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1) Cooking changes the appearance and composition of foods.
Using your knowledge of chemistry, comment on the changes to food that
may occur during cooking.
2) A TV programme was reproducing a pharmacy from the 19th century
and planned to use the original 19th century pharmacy jars that had
been kept in a museum. The TV company wanted to know what
compounds the jars were likely to contain now.
Substances used in pharmacies over a hundred years ago included:
• Essential oils dissolved in ethanol.
Some molecules included in these essential oils were:
 Ointments that contained animal fats like lard, beef fat or beeswax.
Using your knowledge of chemistry, comment on what compounds the old
pharmacy jars might contain now. (Specimen)
3) Argon was discovered in 1890s when samples of nitrogen prepared by
different methods were compared. The element name was derived from
the Greek argos, which means “lazy one”.
Two samples of nitrogen can be prepared as shown.
Method 1 Removing carbon dioxide and oxygen from the air.
Method 2 Reaction of sodium nitrite with ammonium chloride.
NaNO2(s) + NH4Cl(s) → NaCl(s) + N2(g) + 2H2O(ℓ)
Heated magnesium metal can react with nitrogen gas to give magnesium
3Mg(s) + N2(g) → Mg3N2(s)
Using your knowledge of chemistry, comment on the discovery and naming of
4) Ageing of wines
Wine is a complex combination of many chemical compounds, which
change as they interact with each other and their environment to give
the wine its character.
A perfectly aged wine will have an optimal combination of three things:
fruit flavours, fermentation flavours, and ageing flavours.
The wine-making process has two phases; the maturation phase and the
ageing phase.
During the maturation phase, the grape juice is first fermented in large
vats producing ethanol and smaller amounts of higher alcohols such as
3-methylbutan-1-ol and butan-2,3-diol. Exposure to oxygen at this stage
causes the yeasts in the grape skins to multiply and allows other
chemical reactions to take place. The wine is then transferred to wooden
barrels and allowed to mature.
After maturation the wine is bottled and allowed to age. Wine experts
recommend that bottled wine is stored at a constant 13ºC. At this
temperature desirable chemical reactions take place slowly but
unwanted chemical reactions are unable to take place.
Using your knowledge of chemistry, comment on how the maturation
and ageing processes might affect the character of the wine.
5) Traces of a liquid were discovered in a bottle believed to contain
perfume belonging to Queen Hatshepsut, ruler of Egypt over 3500 years
Perfumes were made by dissolving plant extracts containing pleasant
smelling terpenes and esters in an edible oil. A little ethanol and water
may also have been added.
Using your knowledge of chemistry, comment on the possible smell(s)
when such a bottle is opened after being stored for thousands of years.
6) Hydrogels are used in disposable nappies. They are fine powders that
can absorb up to 500 times their own weight in water.
A hydrogel is a very long molecule with carboxyl groups at regular
intervals along its length. A short section of a hydrogel molecule is
shown below.
Hydrogels are extremely good at soaking up water because the water
molecules are strongly attracted to them.
Using your knowledge of chemistry, comment on how suitable
hydrogels would be for absorbing liquids or solutions spilled in a
chemistry lab.
(Revised, 2012)
7) The flavour and texture of chocolate comes from a blend of compounds.
Using your knowledge of chemistry, describe how you could show that
there are ionic compounds and covalent compounds present in
8) Cooking involves many chemical reactions. Proteins, fats, oils and esters
are some examples of compounds found in food. A chemist suggested
that cooking food could change compounds from being fat-soluble to
Use your knowledge of chemistry to comment on the accuracy of this
(Revised, 2013)
9) Blocked drains can be very unpleasant. Common causes of blocked drains
in homes are fats, hair and food waste.
Using your knowledge of chemistry, comment on chemical methods
that might be used to unblock drains.
(Revised, 2014)
Desirable characteristics for a supermarket ready meal are that it:
• has good flavour;
• retains its appearance and texture;
• has a long shelf life.
Using your knowledge of chemistry, comment on how manufacturers
can achieve these characteristics.
Patterns in the Periodic Table
The periodic table is an arrangement of all the known elements in order of
increasing atomic number. The reason why the elements are arranged as
they are in the periodic table is to fit them all, with their widely diverse
physical and chemical properties, into a logical pattern. Periodicity is the
name given to regularly-occurring similarities in physical and chemical
properties of the elements.
Some Groups exhibit striking similarity between their elements, such as
Group 1, and in other Groups the elements are less similar to each other,
such as Group 4, but each Group has a common set of characteristics.
Adapted from Royal Society of Chemistry, Visual Elements (rsc. org)
Using your knowledge of chemistry, comment on similarities and
differences in the patterns of physical and chemical properties of elements
in both Group 1 and Group 4.
(Revised, 2015)
12) Occasionally, seabirds can become contaminated with hydrocarbons
from oil spills. This causes problems for birds because their feathers lose
their waterproofing, making the birds susceptible to temperature changes
and affecting their buoyancy. If the birds attempt to clean themselves to
remove the oil, they may swallow the hydrocarbons causing damage to their
internal organs.
Contaminated seabirds can be cleaned by rubbing vegetable oil into their
feathers and feet before the birds are rinsed with diluted washing-up liquid.
Using your knowledge of chemistry, comment on the problems created for
seabirds by oil spills and the actions taken to treat affected birds.
(New 2015)
The viscosity of alcohols depends on a number of factors:
• the strength of intermolecular forces
• the size of the molecule
• temperature
These factors can be investigated using alcohols and apparatus from the
lists below.
measuring cylinders
plastic syringes
glass tubing
metre stick
ball bearing
clamp stands
Using your knowledge of chemistry, identify the alcohols and apparatus
that you would select and describe how these could be used to
investigate one, or more, of the factors affecting the viscosity of
The chemical industry creates an immense variety of products
which impact on virtually every aspect of our lives. Industrial scientists,
including chemical engineers, production chemists and environmental
chemists, carry out different roles to maximise the efficiency of
industrial processes.
Using your knowledge of chemistry, comment on what industrial
scientists can do to maximise profit from industrial processes and
minimise impact on the environment.