1) Basic familiarity with Atomic Labels.
You will need a Periodic Table and list of elements. These are available on the inside covers of
any general chemistry text.
1.1) What are the symbols of the following atoms?
Hydrogen, Carbon, Sodium, Iron, Radon, Uranium
1.2) What are the names of the atoms with the symbols?
He, Be, S, Mg, Hg, Xe
1.3) What are the names and symbols of the atoms with atomic numbers?
3, 8, 29, 58, 74, 82
1.4) Write down the symbol, atomic number and the average atomic mass of the atoms?
Nitrogen, Chlorine, Chromium, Bismuth, Holmium, Thorium
Some less chemical, more general interest questions:
1.5) What do the following atomic labels/names have in common?
Ga, Po, Ge, Eu, Am
1.6) The symbols, Na, K, Hg, Pb, Sn, Sb, Fe, Cu, Ag, Au, have no obvious relationship to the
modern names of the elements. What are the modern names and what did the symbols originally
stand for?
1.7) There is no atom with the symbol Di, yet there used to be bottles of the chemical Di(NO3)3
available. Who made the mistake of thinking that Di, didymium, was an element and what was it
really?
2) Basic familiarity with number of protons, neutrons and electrons.
2.1) How many protons, neutrons and electrons are there in each of the following atoms?
12
C, 40Ar, 70Ga, 89Y, 197Au, 226 Ra
(Make sure you know the names of the atoms too.)
2.2) An atom that has lost electrons has a positive charge and is called a cation and one that has
gained electrons is negatively charged and is called an anion. How many electrons are there in
each of the following ions?
H+, Cl-, Al3+, O2-, Cu2+, I2.3) How many protons, neutrons and electrons are there in each of the following ions?
1 + 19 - 39 + 55
H , F , K , Fe 2+, 56Fe 3+, 107Ag+
2.4) Fill in the gaps in the following table, assuming each column represents a neutral atom
52
Symbol
Cr
Protons
25
82
Neutrons
30
64
136
Electrons
48
86
Mass Number
222
207
Name
2.5) Fill in the gaps in the following table:
59
Symbol
Co 3+
Protons
34
Neutrons
46
Electrons
36
Net Charge
Mass Number
Name
76
116
80
120
78
2+
3) Basic familiarity with isotopes and average atomic masses
3.1) Carbon has two naturally occurring isotopes, 12C and 13C. How are they different? What are
the two naturally occurring isotopes of boron? The isotope of hydrogen, 2H, is called deuterium
and has its own atomic symbol, D. How many protons, neutrons and electrons are there in the ion
D+ ?
3.2) Fluorine exists as a single isotope, 19F. What is its accurate atomic mass? What units is this
in? What is the mass of a 19F atom in kg?
3.3) The table gives the accurate atomic masses of the isotopes of C, Cl and Mg and their natural
abundances. Make sure that the values for C agree with the average atomic mass. Calculate the
natural abundance of 37Cl and the average atomic mass of Mg.
Carbon
Chlorine
Magnesium
12
35
24
C
12.0000
Cl
34.9675
Mg
23.9850
98.93%
75.78%
78.99%
13
37
25
C
13.0033
Cl
36.9659
Mg
24.9858
1.07%
??
10.00
26
Mg
25.9826
11.01%
average
12.01
35.45
??
atomic mass
3.4) How many naturally occurring isotopes does Xe have? List their atomic number, atomic
mass number, number of neutrons and abundance.
4) Basic familiarity with elements, ions and molecules
4.1) Identify the elements that exist as a) monatomic gases at room temperature,
diatomic gases at room temperature, c) liquids at room temperature.
b)
Identify the semi-metal elements and the non-metal elements.
4.2) Look up a table of the composition of air and identify the three elements that contribute the
largest percentage contributions. Which two compounds make significant contributions to the
composition of air?
4.3) What are the molecular masses (accurate to one decimal place) of the following elements?
Cl2, S8, Xe, P4, H2 (state the units)
4.4) Write the following structural formulae as molecular formulae:
(e.g. structural formula CH3COOH; molecular formula C2H4O2)
Ca3(PO4)2, K3[Cr(CN)6], CuSO4.5H2O, CH2(OH)CH(NH2).COOH (serine),
H2N(CH2)4CH(NH2)COOH (lysine)
4.5) Identify the cations and anions and their charges (e.g. NaCl: Na+ Cl-) in each of the
following:
CsI, FeO, Al2O3, K2SO4, Ca3(PO4)2, Ni(NO3)2, CuSO4.5H2O
4.6) Determine the ionic charge on each of the following:
Al in Ca(AlO2)2
Al in Al2O3
UO2 in K2(UO2)Cl4
Cr in K3[Cr(CN)6] given that CN- is a common ion
Cr in K2Cr2O7
4.7) Look up the names of each of the following acids and the number of acid hydrogens there
have:
HBr; HNO3; H3PO4; H3PO3; C2H4O2 (CH3CO2H); C2H2O4 (HO2CCO2H)
5) Basic familiarity with moles
Use average atomic masses to at least one decimal place of accuracy.
