Question

Identify the half-equivalence point of the weak base- strong acid titration curve in the above graph. 

Answer 1

After determining equivalence point, half equivalence point can be determined because it's exactly halfway between equivalence point and origin on X- axis. pH doesn't change much at this point.

Equivalence point = midpoint of the steep curve i.e. (3+7)/2 = 5

Volume corresponding to equivalence point is 25 ml

Midpoint of 0- 25ml (on x axis) = (0+25)/2 = 12.5

pH corresponding to 12.5ml volume ~ 9

Half-equivalence point = 9