PRACTICE MODUL SK025 2nd Edition

PRACTICE MODULE CHAPTER 2 SK 025

Simple Calorimeter – Enthalpy of neutralisation question

9. When a student mixes 50 ml HCl(1M) and 50 ml NaOH (0.8M) in a coffee cup
calorimeter, the temperature of the resultant solution increase from 21°C to 27.5°C.
Calculate the enthalpy of neutralization , assuming that no heat absorbed by
calorimeter.

[ Assume density of solution = density of water = 1 g/ml ; The specific heat of water
is 4.18 J g−1°C−1 ]

Step 1:

Write the
equation
reaction

Step 2:

Calculate no
of moles of
acid and base

Step 3:

Find the
limiting
reactant
between acid
and base (to
find mol of
H2O)

Step 4:

Find q
reaction (heat
release by
reaction)

Step 5:

Relate mol of
water with
heat release
to calculate
enthalpy of
neutralization

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PRACTICE MODULE CHAPTER 2 SK 025

10. 40.0 mL of 1.0 M NaOH were placed in a calorimeter (Ccal = 72.0 J/°C) at 22.0°C and
20.0 mL of 1.5 M H2SO4 at 22.0°C were added. The temperature of the mixture rose
to 29.0°C.
Calculate ∆H for the reaction 2NaOH(aq) + H2SO4(aq) → Na2SO4(aq) + 2H2O(l) from
the following data.
(Ans: -113 kJ)

Tips:

Cc were given
in question.
So, q release
= q Cc +
qsolution

11. A quantity of 200 mL of 0.862M HCl is mixed with 200 mL of 0.431M Ba(OH)2 in a
constant pressure calorimeter that has a heat capacity of 453 J°C-1. The initial
temperature of the HCl and Ba(OH)2 solution is the same at 20.48°C. What is the
final temperature of the mixed solution if the enthalpy of neutralization is -56.2
kJ/mol.
[ specific heat capacity of solution= 4.18 Jg-1 °C-1, density of solution = 1 gcm-3]
(ans: 25.04°C)

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PRACTICE MODULE CHAPTER 2 SK 025

12. 100 cm3 of 2.0 mol dm-3 hydrochloric acid and 100 cm3 potassium hydroxide solution,

both at initial temperature of 30.0°C are mixed in a calorimeter. The maximum

temperature of the solution is 41.0°C. Calculate the enthalpy of neutralisation for the

reaction.

(ans: ΔH = - 45.98 kJmol-1 )

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PRACTICE MODULE CHAPTER 2 SK 025

MIND MAP 2.3 and 2.4 (✿◠‿◠)
2.3 HESS’S
LAW

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PRACTICE MODULE CHAPTER 2 SK 025

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PRACTICE MODULE CHAPTER 2 SK 025

WORKSHEET 2.3 : HESS’S LAW
CComplete the blanks with suitable enthalpies

1.

2.

3

4 Calculate ΔHo for the conversion of methane in chloroform.

CH4(g) + 3Cl2(g) → CHCl3(g) + 3HCl(g)

By combining the following equation:

½H2(g) + ½Cl2(g) → HCl(g) ΔHo = -92.3 kJ/mol C(graphite)
C(s) + 2H2(g) → CH4(g) ΔHo = -74.5 kJ/mol

C(graphite) + ½H2(g) + 3/2 Cl2(g) → CHCl3(g) ΔHo = -135.1 kJ/mol

ANSWER:
Step 1: Target equation

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PRACTICE MODULE CHAPTER 2 SK 025

Step 2: Change all thermochemical equaion & magnitud given based on
the target equation

Step 3:Terminated other than target equation

Step 4: Calculate the enthalpy of formation for target equation

5 Calculate and construct diagram for enthalpy solution of magnesium fluoride based on
data below:

Lattice energy of MgF2 – 3121 kJ/mol
Enthalpy of hydration Mg2+ ion –1903 kJ/mol

Enthalpy of hydration F - 461 kJ/mol
ANSWER:

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PRACTICE MODULE CHAPTER 2 SK 025

6 Calculate and construct diagram for enthalpy hydration of KI based on data below:

Lattice energy of KI – 632 kJ/mol

Enthalpy of solution KI + 13 kJ/mol

Answer :

7 From the data below

(a) Construct the enthalpy (energy) cycle for sodium chloride solution

(b) Calculate the enthalpy of hydration of Cl- ion

Lattice energy of NaCl – 776 kJ/mol

Enthalpy of hydration Na+ – 390 kJ/mol

Enthalpy of solution NaCl + 6 kJ/mol

ANSWER:

