic cell principles
Identify cathode gains electrons
Note anode loses electrons
Confusing anode and cathode processes
A secondary cell is one
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None required
Define secondary cell
Understand recharging reverses reactions
Identify current direction must oppose discharge
Confusion about current direction
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Think about reaction reversal
None required
Define secondary cell
Understand recharging reverses reactions
Identify current direction must oppose discharge
Confusion about current direction
The half-life period of a 1st order reaction is 60 minutes. What percentage will be left over after 240 minutes?
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β’ tβ/β = (2.303/k)log 2
β’ k = [2.303/60]log 2
β’ t = (2.303/k)log(a/[a-x])
Calculate k using half-life equation: tβ/β = (2.303/k)log 2
Substitute t=240 min and solve: log(a/[a-x]) = 4log 2
Calculate remaining percentage: [a-x] = 100/16 = 6.25%
Students often forget to convert final concentration to percentage
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Use half-life to find k first, then use it in time equation
β’ tβ/β = (2.303/k)log 2
β’ k = [2.303/60]log 2
β’ t = (2.303/k)log(a/[a-x])
Calculate k using half-life equation: tβ/β = (2.303/k)log 2
Substitute t=240 min and solve: log(a/[a-x]) = 4log 2
Calculate remaining percentage: [a-x] = 100/16 = 6.25%
Students often forget to convert final concentration to percentage
Which statement is incorrect?
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Rate = k[A]Λ£[B]ΚΈ
Check rate law determination
Consider experimental methods
Identify false statement
Rate law confusion
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Rate law can be determined
Rate = k[A]Λ£[B]ΚΈ
Check rate law determination
Consider experimental methods
Identify false statement
Rate law confusion
Which aqueous solution has highest freezing point?
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ΞTf = Kf Γ m Γ i
Calculate i-factor for each
Compare number of ions
NHβCl has lowest i
i-factor calculation
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Less ions = higher FP
ΞTf = Kf Γ m Γ i
Calculate i-factor for each
Compare number of ions
NHβCl has lowest i
i-factor calculation
Hydrogenation of vegetable oils in presence of finely divided nickel as catalyst is
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Oil(l) + Hβ(g) -[Ni(s)]β
Check phase of reactants
Check phase of catalyst
Compare phases
Catalyst phase confusion
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Different phases = heterogeneous
Oil(l) + Hβ(g) -[Ni(s)]β
Check phase of reactants
Check phase of catalyst
Compare phases
Catalyst phase confusion
For reaction (1/2)A β 2B, rate of disappearance of A related to rate of appearance of B by
π₯³ Wohoo! Correct answer
RateβAβ:RateβBβ = 1:4
Write balanced equation
Compare coefficients
Use stoichiometry
Stoichiometric ratio
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Consider stoichiometric ratio
RateβAβ:RateβBβ = 1:4
Write balanced equation
Compare coefficients
Use stoichiometry
Stoichiometric ratio
In electrolysis of NaCl(aq), anode half cell reaction is
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2Clβ» β Clβ + 2eβ»
Compare EΒ° values
Consider conditions
Identify anode reaction
Half-cell identification
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Oxidation at anode
2Clβ» β Clβ + 2eβ»
Compare EΒ° values
Consider conditions
Identify anode reaction
Half-cell identification
Given half cell reactions with EΒ°: Strongest reducing agent?
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EΒ°(ZnΒ²βΊ/Zn) = -0.76V
Compare EΒ° values
Most negative = strongest
Zn has -0.76V
Potential comparison
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Check reduction potentials
EΒ°(ZnΒ²βΊ/Zn) = -0.76V
Compare EΒ° values
Most negative = strongest
Zn has -0.76V
Potential comparison
NaClOβ converts to NaClOβ, how many moles formed with 3F charge?
π₯³ Wohoo! Correct answer
n = Q/nF
Write balanced equation
Calculate eβ» needed
Use Faraday relation
Faraday calculation
π’ Uh oh! Incorrect answer, Try again
2eβ» per molecule
n = Q/nF
Write balanced equation
Calculate eβ» needed
Use Faraday relation
Faraday calculation
The Vant Hoff's factor 'i' accounts for
π₯³ Wohoo! Correct answer
i = actual/normal
Consider solution behavior
Check ionic dissociation
Relate to colligative
Factor interpretation
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i measures dissociation
i = actual/normal
Consider solution behavior
Check ionic dissociation
Relate to colligative
Factor interpretation
When pure solvent diffuses out through semipermeable membrane, process is
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ΞP > Ο (for RO)
Consider direction
Check pressure
Identify process
Process direction
π’ Uh oh! Incorrect answer, Try again
Solvent out = RO
ΞP > Ο (for RO)
Consider direction
Check pressure
Identify process
Process direction
The value of rate constant of a pseudo-first-order reaction
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Rate = k[A], k includes [B]excess
Understand pseudo order
Check concentration effects
Evaluate rate law
Students confuse true and pseudo orders
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Excess reactant concentration
Rate = k[A], k includes [B]excess
Understand pseudo order
Check concentration effects
Evaluate rate law
Students confuse true and pseudo orders
For a cell reaction involving two-electron changes, EΒ°cell = 0.3 V at 25Β°C. The equilibrium constant of the reaction is
π₯³ Wohoo! Correct answer
K = exp(-nFEΒ°/RT)
Use Nernst equation
Apply electron number
Calculate K
Students forget temperature factor
π’ Uh oh! Incorrect answer, Try again
ΞGΒ° = -nFEΒ° = -RTlnK
K = exp(-nFEΒ°/RT)
Use Nernst equation
Apply electron number
Calculate K
Students forget temperature factor
Which of the following is not a conductor of electricity?
