Reactivity Tests - Metals
Chemistry: Edexcel IGCSE, topic 10.1.5
Reactions of Metals
Reactive metals with water
- Potassium, sodium and lithium all react quickly with cold water to produce a metal hydroxide and hydrogen gas.
Reactive metals with water cont.
- Potassium is the most reactive so reacts very quickly. The hydrogen produced ignites instantly and the metal also sets alight, sparking and burning with a lilac flame.
- Sodium fizzes rapidly and melts to form a ball that moves around on the water surface.
- Lithium fizzes steadily and floats, becoming smaller until it eventually disappears.
Reactions with dilute acids
- Most metals react with dilute acids to produce a salt and hydrogen gas.
- The exceptions are copper, silver, gold and platinum. They are not reactive enough to react.
- The metals that react with dilute acids but not cold water are magnesium, aluminium, zinc, iron and lead (iron and lead react slowly).
Metal extraction
- Most metals are only found as compounds because the metal has reacted with other elements in the past.
- Because of this, the metal has to be extracted from the ore where the metal compound is found.
Extraction with carbon
- Metals that are less reactive than carbon can be extracted from their oxides by reducing with carbon.
- Carbon is used because it is cheap and abundant.
- In the reduction, the metal oxide loses oxygen to form a pure metal.
- Reduction with carbon normally involves heating the metal oxide in the presence of the carbon, which is often used in the form of coal.