acid - a substance
is an acid or is acidic if it has pH less than 7. Acidic substances
turn universal indicator red, orange or yellow.
algae - a very
simple type of plant, that lives in water, or on moist ground.
- the chemical name for limestone. Its formula is CaCO3.
All carbonates are insoluble in water. Calcium carbonate is one
of the minerals responsible for hard water.
carbon dioxide -
a compound made up of one atom of carbon and 2 atoms of oxygen.
Its formula is CO2. Carbon dioxide is a non
metal oxide and is acidic. It is present in tiny amounts in the
atmosphere, less than 0.035%. When plants and animals respire they
give out CO2. Carbon dioxide is also added
to the atmosphere when fossil fuels, like petrol, are burnt. Plants
remove carbon dioxide when they make their own food, by the process
of photosynthesis. Carbon dioxide is also removed when it dissolves
in water to produce insoluble carbonates and soluble hydrogen carbonate
- the physical change in which a cooled gas turns into a liquid.
a substance in which two or more elements are chemically combined.
- what happens to lakes and rivers if too much nitrate gets into
the water. Nitrates are from fertilisers. The nitrates encourage
algae to grow. This cuts out light to water plants that live below
the surface. Without light, the plants die and rot away. This removes
all the oxygen in the water and all life in the water dies!
- the physical change during which a liquid turns to a gas at a
temperature below the boiling point.
- a chemical that provides the necessary nutrients for plants to
filtrate - the
clear liquid obtained during filtration. This is the liquid that
comes through the filter funnel.
gypsum - a mineral
found in rocks. Its chemical formula is CaSO4.2H2O,
- Water that contains calcium and magnesium ions. This type of water
will not form a stable lather with soap.
- describes a chemical that does not dissolve in a solvent.
- the common name for calcium carbonate. Limestone is a sedimentary
- all liquid and solid forms of water that fall from the atmosphere.
- an insoluble chemical produced during a chemical reaction.
- water which contains more sodium ions than hard water. Soft water
makes soaps form a lather (bubbles) better than hard water. Soft
water does not make your kettle fur up.
soluble - describes
a solid chemical (e.g., salt) that dissolves in a solvent.
solvent - the
liquid (e.g., water) in which a solute dissolves to make a solution.
- a suspsension is when very small particles of a solid are suspended,
or held, in a liquid. They don't settle to the bottom of the liquid,
but instead are spread all around it.
decomposition - using heat to break a compound down into
Year 9 students using the web based water activities
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