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PRACTICE MODULE CHAPTER 2 SK 025

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PRACTICE MODULE CHAPTER 2 SK 025

WORKSHEET 2.4 : BORN HABER CYCLE
Complete the blanks with suitable enthalpies

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PRACTICE MODULE CHAPTER 2 SK 025

2
3

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PRACTICE MODULE CHAPTER 2 SK 025

4
5

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PRACTICE MODULE CHAPTER 2 SK 025

Construct energy level diagram
1 By using the following data a Born-Haber cycle, calculate enthalpy formation of

CaF2(s). Draw an energy level diagram showing the energy changes.
ANSWER:

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PRACTICE MODULE CHAPTER 2 SK 025

2 By using the following data a Born-Haber cycle, calculate lattice formation energy
of MgO(s). Draw an energy level diagram showing the energy changes
ANSWER:

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PRACTICE MODULE CHAPTER 2 SK 025

Construct Born Haber cycle
Worksheet 2.6
1 Using the following data, determine the enthalpy of formation of sodium chloride

with construct a diagram Born-Haber cycle.
ANSWER:

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PRACTICE MODULE CHAPTER 2 SK 025

2. Using the following data, determine the lattice energy of sodium oxide, Na2O with
construct a diagram Born-Haber cycle.
Enthalpy atomisation of sodium = +108 kJ mol-1
Enthalpy of atomization of oxygen = +249.2 kJ mol-1
First ionisation energy of sodium = +496 kJ mol-1
1st electron affinity of oxygen = -141 kJ mol-1
2nd electron affinity of oxygen = +790 kJ mol-1
Enthalpy of formation of Na2O(s) = - 416 kJ mol-1
ANSWER:

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PRACTICE MODULE CHAPTER 2 SK 025

3. Using the following data, determine the lattice formation energy of MgO(s) with
construct a diagram Born-Haber cycle.
Enthalpy of atomization of Mg(s) = +146 kJ mol-1
Enthalpy of atomization of O2(g) = +249.2 kJ mol-1
First ionisation energy of Mg(g) = +736 kJ mol-1
Second ionisation energy of Mg(g) = +1450 kJ mol-1
First electron affinity of O(g) = -141 kJ mol-1
Second electron affinity of O(g) = +744 kJ mol-1
Enthalpy of formation of MgO(s) = -601.7 kJ mol-1
ANSWER:

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PRACTICE MODULE CHAPTER 2 SK 025

4 The lattice energy of lithium chloride is -848 kJ mol-1 and that of sodium chloride is
-776 kJ mol-1.
a) Using sodium chloride as an example, define lattice energy.
b) Explain why the lattice energy of lithium chloride is more exothermic
than that of sodium chloride.

WORKSHEET 2,7 (OBJECTIVE QUESTIONS)

1. The equation below represent :
Mg2+ (g) + 2CI- (g) → MgCI2(s)
A Lattice energy

B Enthalpy of formation
C Enthalpy of atomisation

D Electron affinity

2. Lattice energy becomes more exothermic when….
A Size of ions are small
B Charge of ions are small
C Attractive forces weaker
D Larger size

3. Using the equation below:

C(s) + O2(g) → CO2(g ΔH= -390 kJ
Mn(s) + O2(g) → MnO2(s) ΔH= -520kJ

What is ΔH (in kJ) for the following reaction?

MnO2(s) + C(s) → Mn(s) + CO2(g)

A 910
B 130
C -130
D -910

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PRACTICE MODULE CHAPTER 2 SK 025

4

What is the value of enthalpy of formation of NaF(s)?

A -928
B -574
C +107
D +496

5 Which equation represent the process that occurs when the standard enthalpy of
atomisation of iodine is measured?

A I2 (s) → I(g)
B ½ I2 (s) → 2I(g)

C ½ I2 (g) → I(g)
D I2 (s) → 2I(g)

6 Living plants produce glucose in the process of photosynthesis according to this

equation:
6CO2(g) + 6H2O(l) + energy → ¼ C6H12O6(s) + 6O2(g)
Is this reaction endothermic or exothermic, and is the value of ∆Hº positive or

negative?

A endothermic, positive

B endothermic, negative

C exothermic, positive

D exothermic, negative

7. In order to produce 972 kJ of heat, how many grams of H2 must burn?

H2(g) + ½O2(g) ¼ H2O(g) H= + 243 kJ

A 0.250 g

B 4.04 g

C 8.08 g

D 16.0 g

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PRACTICE MODULE CHAPTER 2 SK 025

8. What is 4.18 J?

A The heat required to raise the temperature of one gram of water by one Celsius
degree.