π₯³ Wohoo! Correct answer
Conductivity needs mobile charges
Check ion mobility
Consider electron flow
Evaluate conductivity
Students forget ion mobility requirement
π’ Uh oh! Incorrect answer, Try again
Ions must be mobile
Conductivity needs mobile charges
Check ion mobility
Consider electron flow
Evaluate conductivity
Students forget ion mobility requirement
The temperature coefficient of a reaction is 2. When the temperature is increased from 30Β°C to 90Β°C, the rate of reaction is increased by
π₯³ Wohoo! Correct answer
Rate = 2^(ΞT/10)
Calculate temperature difference
Apply rate rule
Use coefficient value
Students forget to divide temperature difference by 10
π’ Uh oh! Incorrect answer, Try again
Rate doubles every 10Β°C
Rate = 2^(ΞT/10)
Calculate temperature difference
Apply rate rule
Use coefficient value
Students forget to divide temperature difference by 10
Isotonic solutions are solutions having the same
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Ο = MRT
Compare colligative properties
Understand osmosis
Check concentration effect
Students confuse different colligative properties
π’ Uh oh! Incorrect answer, Try again
Equal solute concentration
Ο = MRT
Compare colligative properties
Understand osmosis
Check concentration effect
Students confuse different colligative properties
Plot of tβ/β vs [R]β for a reaction is straight line parallel to x-axis. Unit for rate constant is
π₯³ Wohoo! Correct answer
k = 0.693/tβ/β
Identify order from graph
Check tβ/β formula for first-order
Determine k units
Not relating tβ/β to reaction order
π’ Uh oh! Incorrect answer, Try again
Constant tβ/β indicates first order
k = 0.693/tβ/β
Identify order from graph
Check tβ/β formula for first-order
Determine k units
Not relating tβ/β to reaction order
At a particular temperature, the ratio of molar conductance to specific conductance of 0.01 M NaCl solution is
π₯³ Wohoo! Correct answer
Ξm = ΞΊ Γ (1000/c)
Use conductance relation
Apply concentration
Calculate ratio
Confusion between molar and specific conductance
π’ Uh oh! Incorrect answer, Try again
Ξm = ΞΊ/c
Ξm = ΞΊ Γ (1000/c)
Use conductance relation
Apply concentration
Calculate ratio
Confusion between molar and specific conductance
Electrolytic refining is used to purify which of the following metals?
π₯³ Wohoo! Correct answer
Anode: M β MΒ²βΊ + 2eβ»
Cathode: MΒ²βΊ + 2eβ» β M
Consider electrode potential
Check metal reactivity
Evaluate purification method
Students confuse electrolytic and pyrometallurgical refining
π’ Uh oh! Incorrect answer, Try again
Look for commonly refined metals
Anode: M β MΒ²βΊ + 2eβ»
Cathode: MΒ²βΊ + 2eβ» β M
Consider electrode potential
Check metal reactivity
Evaluate purification method
Students confuse electrolytic and pyrometallurgical refining
For the reaction, 2SOβ + Oβ β 2SOβ, The rate of disappearance of Oβ is 2 Γ 10β»β΄ mol Lβ»ΒΉ sβ»ΒΉ. The rate of appearance of SOβ is
π₯³ Wohoo! Correct answer
Rate ratios = stoichiometric ratios
Write balanced equation
Apply stoichiometric ratio
Calculate relative rates
Students ignore stoichiometric coefficients
π’ Uh oh! Incorrect answer, Try again
Consider coefficients
Rate ratios = stoichiometric ratios
Write balanced equation
Apply stoichiometric ratio
Calculate relative rates
Students ignore stoichiometric coefficients
Which of the following aqueous solutions should have the highest boiling point?
