[lily_m]

Hello everyone, can anyone help me with this. In my lab report i've been asked 'how does potassium hydrogen sulphate function as an acid and look up its pKa value'. After much time searching for this i've come up with nothing. can anyone please help 

[azmanam]

Couple of hints:

Do you know what it means when a compound is said to be amphoteric?  That will be a useful concept here.

Also, monocation,monoproton compounds are sometimes referred to with the prefix bi.  For example, carbonic acid is H2CO3.  The monopotassium salt of that, KHCO3, could be called potassium hydrogen carbonate, but is also called potassium bicarbonate.  so 'hydrogen sulfate' is sometimes written bisulfate.

Also, the pka for acids with more than one acidic proton are usually all written with the fully protonated acid.  thus, when you look up the pka for carbonic acid, you'll see 2 values.  One for the diprotonated compound, and one for the monoprotonated compound.

I hope these hints will help you find the pka value you're looking for!

You might want to check this page out, too:
http://www.chemicalforums.com/index.php?page=pkavalues