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L1 Acids and Bases
Definitions for AS90944 part B acids and bases
| Term | Definition |
|---|---|
| Acid | A substance that is able to donate a hydrogen ion (proton). |
| Base | A substance that is able to accept a hydrogen ion (proton). A basic solution contains hydroxide ions (OH-). |
| Alkali | A base that is soluble in water |
| Indicator | Substance that changes colour in the presence of acid or base. |
| Litmus | Red litmus- acid → red Red litmus – base →blue; Blue litmus- acid →red Blue litmus – base →blue. |
| Universal indicator | Mixture of indicators that change colour at different pH’s. pH 1→→→→→→→→→→→→→→→→→→→→→→→14; red --> orange→yellow→green→lilac →blue →purple. |
| pH | A number that represents the concentration of the hydrogen ions in a solution. |
| pH scale | A scale formed from the pH of different solutions. |
| Neutral | Having a pH of 7, ie neither acidic nor basic. |
| Neutralisation | Making an acidic solution less acidic or a basic solution less basic. |
| Antacids | Substances that are taken to relieve stomach acidity. |
| Metal salts | Ionic compounds except oxides or hydroxides. |