B The heat required to raise the temperature of one mole of water by one Celsius
degree.

C The heat required to raise the temperature of one gram of substance by one
Celsius degree.

D The heat required to raise the temperature of one mole of substance by one
Celsius degree.

9. What happens to the water in a calorimeter when an exothermic reaction occurs in it?
A It absorbs heat, and a drop in temperature is observed.
B It absorbs heat, and a rise in temperature is observed.
C It releases heat, and a drop in temperature is observed.
D It releases heat, and a rise in temperature is observed.

10 Which is true for an exothermic reaction?
A The ∆H is positive.

B The products have less potential energy than the reactants.

C The reactants have more kinetic energy than the products.

D The reactants are below the products in the potential energy diagram.

WORKSHEET 2.8 ( MODEL PSPM)

Q1: clone PSPM 2007/2008

The enthalpy of combustion of fructose, C6H12O6 is 21.2 kJ mol -1. An amount of 2.63
g of C6H12O6 was completely combusted in a bomb calorimeter at 25 °C.

[ 5 marks]
i) Write the thermochemical equation for the reaction.
ii) Calculate the final temperature if the calorimeter contains 225.0 mL of water.

(ans: 25.33°C)

Q2: clone PSPM 2011/2012
The enthalpy of combustion of benzoic acid is -3226.7 kJmol-1. When 3.2 g benzoic
acid, C6H5COOH is completely combusted in a bomb calorimeter containing 2.0 kg
of water, the temperature of the water increased by 3.8°C. Calculate the heat
capacity of the calorimeter.
(ans: C = 1.39 x 104 J˚C-1)
[5 marks]

Q3: clone PSPM 2019/2020
a) Ethanol, CH3CH2OH is produced from fermentation of sugarcane and widely used as

an alternative fuel to replace petrol. A 1.00 g sample of ethanol was burned in a
calorimeter, which has a total heat capacity of 11.0 kJ oC-1. The temperature of the
calorimeter and its contents increased from 25.0 oC to 27.7 oC.

[ 6 marks]

i)Write a balanced chemical equationthat takes place in the bomb calorimeter.

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PRACTICE MODULE CHAPTER 2 SK 025

ii) Calculate the enthalpy of combustion of ethanol per mol.
(ans: -1368.66 kJ)

b) Born haber cycle for the formation of calcium sulphide is given in FIGURE 2.
( The cycle is not drawn to scale)
[6marks]

Ca2+(g) + S2-(g)

Ca2+(g) + S(g)

ΔH5 -200 kJ mol-1 ΔH6
ΔH4 +1145 kJ mol-1 Ca2+(g) + X

Ca+(g) + S(g)

ΔH3 +590 kJ mol-1 -3013 kJ mol-1 ΔH7
Ca(g) + S(g)

ΔH2 +279 kJ mol-1
Ca(g) + S(s)

ΔH1 +178 kJ mol-1
Ca(s) + S(s)

ΔH8 -482 kJ mol-1 CaS(s)

i) Name the enthalpy changes for ∆H7 and ∆H8.
ii) Identify the species X formed from ∆H5.
iii)Use the data in FIGURE 2 to calculate the value of ∆H6.

iv) Will the lattice energy for CaO be larger or smaller than CaS? Explain briefly.

Q4: clone PSPM 2020/2021

a) TABLE 1 shows the lists of standard enthalpy change associated with the solubility

of silver chloride, AgCl.

TABLE 1

Enthalpy ∆ ° (kJ mol-1)

Lattice energy of AgCl +915

Hydration energy of Ag+ -465

Hydration of Cl- -364

i) Construct the thermochemical cycle to show the relationship between lattice energy,

hydration energy and enthalpy of solution for AgCl.

ii) Calculate the enthalpy of solution of AgCl.

b) Arrange the following substances in ascending order of lattice energy. Explain your

answer.

AlCl3, MgCl2, NaCl

Prepared by : Mdm Suhaibah Binti Mustafa & Mdm Siti Fatimah Binti Md Sollhi
Checked by : Mdm Noor Shuhada bt Rahim & Mdm Wan Rosilah bt Wan Llah

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PRACTICE MODULE CHAPTER 3 SK025

WORKSHEET 3.1: GALVANIC CELL

Define
a. standard electrode potential

b. standard cell potential, Eocell

STANDARD HYDROGEN ELECTRODE

1. a. WORKSHEET 3.2
Draw a labelled diagram of standard hydrogen electrode (SHE).

b. Explain how to construct the standard hydrogen electrode.

c. Draw a completely labelled diagram to show how the standard electrode
potential of zinc can be determined using SHE.

