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October 21, 2025, 10:22:50 pm
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Author Topic: Memorising constants  (Read 635 times)  Share 

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MattZhang

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Memorising constants
« on: July 07, 2011, 02:12:11 pm »
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Hiya,
     do you guys know if we have to memorise the acidity constants for common acids for the end of year exam? In the data book the acidity constants of some weak acids are given but theres nothing about strong acids. Also, do we have to memorise the ionisation constants of water for different temperatures or should we just assume it is always = 10^-14?

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stonecold

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Re: Memorising constants
« Reply #1 on: July 07, 2011, 02:21:56 pm »
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No, you don't have to memorise them.  That is what the book is for.

And strong acids have very large acidity constants, because ionisation is close to 100%.

You only need to know the ionisation constant for water at 25 degrees.

But, you should know that the self ionisation of water is an endothermic reaction and be able to answer questions such as

Water stored at 40 degrees would
A.  Have a pH = 7 and be neutral
B.  Have a pH > 7 and be neutral
C.  Have a pH > 7 and be alkaline
D.  Have a pH < 7 and be neutral
E.  Have a pH < 7 and be acidic
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2011-13: BBiomed (Microbiology & Immunology Major) @ UniMelb


VCE 2009'10: English 46 | English Language 49 | Chemistry 50 | Biology 50 | Further Mathematics 48 | Mathematical Methods CAS 39
ATAR: 99.85

"Failure is not when one falls down but rather when one fails to get up" - unknown

MattZhang

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Re: Memorising constants
« Reply #2 on: July 07, 2011, 02:32:48 pm »
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Cheers bro :D
Also, for that question you put, would the answer be D?
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stonecold

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Re: Memorising constants
« Reply #3 on: July 07, 2011, 02:33:31 pm »
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Quote from: MattZhang on July 07, 2011, 02:32:48 pm
Cheers bro :D
Also, for that question you put, would the answer be D?

Sure is!  :D
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2011-13: BBiomed (Microbiology & Immunology Major) @ UniMelb


VCE 2009'10: English 46 | English Language 49 | Chemistry 50 | Biology 50 | Further Mathematics 48 | Mathematical Methods CAS 39
ATAR: 99.85

"Failure is not when one falls down but rather when one fails to get up" - unknown

MattZhang

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Re: Memorising constants
« Reply #4 on: July 07, 2011, 02:35:59 pm »
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thanks mate, been real helpful  :)
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