2 1.2: Identify that indicators such as litmus, phenolphthalein, methyl
orange and bromothymol blue can be used to determine the acidic or
basic nature of a material over a range , and that the range is identified
by change in indicator change
2.1.1 Aim: To prepare acidic and
alkaline solutions of different
concentrations and use
these to investigate the
colour change in a range of
2.1.3 Safety inspection: Wear safety goggles. Sodium
hydroxide is caustic (able to burn or corrode
organic tissue) and hydrochloric acid is corrosive.
Avoid contact with skin. If contact occurs, wash
with plenty of water and soap.
3 1.3: Identify and describe some everyday uses of
indicators including the testing of soil acidity/basicity
3.1 Soil Testing
Some plants grow best in acidic soils; others need slightly alkaline (basic) conditions. Farmers and keen gardeners use simple test kits containing an indicator and colour chart, to test the soil. They can then adjust the soil pH to get the best results
3.2 Water Testing
Swimming pools need regular testing for acidity to better maintain their water quality and hygiene. Aquariums must be maintained at very specific pH levels for the health of their inhabitants.
3.3 Effluent (Liquid waste or sewage) Testing
We can use indicators to assess the acidity levels of certain types of pollution from industries. Industry technicians and government authorities use indicators to monitor the pH of waste water and natural waterways.
4 1.4: Perform a first hand investigation to prepare and test a natural indicator
4.1 Aim: To prepare an indicator solution from red
cabbage and test the resulting indicator on a
range of substances
4.2 Safety Inspection: Wear safety glasses. Sodium hydroxide is
caustic and hydrochloric acid is corrosive. Avoid contact with
skin. If contact occurs wash with plenty of water.