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PRACTICE MODULE CHAPTER 3 SK025

2. Given the following cell notation for an electrochemical cell at 25oC is:
Pt (s)│H2 (g, 1 atm)│H+ (aq, 1.0 M)║Ag+ (aq, 1.0 M)│Ag (s)
[ Given: Eo Ag+I Ag(s) = + 0.80 V and Eo H+I H2(g) = 0.00 V ]

a. Explain how the concentration of the solution at the anode and the cathode
would change after the cell had been discharged continuously.
At the anode :

At the cathode :

b. From the given cell notation, draw a labelled diagram of the cell and show
the direction of the electron flow.

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PRACTICE MODULE CHAPTER 3 SK025

STANDARD ELECTRODE POTENTIAL

WORKSHEET 3.3
1. Given :

Al3+(aq) + 3e- → Al(s) Eo = - 1.66V

Pb2+(aq) + 2e- → Pb(s) Eo = - 0.13 V

A Galvanic cell was set up at 25oC. The cell was consisting of an Al electrode
in 1.0 M Al(NO3)3, a Pb electrode in 1.0 M Pb(NO3)2 and a KCl salt bridge.
Answer the questions below :

a. Write the overall cell reaction.

Anode :

Cathode :

Overall cell reaction :

b. Write cell notation of the reaction.

c. Name the oxidizing and reducing agent.

Oxidising agent : Reducing agent :

d. Which electrode will increase in weight? Explain your answer.

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PRACTICE MODULE CHAPTER 3 SK025
2. Given the following cell notation for an electrochemical cell at 25oC is:Co(s) |

Co2+ (aq, 0.01 M) || Au3+ (aq, 0.10 M) | Au(s)
[ Given: Eo Co2+I Co(s) = +0.28 V and Eo Au3+I Au(s) = +1.50 V ]
Describe the operation of the cell and state the movement of its electronsand ions.

3. The table shows the electrode potentials for various metals

a. Arrange the metals given above in order of increasing strength as reducing
agent.

b. State the strongest oxidising agent
c. Explain why F oxidises D to D2+ but C does not.

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PRACTICE MODULE CHAPTER 3 SK025
4. Describe the operation of the hydrogen-oxygen cell by based on the movement

of its electrons and ions in:
a. acidic medium;

b. basic medium.

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PRACTICE MODULE CHAPTER 3 SK025

NERNST EQUATION

WORKSHEET 3.4

1. Given the following cell notation for an electrochemical cell at 25oC is:
Al(s) | Al3+ (aq, 1.00 M) || Pb2+ (aq, 1.00 M) | Pb(s)

[ Given: Eo Pb2+I Pb(s) = - 0.13 V and Eo Al3+I Al(s) = - 1.66 V ] [ Ans : 1.53 ]
a. Calculate the standard cell potential, Eocell.

b. Calculate the cell potential, Ecell. Predict spontaneity of the reaction.
[ Ans : 1.53 ]

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PRACTICE MODULE CHAPTER 3 SK025

2. A half-cell containing 0. 1 M Au3+ and an Au electrode is coupled with another half-
cell containing 0.01 M Co2+ solution and a Co electrode. The standard reduction

potentials are given below :

Co2+(aq) + 2e → Co (s) E0 = +0.28V
Au3+(aq) + 3e → Au (s) E0 = +1.50V

a. Calculate the the standard cell potential, Eocell and the cell potential, Ecell.
[ Ans : 1.78, 1.82 ]

b. Predict spontaneity of the reaction. Explain.
c. What could be done to obtain a higher Ecell value than that of (a)?

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PRACTICE MODULE CHAPTER 3 SK025

3. A galvanic cell consists of a Ni electrode in a 0.01 M Ni2+ solution and a Co
electrode in a 1.00 M Co2+ solution.

[ Given: Eo Ni2+I Ni(s) = - 0.25 V and Eo Co2+I Co(s) = - 0.28 V ]

a. Write the cell notation for this reaction

b. Calculate the cell potential, Ecell. Determine whether or not the reaction

would proceed spontaneously. [ Ans : - 0.0292]

c. Calculate the equilibrium constant, K for the reaction. [ Ans : 10.32]
At equilibrium, Q=K when Ecell = 0

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PRACTICE MODULE CHAPTER 3 SK025

