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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: ggxoxo on July 07, 2011, 03:36:58 pm

Title: Autoprotolysis constant
Post by: ggxoxo on July 07, 2011, 03:36:58 pm

Hi,

I'm normally in the biol section so yeah...; anyway, i'm only in yr.11 so this might be a dumb question.

I read that Kw of water is 1 x 10^(-14) at 25 degrees celsius. But what happens to the constant if it's not 25 degrees celsius and it's not pure water. I'm doing questions right now and it does not say that it is 25 degress C and it just syas 'water'. Do we just assume that it is so and accept that we use Kw= 10^(-14)?

Title: Re: Autoprotolysis constant
Post by: Graphite on July 07, 2011, 03:56:41 pm

Assume 25 when not stated. However in exams I believe they would state it explicitly to avoid confusion.

You need to learn about Le Chatelier's principle to predict the change in Kw when the temperature is increased/decreased above/below 25 degrees. So at year 11 don't worry yet.

Title: Re: Autoprotolysis constant
Post by: ggxoxo on July 07, 2011, 03:58:40 pm

thank you!!! Ur a lifesaver!