1/ 1
TUTORIAL 1
INTRODUCTION
This tutorial covers elementary topics in Sections 1 and 2 of the syllabus. Most of
the answers can be found in Chapters 1 and 2 of the strongly recommended
textbook: Chemistry: The Central Science.
Here are steps for completing the tutorial:
In your own time:

Read and understand the questions

Formulate an answer or solution

Write out the solution neatly in an exercise book or file; not on the question
pages.
At the tutorial:

Introduce yourself to the group.

Discuss each question with your colleagues and try to agree on the correct
answer.

As a last resort, you can get assistance from a tutor.

Correct and update your written answers.
1:
Introduction: Matter and Measurement
Elements, compounds and mixtures
1.
Which of the following represent elements and which represent compounds?
(a)
(e)
2.
H
P4
(b)
(f)
H2
PH3
(c)
CO
(d)
Co
Which of the following is a chemical property and which is a physical property?
(a)
(b)
(c)
(d)
Chlorine gas liquefies at 35C under normal pressure.
Hydrogen burns in chlorine gas.
Bromine is a red-brown liquid.
Iron rusts in an atmosphere of moist air.
1/ 2
3.
(a)
Explain whether or not:
(i)
a solid can be a mixture
(ii)
a gas can be heterogeneous
(iii)
a mixture can be homogeneous
(b)
What distinguishes a (pure) substance from a mixture?
(c)
Classify each of the following as a pure substance or a mixture:
(i)
air
(ii)
carbon dioxide
(iii)
copper oxide
(iv)
oxygen
(v)
copper
(vi)
brass
SI units
4.
(a)
Complete the following table giving details of the seven fundamental
(SI) units:
Physical Quantity
Unit
Abbreviation
Length
kilogram
Time
A
K
Amount of Substance
Luminous intensity
(b)
candela
Complete the following table giving details of the most common derived
(SI) units:
Physical Quantity
Unit
Abbreviation
Volume
newton
J
pascal
W
Electric Potential
Definition in
fundamental units
1/ 3
(c)
Complete the following table for decimal fractions or multiples:
Fraction
103
Prefix
Symbol
Multiple
103
femto
micro
Prefix
Symbol
mega
G
n
1012
5.
Convert:
(a)
23.17C to K
(b)
300K to C
(c)
a change in temperature, T, of 10C to a change in temperature in
degrees kelvin
15 cm3 to m3
(e)
the density of mercury which, is 13.59 g/cm3 at 20C, to its density in
kg/m3.
6.
Ans:15 x 106 m3
(d)
Ans: 13.59 x 103 kg/m3
Mercury pollution has serious consequences for health since mercury, a
cumulative poison, eventually results in irreversible brain damage. A sample
from a lake of surface area 100 km2 and average depth of 5.0 m was found to
contain 0.50 g Hg cm3. What is the total mass (kg) of Hg in the lake?
Ans: 2.5 x 105 kg
Significant Figures
When doing calculations it is important to report your answer to the precision
required for the problem. For example, 1.4 g is not the same as 1.40 g.
RULES FOR SIGNIFICANT FIGURES
Addition and Subtraction
Add or subtract the numbers, then round off the result to the least number of decimal
places in the set of numbers, e.g.,
11.62 + 4.052 + 164.6 + 3.8802 = 184.1522
Now round off to 1 decimal place: 184.2
1/ 4
Deciding whether zeros are significant
Zeros complicate matters because they serve two purposes in a number. A zero
may indicate that a given decimal place has been measured to be zero and hence is
significant; or it may be used to indicate the position of the decimal point, in which
case it is not a significant figure. Hence 0.0123 has three significant figures; 0.1060
has four; 0.01200 has four; 101.0010 has seven. To avoid confusion, write the
numbers in exponential notation; in this way the exponent locates the decimal point
and only significant figures are included in the base:
1.23
1.060
1.200
1.010010
x
x
x
x
102
101
102
102
-
3 significant figures
4
“
“
4
“
“
7
“
“
Multiplication and Division
Express the answer to the same number of significant figures as does the factor
having the smallest number of significant figures.
Hence
 2.56 1.9  3.725 
 6.02 x 1023   0.00171
has the answer 1.760059062 x 1020 on a calculator. Since the second factor in the
numerator (1.9) only has two significant figures, the answer should be 1.8 x 1020.
7.
The mass of a body is 1.040 kg, and its speed is 13.341 m s1. The kinetic energy
of the body is given by KE = ½ mv2. Substituting these values into the
formula on a calculator yields the answer 92.55078612 J. How should the KE
of the body be reported?
Ans: 92.55 J
8.
Perform the following mathematical operation and express each result to the
correct number of significant figures.
(a)
4.02 x 163.2 x (38.602  1.0443)
Ans: 2.46 x 104
(b)
9.
A percent calculation:
8.943
x 100
9.024
Ans: 99.10
Explain in your own words the difference between accuracy and precision
when applied to a set of measurements.
1/ 5
2:
Atoms, Molecules and Ions
10.
(a)
(b)
11.
Which of the following are pairs of isotopes?
2 
3
(i)
and 13 H
(ii)
and 24 H e
1H
2H e
4

14 
12
3
(iii)
(iv)
1 H and 2 He
6 C and 7 N
If an anion X-1 of an element X has 64 nucleons and 31 electrons, what
is the mass number of the element? Identify X.
(a)
Name the elements represented by the following symbols.
(i)
Mg and Mn
(iv)
Pt and Pd
(ii)
Si, Sc and S
(v)
Rb and Br
(iii)
Ag and Au
(b)
Give symbols for the following elements:
tin, lead, iron, mercury, sodium, potassium and phosphorus.
12.
Using the periodic table to guide you, predict the formula and name the
compound formed by the following elements:
(a)
Ga and F
(b)
Li and H
(c)
Al and I
(d)
K and S
13.
Give the chemical formula of the chlorite ion, the chlorate ion, the perchlorate
ion and the hypochlorite ion.
14.
(a)
(b)
15.
(a)
(b)
Write the chemical formula for
(i)
copper(II) oxide
(ii)
iron(III) carbonate
Name the compound: SnO
Give the names of: SF6 and IF5.
Give the chemical formulas for: dinitrogen tetroxide and
tetraphosphorus hexasulphide.
Solutions to tutorials will be posted on line at the end of the week that the tutorial is
done. They will stay online for one week only. They are not available from the
Department once they have been taken down.