4. A galvanic cell consisting of Ag and hydrogen electrodes. The pressure of
hydrogen gas is 1 atm. The Ag electrode is immersed in Ag+ solution and the
hydrogen electrode is immersed in sulphuric acid solution.
[ Given: Eo Ag+I Ag(s) = +0.80 V and Eo H+I H2(g) = 0.00 V ]

a. Write the balanced equation for the cell reaction.

b. Calculate the cell potential at 25oC if the concentration of Ag+ is 1.00 M
andthe concentration of sulphuric acid solution is 1.50 M.
[ Ans : 0.79]

c. What could be done to obtain a higher Ecell value than that of (a)?
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PRACTICE MODULE CHAPTER 3 SK025

5. Given :

Zn2+(aq) + 2e- → Zn(s) Eo = - 0.76 V
Cu2+(aq) + 2e- → Cu(s) Eo = + 0.34 V
A galvanic cell consists of a Zn electrode in a 1.80 M Zn2+ solution and a Cu
electrode in an unknown concentration of Cu2+ solution at 25oC.

a. Write the overall cell reaction.

b. Write cell notation of the reaction.

c. Name the oxidizing and reducing agent.

Oxidising agent : Reducing agent :

d. Calculate the concentration of Cu2+ solution if the cell potential is 1.07 V
[ Ans : 0.2]

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PRACTICE MODULE CHAPTER 3 SK025

6. Consider a galvanic cell in which the following reaction occurs at 25oC:

Zn(s) + 2H+(aq) → H2(g) + Zn2+(aq)

The cell potential is 0.56 V when the concentration of Zn2+ is 1.00 M and the
pressure of hydrogen gas is 1 atm.

a. What is the concentration of H+ in the half cell? [ Ans : 4.18 x 10-4]

b. Calculate the equilibrium constant, K for the reaction. 25

[ Ans : 4.79 x 10 ]

WORKSHEET 3.5: ELECTROLYTIC CELL

1. An electrolytic cell was set up at 25oC. The cell was consisting of copper
electrodes in 1.0 M CuSO4 solution. The Cu electrode are connected to the D.C.
power supply. Answer the questions below :
a. Draw and label the cell diagram to represent the electrolytic cell above.

b. Describe the operation of the electrolytic cell above.
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PRACTICE MODULE CHAPTER 3 SK025

FACTORS AFFECTING THE PRODUCTS OF ELECTROLYSIS:
Type of Electrolyte Used

Type of Anode (+) Cathode (-)
Electrolyte
➢ Species that being discharged : Cl- ➢ Species that being discharged : Na+
Used ➢ Equation : 2Cl–(l) → Cl2(g) + 2e- ➢ Equation : Na+(l) + e- → Na(l)
➢ Product formed : Cl2(g) evolved ➢ Product formed : Na metal deposited
Molten Salt
NaCl

Dilute ➢ Species that being discharged : H2O ➢ Species that being discharged : H2O

Aqueous NaCl ➢ Reason : Eo for H2O molecules is less ➢ Reason : Eo for H2O molecules is more
positive positive

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PRACTICE MODULE CHAPTER 3 SK025

➢ Equation : ➢ Equation :
2H2O(l) → O2(g) + 4H+(aq) + 4e- 2H2O (l) + 2e- → H2 (g) + 2OH- (aq)

➢ Product formed : O2(g) evolved ➢ Product formed : H2(g) evolved

Concentrated ➢ Species that being discharged : Cl- ➢ Species that being discharged : H2O
Aqueous NaCl ➢ Reason : high concentration of
➢ Reason : Eo for H2O molecules is more
solution positive
➢ Equation : 2Cl–(aq) → Cl2(g) + 2e-
➢ Equation :
➢ Product formed : Cl2(g) evolved 2H2O (l) + 2e- → H2 (g) + 2OH- (aq)

➢ Product formed : H2(g) evolved

Aqueous ➢ Species that being discharged : H2O ➢ Species that being discharged : H2O
Na2SO4
➢ Reason : SO42- has highest oxidation ➢ Reason : Eo for H2O molecules is more
state positive

➢ Equation : ➢ Equation :
2H2O(l) → O2(g) + 4H+(aq) + 4e- 2H2O (l) + 2e- → H2 (g) + 2OH- (aq)

➢ Product formed : O2(g) evolved ➢ Product formed : H2(g) evolved

FACTORS AFFECTING THE PRODUCTS OF ELECTROLYSIS:
Type of Electrolyte Used

WORKSHEET 3.6

Electrolysis of molten, dilute and concentrated aqueous solution of NaCl using platinum

electrode yielded different products. State the products formed in all three electrolysis

above and give your reason.

