How do geologists track the movements of continents?
Changes in magnetic patterns; linked to radioactive decay.
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How was limestone formed?
Shellfish died and formed sedimentary rocks which compacted and hardened to form limestone (a sedimentary rock). Plate movements pushed this rock to the surface, and the rocks above it eroded away to expose limestone.
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Where was coal formed?
In wet, swampy conditions when plants and ferns died and became buried.
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How was salt formed?
Rivers brought dissolved rocks into the sea, which evaporated with global warming and left the salt dry. This salt formed salt rocks.
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What does coal contain?
Fossils of the plants that formed it.
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What does limestone contain?
Shell fragments from sea creatures.
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What do ripple marks in rocks indicate?
Water flow from rivers/waves in the sea.
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What do rock salts contain?
Water/wind-eroded grains
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Formula for salt?
NaCl
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Is rock salt soluble?
Nah
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Why does rock salt have a grip?
Contains sand.
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How does salt mining contaminate water supplies?
Water could flow into the mines and let salt flow out into water supplies.
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What makes salt a hazard?
There are risks linked to consumption. These are: high blood pressure; prevents bacteria growth; heart failure; strokes
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How can risks be estimated?
Measuring salt intake.
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What colour does litmus paper turn in acids/alkalis?
Blue in alkalis; red in acids.
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What are alkalis used for?
Dying clock; neutralising acid soil; making soap; making glass.
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What can be used to neutralise acidic soils in coastal areas?
Seaweed ash (soda), or seaweed.
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What is the LeBlanc process used for?
Manufacturing alkali.
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Describe the LeBlanc process?
Salt and limestone is reacted and heated with coal to make sodium carbonate, which gives off large amounts of hydrogen chloride.
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The downside to the LeBlanc process?
Produces a lot of solid waste that gives off hydrogen sulphide (a toxic gas).
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How were the harmful gases produced by this method turned into useful substances?
Oxidation turned hydrogen chloride into chlorine. Chloride was used to bleach textiles prior to dying, and hydrochloric acid creates other chemicals.
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What are alkalis?
Soluble metal hydroxides or carbonates with a pH greater than 7. Blue/lilac colour.
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Hydroxide + Acid ->
Salt + Water
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Carbonates + Acid ->
Salt + Water + CO2
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What does the electrolysis of brine produce? How?
Chlorine gas, hydrogen gas, sodium hydroxide; by breaking up compounds using electricity.
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What is an anode?
Positive electrode.
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What is a cathode?
Negative electrode.
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Which elements attract to which cathode during electrolysis?
Chlorine forms at the anode, and hydrogen at the cathode.
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What is chlorine used for?
Making PVC/plastics; medicines; crop protection.
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What is hydrogen used for?
Margarine; rocket fuel; fuel cells in vehicles.
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What is sodium hydroxide used for?
Paper recycling; industrial cleaners; refining aluminium.
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How do we assess the level of risk in a chemical?
How much causes harm; how much of it is useful; how likely it is to escape into the environment; who/what it affects.
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What does LCA stand for?
Life cycle assessment.
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What is a Life Cycle Assessment?
It measures the energy used to make, use and dispose of a substance, and the environmental impacts of all 3.
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What do we need to consider at each stage of an LCA?
How many natural resources are needed; how much energy is needed; how much water and air is used; how is the environment is affected?
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Other cards in this set
Card 2
Front
How do geologists track the movements of continents?
Back
Changes in magnetic patterns; linked to radioactive decay.
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