Fizzy Acid Reactions
Name the gas each salt gives with dilute acid.
Setting up the bench…
What this lesson covers
Why it matters
Drip dilute acid on three salts and three different gases fizz out — each with its own tell-tale test.
Predict first
Which gas turns limewater milky?
A carbonate or bicarbonate gives CO₂ (turns limewater milky); a sulphite gives SO₂ (smell of burning sulphur, turns acidified K₂Cr₂O₇ green); a sulphide gives H₂S (rotten-egg smell, blackens lead acetate paper).
- Carbon dioxide — correct
- Hydrogen
- Sulphur dioxide
What you do
Match each salt to the gas it releases with dilute acid.
Check yourself
A gas with a rotten-egg smell that blackens lead acetate paper is…
H₂S has the rotten-egg smell; SO₂ smells of burning sulphur; CO₂ is odourless.
A carbonate is identified because, with acid, it gives a gas that…
CO₂ turns limewater milky; it does NOT relight a splint (that is oxygen).
- H₂S — correct
- CO₂
- SO₂
- turns limewater milky — correct
- smells of rotten eggs
- relights a glowing splint