Eo Na+/Na = - 2.71 V Eo Cl2/Cl- = +1.36 V
Eo H2O/ H2 = - 0.83 V Eo H2O/ O2 = +1.23 V

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PRACTICE MODULE CHAPTER 3 SK025

i. Molten NaCl

ii. Dilute NaCl aqueous solution
iii. Concentrated NaCl aqueous solution

FACTORS AFFECTING THE PRODUCTS OF ELECTROLYSIS:
Type of Electrode Used

Type of Electrode Used Anode (+) Cathode (-)

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PRACTICE MODULE CHAPTER 3 SK025

INERT ELECTRODE ⮚ Species that being ➢ Species that being
Diagram: discharged : H2O discharged : Cu2+

⮚ Reason : SO4 has highest ⮚ Reason : Eo for Cu is more
positive
2-

oxidation state

⮚ Equation : ⮚ Equation :
2H2O(l) → O2(g) + 4H+(aq) Cu2+(aq) + 2e- → Cu(s)

⮚ Product formed : O2(g) ⮚ Product formed : Cu (s)
gas evolved deposited

ACTIVE ELECTRODE ⮚ Species that being ⮚ Species that being
Diagram: discharged : Cu2+ discharged : Cu2+

⮚ Reason : active electrode ⮚ Reason : Eo for Cu is more
used positive

⮚ Equation : ⮚ Equation :
Cu (s) → Cu2+(aq) + 2e- Cu2+(aq) + 2e- → Cu(s)

⮚ Product formed : Cu2+ ⮚ Product formed : Cu (s)
formed deposited

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PRACTICE MODULE CHAPTER 3 SK025
FARADAY’S FIRST LAW
WORKSHEET 3.7
State the Faraday’s First Law.

QUESTION 1:

An aqueous solution of silver nitrate, AgNO3 is electrolysed using platinum electrodes.
During electrolysis, a current 2.00 A was passed through the solution for 1.50 hours.
Calculate the mass of product formed at each electrode.

[Answer : anode: 0.89 g, cathode : 12.07 g]

Calculate the mass of product formed at ANODE electrode.

STEP 1:

1. Choose species that discharged
at anode.

2. Write the oxidation half cell equation.
3. State product formed at anode.

**anode : (+ve) terminal

STEP 2:
Associate Q based on Faraday’s Law

☞ relate the Faraday’s Law to the half
cell equation from STEP 1

Tips:
1 mol x = 1 mol e- = 1 F = 96500 C
1 mol x = 4 mol e- = 4 F = 4 x 96500 C

**unit of Q is Coulomb, C

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PRACTICE MODULE CHAPTER 3 SK025

STEP 3:
Calculate Q used in the reaction
**Formula : Q = It

STEP 4:

Calculate mol used in the reaction.

☞ write the stoichiometry equation and

relate mol & Q from STEP 2 with the
Q from STEP 3.

STEP 5:

Calculate the mass of product formed
at anode.
**mass = mol x Mr

Calculate the mass of product formed at CATHODE electrode.

STEP 1:
1. Choose species that discharged at

cathode.
2. Write the reduction half cell equation.
3. State product formed at cathode.
**Tips : cathode : (-ve) terminal
STEP 2:
Associate Q based on Faraday’s Law

☞ relate the Faraday’s Law to the half

cell equation from STEP 1

Tips:
1 mol x = 1 mol e- = 1 F = 96500 C
1 mol x = 2 mol e- = 2 F = 2 x 96500 C

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PRACTICE MODULE CHAPTER 3 SK025

STEP 3:
Calculate Q used in the reaction
**Formula : Q = It

STEP 4:
Calculate mol used in the reaction.

☞ write the stoichiometry equation and

relate mol & Q from STEP 2 with the
Q from STEP 3.

STEP 5:
Calculate the mass of product formed
at anode.
**mass = mol x Mr

QUESTION 2:

In an electrolysis experiment, a current of 3.50 A is flowed through a molten calcium

bromide, CaBr2 for 1 hour by using inert electrode. Calculate the mass of product

formed at cathode. [ Ans : 2.62 g ]

STEP 1:
1. Choose species that discharged at

cathode and write its half cell equation.
2. State product formed at cathode.

**Tips : cathode : (-ve) terminal

STEP 2:
Associate Q based on Faraday’s Law

☞ relate the Faraday’s Law to the half

cell equation from STEP 1

Tips:
1 mol x = 2 mol e- = 2 F = 2 x 96500 C

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PRACTICE MODULE CHAPTER 3 SK025
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PRACTICE MODULE CHAPTER 3 SK025

STEP 3:
Calculate Q used in the reaction
**Formula : Q = It

STEP 4:
Calculate mol used in the reaction.

