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 Form 4 Chemistry online lessons on acids, bases and salts

Comparing the strength of acids using rate of evolution of hydrogen

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Answer Text:
Comparing the strength of acids Using rate of evolution of hydrogen:
Apparatus:
- Boiling tubes; 1M HCl/# H_2SO_4#/ #HNO_3#; Methanoic acid/ tartaric acid; magnesium ribbon.
Procedure:
- One boiling tube is half filled with 1M HCl; while another is half filled with 1M Ethanoic acid.
- 2 pieces of magnesium ribbons are cleaned to remove a layer of oxide on the surface.
- One of the two pieces is put in each tube of the acid.
Observations:
- Hydrochloric acid evolves hydrogen much more quickly than Ethanoic acid yet they were of equal concentration.
Conclusion
-Hydrochloric acid is a strong acid;
- Ethanoic acid is a weak acid.
Note: -
-The same experiment can be repeated with marble chips (#CaCO_3#) in acids of same concentration.
The marble chips dissolve more quickly in HCl, which is a strong acid.
Apparatus:
- Boiling tubes; 1M HCl/ #H_2SO_4#/ #HNO_3#; Methanoic acid/ tartaric acid; magnesium ribbon.
Procedure:
- One boiling tube is half filled with 1M HCl; while another is half filled with 1M Ethanoic acid.
- 2 pieces of magnesium ribbons are cleaned to remove a layer of oxide on the surface.
- One of the two pieces is put in each tube of the acid.
Observations:
- Hydrochloric acid evolves hydrogen much more quickly than Ethanoic acid yet they were of equal concentration.
Conclusion
-Hydrochloric acid is a strong acid;
- Ethanoic acid is a weak acid.
Note: -
-The same experiment can be repeated with marble chips (#CaCO_3#) in acids of same concentration.
The marble chips dissolve more quickly in HCl, which is a strong acid.


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