Science for Kids/A chemical reaction


Hope you have not forgot me. I'd earlier asked you a question regarding a chemical analysis.

Now I want a help with an equation. Can you tell me what happens if sulfurous acid is made to react with bromine?

Hi AB,

This comes from Wikipedia:

With bromide ions

The bromide ions are strong enough reducing agents to reduce the concentrated sulphuric acid. In the process the bromide ions are oxidised to bromine.

The bromide ions reduce the sulphuric acid to sulphur dioxide gas. This is a decrease of oxidation state of the sulphur from +6 in the sulphuric acid to +4 in the sulphur dioxide.

You can combine these two half-equations to give the overall ionic equation for the reaction:

Note:  If you aren't confident about redox reactions, electron-half equations, and oxidation states you really ought to follow this link before you go any further.

What you see in this reaction are the steamy fumes of hydrogen bromide contaminated with the brown colour of bromine vapour. The sulphur dioxide is a colourless gas, so you couldn't observe its presence directly.

Go to the website for the chemical reaction.

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Ralph Salier-Hellendag


Science Fair Judge for many years and experience with robotics, biology, chemistry, industrial processes, metalurgy and metal forming.


Science Fair Judge for many years and have helped several students get to state level competition. Most recently 2 of my students received state level awards and one went on to the nationals in Washington DC.

BA Archaeology - Anthropology
MA Business Anthropology

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