☞ write the stoichiometry equation and

relate mol & Q from STEP 2 with the
Q from STEP 3.

STEP 5:
Calculate the mass of product formed
at anode.

QUESTION 3:

When 0.60 A of an electrical current is passed for 11.7 minutes, all the permanganate ions
in 15.00 mL solution has been reduced. Determine the original concentration of
permanganate ions, MnO4-.

Given: MnO4- + 8 H+ + 5e → Mn2+ + 4 H2O [Ans : 5.82 x 10-2 M]

STEP 1:

Calculate Q used in the reaction

**Formula : Q = It

STEP 2:
Associate Q based on Faraday’s Law
relate the Faraday’s Law to theequation
given.
Tips:1 mol x = 5 mol e- = 5 F = 5 x 96500 C

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PRACTICE MODULE CHAPTER 3 SK025

STEP 3:

Calculate mol used in the reaction.

☞ write the stoichiometry equation

and relate mol & Q from STEP 2
with the Q from STEP 1.

STEP 4:
Calculate the concentration of MnO4-

Concentration = mol
volume (L)

WORKSHEET 3.8
MULTIPLE CHOICE QUESTIONS
Answer ALL the questions
1. What is the function of salt bridge in voltaic cell ?

A. Acts as a mechanism to allow mechanical mixing of the solutions

B. Allows charge balance to be maintained in the cell

C. Is not necessary in order for the cell to work

D. Drives free electrons from one half-cell to the other

2. By referring to the cell diagram
Cu(s) I Cu2+(aq) II F2 (g) I F-(aq) I Pt (s)
A. The reduction compartment is on the right
B. The Cu2+ ion are reduced

C. The flaming gas is reduced to F2

D. Platinum is oxidized by the flaming gas

3. Which of the following half-cell diagrams is not correctly written?
A. Pb2+(aq) I Pb(s)
B. Pt(s) I Cu+(aq),Cu2+(aq)
C. H2(g), H+(aq) I Pt(s)
D. Pt(s) I[Fe(CN)6]4-(aq), [Fe(CN)6]3-(aq)

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PRACTICE MODULE CHAPTER 3 SK025

4. What is the cell reaction for the voltaic cell below?
Zn (s) I Zn2+ (aq) II Cl2(g) I Cl-(aq) I Pt (s)

A. Zn (s) + 2Cl- (aq) → Cl2(g) + Zn2+(aq)
B. Zn (s) + Cl2(g) → Zn2+(aq) + 2Cl-(aq)
C. 2 Zn2+ (aq) + 4 Cl-(aq) → 2Cl2(g) + 3 Zn2+(aq)
D. Zn2+(aq) + 2Cl-(aq) → Zn2+(aq) + 2Cl(g)

5. Given below two half cell potentials: Eo= -0.44 V
Eo = -0.25 V
Fe2+ + 2e → Fe
Ni2+ + 2e → Ni

When both half-cells are joined together to form a voltaic cell,which of the following
statements is TRUE?

A. The nickel electrode gain mass and the nickel electrode is the cathode
B. The iron electrode gain mass and the iron electrode is the cathode
C. The nickel electrode loses mass and the nickel electrode is the anode
D. The iron electrons loses mass and the iron electrode is the cathode

6. What is the standard cell potential for the cell

Zn(s) I Zn2+ (aq,1M) || Cu2+ (aq,1M) I Cu(s)
Eo for Zn / Zn2+ (1M) = –0.76 V & Cu2+ / Cu = + 0.34 V

A. + 0.42 V

B. - 0.42 V
C. – 1.10 V

D. + 1.10 V

7. Normal aluminium electrode coupled with normal hydrogen electrode gives an emf of

1.66 volts. So the standard electrode potential of aluminium is
A. +0.83 V
B. +1.66 V

C. -1.66 V
D. – 0.83 V

8. The standard EMF for the given cell reaction Zn(s) + Cu2+(aq) → Cu(s) + Zn2+(aq) is
1.10 V at 25o C. The EMF for the cell reaction, when 0.1 M Cu2+ and 0.1 M
Zn2+ solutions are used, at 25o C is
A. +1.10 V
B. -0.110 V
C. +0.110 V

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PRACTICE MODULE CHAPTER 3 SK025

D. -1.10 V

9. The standard reduction electrode potential for several half-reactions at 298K are
shown below:

Electrode reaction Eo (V)
X2 + 2 e → 2X- + 0.54
Y3+ + e → Y2+ +0.77
Z2+ + 2e → Z -0.25

Which of the following species is the strongest oxidising agent?