π₯³ Wohoo! Correct answer
ΞTb = iKbm
Count total ions
Calculate van't Hoff factor
Compare colligative properties
Students forget to count total ions
π’ Uh oh! Incorrect answer, Try again
More ions = higher boiling point
ΞTb = iKbm
Count total ions
Calculate van't Hoff factor
Compare colligative properties
Students forget to count total ions
The charge required for the reduction of 1 mole of MnOββ» to MnOβ is
π₯³ Wohoo! Correct answer
Q = nFeβ»
Calculate oxidation states
Find electron change
Apply Faraday's law
Confusion in oxidation state changes
π’ Uh oh! Incorrect answer, Try again
Count electrons transferred
Q = nFeβ»
Calculate oxidation states
Find electron change
Apply Faraday's law
Confusion in oxidation state changes
Solution A (acetone in chloroform) and B (acetone in CSβ) show which deviation from Raoult's law
π₯³ Wohoo! Correct answer
Deviation β interactions
Check solute-solvent interactions
Compare with pure component interactions
Determine deviation type
Not considering molecular interactions
π’ Uh oh! Incorrect answer, Try again
Compare intermolecular forces
Deviation β interactions
Check solute-solvent interactions
Compare with pure component interactions
Determine deviation type
Not considering molecular interactions
Non-volatile solute 'A' tetramerizes in water to 80%. 2.5g in 100g water lowers freezing point by 0.3Β°C. Molar mass of Aβ is (Kf=1.86)
π₯³ Wohoo! Correct answer
ΞTf = Kf Γ m Γ i
Calculate effective particles
Apply freezing point depression
Consider tetramerization
Not considering association
π’ Uh oh! Incorrect answer, Try again
Account for degree of association
ΞTf = Kf Γ m Γ i
Calculate effective particles
Apply freezing point depression
Consider tetramerization
Not considering association
Given: EΒ°(MnΒ²βΊ/Mn)=1.5V and EΒ°(Mnβ΄βΊ/MnΒ²βΊ)=1.2V, then EΒ°(Mnβ΄βΊ/Mn) is
π₯³ Wohoo! Correct answer
EΒ°total = EΒ°β + EΒ°β
Write half-cell reactions
Apply EΒ°cell = EΒ°red + EΒ°oxd
Sum potentials correctly
Not adding potentials correctly
π’ Uh oh! Incorrect answer, Try again
Use relationship between reduction potentials
EΒ°total = EΒ°β + EΒ°β
Write half-cell reactions
Apply EΒ°cell = EΒ°red + EΒ°oxd
Sum potentials correctly
Not adding potentials correctly
An aqueous solution of CuSOβ is subjected to electrolysis using inert electrodes. The pH will
π₯³ Wohoo! Correct answer
2HβO β Oβ + 4HβΊ + 4eβ»
Write anode reaction: 2HβO β Oβ + 4HβΊ
Write cathode reaction: CuΒ²βΊ + 2eβ» β Cu
Net increase in HβΊ concentration
Not considering water electrolysis
π’ Uh oh! Incorrect answer, Try again
Look for HβΊ production
2HβO β Oβ + 4HβΊ + 4eβ»
Write anode reaction: 2HβO β Oβ + 4HβΊ
Write cathode reaction: CuΒ²βΊ + 2eβ» β Cu
Net increase in HβΊ concentration
Not considering water electrolysis
One litre solution of MgClβ electrolyzed by passing 1A current for 16min 5sec. Original concentration was (Mg=24)
π₯³ Wohoo! Correct answer
It = nFM
Calculate time in seconds: 965s
Apply Faraday's law: m = (ItΓM)/(nF)
Convert mass to molarity
Forgetting to convert time to seconds
π’ Uh oh! Incorrect answer, Try again
Use Faraday's equation
It = nFM
Calculate time in seconds: 965s
Apply Faraday's law: m = (ItΓM)/(nF)
Convert mass to molarity
Forgetting to convert time to seconds
Relative lowering of vapor pressure of a dilute solution of glucose in 1 kg water is 0.002. The molality is
π₯³ Wohoo! Correct answer
(Pβ-P)/Pβ = nβ/(nβ+nβ)
Apply Raoult's law: (Pβ-P)/Pβ = xβ
Convert to molality using relative pressure
molality = 0.002/0.018 = 0.111
Not converting mole fraction to molality
π’ Uh oh! Incorrect answer, Try again
Use relation between molality and vapor pressure
(Pβ-P)/Pβ = nβ/(nβ+nβ)
Apply Raoult's law: (Pβ-P)/Pβ = xβ
Convert to molality using relative pressure
molality = 0.002/0.018 = 0.111
Not converting mole fraction to molality
Which is an example of homogeneous catalysis?
π₯³ Wohoo! Correct answer
SOβ + NOβ β SOβ (all gases)
Check phase of catalyst
Verify reactant phase
Confirm homogeneity
Not checking phase of catalyst
π’ Uh oh! Incorrect answer, Try again
Catalyst and reactants in same phase
SOβ + NOβ β SOβ (all gases)
Check phase of catalyst
Verify reactant phase
Confirm homogeneity
Not checking phase of catalyst
1L of 2M CHβCOOH mixed with 1L of 3M CβHβ OH, rate after dilution with equal volume of water will be
π₯³ Wohoo! Correct answer
Rate = k[acid][alcohol]
Calculate new concentrations
Apply rate equation
Compare rates
Not considering concentration changes
π’ Uh oh! Incorrect answer, Try again
Rate β [CHβCOOH][CβHβ OH]
Rate = k[acid][alcohol]
Calculate new concentrations
Apply rate equation
Compare rates
Not considering concentration changes
The number of moles of electron required to reduce 0.2 mole of CrβOβΒ²β» to CrΒ³βΊ
π₯³ Wohoo! Correct answer
CrβOβΒ²β» + 14HβΊ + 6eβ» β 2CrΒ³βΊ + 7HβO
Write half reaction
Balance electrons
Calculate moles needed
Forgetting to account for stoichiometry
π’ Uh oh! Incorrect answer, Try again
Count electrons in reduction equation
CrβOβΒ²β» + 14HβΊ + 6eβ» β 2CrΒ³βΊ + 7HβO
Write half reaction
Balance electrons
Calculate moles needed
Forgetting to account for stoichiometry
Which is a wrong statement?
