Im really confused. Sometimes you have to work out which of the acid or salt is in excess and sometimes you dont.
An acidic buffer solution is obtained when sodium ethanoate is dissolved in aqueous
(i) Calculate the pH of the buffer solution formed at 298 K when 0.125 mol of sodium
ethanoate is dissolved in 250 cm3 of a 1.00 mol dm–3 solution of ethanoic acid.
The acid dissociation constant, Ka, for ethanoic acid is 1.70 × 10–5 mol dm–3 at
For this question you dont look at the excess why?
A buffer solution is formed when 2.00 g of sodium hydroxide are added to 1.00 dm3 of a
0.220 mol dm–3 solution of ethanoic acid.
Calculate the pH at 298 K of this buffer solution
for this question you do look at which is in excess why?
whats the difference and how do i know when to look at which is in excess
i can see for one it says the salt is added to the acid
the other the salt is dissolved in the acid
is this the decider?
base + acid => salt + water.
With buffers you need to find the concentration of the acid and the salt.
In the first question your given the details about the salt, but in the second question you need to find the concentration of the salt from equation. I hope this helped
well good luck i hate buffers