Relative acidity

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Baoying Li 1B
Posts: 113
Joined: Sat Aug 17, 2019 12:18 am

Relative acidity

Postby Baoying Li 1B » Sun Dec 01, 2019 9:48 pm

What are the rules to distinguish which is a stronger acid or a weaker acid?

Aarja Pavade 1H
Posts: 103
Joined: Sat Aug 17, 2019 12:18 am

Re: Relative acidity

Postby Aarja Pavade 1H » Sun Dec 01, 2019 9:58 pm

Strong acids produce more protons than a weak acid. Strong acids are completely ionized in solution while weak acids are incompletely ionized.

Yiyang Jen Wang 4G
Posts: 76
Joined: Wed Nov 21, 2018 12:18 am

Re: Relative acidity

Postby Yiyang Jen Wang 4G » Sun Dec 01, 2019 10:01 pm

Strong acids are fully ionised but weak acids are only partly ionised in solution. At the same concentration, weak acids have a higher pH value(lower concentration of hydrogen ions) than strong acids.

Ashley Wang 4G
Posts: 103
Joined: Wed Sep 11, 2019 12:16 am

Re: Relative acidity

Postby Ashley Wang 4G » Sun Dec 01, 2019 10:03 pm

In lecture, Dr. Lavelle mentioned two criteria/trends for determining relative acidity:

1. acids with a longer acid-H bond are stronger, as they can lose the H+ more easily. eg. HI is a stronger acid than HBr
2. the stability of the resulting anion: oxoacids where the oxygen is bonded to a more electronegative atom will have a more stable anion. eg. hypochlorous acid is more acidic than hypobromous acid

Note, however, that this to refers to the relative acidity! So it wouldn't really tell you which are strong and weak acids, only in comparison to each other.

Hope this helped!

John Arambulo 1I
Posts: 58
Joined: Sat Jul 20, 2019 12:15 am

Re: Relative acidity

Postby John Arambulo 1I » Sun Dec 01, 2019 10:04 pm

There are no rules in distinguishing strong or weak acids. There are trends/guidelines to help you know/predict if an acid is strong or weak relative to another one. You can look down a group, across a period, and or see if there is resonance and or inductive effect.


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