Download Chem 110 (2013)Tutorial 2 Solutions

School of Chemistry & Physics, University of KwaZulu-Natal, Westville Campus, Durban
General Principles of Chemistry – CHEM110
Tutorial 2 – 27 February & 1 March 2013
1.
Chlorine has two naturally occurring isotopes 35Cl with an atomic mass of 34.968 u and a
natural abundance of 75.53%, and 37Cl with atomic masses of 36.956 u and a natural
abundance of 24.47%. Calculate the average atomic mass of chlorine.
AM =
(
% Cl-35 x IMCl-35
100
)
AM =
(
75.53 x 34.968
100
)
+
AM =
(
2641
100
904.3
100
)
+
(
(
+
AM
% Cl-37 x IMCl-37
100
24.47 x 36.956
100
(
)
)
)
= 26.41 + 9.043
= 35.45 u
2. Write the chemical formula for each of the following compounds:
a)
potassium sulfate
K2(SO4)
b)
magnesium sulfide
MgS
c)
calcium phosphate
Ca3(PO4)2
d)
silver perchlorate
AgClO4
e)
iron(III) dichromate
Fe2(Cr2O7)3
f)
tetraphosphorus heptoxide
g)
copper(II) cyanide
h)
potassium hydrogen phosphate
K2HPO4
i)
diammonium hydrogen phosphate
(NH4)2HPO4
j)
cobalt(I) chloride
P4O7
Cu(CN)2
CoCl
3. Name each of the following compounds, and classify it as ionic or molecular:
(a) PbO
(f) Cr2O3
(b) CuS
(g) Cl2O9
(c) P3O6
(h) Fe2(SO4)3
(d) K2CrO4
(e) RbCN
(i) ICl5
(a) lead oxide, I
(b) copper(II) sulfide, I
(c) triphosphorus hexoxide, M
(d) potassium chromate, I
(e) rubidium cyanide, I
(f) chromium(III) oxide, I
(g) dichlorine nonoxide, M
(h) iron(III) sulfate, I
(i) iodine pentachloride,M
4.1
Balance the following equations:
(a) 2H3PO4 + 3Mg(OH)2 → Mg3(PO4)2 + 6H2O
(b) BaCO3 + 2HCl → H2O + CO2 + BaCl2
4.2
Aluminium oxide,Al2O3 , reacts with water to give Al(OH)3. Write a balanced
equation for this process.
Al2O3(s) + 3H2O(l) → 2Al(OH)3(s)
5.
Which of the following reactions represents a (i) combination reaction, (ii) a
decomposition reaction, (iii) a displacement reaction or (iv) combustion reaction?
(a)
(b)
(c)
(c)
2Na(s) + 2H2O(ℓ) → 2NaOH(aq) + H2(g) displacement rxn
2H2O + electric current → 2H2(g) + O2(g) decomposition rxn
2SrO(s) + CO2(g) → SrCO3(g) combination rxn
C3H8(g) + 5O2 → 3CO2(g) + 4H2O(g) combustion rxn