Hodder Science catalogue 2024 - Flipbook - Page 25
WJEC GCSE
Student Books
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Adrian Schmit, Jeremy Pollard
Develop your students’ scientific thinking and practical skills.
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• Provide support for all WJEC specified practicals
• Support the mathematical and working scientifically requirements
• Provide opportunities for co-teaching with Double Award content clearly
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Biology • 9781471868719
Chemistry • 9781471868740
Physics • 9781471868771
Welsh language Biology • 9781510400313
Welsh language Chemistry • 9781510400320
Welsh language Physics • 9781510400337
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Water
▶ Drinking water
Water is essential for life
and so it is important that
everyone has
access to enough clean
drinking water. Already,
in many areas of the
world, people are struggling
to get enough good quality
water. Even in developed
countries, increasing demands drinking
for a variety of uses are
for water
putting
warming has affected rainfall strains on the water supply. Global
patterns and, if these effects
there could be problems
continue,
in supplying water to some
populations.
This section describes the
main issues in the future
water.
for drinking
Specification coverage
This chapter covers specifi
cation Unit 1, Topic 1.3 (Chemistry)
and Unit 2, Topic 2.3 (Double
award) and is called Water.
It covers the composition and
treatment of the water supply,
including fluoridation. Different
types of water hardness are
described, related to the ions
and equations involved.
Look inside
Reducing water consumptio
n
Over the last 100 years, water
consumption has steadily
world (see Figure 3.2). Some
risen across the
of
of water in homes, but there this rise has been due to increased use
has also been a steep rise
in the
water used by industry. In
the home, people are encouraged amount of
water consumption by taking
to reduce
the following measures:
▶ What’s in our water?
vegetables.
Dissolved
gases
Microorganisms
Pollutants
Figure 3.1 Swimming in a complex
solution.
2
s inhabit every place
including water. Natural
supplies of water will contain on Earth,
numbers of bacteria and
other forms of microscopic vast
life. Some
of these microorganism
s can cause disease and so
it is inadvisable
to drink untreated water
from
treatments remove harmful, rivers, lakes and streams. Water
but not all microorganism
s.
▶ Pollutants. Most
of the water
by travelling over or through in rivers and lakes arrives there
pick up pollutants. Chemical soil and rock, and en route it can
fertilisers and pesticides
to farm land and animal
applied
wastes
and lakes by rainfall. Sometimes,can be washed through to rivers
pollutants may be deliberately
dumped into water, although
there are legal measures
to try to prevent this.
in the UK
before using it.
6,000
5,000
▶ Microorganisms.
Microorganism
lons
running when cleaning
Try free for 30 days!
your teeth or rinsing
▶ Having a water meter
ûtted so that water use
can be monitored.
▶ Ensuring your washing
FFigure
iggure 3.2 Global water consumption
and
projection of
o future use 1900–2025
m3)
Solute Chemical which is dissolved
in a
solvent to form a solution.
▶ Taking shorter showers.
▶ Re-using bath or sink
water for watering plants.
▶ Having toilets with
a setting to allow a smaller
üush.
▶ Insulating water pipes
to reduce the chances of
bursting in winter.
▶ Not leaving water
Consumption (billions
Key term
View sample material
from WJEC GCSE
Chemistry
The one chemical formula
that almost everyone knows
for water, H O. That is the
is
formula for the compound, the one
2
we encounter every day
but the water
has a lot more in it than
just hydrogen and
oxygen. Whether it is tap
water, rain, spring water,
river water or the
sea, the water is far from
8pure9. In science lessons,
you will often
use distilled water rather
than tap water, because
distilled water has
many of the impurities
removed. So, what are these
impurities? We
will look at tap water later
in this chapter, but for the
just consider what is in
moment, let9s
8natural9 water supplies
(Figure 3.1):
▶ Solvents. Water is
a great solvent, and all sorts
of things dissolve
in it. The solutes fall into
two categories:
▶ Ions of many sorts.
As water
it dissolves many chemicals, runs over or through the ground,
which form ions in the
Some of the most common
water.
ions found are sodium,
magnesium, sulfate, hydrogencarbo
calcium,
nate and chloride.
▶ Dissolved gases. The
gases in the atmosphere
can dissolve
water to different extents.
The most important dissolved in
are oxygen (which aquatic
organisms need for respiration)gases
and carbon dioxide (needed
by plants to make food
photosynthesis).
by
Drinking water
3
4,000
machine or dishwasher
has a full load
Key
World
Europe
North America
South America
Africa
Asia
Australia & Oceania
Request eInspection
Copies on our website
3,000
2,000
1,000
500
0
1900 1940 1950 1960
Discussion points
Dis
Why do yo
you think water
consumpti
consumption has increased
steadily over
ov the last 100 years?
Key term
Desalination
D
esalination R
Removing salt from sea
water to convert
con
it into water fit for
drinking.
Abstracting water
1970 1980 1990 1995
Year
2000 2010 2025
Abstraction is the term
used
temporarily or permanently) for extracting water (either
like pumping underground for human use. This includes things
water to the surface, building
reservoirs, taking water
dams and
from
and desalinating sea water. rivers or lakes, collecting rainwater
Some of these measures
may
because of their environmental be opposed by local populations
impact. This is especially
with the building of dams
the case
and reservoirs, both of
which require the
üooding of large areas of
land, destroying habitats
and altering the
appearance of the area.
3
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