Calculating pH given only concentrations?

Question

I'm having a lot of trouble with this question, which appears simple. The questions are of this form.

Find the pH when 90mL of 0.105mol/L HCl and 100mL of 0.116mol/L sodium acetate are combined.

Can anyone start me in the right direction, or solve this one, so I can continue with all of the rest?

Answer 1

Here is the methodology

Write the reaction

HCl + CH3COONa -> CH3COOH +NaCl

find out how many moles of each reactant you have
find the limiting reagent
find how many moles acid (CH3COOH) was formed
find how many moles of the reactant that was in excess remained.
Calculate the final volume and use it together with the moles you calculated to find the respective concentrations.

If CH3COONa remained you have a buffer and you use the Henderson-Hasselbalch equation
pH=pKa+log[conj.base]/[acid]

If nothing remained then you have to find the pH of a solution of a weak acid. Set up an ICE table and solve the equation coming from the Ka. Once you find x, then pH=-logx.

If HCl remained, set-up an ICE table with initial amount not only for acetic acid but also for H+ (it will be the H+ from the remaining HCl). Once you find x, pH= -log(x+[HCl]remaining )

Answer 2

pH= - log (0.05M) pH = unfavourable (log- is a button on your calculator) circumstances molarity concentration Molar concentration of hydrogen = a million circumstances 10 to the capacity of unfavourable ph your answer would be in moles in line with litre (mol/L)