We are being asked to determine the volume of the 0.33 M HI solution at half-equivalence point upon titration with 25 mL 0.24 M (CH3)2NH (weak base)
Recall that at half-equivalence point, the moles of the weak base will be reduced by half.
In this case, we have to determine the moles of (CH3)2NH using the volume and its molarity.
Then divide it by two and use stoichiometry to relate it to how much HI is needed to reach these moles of weak base
Thus we need to follow the steps:
Step 1. Calculate the moles of (CH3)2NH
Step 2. Calculate the moles of HI
Step 3. Use dimensional analysis to find V of HI
Determine the volume in mL of 0.33 M Hl(aq) needed to reach the half-equivalence (stoichiometric) point in the titration of 25 mL of 0.24 M (CH3)2NH(aq)(aq). The Kb of dimethylamine is 5.4 x 10-4.
a. 2.27 mL
b. 4.55 mL
c. 9.09 mL
d. 14.2 mL
e. 28.4 mL