π₯³ Wohoo! Correct answer
k = Aeβ»α΄±α΅/α΄Ώα΅
Check Arrhenius equation
Verify catalyst effect
Compare statements
Not understanding catalyst role
π’ Uh oh! Incorrect answer, Try again
Catalyst lowers activation energy
k = Aeβ»α΄±α΅/α΄Ώα΅
Check Arrhenius equation
Verify catalyst effect
Compare statements
Not understanding catalyst role
The rate constant of a reaction is given by k=PZeβ»Eβ/RT under standard notation. To speed up the reaction, which factor should be decreased?
π₯³ Wohoo! Correct answer
k = PZeβ»Eβ/RT
Analyze Arrhenius equation
Check temperature effect
Identify rate-limiting factor
Arrhenius equation
π’ Uh oh! Incorrect answer, Try again
Lower activation energy increases rate
k = PZeβ»Eβ/RT
Analyze Arrhenius equation
Check temperature effect
Identify rate-limiting factor
Arrhenius equation
The time required for 60% completion of a first order reaction is 50 min. The time required for 93.6% completion of the same reaction will be
π₯³ Wohoo! Correct answer
None
Use first order equation
Calculate rate constant
Find t for 93.6%
First order kinetics
π’ Uh oh! Incorrect answer, Try again
k = (2.303/t)log[aβ/(aβ-x)]
None
Use first order equation
Calculate rate constant
Find t for 93.6%
First order kinetics
In which of the following cases a chemical reaction is possible?
π₯³ Wohoo! Correct answer
AgβΊ + Cu β CuΒ²βΊ + Ag
Compare EΒ° values
Check reactivity series
Identify possible reaction
Metal reactivity
π’ Uh oh! Incorrect answer, Try again
Cu reduces AgβΊ
AgβΊ + Cu β CuΒ²βΊ + Ag
Compare EΒ° values
Check reactivity series
Identify possible reaction
Metal reactivity
For an elementary reaction 2A + 3B β 4C + D, when rate of appearance of C at time 't' is 2.8Γ10β»Β³ mol Lβ»ΒΉSβ»ΒΉ, rate of disappearance of B at 't' will be
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None
Write rate expression
Use stoichiometry
Calculate rate ratio
Rate relationships
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-rB/rC = 3/4
None
Write rate expression
Use stoichiometry
Calculate rate ratio
Rate relationships
When an aqueous solution of NaF is electrolyzed between inert electrodes, the product obtained at anode is
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2HβO β Oβ + 4HβΊ + 4eβ»
Check oxidation potentials
Compare EΒ° values
Identify anode product
Electrolysis products
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Water oxidizes before Fβ»
2HβO β Oβ + 4HβΊ + 4eβ»
Check oxidation potentials
Compare EΒ° values
Identify anode product
Electrolysis products
Given EΒ°FeΒ³βΊ/FeΒ²βΊ = +0.76V and EΒ°Iβ/Iβ» = +0.55V, the equilibrium constant for the reaction taking place in galvanic cell consisting of above two electrodes is [2.303RT/F = 0.06]
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ΞGΒ° = -nFEΒ° = -RTlnK
Calculate EΒ°cell
Use Nernst equation
Find equilibrium constant
Cell potential
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logK = nEΒ°/0.06
ΞGΒ° = -nFEΒ° = -RTlnK
Calculate EΒ°cell
Use Nernst equation
Find equilibrium constant
Cell potential
When solute 'X' dimerises in water to the extent of 80%, if 2.5g of 'X' in 100g of water increases boiling point by 0.3Β°C, the molar mass of 'X' is [Kβ=0.52K kg molβ»ΒΉ]
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ΞTb = Kb Γ m Γ i
Calculate i factor
Use ΞTb formula
Find molar mass
Degree of association
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Consider dimerization
ΞTb = Kb Γ m Γ i
Calculate i factor
Use ΞTb formula
Find molar mass
Degree of association
Which of the following pair of solutions is isotonic?
