Beryllium and Magnesium

Beryllium and magnesium

These are just like the reactions with dilute hydrochloric acid, and you have probably been familiar with the reaction between magnesium and dilute sulphuric acid almost since you started doing chemistry. Bubbles of hydrogen are formed, together with colourless solutions of beryllium or magnesium sulphate.

For example:

Calcium, strontium and barium

Calcium sulphate is sparingly soluble, and you can think of strontium and barium sulphates as being insoluble. That means that you will get a layer of insoluble sulphate on all of these which will slow down the reaction or stop it entirely.

In the calcium case, you will get some hydrogen produced together with a white precipitate of calcium sulphate.

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Note: With strontium and barium, I have never actually seen either reaction, nor can I find any video clips on the web. I would expect the reactions to never really get going, leaving the metal coated with a white solid. If you have any direct knowledge of this, preferably with a bit of video to support it, could you let me know via the address on the about this site page.

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Reactions with nitric acid

These are more complicated. When most metals react with most acids, what they are actually doing is reducing hydrogen ions to hydrogen gas by adding electrons to the hydrogen ions. The metal is, of course, oxidised to positive metal ions because it loses electrons.

But nitrate ions are also easily reduced to products like nitrogen monoxide and nitrogen dioxide.

So metals reacting with nitric acid tend to give oxides of nitrogen rather than hydrogen. If the acid is relatively dilute, you tend to get nitrogen monoxide, although this immediately reacts with oxygen in the air to make brown nitrogen dioxide.

Concentrated nitric acid gives