5.1) How many moles and how many molecules are there in 10g of each of the elements Cl2, S8,
P4, H2, Fe?
5.2) How many moles of each of the following compounds are contained in 100g of the
compound? How many moles of each type of atom in the compound are contained 10g of the
compound?
Fe2O3, NaNO3, CH3COOH, KHSO4, K2(UO2)Cl4
5.3) How many moles of the specified substance are there in each of the following?
5.0 g of glucose, C6H12O6. (A teaspoon of sugar.)
300mg of aspirin, C9H8O4. (A standard aspirin tablet.)
0.75 g of NaCl.
(A pinch of salt.)
150 ml of H2O.
(A glass of water, density of water 1g ml-1)
12.5 kg of Au.
(A gold bar.)
5.4) How many moles of the specified substance are there in each of the following?
Look up the value of the Gas Constant where needed and be careful about the units.
200ml of pure bromine Br2(l).
(Density of liquid bromine, 3.1 g ml-1)
A lead (Pb) brick 3.5cm x 6.5cm x 20.0cm (Density of lead, 11.34 g cm3)
HNO3 in 25 ml of a 0.02 mol l-1 solution of nitric acid, HNO3 (aq)
2 litres of He at room temperature and atmospheric pressure. (A helium balloon.)
15.5 g of C(s) are burnt in oxygen and forms 56.8 g of CO2(g). How many moles of
CO2 is this and how many moles of O2 were consumed?
5.5) The healthy level of cholesterol (C27H46O) in blood is 5 mM (milli-molar, or
5x10-3 mol l-1). The average volume of blood in a human male is a 4.7 litres. What mass of
cholesterol does the blood of a healthy human male contain? According to US Department of
Agriculture figures, a tablespoon of butter (14g) contains 30 mg of cholesterol. How many moles
of cholesterol are in a standard 454g block of butter?
5.6) 234.5 g of CaCO3(s) are heated and decompose: CaCO3(s)  CaO(s) + CO2(g)
How many moles of lime, CaO(s), are formed and if the gas is collected what volume will it
occupy at 28oC and 1.03 atmos pressure?
6) Empirical and Molecular Formulae
6.1) For each of the following molecules, what is the molecular mass of the molecule? How
many atoms of each type are there in the molecule? What fraction of the molecular mass is due
to the most numerous type of atom? Which type of atom accounts for the largest percentage of
the molecular mass? Is the empirical formula different to the molecular formula?
C2H4, Na2SO4, CH3CO2H, (NH4)(NO2), C6H5CO2CH3
6.2) L-Dopa, a drug used in the treatment of Parkinson’s disease, is 54.8% carbon, 5.62%
hydrogen, 7.10% nitrogen and 32.6% oxygen. What is the empirical formula of the compound?
6.3) Caffeine, a stimulant in coffee and tea and often found in OTC painkillers, has a molar mass
of 194.19g/mol and mass composition 49.48% C, 5.19% H, 28.85% N and 16.48% O. What is
the molecular formula of caffeine?
6.4) Ethyne and benzene both have the same empirical formula, CH. Look up (anywhere you like
but a text book is a good idea) their molecular masses and their molecular formulae and explain
how this occurs. Are there any other molecules that are known to exist (no matter for how short a
time) with the same empirical formula?
7) Balancing equations and mole calculations based on equations
7.1) Balance each of the following chemical equations:
i.
H2 + O2 → H2O
ii.
Na2S + ZnCl2 → ZnS + NaCl
iii.
Mg + N2 → Mg3N2
iv.
(NH4)2Cr2O7 → Cr2O3 + H2O + N2
v.
CH4 + O2 → CO2 + H2O
vi.
Ca(OH)2 + HCl → CaCl2 + H2O
vii.
H3PO4 + Mg(OH)2 → Mg3(PO4)2 + H2O
viii.
S8 + F2 → SF6
ix.
C3H6 + NH3 + O2 → C3H3N + H2O
x.
I2 + HNO3 → HIO3 + NO2 + H2O
7.2) Balance each of the following equations
i.
ii.
iii.
iv.
v.
vi.
vii
viii.
ix.
x.