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i = 1 + Ξ±(n-1)
Calculate total ions
Compare concentrations
Check van't Hoff factor
van't Hoff factor
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Equal number of particles
i = 1 + Ξ±(n-1)
Calculate total ions
Compare concentrations
Check van't Hoff factor
van't Hoff factor
The pair of electrolytes that possess same λ°m value in Debye-HΓΌckel-Onsagar equation, Ξ»m = λ°m - AβC is
π₯³ Wohoo! Correct answer
Ξ»m = λ°m - AβC
Check ion mobility
Compare charge
Analyze conductance
Conductance concepts
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Similar ion mobilities
Ξ»m = λ°m - AβC
Check ion mobility
Compare charge
Analyze conductance
Conductance concepts
If 3g of glucose (molar mass = 180g) is dissolved in 60g of water at 15Β°C, the osmotic pressure of the solution will be
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Ο = (nRT)/V
Use Ο = MRT
Calculate concentration
Convert to appropriate units
Unit conversion errors
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Remember temperature in Kelvin
Ο = (nRT)/V
Use Ο = MRT
Calculate concentration
Convert to appropriate units
Unit conversion errors
The rise in boiling point of a solution containing 1.8 g of glucose in 100g of solvent is 0.1Β°C. The molal elevation constant of the liquid is
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ΞTb = KbΓ(wΓ1000)/(MΓW)
Use ΞTb = KbΓmΓi
Calculate molality
Solve for Kb
Forgetting to convert units
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Consider van't Hoff factor
ΞTb = KbΓ(wΓ1000)/(MΓW)
Use ΞTb = KbΓmΓi
Calculate molality
Solve for Kb
Forgetting to convert units
Solubility of a gas in a liquid increases with
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Henry's law: C = KP
Apply Henry's law
Consider Le Chatelier's principle
Temperature effect on solubility
Confusing temperature effects
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Pressure directly proportional to solubility
Henry's law: C = KP
Apply Henry's law
Consider Le Chatelier's principle
Temperature effect on solubility
Confusing temperature effects
The molar conductivity is maximum for the solution of concentration
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Ξβ = ΞΊΓ1000/M
Compare concentrations
Recall Ξβ vs concentration
Lowest concentration has highest Ξβ
Forgetting inverse relationship
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Ξβ increases with dilution
Ξβ = ΞΊΓ1000/M
Compare concentrations
Recall Ξβ vs concentration
Lowest concentration has highest Ξβ
Forgetting inverse relationship
In Fuel cells _____ are used as catalysts
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Hβ + Β½Oβ β HβO
Identify catalyst types
Consider electrode reactions
Pt-Pd best for Hβ oxidation
Confusing different metal catalysts
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Noble metals are best catalysts
Hβ + Β½Oβ β HβO
Identify catalyst types
Consider electrode reactions
Pt-Pd best for Hβ oxidation
Confusing different metal catalysts
Which of the following colligative properties can provide molar mass of proteins, polymers, and colloids with greater precision?
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Ο = MRT (van't Hoff equation)
Compare properties
Consider molecular size effect
Osmotic pressure most sensitive
Confusing different colligative properties
π’ Uh oh! Incorrect answer, Try again
Ο = MRT relationship
Ο = MRT (van't Hoff equation)
Compare properties
Consider molecular size effect
Osmotic pressure most sensitive
Confusing different colligative properties
An aqueous solution of alcohol contains 18g of water and 414g of ethyl alcohol. The mole fraction of water is
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X(water) = n(water)/(n(water) + n(alcohol))
Calculate moles of each component
Find total moles
Calculate mole fraction
Confusing mass and mole ratios
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Mole fraction = moles of component/total moles
X(water) = n(water)/(n(water) + n(alcohol))
Calculate moles of each component
Find total moles
Calculate mole fraction
Confusing mass and mole ratios
Half-life of a reaction is found to be inversely proportional to the fifth power of initial concentration, the order of reaction is
π₯³ Wohoo! Correct answer
tβ/β β 1/aβ΅ β n = 6
Use formula: tβ/β β 1/aβΏβ»ΒΉ
If tβ/β β 1/aβ΅, then n-1 = 5
n = 6
Forgetting to add 1 to power
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Order = power + 1
tβ/β β 1/aβ΅ β n = 6
Use formula: tβ/β β 1/aβΏβ»ΒΉ
If tβ/β β 1/aβ΅, then n-1 = 5
n = 6
Forgetting to add 1 to power
For nth of reaction, Half-life period is directly proportional to
π₯³ Wohoo! Correct answer
tβ/β β 1/aβΏβ»ΒΉ
Write half-life formula for nth order
tβ/β β 1/aβΏβ»ΒΉ
Check given options
Confusing power relationships
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Half-life depends on initial concentration for orders other than first
tβ/β β 1/aβΏβ»ΒΉ
Write half-life formula for nth order
tβ/β β 1/aβΏβ»ΒΉ
Check given options
Confusing power relationships
Specific conductance of 0.1 M HNOβ is 6.3Γ10β»Β² ohmβ»ΒΉ cmβ»ΒΉ. The molar conductance of the solution is
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Ξβ = (1000 Γ ΞΊ)/M
Use formula: Ξβ = (1000 Γ ΞΊ)/M
Ξβ = (1000 Γ 6.3Γ10β»Β²)/0.1
Ξβ = 630 ohmβ»ΒΉ cmΒ² molβ»ΒΉ
Forgetting to multiply by 1000
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Remember to multiply by 1000 for conversion to molar conductance
Ξβ = (1000 Γ ΞΊ)/M
Use formula: Ξβ = (1000 Γ ΞΊ)/M
Ξβ = (1000 Γ 6.3Γ10β»Β²)/0.1
Ξβ = 630 ohmβ»ΒΉ cmΒ² molβ»ΒΉ
Forgetting to multiply by 1000
For spontaneity of a cell, which is correct?
