CHEMISTRY SK015 | TUTORIAL CHAPTER 1.0 | MATTER

CHEMISTRY SK015 | 2021/2022
TUTORIAL TOPIC 1: MATTER

1.1: Atoms and Molecule

1. a) Define:
i. proton number
ii. nucleon number
iii. isotopes

b) Write the isotope notation for each of the following species:

Species protons Number of electrons
neutrons

P1 02

Q1 1 0

R 9 10 10

S2 22

c) State the number of sub-atomic particles for each of the following
elements:
i. silicon-28
ii. chlorine-37

2. a) Define relative atomic mass.
b) An atom of X is twice as heavy as one carbon-12 atom. Determine the relative
atomic mass of element X.
c) The relative atomic mass of element Y is 32. Calculate the mass of one
atom of Y in gram.

3. a) Chlorine isotopes occur naturally as 35Cl and 37Cl. The ratio of the relative
abundance of these two isotopes is 35 Cl = 3.127.
37 Cl
Based on the scale of 12C = 12.00, the isotopic mass of 35Cl and 37Cl are
34.9689 amu and 36.9659 amu respectively. Calculate the average atomic
mass of chlorine.

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CHEMISTRY SK015 | 2021/2022
TUTORIAL TOPIC 1: MATTER

b) The following is the mass spectrum of zirconium. Calculate the average
atomic mass of zirconium.

52

% intensity 13
14
12 mass (amu)
9

90 91 92 93 94

1.2: Mole Concept

1. The hydrated copper(II) sulphate, CuSO4.5H2O is the compound used to prepare
CuSO4 solution. Given a sample of 10.0 g CuSO4.5H2O, calculate the:
a) number of moles of CuSO4.5H2O.
b) number of moles of copper atoms.
c) mass of anhydrous copper(II) sulphate.

2. Analysis of a gaseous hydrocarbon compound gives the following percent
composition by mass: 85.7% C and 14.3% H.
a) Define empirical formula and molecular formula.
b) Determine the empirical formula of the hydrocarbon.
c) 0.25 g of this compound occupies a volume of 100 mL at STP. Determine the
molar mass and the molecular formula of the hydrocarbon.

3. A complete combustion of a hydrocarbon forms 1.10 g of CO2 and 0.45 g of H2O.
The molar mass of the hydrocarbon is 84.0 g mol–1. Determine its empirical and
molecular formula.

4. a) Define molality.
b) The density of 10.5 molal NaOH solution is 1.33 g mL–1 at 20.0C. Calculate:
i. the mole fraction of NaOH.
ii. the percentage by mass of NaOH.
iii. the molarity of the solution.
c) The density of 95% by mass of sulphuric acid solution, H2SO4 is 1.84 g mL−1.
Calculate:
i. the molarity of H2SO4.
ii. the volume of the acid needed to prepare 1.0 L of 0.50 M solution.

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CHEMISTRY SK015 | 2021/2022
TUTORIAL TOPIC 1: MATTER

5. a) A 400 mL of perfume solution contains 50.0 mL of alcohol. What is the
concentration
of alcohol by volume in this solution?
b) Calculate the volume of ether required to make a 30 dm3 of ether-water
solution which is 40% of ether by volume.

1.3: Stoichiometry

1. Balance the equations below: (acidic)
a) C4H10(g) + O2(g) ⎯→ CO2(g) + H2O(l) (basic)
b) Fe(s) + H2O(l) ⎯→ Fe3O4(s) + H2(g)
c) Cr(OH)3(aq) + IO3−(aq) ⎯→ CrO32−(aq) + I−(aq)
d) Cl2(aq) ⎯→ ClO4−(aq) + Cl−(aq)

2. An impure sample of zinc weighing 50.0 g reacts with excess hydrochloric acid to
produce 18.0 L hydrogen gas at room condition.
a) Write a balanced equation for the reaction.
b) Calculate the mole of H2 gas produced.
c) Determine the percentage of zinc in the impure sample.

3. A sample of 1.55 g of iron ore is dissolved in an acid solution in which the iron is
converted into Fe2+ ions. The solution formed is then titrated with KMnO4 which
oxidises Fe2+ ions to Fe3+ ions while the MnO4- ions are reduced to Mn2+ ions.
The titration requires 92.95 mL of 0.0200 M KMnO4 to reach the equivalence point.
a) Write a balanced equation for the titration.

b) Calculate the percentage of iron in the sample.

4. A reaction between 7.0 g of copper(II) oxide, CuO and 50 mL of 0.20 M nitric acid,
HNO3 produces copper(II) nitrate, Cu(NO3)2 and water.
a) Define limiting reactant.
b) Write a balanced chemical equation for the above reaction.
c) Determine the limiting reactant.
d) Calculate the expected mass of copper(II) nitrate formed.
e) Determine the percent yield if the actual mass of copper(II) nitrate obtained
from the reaction is 0.85 g.

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