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I did an experiment with egg shells and acid. The egg shells were soaked in varying concentrations of fluoride and it is seen the rate of reaction decreases with higher concentrations of fluoride ions.

I performed this with hydrochloric acid, citric acid and ethanoic acid however-if the percentage decrease in the rate of reaction from the egg shells soaked in distilled water to the egg shells soaked in the highest concentration of fluoride ions Is calculated, it is largest for HCl, then citric and ethanoic with a 9/10% each time

This showed that fluoride had a greater effect for HCl than citric why is this?

Why would this happen?
23 months ago

Chemistry Question asked by Salesh

Both hcl and hf are termed strong acids, with 100% dissociation whereas the other two acids mentioned are weaker and do not dissociate as much as the former. However, concentration may also affect, albeit slight/ variable rates of reactions if you are comparing weak vs strong acids, hence the term acid dissociation constants and pka and pH values.
06/01/2016 19:35:56 | comment by Hector
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HF is one the special case which itself is a weak acid. It does not dissociate fully due to the short and strong H-F bond. But it is a very dangerous substance as it is highly corrosive. It can dissolve nearly everything without deprotonating.
21/04/2017 21:40:50 | comment by Kin Boon
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The rate of reaction depends on the concentration of hydrogen ions, the greater the concentration the faster the rate. Hydrochloric acid is a strong acid so would give a high concentration of hydrogen ions and so a faster reaction. Contrary to the reply above, hydrofluoric acid is a weak acid. The fluoride ions would combine with the hydrogen ions so reducing their concentration and slowing the reaction. Citric acid is also a weak acid but slightly stronger than hydrofluoric, hence the flouride ions would have less effect as the concentration of hydrogen ions would only be reduced slightly. Ethanoic acid is a weaker acid than hydrofluoric so the flouride ions should have no effect.
Answered by Michael | 23 months ago
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