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ΞG = -nFE
Recall relationship between ΞG and spontaneity
ΞG must be negative for spontaneous process
ΞG = -nFE
Confusing sign conventions
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For spontaneous process, ΞG must be negative
ΞG = -nFE
Recall relationship between ΞG and spontaneity
ΞG must be negative for spontaneous process
ΞG = -nFE
Confusing sign conventions
The rate of the reaction CHβCOOCβHβ + NaOH β CHβCOONa + CβHβ OH is given by Rate = K[CHβCOOCβHβ ][NaOH]. If concentration is expressed in mol Lβ»ΒΉ, the unit of K is
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K = Rate/[A][B] for 2nd order
Identify order of reaction from rate equation
Total order = 1 + 1 = 2
Units for 2nd order = L molβ»ΒΉ sβ»ΒΉ
Forgetting to consider total order when determining units
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Rate constant units depend on overall order of reaction
K = Rate/[A][B] for 2nd order
Identify order of reaction from rate equation
Total order = 1 + 1 = 2
Units for 2nd order = L molβ»ΒΉ sβ»ΒΉ
Forgetting to consider total order when determining units
A first order reaction is half completed in 45 min. How long does it need 99.9% of the reaction to be completed?
π₯³ Wohoo! Correct answer
tββ.β% = 10tβ β%; k = 0.693/tβ β%
For first order reaction, tββ.β% = 10tβ β%
tβ β% = 45 min
10 Γ 45 min = 450 min = 7.5 hours
Students often forget to convert minutes to hours
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First order reaction half-life is independent of concentration
tββ.β% = 10tβ β%; k = 0.693/tβ β%
For first order reaction, tββ.β% = 10tβ β%
tβ β% = 45 min
10 Γ 45 min = 450 min = 7.5 hours
Students often forget to convert minutes to hours
Resistance of 0.1M weak acid HA in conductivity cell is 2Γ10Β³Ξ©. Cell constant 0.78cmβ»ΒΉ and λ°m=390ScmΒ²molβ»ΒΉ. pH of solution is
π₯³ Wohoo! Correct answer
pH = -log[HβΊ]
Calculate conductivity
Find degree of ionization
Calculate pH
Conductance calculation confusion
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ΞΊ = G*/R
pH = -log[HβΊ]
Calculate conductivity
Find degree of ionization
Calculate pH
Conductance calculation confusion
In which reaction rate constant has unit molLβ»ΒΉsβ»ΒΉ
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Zero order kinetics
Check reaction order
Analyze units
Identify zero order
Rate constant unit confusion
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Rate = k[A]β°
Zero order kinetics
Check reaction order
Analyze units
Identify zero order
Rate constant unit confusion
During electrolysis of brine using inert electrodes
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2Clβ» β Clβ + 2eβ»
Consider electrode reactions
Check standard potentials
Analyze products
Product prediction confusion
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Preferential discharge
2Clβ» β Clβ + 2eβ»
Consider electrode reactions
Check standard potentials
Analyze products
Product prediction confusion
Consider 4 electrodes: AgβΊ(0.0001M)/Ag(s), AgβΊ(0.1M)/Ag(s), AgβΊ(0.01M)/Ag(s), AgβΊ(0.001M)/Ag(s); EΒ°AgβΊ/Ag=0.80V. Reduction potential order is
π₯³ Wohoo! Correct answer
Concentration effect
Use Nernst equation
Calculate potentials
Arrange in order
Concentration effect confusion
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E = EΒ° + (0.059/n)log[MβΊ]
Concentration effect
Use Nernst equation
Calculate potentials
Arrange in order
Concentration effect confusion
Rate constants kβ=10ΒΉβΆeβ»Β²β°β°β°/T and kβ=10ΒΉβ΅eβ»ΒΉβ°β°β°/T. Temperature at which kβ=kβ is
π₯³ Wohoo! Correct answer
T = 1000/2.303
Equate kβ and kβ
Take ln
Solve for T
Equation solving confusion
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ln(10ΒΉβΆ/10ΒΉβ΅) = (2000-1000)/T
T = 1000/2.303
Equate kβ and kβ
Take ln
Solve for T
Equation solving confusion
For a reaction, rate constant at 300K is 6.0Γ10β»β΅sβ»ΒΉ. Value of Arrhenius factor A at infinitely high temperature is
π₯³ Wohoo! Correct answer
k = 6Γ10β»β΅ = Aeβ»Ea/300R
Use Arrhenius equation
Consider Tββ
Solve for A
Temperature effect confusion
π’ Uh oh! Incorrect answer, Try again
k = Aeβ»Ea/RT
k = 6Γ10β»β΅ = Aeβ»Ea/300R
Use Arrhenius equation
Consider Tββ
Solve for A
Temperature effect confusion
A sample of water is found to contain 5.85%(w/w) of AB (molecular mass 58.5) and 9.50%(w/w) XYβ (molecular mass 95). Assuming 80% ionisation of AB and 60% ionisation of XYβ, the freezing point of water sample is [Given: Kf for water 1.86K kg molβ»ΒΉ, Freezing point of pure water is 273K and A,B and Y are monovalent ions]
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ΞTf calculations
Calculate molality
Find van't Hoff factor
Apply ΞTf formula
Depression calculation
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ΞTf = KfΓmΓi
ΞTf calculations
Calculate molality
Find van't Hoff factor
Apply ΞTf formula
Depression calculation
Dimerisation of solute molecules in low dielectric constant solvent is due to
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H-bonding
Consider interactions
Check solvent effect
Analyze bond type
Bond type confusion
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Intermolecular forces
H-bonding
Consider interactions
Check solvent effect
Analyze bond type
Bond type confusion
Salt water reduces swelling in feet due to
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HβO moves to concentrated solution
Consider concentration
Check water movement
Analyze process
Process direction confusion
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Higher salt concentration
HβO moves to concentrated solution
Consider concentration
Check water movement
Analyze process
Process direction confusion
A 30% solution of hydrogen peroxide is
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HβOβ β HβO + Β½Oβ
Convert percentage
Calculate volume
Apply formula
Volume strength confusion
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1mL gives x mL Oβ
HβOβ β HβO + Β½Oβ
Convert percentage
Calculate volume
Apply formula
Volume strength confusion
For which one of the following mixtures is composition uniform throughout?
