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The main way to compare is to look at their corresponding Ka values. Higher values mean that the forward reaction is more favored, which thereby means that the acid dissociates to a greater extent and is therefore stronger.
Katherine Chhen 3I wrote:Would the pKa and Ka values be given or would we have to calculate that ourselves?
You only need one value to make the comparison, so if you're given either the Ka or pKa, you can tell which one is the stronger acid. However, sometimes you may not be given either of these values. If this is the case, we would do something similar to what we did in Wednesday's lecture. We would compare the bond lengths involving the protons and we would also look for any electron-pulling molecules, allowing us to compare the relative acidities of multiple acids. I believe we haven't learned how to calculate Ka or pKa yet, which means that we probably will not be tested on it. Professor Lavelle may teach this to us next week, though, and if he does, it will probably be tested. Hope this helps!
For strong acids (no kA value provided), observe bond length. For weak acids, the stronger acid is the one with a higher kA value (concentration of the products divided by the concentration of the reactants).
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