Reactions of Metals (GCSE Chemistry)
Reactions of Metals
Reactions with Acids and Water
Reactions with Water
- Metals can react with water and acid. As mentioned previously, the reactivity series is based on how the metals react with water and acid. These reactions occur at room temperature and do not occur with steam.
- Only highly reactive metals will react with water. Metals only react with water if they are highly reactive, such as potassium, sodium, lithium and calcium. At the end of the reaction, they form a metal hydroxide and hydrogen gas. These reactions give out a lot of heat, and can be explosive. The more reactive the metal, the more violent the reaction.
- A hydroxide and hydrogen are formed. When we react potassium with water, we will form potassium hydroxide and hydrogen gas. This is shown by the following equation.
2K(s) +2H2O(l) → 2KOH(aq) + H2(g)
Potassium + water → potassium hydroxide + hydrogen
Reactions With Weak Acids
- Metals above hydrogen in the reactivity series react with acids. The following reaction will occur.
Metal + Acid → Metal salt + hydrogen.
For example:
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
Magnesium + hydrochloric acid → magnesium chloride + hydrogen
- Some metals react explosively. Metals such as potassium, sodium and lithium react explosively with acids. This is because a lot of heat energy is released in the reaction, causing the hydrogen to explode. Less reactive metals like magnesium, zinc and iron react less explosively. Bubbles of hydrogen gas can be seen on the metal surface.
- Copper is extremely unreactive. Copper is at the bottom of the reactivity series. As it is below hydrogen in the reactivity series, it is not reactive enough to displace hydrogen from the acid. There is no reaction with cold and/or dilute acids.
- Comparing reactivity of metals. More reactive metals will react at a faster rate than less reactive metals.The rate of reaction is determined by the rate at which bubbles are given off. The more reactive a metal is, the more bubbles are given off in a given time.
The different reactions of metals include displacement reactions, oxidation reactions, and reaction with acids.
A displacement reaction occurs when a more reactive metal displaces a less reactive metal from its compound, resulting in the formation of a new compound and a new metal.
An oxidation reaction occurs when a metal reacts with oxygen to form an oxide. This reaction is commonly known as rusting.
When a metal reacts with an acid, a salt and hydrogen gas are produced. The type of salt produced depends on the type of acid used and the metal involved.
An example of a displacement reaction is when magnesium is added to copper sulfate solution, displacing the copper and forming magnesium sulfate.
An example of an oxidation reaction is when iron reacts with oxygen to form iron oxide, commonly known as rust.
An example of a reaction with acid is when zinc is added to hydrochloric acid, producing zinc chloride and hydrogen gas.
The reactivity series of metals determines the likelihood of a metal reacting with another substance. Metals higher up in the reactivity series are more likely to react with other substances and displace metals lower down in the series.
Understanding the reactions of metals is important for many industries, such as construction, manufacturing, and transportation, as it allows for the selection of appropriate metals for specific applications and helps to prevent damage and failure due to incompatible metal interactions.
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