A. X-
B. Y3+
C. Z
D. X2

10. In an electrolytic cell the electrode at which the electrons enter the solution is called
the ______ ; the chemical change that occurs at this electrode is called _______.

A. anode, reduction
B. cathode, oxidation
C. anode, oxidation
D. cathode, reduction

11. Which of the following statement about electrolysis is correct?
A. Oxidation occurs at the cathode
B. Electrons flow from the cathode to the anode in the external circuit
C. The more reactive the metal, the less readily the metal is discharged during
electrolysis
D. The number of moles of a metal deposited during electrolysis is proportional to
the quantity of electricity used and the charge on the metal ion

12. Determine the products at the cathode in an electrolytic cell containing aqueous
Na2SO4 and two platinum electrodes.
A. Hydrogen gas
B. Sodium metal
C. Oxygen gas
D. Sulphur dioxide gas

13. The half-reaction that occurs at the anode during the electrolysis of molten sodium
bromide is:
A. Na+ + e- → Na
B. Na → Na+ + e-
C. 2 Br- → Br2 + 2 e-
D. Br2 + 2 e- → 2 Br-

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PRACTICE MODULE CHAPTER 3 SK025

14. How many gram of Zn can be plated out at the cathode if a solution of Zn2+ is
electrolysed by a current of 1.00 A for 60 minutes?
A. 0.61 g
B. 1.21 g
C. 2.43 g
D. 2.22 g

15. Determine the mass gain by cathode of an electrolytic cell when a current of 0.5 A
passed through Au(NO3)3 solution for 30 minutes (Ar of Au =198).
A. 17.9 g
B. 2.42 g
C. 3.68 g
D. 0.62 g

WORKSHEET 3.9
MODEL OF PSPM QUESTIONS
1. The standard reduction potentials of Co2+ and Ni2+ are given below :

Co2+(aq) + 2e → Co (s) Eo = -0.28 V
Ni2+(aq) + 2e → Ni (s) Eo = -0.25 V

Given that the initial concentrations of Ni2+ and Co2+ are 0.01 M and1.00 M
respectively, determine whether or not the following reaction would proceed
spontaneously.

Co (s) + Ni2+(aq) → Co2+(aq) + Ni (s)
Calculate the equilibrium constant for the reaction.

(ans: 10.31)
2. A half-cell containing 0.01 M Co2+ and a cobalt electrode is coupled with another half-

cell containing 0.1 M Au3+ and a gold electrode using a salt bridge at 25oC. The
standard reduction potentials for Co2+ and Au3+ are –0.28V and +1.50V respectively.
Calculate the cell potential under the stated conditions.

(ans: + 1.82 V)
3. A current of 3.20 A is passed through molten indium halide in an electrolytic cell for

a period of 40.0 minutes. A deposit of 4.57 g indium, In is formed. Determine the
oxidation state of In in the halide.
[Relative Atomic Mass of In = 114.8]

(ans: +2)

Prepared by : Mdm Norihan & Mdm Nurul Azwa
Checked by : Mdm Sharifah Fadthyah

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PRACTICE MODULE CHAPTER 5 SK 025

i- THINK MAP

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PRACTICE MODULE CHAPTER 5 SK 025

CHAPTER 5 : ALKANE

5.1 : STRUCTURE AND NAMING OF ALKANE
WORKSHEET 5.1 (a), (b) & (c)

1. Name this following alkane with correct IUPAC name.

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PRACTICE MODULE CHAPTER 5 SK 025

2. Draw the structural formula for the following molecules.
a. 4-ethyloctane
b. 2-methylnonane
c. 3,3-dimethylpentane
d. 3-ethylpentane
e. 3-ethyl-2-methylheptane
f. 2,2,3-trimethyl-butane
g. 3-ethyl-2,2-dimethyl-hexane

WORKSHEET 5.1 (a), (b) & (c)
For each alkane write the correct IUPAC name.

1. CH3CH2CH2CH3 =
2. CH3CH(CH3)CH3 =

3. =

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PRACTICE MODULE CHAPTER 5 SK 025

4. =

5. =

6. =
7.

=

8. =

9.
10.

=

92

11. PRACTICE MODULE CHAPTER 5 SK 025
= =

12.

WORKSHEET 5.1 (a), (b) & (c)
Draw the structure for the following IUPAC name.

1. 2-methylpentane -

2. 2,2-dimetylbutane -

3. 4-ethyl-3-methylnonane -

4. 2,3,4-trimethylheptane -

93