THE UNIVERSITY OF ZAMBIA
DEPARTMENT OF CHEMISTRY
CHE1010 Tutorial sheet 1
2021/22
Answer all questions in a fresh hard cover A4 size note book.
Due date for submission will be informed later
1. Multiple choice questions
(i)
(ii)
(iii)
(iv)
Determine the number in mg in 0.020 kg tin (Sn)
(a) 20,000 (b) 2,000 (c) 0.020 x 10-2 (d) 0.0020
Convert 2875 cm3 to liters
(a) 28.75 liters (b) 2.8750 liters (c) 0.02875 liters (d) 2.875 liters
A metallurgist is making an alloy that consist of 325 g of chromium and 2.5 kg
of iron. Find the total mass of mixture in kg. (notice the significant figures)
(a) 2.83 kg (b) 2.8 kg (c) 0.028 kg (d) 2.82 kg
The density of lead (Pb) is 11.34 g/mL. Calculate the density in kg/L
(a) 0.0001134 kg/L (b) 0.01134 kg/L (c) 0.00001134 kg/L (d) 11340 kg/L
2. Match with the right number of significant figures
(i)
(ii)
(iii)
(iv)
4500
0.0450
4500.
0.045
(a) 3
(b) 2
(c) 1
(d) 4
3. Complete the following and round to the correct number of significant figures
4.
(a) Convert 150 miles to cm.
(b) convert12.1 gallons to cm3
(c) convert mg to microgram
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5. Comment on the accuracy, precision and combination of both in the 3 runs carried out
using 3 different dispensers.
6. Express in exponential notation and correct number of SF
(a) 704 (b) 0.007157 (c) 1000.00
7. True or False
(a) The number of eggs in a basket is exact
(b) The number of mm in 1cm is uncertain
(c) 0.8 has one SF
(d) 0.08 has 2 SF
(e) 0.008 has 1 SF
8. Perform the following calculations and report to correct number of SF
(i)
(5.63 x102 ) x ( 7.4 x 103)
(ii)
28.0 ÷ 13.483
9. Assign the correct oxidation number to the individual atom or ion below
(i) Mn in MnO2
2
(ii) I in IO3(iii) C in HCO3(iv) Fe in Fe2(SO4)3
(v) O in Na2O2
(vi) S in S8
10. Name the given compounds : CuCl, Mg(OH)2, Cu3As
11. Give the correct chemical formula for the named compounds
(i)
(ii)
Strontium chloride (ii) titanium (IV) Iodide
Iron (III) oxide (iv) Cobalt (II) nitride
12. Give the number of protons, electrons, and neutrons in neutral atoms of each of the
following isotopes:
(a)
10
5𝐵
(b) 199
80𝐻𝑔
13. Define relative atomic mass.
14. Lithium has two naturally occurring isotopes: 6Li (7% abundance) and 7Li (93%
abundance). Calculate the relative atomic mass of lithium.
15. Iridium has a relative atomic mass of 192.22 and consists of Ir-191 and Ir-193 isotopes.
Calculate the percentage composition of a naturally occurring sample of iridium.
16. Determine the mass of each of the following:
(a) 10.2 mol ethane, C2H6
(b) 1.6 × 10−3 mol Na2SO4
17. Determine the empirical formula for the compound with the following percent
compositions: 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen
18. Determine the molecular formula of a compound with an empirical formula of NH2 and a
molar mass of 32.06 g/mol.
19. Consider the reaction below.
I2O5 (g) + 5 CO (g) -------> 5 CO2 (g) + I2 (g)
80.0 grams of iodine (V) oxide, I2O5, reacts with 28.0 grams of carbon monoxide, CO.
Determine the mass of iodine I2, which could be produced.
20. On complete combustion, 0.246 g of an organic compound gave 0.198 g of CO2 and
0.1014 g of H2O. What is the ratio of carbon and hydrogen atoms in the compound?
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21. An ingestion tablet contains a mass of 0.30 g of magnesium hydroxide [Mg(OH)2] as
its only basic ingredient. The balanced chemical equation between magnesium and
hydrochloric acid (HCl(aq)), the acid produced in the stomach is as follows:
Mg(s) + 2HCl(aq) ⟶ Mg(OH)2(aq) + H2O(l)
(i) Calculate the volume of 0.1 M neutralised by two of these ingestion tablets?
(ii) What mass of the salt is formed in this neutralisation reaction?
(iii) How many magnesium ions are present in this amount of a salt?
22. In an experiment, 1.90 g of NH3 reacts with 4.96 g of O2.
4NH3(g) + 5O2(g) ⟶ 4NO(g) + 6H2O(g)
(i) Which is a limiting reactant? Show your working.
(ii) How many grams of excess reactant remain? Show your working.
(iii) How many grams of NO is formed? Show your working
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