Samuel F. answered • 02/22/20
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Chemical Engineer with 5+ Years of Tutoring Experience
Hello Minhui!
I belive this question wants you to relate the strength of the acid with the rate of the reaction, the stronger the acid, faster is the reaction.
The general reaction of this problem is:
CaCO3 + 2H+ → H2O + CO2 + Ca2+
The reaction CaCO3+HCl has the biggest rate of reaction and CaCO3+citric acid has the smallest
Samuel F.
in your example, yes. This is not the case with reactions that reach an equilibrium, because the never end.
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02/22/20
Minhui R.
I learned that pKa is the mesurement for the acidity. How can we compare acidity of citric acid(pKa : 4.8) and acetic acid(pKa1: 3.13 pKa2: 4.76 pKa3: 6.40)?
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02/23/20
Samuel F.
The lower the pKa, higher the acidity. I believe you changed the values of pKa of the acids. The acetic acid is a monoacid and the citric acid is a triacid. If you values are corrected (pKa1: 3.13 pKa2: 4.76 pKa3: 6.40) for citric acid and (pKa : 4.8) for the acetic acid. Then the citric acid is actually a stronger acid than the acetic acid. In this kind of problem you check the first pKa, who has the lowest is the strongest acid.
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02/23/20
Minhui R.
Oh that's true. Thank you again
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02/23/20
Minhui R.
Thank you! And if I understand correctly, the bigger the rate of reaction is, the faster the reaction ends right?02/22/20