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Chemistry
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Ant Wasp Nettle leaves
Figure 5.9: Organisms which produce acids and alkalis
Relieving indigestion
Indigestion is a discomfort in the stomach that is associated with difficulty in
digesting food. It is caused by the presence of excess acid like hydrochloric acid
in the stomach. The excess acid can be neutralised by taking a liquid or tablets that
contain magnesium or sodium hydrogencarbonate commonly known as antacids.
Soil treatment
Most plants grow well in soils that have optimal pH values. When soils are too
acidic, for example, due to applications of ammonium based fertilisers, chemicals
such as calcium oxide (quicklime) and calcium hydroxide (slaked lime) are added
to adjust the soil pH (Figure 5.10). Such chemicals that neutralise the soil acidity
are called liming materials.
Figure 5.10: Soil liming
Treating factory wastes
Liquid wastes from factories often contain acids and bases. If the wastes get into
water bodies such as lakes, ponds and rivers, they can harm aquatic organisms like
fish. Acidic wastes can be controlled by adding bases such as calcium hydroxide
to neutralise them.
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