Acids and alkalis
- Acids are substances which produce H+ ions when we add them to water.
- Bases are substances that will neutralise acids.
- An alkali is a soluble base. Alkalis produce OH- ions when we add them to water.
- We use the pH scale to show how acidic or alkaline a solution is.
Making salts from metals or bases
- When we react an acid with a base a neutralisation reaction occurs.
- The reaction between an acid and a base produces salt and water.
- Salts can also be made by reacting a metal with an acid. This reaction also produces hydrogen gas as well as a salt.
Making salts from solutions
- An indicator is needed when we produce a salt by reacting an alkali with an acid to make a soluble salt.
- Insoluble salts can be made by reacting two solutions to produce a precipitate.
- Precipitation is an important way of removing some substances from wastewater.