Acids (C1.1)

Acids (C1.1)

1. Indigestion

   • Stomachs produce HCl to help digest food. It kills bacteria and enzymes break down the food we eat.
     • The stomach can produce too much acid, causing heart burn or indigestion. To stop this, we use antacids. Antacids are bases- bases are substances which neutralise acids.
       • All neutralisations between an acid and a base produce a salt and water. acid+base= salt+water
         • Some bases are soluble. A base which has been dissolved in water is called an alkali.
         • carbonates also produce Carbon Dioxide.

2. Neautralisation

   • Hazard symbols are used to warn people how dangerous an acid may be. They display images which represent corrosive, irritant, flammable and toxic, as well as many others.
     • There are three substances which are used for neautralisation: metal hydroxides, metal oxides and metal carbonates. Metal oxides and hydroxides both produce a salt and water when reacted with an acid, however metal carbonates produce carbon dioxide as well.
     • The three types of acid all also produce specific salts. Sulfuric acid produces sulfates, nitric acid produces nitrates ad hydrochloric acid produces chlorides.

3. Electrolysis

   • Electrolysis is the decomposition of compounds using electricity. Hydrochloric acid is made up of chlorine and hydrogen, so when it is elctrolised, it becomes chlorine and hrydrogen.
   • The electrolysis of water produces oxygen and hydrogen. To test for these gases there are two experiments. Hydrogen is tested sing the squeaky pop test. To do this you hold up a burning splint to the gas, if it causes a squeaky pop, the gas is hydrogen. To test for oxygen you hold a glowing splint up to the gas. If the gas is oxygen the splint will relight.

4. The importance of chlorine

   • Chlorine can be obtained from the electrolysis of sea water (brine). This is because sea water contains an abundance of chloride salts.
     • To test for chlorine we use a piece of damp blue litmus paper. We hold it up to the gas and if it turns red and then white the gas is chlorine. All acids will turn the paper red, however it is only chlorine which bleaches it- turning it white.
   • Chlorine is yellowy-green, toxic and it has many uses. Some of these include; to clean pools (it kills bacteria), to treat water and kill microorganisms, in manufacturing bleach and other cleaning products, to manufacture plastics (specifically pollycloroethene or PVC)
     • However there are some problems caused by the use of chlorine. About 45 million tonnes of chlorine are produced everyday with the use of electrolysis, and some of it leaks. As chlorine is toxic this can be incredibly dangerous.

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