Agriculture: the pH of soil affects which crops can be grown. Farmers and gardeners always check the pH of their soil. If the soil is too acidic, most crops will not grow well. Farmers can spread powdered limestone (calcium carbonate) on acidic soil to raise its pH.
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Fig. 13.3.5 Testing the pH of soil
Learn more about soil pH in Biological World 6.2
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Treating indigestion: heartburn is caused by too much hydrochloric acid in the stomach. Indigestion remedies, such as Milk of Magnesia, are made up of a base that will neutralise this acid. The acid in the stomach and the base in the tablet react to give salt and water.
z Which indigestion remedy is best?
Plan, design, carry out and write up an investigation to determine the most effective indigestion remedy.
1. What prior knowledge will you use to help you design this activity? 2. How will you ensure you carry out a fair test? 3. What factors will you measure to find out how effective an indigestion tablet is? 4. What will your results table look like? 5. What graph will you use to best represent the data you have collected?
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Personal hygiene products: toothpaste is slightly basic to neutralise the plaque acid in your mouth. Shampoo is also slightly basic to balance the slight acidity of hair. Conditioner is slightly acidic to neutralise the effect of shampoo on the hair and make hair more manageable and shiny.
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Treating stings and bites: bee stings and ant bites are acidic. This is why the skin around the sting becomes inflamed and irritated. Rubbing bicarbonate of soda (sodium hydrogencarbonate) on the area can neutralise the acidity of the sting.
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Personal hygiene products balance the body’s natural pH
230 Suggesting a cure
Wasp stings are alkaline. As a class, discuss possible remedies to relieve the symptoms of a wasp sting.
