We're being asked to calculate the pH a) before HCl is added; b) at the half-equivalence point; and c) at the equivalence point.
a) before HCl is added
NaHCOO (sodium formate) will break up in the solution:
• NaHCOO(aq) → Na+(aq) + HCOO-(aq)
• HCOO- is the conjugate base of HCOOH → HCOO- is a weak base
• HCOO- → weak base → proton acceptor
• H2O → will act as the weak acid → proton donor
Equilibrium reaction: HCOO-(aq) + H2O(l) ⇌ HCOOH(aq) + OH-(aq)
Step 1: Construct an ICE chart for the reaction.
25.0 mL of 0.2 M sodium formate was titrated with 0.1 M HCl. What is the pH: a) before HCl is added; b) at the half-equivalence point; and c) at the equivalence point? Possible answers, respectively, are given below.
A. 8.52; 3.75; 2.46
B. 7.52; 4.75; 3.46
C. 6.52; 5.75; 5.46
D. 5.52; 2.75; 1.46
E. 9.52; 6.75; 4.46
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