The Student Room Group

equilibrium chemistry

equilibrium: CH CH COOH H+ + CH CH COO– 32 32
presence of buffer
DO NOT ALLOW HA and A– in this equilibrium expression
Added alkali
Equilibrium responses must refer back to a written equilibrium.
IF no equilibrium shown, use the equilibrium as written in expected answers (which is also written on page 6 of the paper)
CH3CH2COOH reacts with added alkali
ALLOW weak acid reacts with added alkali
OR added alkali reacts with H+ OR H+ + OH– 
CH CH COO– OR Equilibrium right 32
Added acid
CH3CH2COO– reacts with added acid OR [H+] increases
ALLOW conjugate base reacts with added acid DO NOT ALLOW salt reacts with added acid
CH3CH2COOH OR Equilibrium left

can someone explain why it shifts left/right
I thought that when it reacts with x it would move in the direction of x to replace what has been lost? thanks
If H+ is added then the equilibrium will shift to remove the added H+. H+ + A- --> HA
If OH- is added it will remove H+ so equilibrium will shift to replace some of the H+. HA --> H+ + A-. Is this what you were looking for?

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