Acids And Alkalis Flashcards
What is an acid?
An acid has a pH that is lower than 7. The lower the pH the stronger it is. Weak ones can taste sour, strong ones are corrosive.
What can acids be useful for?
- Citric acid is found in citrus fruits (lemon, lime, orange, etc.)
- Hydrochloric acid is our stomach acid, and it helps us digest food
- vinegar (Ethanoic acid) is used as a preservative
- Omega 3 fatty acids protect us from certain diseases
- Sulphuric acid is used in car batteries
- the bacteria in your mouth create acid to help digest food
- Methanoic acid is very useful to bees and nettles
- Tap water is very slightly acidic.
What are the dangers of acids?
Acids of a certain pH can be corrosive.
Other than this, weaker acids may also be toxic. Weaker acids could also be irritant. Most strong acids are also an environmental hazard.
What colour do indicators turn with an acid?
Litmus paper turns red, when dipped in an acid.
Universal indicator will be a warm colour, somewhere from an olive colour if it is very weak, to bright red if it is very strong.
What is an alkali?
Alkalis have a pH that is above 7. Weak ones feel soapy, and strong ones are caustic.
What can alkalis be useful for?
- Sodium hydroxide is used to make paper, detergents and soap
- Potassium hydroxide is used in farming to make acidic soil more alkaline so that plants will grow better in it
- Potassium hydroxide is also used as an electrolyte in alkaline batteries
- alkalis can be found in toothpaste (but they are very weak and not very concentrated
How can alkalis be harmful?
Strong alkalis can be caustic or an environmental hazard. Weak alkalis can be irritant.
How do indicators react to alkalis?
Alkalis turn litmus paper blue.
Universal indicator will become a cold colour, the weakest being a turquoise and the strongest being a deep purple.
What is neutralisation?
A neutral substance is neither acidic nor alkaline. Neutralisation is a chemical reaction that involves an acid and an alkali joining to have a pH of 7. Universal indicator or litmus paper turns bright green if dipped in a neutral substance, such as distilled water.
