Carbonate Fizz Test
React HCl with carbonates to release CO2
What this lesson covers
Why it matters
Pour dilute hydrochloric acid over a marble chip and watch it erupt in bubbles. The gas released turns limewater milky, revealing its true identity.
The idea in plain words
Match the reactants to the products: CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂. Notice the salt, water, and gas formation.
Predict first
What gas is produced when carbonates react with dilute acids?
Carbonates and hydrogen carbonates always release carbon dioxide gas when reacting with acids.
- Oxygen
- Carbon dioxide — correct
- Hydrogen
- Chlorine
What you do
Test both calcium carbonate and sodium hydrogen carbonate with dilute HCl. Observe the effervescence and confirm the gas with limewater.
Check yourself
Which observation confirms the gas is carbon dioxide?
CO₂ reacts with calcium hydroxide in limewater to form insoluble calcium carbonate, turning the solution milky.
In the reaction NaHCO₃ + HCl → NaCl + H₂O + CO₂, what type of reaction is this?
This is a double decomposition reaction where ions exchange partners to form salt, water, and carbon dioxide.
Why does effervescence occur in both reactions?
Effervescence is the visible escape of CO₂ gas bubbles formed during the reaction.
- It burns with a pop
- It turns limewater milky — correct
- It relights a glowing splint
- It turns blue litmus red
- Decomposition
- Double decomposition — correct
- Displacement
- Combination
- The acid is boiling
- Carbon dioxide gas is being released — correct
- The salt is dissolving rapidly
- Water is evaporating