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House hold substances

House hold substances. Recall household substances which are acids or bases and the properties of acids and bases Determine the strengths of acids and bases using universal indicator solution and the pH scale. Acids in the home.

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House hold substances

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  1. House hold substances Recall household substances which are acids or bases and the properties of acids and bases Determine the strengths of acids and bases using universal indicator solution and the pH scale

  2. Acids in the home • Acids are very common substances that are used widely in everyday life. • Some occur naturally, and some are synthetic or man-made. • Some acids can be dangerous because they are corrosive, they can eat away metals and burn your skin. E.g. Car batteries contain sulfuric acid (H2SO4) • However, many acids are safe to eat and drink. They have a sour taste, e.g. citrus fruits and tomatoes which contain citric acid. Yoghurt contains lactic acid, vinegar contains ethanoic (acetic) acid, and grapes contain tartaric acid. The bubbles in soft drinks are due to carbon dioxide which dissolves in water to form carbonic acid.

  3. The hydrochloric acid in your stomach is essential for digestion • and the DNA that makes you different from everybody else is deoxyribonucleic acid. • Acids on your skin sting because they are corrosive and attack your body tissues. This is why lemon juice stings if you get it in a cut on your finger. And bees and ants sting because they inject you with formic acid. • You can eat fruit which contains acids because the acid is very dilute. A dilute acid is one which contains a large amount of water and a small amount of acid. The opposite of dilute is concentrated, and concentrated acids need to be handled with care.

  4. Bases in the home: • Bases are used in the home for two purposes. They neutralise (cancel out the effect of) acids. E.g. toothpaste is a weak base used to neutralize the acids formed by plaque bacteria on your teeth. • Bases are also used to dissolve grease and dirt. Oven cleaners and drain cleaners usually contain sodium hydroxide (NaOH, caustic soda ) which dissolves grease. • Other household cleaners contain ammonia, which can be used to remove dirt from floors or clean windows. • Bases which are soluble in water are called alkalis. The reason they feel soapy is because they turn the oils on your skin into soap

  5. Practical • Look at some of the chemicals set up around the room. We can test them to see which ones are acids and which are bases. • Aim: to test common chemicals and find out what their pH is. • Method: • Place a little of the chemical in the spotting tile. • Add 1-2 drops of universal indicator solution • Write down the colour and the pH of the substance in a table.

  6. Results:

  7. Conclusion: we tested the various pH of different chemicals and placed them on a pH scale:

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