Experiment: Investigating the gas produced by acids and carbonates

Aim: To investigate the reaction of acids and carbonates and the gas that is produced

Materials: sodium corbonate/sodium hydrogen carbonate (baking soda), dilute hydrochloric acid/vinegar, lime water/ligted splint, 2 test tubes

Acids and carbonates react to release carbon dioxide

Method

1. Half fill one of the test tubes with lime water
2. Put a small amount of the carbonate into a second test tube
3. Pour some acid/vinegar over the carbonate
4. Put a cork/thumb over the test tube to trap the gas that is produced
5. Remove your thumb/cork and “pour” the gas into the second test tube (with lime water)
6. Place a thumb over the test tube with limewater and shake it.
7. Alternatively you might try insterting a lighted splint into the first test tube quickly after removing your thumb or the cork

Observation and results

• There is fizzing/effervescence and bubbles forming when the acid is added to the carbonate
• The gas builds up and its pressure can be felt on the thumb
• The sound of gas escaping can be heard when the cork/thumb is removed
• The gas produced turns lime water milky
• It also extinguishes a lighted splint when it’s inserted in the first test tube

Conclusion

• Acids react with carbonates to produces carbon dioxide
• \text{carbonate+acid}\rightarrow\text{salt+water+carbon dioxide}

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