Nigel Baldwin | Magnesium plus sulphuric acid NPGF8193 @nigelbaldwin3184 | Uploaded February 2023 | Updated October 2024, 2 hours ago.
High School Chemistry

IGCSE Chemistry

Making a salt

Method 1
acid + metal = salt + hydrogen

An excess of magnesium metal is added to a small volume of sulfuric acid in a beaker.

Magnesium reacts with sulfuric acid
Q1 What gas is produced?
Q2 What salt is produced?

The reaction can be monitored by observing the bubbles of colourless gas produced. However, magnesium also reacts slowly with water producing bubbles of the same colourless gas, so it is just as well to monitor the pH using Universal Indicator paper.

The reaction can be stopped by filtering off the excess magnesium metal when the pH reaches 6.

Answers to the questions above
1 Hydrogen gas
2 Magnesium sulphate

The salt produced is usually obtained in it's hydrated form, i.e. it contains water of crsytallisation.

Q3 What is the formula of the most commonly encountered hydrated form of magnesium sulfate?

Answer
Magnesium heptahydrate MgSO4·7H2O