Outline 6 Learning Objective

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Samantha Pedersen 2K
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Outline 6 Learning Objective

Postby Samantha Pedersen 2K » Mon Dec 07, 2020 12:35 pm

One of the learning objectives on Outline 6 says, "Explain why solutions of weak acids have higher pH values than solutions of strong acids at the
same concentration." It intuitively makes sense to me that solutions of weak acids have higher pH values than solutions of strong acids at the same concentration, but I'm hoping someone could provide a conceptual explanation for why this is the case. Does it have to do with the fact that strong acids fully dissociate in solution whereas weak acids do not fully dissociate? Thank you!

KatarinaReid_3H
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Re: Outline 6 Learning Objective

Postby KatarinaReid_3H » Mon Dec 07, 2020 12:40 pm

Yes. The concentration is just saying how many moles we have of the particular compound in some amount of liters of water. Thus, comparing concentrations for different acids would not be correct. Instead, you should look at the Ka values or the acid dissociation constant. This will tell you how much the acid will dissociate in water. Meaning, how likely is it to give up a proton to a water molecule. Thus, larger Ka values mean that more protons will be given up, so it is a stronger acid.

Margaret Wang 2D
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Re: Outline 6 Learning Objective

Postby Margaret Wang 2D » Mon Dec 07, 2020 12:46 pm

Weaker acids do not give off all the protons they have available, whereas strong acids give off essentially all of their available H+ to form H3O+. For example, HCl would give off every single H+ from every single HCl molecule when put in water, whereas acetic acid CH3COOH may only give off 50% (I made this percentage up to demonstrate the difference, idk if it's actually 50%)


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