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No formula involved.
Homogeneous mixtures have uniform composition throughout.
Aqueous sugar solution dissolves uniformly without phase separation.
Final Answer: Option D; sugar solution is homogeneous.
Assuming phase-separated mixtures like oil and water to be uniform.
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Differentiate between homogeneous and heterogeneous mixtures.
No formula involved.
Homogeneous mixtures have uniform composition throughout.
Aqueous sugar solution dissolves uniformly without phase separation.
Final Answer: Option D; sugar solution is homogeneous.
Assuming phase-separated mixtures like oil and water to be uniform.
Which one of the following does not represent Arrhenius equation?
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k = Ae^(-Ea/RT) and related variations.
Recognize the valid forms of Arrhenius equation.
Compare all forms of the equation. The correct forms involve negative exponential or logarithmic terms.
Final Answer: Option D does not match the equation.
Misinterpreting positive exponents as valid forms.
π’ Uh oh! Incorrect answer, Try again
Recall valid mathematical forms of Arrhenius equation.
k = Ae^(-Ea/RT) and related variations.
Recognize the valid forms of Arrhenius equation.
Compare all forms of the equation. The correct forms involve negative exponential or logarithmic terms.
Final Answer: Option D does not match the equation.
Misinterpreting positive exponents as valid forms.
For the reaction PClβ β PClβ + Clβ, rate and rate constant are 1.02 Γ 10β»β΄ mol/L/s and 3.4 Γ 10β»β΅ sβ»ΒΉ respectively. What is [PClβ ]?
π₯³ Wohoo! Correct answer
Rate = k[Reactant].
Use the formula Rate = k[PClβ ].
Rearrange to find [PClβ ]: [PClβ ] = Rate / k = (1.02 Γ 10β»β΄) / (3.4 Γ 10β»β΅).
Final Answer: [PClβ ] = 3.0 mol/L.
Forgetting to divide rate by rate constant or misplacing units.
π’ Uh oh! Incorrect answer, Try again
Relate rate and rate constant to molarity.
Rate = k[Reactant].
Use the formula Rate = k[PClβ ].
Rearrange to find [PClβ ]: [PClβ ] = Rate / k = (1.02 Γ 10β»β΄) / (3.4 Γ 10β»β΅).
Final Answer: [PClβ ] = 3.0 mol/L.
Forgetting to divide rate by rate constant or misplacing units.
For the reaction A β B, Ea = 50 kJ molβ»ΒΉ and ΞH = -20 kJ molβ»ΒΉ. After catalyst decreases Ea by 10 kJ molβ»ΒΉ, find Ea (backward)
π₯³ Wohoo! Correct answer
ΞH = Ea(f) - Ea(b).
Use the relation ΞH = Ea(f) - Ea(b).
Ea(forward) = 50 - 10 = 40 kJ/mol. Hence Ea(backward) = ΞH + Ea(f) = -20 + 40 = 60 kJ/mol.
Final Answer: Ea(backward) = 60 kJ/mol.
Incorrectly assuming ΞH = Ea without considering catalyst effect.
π’ Uh oh! Incorrect answer, Try again
Understand catalyst effects on Ea.
ΞH = Ea(f) - Ea(b).
Use the relation ΞH = Ea(f) - Ea(b).
Ea(forward) = 50 - 10 = 40 kJ/mol. Hence Ea(backward) = ΞH + Ea(f) = -20 + 40 = 60 kJ/mol.
Final Answer: Ea(backward) = 60 kJ/mol.
Incorrectly assuming ΞH = Ea without considering catalyst effect.
