Natural sciences
Reactions that occur between different kinds of matter: acids and bases
Educator section
Memorandum
Leaner section
Content
Activity: to name well-known acids and bases and their functions [lo 2.1]
(A) ACIDS AND SOME OF THEIR FUNCTIONS
- Hydrochloric acid
used for cleaning brickwork and cement;
reduces the pH levels of swimming pool water.
- Nitric acid
used in artificial fertilisers, dyes and explosives;
present in plastics.
- Sulphuric acid
probably the most important acid in South Africa;
an effective drying agent;
used in the preparation of fertilisers, dyes, paper and glue.
- Phosphoric acid
used to flavour cold drinks;
used by dentists in dental cement.
- Boric acid
used in many disinfectants;
an effective germicide.
- Citric acid
the acid contained in oranges (citrus fruit).
- Oxalic acid
the acid contained in tomatoes.
- Tartaric acid
used in baking powder.
- Acetylsalicylic acid
the acid in aspirin tablets.
- Ascorbic acid
this is vitamin C.
- Lactic acid
the acid formed when milk turns sour;
lactic acid is also formed in muscles, particularly after vigorous exercise.
(B) BASES AND SOME OF THEIR FUNCTIONS
- Sodium hydroxide
used in the manufacturing of soap;
(also known as caustic soda)
used as a cleanser in drainage pipes.
- Calcium hydroxide
present in milder soaps;
(lime water/whitewash)
used in the agricultural and building.Industries
- Magnesium hydroxide
this is used as a purgative, as well as for other purposes (purgatives encourage the evacuation of the bowels).
- Ammonia
is a general domestic cleaning agent;
is used as smelling salts (sal volatile) because of its pungent smell;
also is an ideal stain remover
Test:
Try to list at least eight acids and three alkalis and their uses (on a separate sheet of paper).
Assessment
Learning Outcome 2: The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.
Assessment Standard 2.2: We know this when the learner categorises information.