Chapter 10

. Method: add a few drops of your test solution to white anhydrous copper (III) sulphate . Positive test: turns from white to blue

. Method: add a few drops of your test solution to blue cobalt (II) chloride paper . Positive test: turns from blue to pink (+ gets hot)

. Pure: contains one substance -> has defined properties . Method: 1) heat sample in a beaker over a Bunsen 2) use a thermometer to measure the temperature at which the sample changes from a liquid to a gas . Positive test: if you find boiling point isn’t 100°C (or melting point 0°C -> solid to liquid) then sample isn’t pure

. Distilled water is used rather than tap water as it contains fewer chemical impurities -> These can interfere with reactions and give experiments of false result

• water from natural resources aren’t pure -> contains impurities, which are useful or harmful substances

. Dissolved oxygen: for aquatic life . Some metal compounds: provide essential minerals for aquatic life

. Some metal compounds: are toxic . Sewage: contains harmful microbes, which cause disease . Some plastics: harm aquatic life . Nitrate + phosphates: lead to deoxygenation of water and damage to aquatic life

. Removes solids

. Removals tastes and oudours

. Kills microbes

. Fertlisers containing nitrogen, phosphorus and potassium -> for improved plant growth - E.g. ammonium salts are nitrates are used as fertilisers

. 78% nitrogen . 21% oxygen . Remaining 1% is a mixture of noble gases and carbon dioxide (0.04%)

. Source: complete combustion of carbon containing fuels . Adverse effect: higher levels of carbon dioxide lead to increased global warming -> climate change

. Sources: incomplete combustion of carbon containing fuels. . Adverse effects: toxic gas

. Source: incomplete combustion of carbon containing fuels. . Adverse effect: increase risk of respiratory problems and cancer

. Source: decomposition of vegetation and waste gases from digestion in animals . Adverse effect: higher levels of methane lead to increased global warming -> climate change

. Source: car engines . Adverse effect: acid rain, photochemical smog and respiratory problems.

. Source: combustion of fossil fuels, which contain sulphur compounds . Adverse effect: acid rain

. Greenhouse gases: gases such as methane and carbon dioxide, which cause global warming

1) the Sun emits thermal energy, which passes through earths atmosphere 2) some of this thermal energy is reflected back into space + rest absorbed by earths surface 3) earths surface then emits thermal energy back out towards space -> greenhouse gases act like an insulating layer and absorb most of the thermal energy that would normally be lost into space and re-emit it in all directions including back towards the Earth -> this warms the earths surface

. Planting trees: carbon dioxide is removed from the atmosphere by plants during photosynthesis -> in the presence of chlorophyll and using energy from light

Lowers methane emissions

. Lowers carbon dioxide emissions

(eg wind, solar) . Lower is carbon dioxide emissions