How many Coulombs are required to oxidise 0.1 mole of H2O to oxygen?
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q = n Γ F (Faraday constant).
Oxidation of water to oxygen involves 4 electrons per molecule.
For 0.1 mole of H2O: (0.1 Γ 2 Γ 96500 = 1.93 Γ 10^4 C).
Final Answer: 1.93 Γ 10^4 C.
Mixing up electron moles or Faraday's constant during calculations.
π’ Uh oh! Incorrect answer, Try again
Use Faraday's Laws of Electrolysis.
q = n Γ F (Faraday constant).
Oxidation of water to oxygen involves 4 electrons per molecule.
For 0.1 mole of H2O: (0.1 Γ 2 Γ 96500 = 1.93 Γ 10^4 C).
Final Answer: 1.93 Γ 10^4 C.
Mixing up electron moles or Faraday's constant during calculations.
Vapour pressure of a solution containing 18 g of glucose and 178.2 g of water at 100Β°C is...
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P_solution = P_water Γ (1 - Ο_solute).
Use Raoultβs law: P_solution = P_water Γ (1 - Ο_solute).
Calculate Ο_solute = moles of solute / (moles of solute + moles of solvent).
Result: P_solution = 760 - 7.6 = 752.4 torr.
Incorrect mole calculation for glucose or water.
π’ Uh oh! Incorrect answer, Try again
Understand Raoult's law application.
P_solution = P_water Γ (1 - Ο_solute).
Use Raoultβs law: P_solution = P_water Γ (1 - Ο_solute).
Calculate Ο_solute = moles of solute / (moles of solute + moles of solvent).
Result: P_solution = 760 - 7.6 = 752.4 torr.
Incorrect mole calculation for glucose or water.
A current of 3A is passed through molten calcium salt for 1 hr 47 min 13 sec. The mass of calcium deposited is...
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Mass = (E Γ I Γ t) / 96500.
Use Faradayβs law: Mass deposited = (E Γ I Γ t) / 96500.
Substituting values: E = 40, I = 3A, t = 6432 s. Result: (40 Γ 3 Γ 6432) / 96500 = 3.99 g β 4.0 g.
Final Mass: 4.0 g.
Errors in time conversion or forgetting valency of calcium during calculations.
π’ Uh oh! Incorrect answer, Try again
Apply Faraday's Law to time-dependent mass calculations.
Mass = (E Γ I Γ t) / 96500.
Use Faradayβs law: Mass deposited = (E Γ I Γ t) / 96500.
Substituting values: E = 40, I = 3A, t = 6432 s. Result: (40 Γ 3 Γ 6432) / 96500 = 3.99 g β 4.0 g.
Final Mass: 4.0 g.
Errors in time conversion or forgetting valency of calcium during calculations.
A mixture of phenol and aniline shows negative deviation from Raoult's law. This is because of:
π₯³ Wohoo! Correct answer
No formula involved.
The negative deviation is due to strong intermolecular hydrogen bonding between phenol and aniline.
Phenol and aniline form stronger intermolecular bonds than with their individual molecules.
Result: Negative deviation due to intermolecular hydrogen bonding.
Assuming polar or non-polar covalent bonds cause deviation.
π’ Uh oh! Incorrect answer, Try again
Recall the nature of molecular interactions.
No formula involved.
The negative deviation is due to strong intermolecular hydrogen bonding between phenol and aniline.
Phenol and aniline form stronger intermolecular bonds than with their individual molecules.
Result: Negative deviation due to intermolecular hydrogen bonding.
Assuming polar or non-polar covalent bonds cause deviation.
The value of 'A' in the equation Ξ»_m = Ξ»_0 - A βC is same for the pair...
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Ξ»_m = Ξ»_0 - A βC (empirical relation).
A depends on ion type and interactions in solution.
NaCl and KBr have similar ionic types and interaction effects.
Result: Value of A is identical for NaCl and KBr.
Assuming all salts affect A equally regardless of charge or type.
π’ Uh oh! Incorrect answer, Try again
Relate ionic properties to conductivity coefficients.
Ξ»_m = Ξ»_0 - A βC (empirical relation).
A depends on ion type and interactions in solution.
NaCl and KBr have similar ionic types and interaction effects.
Result: Value of A is identical for NaCl and KBr.
Assuming all salts affect A equally regardless of charge or type.
Which of the following pairs will show positive deviation from Raoult's Law?
π₯³ Wohoo! Correct answer
None (Conceptual).
Positive deviation occurs when intermolecular forces are weaker in the solution than in pure components.
Benzene and methanol have weak interactions compared to their pure molecular interactions.
Final Answer: Benzene-methanol shows positive deviation.
Confusing positive deviation as stronger interactions between solute and solvent.
π’ Uh oh! Incorrect answer, Try again
Recall weaker molecular interactions.
None (Conceptual).
Positive deviation occurs when intermolecular forces are weaker in the solution than in pure components.
Benzene and methanol have weak interactions compared to their pure molecular interactions.
Final Answer: Benzene-methanol shows positive deviation.
Confusing positive deviation as stronger interactions between solute and solvent.