One important group of chemicals is acids.
Some common acids are – hydrochloric acid, sulphuric acid, nitric acid ethanoic acid
Acids are always used in the liquid form in the laboratory.
There are many acids present in our everyday lives. Lemon juice contains citric acid, ant and nettle stings contain methanoic acid, tea contains tannic acid and vinegar contains ethanoic acid.
You can easily tell if a substance is an acid or not by its’ effect on litmus. Litmus is a purple dye which comes in the form of a solution or as strips of red and blue paper. Blue litmus paper is used for testing acids; if the paper or the solution turns red then the substance is an acid. Red litmus paper cannot be used as neutral solutions would keep the paper red as well as acidic solutions.
Acids have many properties that distinguish them from other substances. These are:
1. Acids have a sour taste, e.g. the taste of vinegar ( ethanoic acid)
2. Acids turn litmus solution red and turn blue litmus paper red also
3. Acids have ph numbers less than 7
4. Acids react with metals, forming hydrogen and a salt
5. Acids react with carbonates, forming a salt, water and carbon dioxide
6. Acids react with alkalis, forming a salt and water
7. Acids react with metal oxides, forming salt and water
* The salts of sulphuric acid are known as sulphates
* The salts of hydrochloric acid are known as chlorides
* The salts of nitric acid are known as nitrates.
Another important group of chemicals are alkalis.
Some common alkalis are – Sodium Hydroxide, Potassium Hydroxide, Calcium Hydroxide, and Ammonia
These are usually solid s but are used in aqueous solutions in the laboratory.
Alkalis are present in many cleaning substances in use in our homes today, especially in kitchen cleaners like oven spray, floor cleaners and creams for sinks. Kitchen cleaners are alkaline because they contain ammonia or sodium hydroxide,...