Worked solutions to student book questions
Chapter 1 What is chemical analysis?
Q1.
Classify the following analyses as qualitative or quantitative:
a an analysis that showed that Vegemite contains 0.55 mg of vitamin B1 and
0.80 mg of riboflavin per 5 g
b detection of toxic materials in the gaseous discharge from a factory
c confirmation of the presence of lead in a sample of blood
d comparison of the concentrations of trace elements in glass fragments removed
from the skin of a ‘hit-and-run’ accident victim with those in the glass fragments
from the broken headlights of a suspect’s car
A1.
a
b
c
d
quantitative
qualitative
qualitative
quantitative
E1.
Explain how qualitative analysis and quantitative analysis of metals in oil are used to
identify wear of engine components.
AE1.
Qualitative analysis is used to determine which metals are present.
Quantitative analysis indicates the amount of each metal present.
E2.
What analytical techniques are used to determine the level of metals in oils?
AE2.
atomic emission spectroscopy, atomic absorption spectroscopy
Q2.
Look at Table 1.1 on page 8 of the student book. List the techniques from the table
that are based on the:
a physical properties of the substance being tested.
b chemical properties of the substance being tested
A2.
a
Based on physical properties of sample – gravimetric analysis, mass
spectrometry, spectroscopic analysis, chromatography*
b Based on chemical properties of sample volumetric analysis, chromatography*
* It could be argued that chromatography is partly physical change and partly
chemical change as weak bonds are formed when molecules adsorb to a surface.
Heinemann Chemistry 2 4th edition Enhanced
Copyright © Pearson Australia 2010 (a division of Pearson Australia Group Pty Ltd)
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Worked solutions to student book questions
Chapter 1 What is chemical analysis?
Chapter review
Q3.
Think back to when you first got up this morning. List every product with which you
were in contact during the first 30 minutes you were awake.
a How many of these products are made from materials that have been processed?
b How many are unprocessed?
c Is there any evidence that any products you have listed were subject to some
process of quality control?
A3.
Individual response required.
Q4.
The ingredients of a bottle of jam are listed on the label as ‘sugar, strawberries, pectin
and food acid (citric acid)’.
a Is this an example of qualitative or quantitative analysis?
b Rewrite this label so that it is an example of analysis of the other type.
A4.
a
b
qualitative analysis
A quantitative analysis might be reported as ‘500 g of this produce contains
approximately 300 g sugar, 100 g fruit, 500 mg pectin and 400 mg food acid’.
Q5.
Which of the following represent example(s) of quantitative analysis?
i A sample of ‘fries seasoning’ contains salt, chicken extract, rice flour, paprika
and chilli.
ii Dry air contains 78% nitrogen vol/vol.
iii A sample of iron ore weighs 23.5 kg.
iv A chocolate biscuit contains 2.3 g protein, 6.6 g fat and 24.4 g carbohydrate per
100 g serve.
A iv only
B i and iv
C ii and iv
D ii, iii and iv
A5.
C. Quantitative analysis gives information about the concentration of a material or
materials in a sample; this can be in terms of w/w, v/v, ppm, %, mol L–1, etc.
Statement I does not give the concentration of the substances. Statement III gives the
mass of the sample but not the concentration of iron ore.
Heinemann Chemistry 2 4th edition Enhanced
Copyright © Pearson Australia 2010 (a division of Pearson Australia Group Pty Ltd)
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Worked solutions to student book questions
Chapter 1 What is chemical analysis?
Q6.
Analytical chemists use a variety of techniques. Give an example of the information
provided by each of the following techniques.
a gravimetric analysis
b volumetric analysis
c chromatography
d spectroscopy
A6.
Some examples which might be included are:
a water content in food
b alcohol content of wine
c amount of a pesticide in food
d structure of a drug or biologically active compound.
Q7.
Research a consumer good whose purity is currently making news. Find out how this
product is analysed.
A7.
Answer depends on the consumer good selected. Table 1.1on page 8 of the student
book provides a guide.
Q8.
Many of the foodstuffs we purchase are subject to quality control and a summary of
their contents is often printed on the label.
a Give three examples of substances that may be found in food and which are
analysed by chemical means.
b How can the information provided in a list of ingredients be used by the
consumer for their benefit?
A8.
a
b
salt content, nutritional values, level of pesticides
information of nature and amount of contents
identify substances to which a person may be allergic
amount of active ingredient – used to compare cost effectiveness of various
brands of the same product.
Q9.
Obtain several brands of spring water and compare the information provided on the
labels.
a What evidence is there that the water has been subject to quality control?
b How might this control have been carried out?
c Compare the ions that that each contains. Are all samples of spring water the
same? How do they differ?
Heinemann Chemistry 2 4th edition Enhanced
Copyright © Pearson Australia 2010 (a division of Pearson Australia Group Pty Ltd)
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Worked solutions to student book questions
Chapter 1 What is chemical analysis?
A9.
a
b
c
list of ingredients
chemical analysis
Different brands of spring water may contain different mineral ions or different
amounts of each depending on its source.
Heinemann Chemistry 2 4th edition Enhanced
Copyright © Pearson Australia 2010 (a division of Pearson Australia Group Pty Ltd)
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