Sodium hydroxide solution cannot be kept in aluminium containers

Sodium hydroxide, also known as lye or caustic soda, is a strong base and is highly corrosive. When it comes into contact with aluminium, it reacts to form sodium aluminate and hydrogen gas. This reaction is exothermic, meaning it releases heat.

Here are the steps of the reaction:

1. Sodium hydroxide reacts with aluminium. The chemical equation for this reaction is: 2Al + 2NaOH + 6H2O → 2NaAl(OH)4 + 3H2

2. This reaction produces sodium aluminate and hydrogen gas. The hydrogen gas can build up and cause the container to burst.

3. The reaction is also exothermic, which means it releases heat. This heat can further accelerate the reaction, making it more dangerous.

4. The sodium aluminate formed in the reaction can also corrode the aluminium container, further damaging it.

For these reasons, sodium hydroxide solution should not be stored in aluminium containers. It's better to use containers made of materials that do not react with sodium hydroxide, such as glass or certain types of plastic.