SO2 +
P4O10 +
CH4 +
Al4C3 +
C4H10O
Fe(OH)3
Mg3N2
Li
+
TiCl4 +
NH4NO3
O2
H2O
Cl2
H2O
+
+
+
N2
H2O
=
=
SO3
=
H3PO4
=
CCl4 +
HCl
=
Al(OH)3
+
O2
=
CO2 +
H2SO4 =
Fe2(SO4) 3
H2SO4 =
MgSO4
=
Li3N
=
TiO2 +
HCl
N2
+
O2
+
CH4
H2O
+
+
H2O
(NH4)2SO4
H2O
7.3) Balance each of the following equations
i.
Ca3P2 +
H2O =
Ca(OH)2
+
PH3
ii.
Al(OH)3
+
HClO4 =
Al(ClO4)3
+
H2O
iii.
AgNO3
+
Na2SO4
=
Ag2SO4
+
iv.
N2H4 +
N2O4 =
H2O +
N2
v.
Al
+
Cl2
=
AlCl3
vi.
C2H4 +
O2
=
CO2 +
H2O
vii.
N2
+
H2
=
NH3
viii. K2O +
H2O =
KOH
ix.
CaC2 +
H2O =
Ca(OH)2
+
C2H2
x.
H2S +
Fe(OH)3
=
Fe2S3 +
H2O
NaNO3
7.4) In the reaction 2C2H6 + 7O2 = 4CO2 + 6H2O if 0.35 moles of ethane (C2H6) are burnt how
many grams of H2O are formed? If 537.8 g of CO2 is formed, how many moles of O2 reacted? If
2 g of ethane react what mass of O2 reacts and what masses of H2O and CO2 are formed?
7.5) Mercuric oxide (HgO2) decomposes when heated, HgO2(s)  Hg(l) + O2(g). If 100g of the
oxide is decomposed, what mass of Hg(l) and how many moles of O2(g) are formed? If the O2 is
collected at 298K and 1.03 atmos pressure, what volume will it occupy?
7.6) Write down the chemical equation involved and calculate what mass (g) of AgBr is formed
when 35.5 mL of 0.184 M AgNO3 is treated with an excess of aqueous HBr?
7.7) Write down the chemical equation involved and calculate what mass (g) of CaF2 is formed
when 47.8 mL of 0.334 M NaF is treated with an excess of Ca(NO3)2?
8) Solutions and Concentration
8.1 In the following the symbol M (molar) stands for mol l-1 (moles per litre)
(a) What is the concentration (M) of sodium ions in 4.57 L of a 0.847 M Na3P solution?
(b) What is the concentration (M) of NaCl in a solution made by mixing 25 mL of 0.100 M NaCl
with 50 mL of 0.100 M NaCl?
(c) What is the concentration (M) of CH3OH in a solution prepared by dissolving 11.7 g of
CH3OH in sufficient water to give 230 mL of solution?
(d) How many moles of Co2+ are present in 0.200 L of a 0.400 M solution of CoI2?
(e) How many moles of bromide are present in 0.50 L of a 0.30 M solution of AlBr3?
8.2) The word ‘molarity’ means ‘concentration in M’:
(a) What is the molarity of an aqueous solution containing 22.5 g of glucose (C6H12O6) in 35.5
mL of solution?
(b) What mass (g) of sodium chloride is there in 55 mL of a 1.90 M aqueous solution of sodium
chloride?
(c) What is the concentration (M) of chloride ions in a 0.193 M solution of KCl?
(d)What is the concentration (M) of iodide ions in a 0.193 M solution of BaI2?
8.3) How many moles of the specified substance are there in each of the following solutions?
NaCl in 50ml of a 0.02 mol l-1 NaCl(aq) solution
CH3CO2H in 125 ml of a 0.834 mol l-1 CH3CO2H(aq) solution
SO42- ion in 48.70 ml of a 2.345 mol l-1 sulphuric acid solution, H2SO4(aq)
NO3- ion in 19.5 ml of a 0.012 mol l-1 solution of Ba(NO3)2(aq)
8.4) What mass in grams of the specified substance is there in each of the following solution?
KCl in 25ml of a 0.25 mol l-1 KCl(aq) solution
Mg(ClO4)2 in 154.6 ml of a .0234 mol l-1 solution of Mg(ClO4)2(aq)
H+ ions in 50 ml of a 0.100 mol l-1 nitric acid solution, HNO3(aq)
OH- ions in 24.8 ml of a 0.105 mol l-1 lime water solution, Ca(OH)2(aq)
Acids, bases and pH