1. Titration curve for the reaction of 0.05M H3PO4 with 0.10M NaOH. 1st equivale

A) H3PO4 + NaOH = NaH2PO4 + H2O B) Ka1 = 7.5

ID: 795182 • Letter: 1

Question

Titration curve for the reaction of 0.05M H3PO4 with 0.10M NaOH.

1st equivalence point: (10.0, 5.0) buffer region 6.5

2nd equivalence point: (20.0, 10.0) buffer region 15.0

a) write the balanced reaction equation for the first equivalence point.

b) Write the approximate pKa of the first acid dissociation and circle the indicate the first equivalence point

Bromocresol (4.7) Phenol Red (7.8) Thymolphthalein (10.0)

c) Calculate the pH of 0.020 M Na3PO4 solution- the concentration at the third equicalence point. (Kb of PO4^3- = 2.8x10^-2)

d) phosphoric acid is a triprotic acid, briefly suggest why there isn't a third equivalence point on the graph.

For each of the following reactions, decide whether the resulting pH is acidic, neutral, or basic.

a) 25mL of .45M H2SO4 is reacted with 25mL of 0.90 M NaOH.

b) 15mL of 0.050 M formic acid, a monoprotic organic acid (HCO2H), is reacted with 15mL of 0.050 M NaOH

c) 25mL of 0.15 M NaOH.

d) 12mL of .10 M ammonia water is reacted with 12mL of 0.10M phosphoric acid (H3PO4).

e) 36mL of 0.10 M ammonia water is reacted with 12mL of 0.10M phosphoric acid (H3PO4).

H3PO4 + NaOH = NaH2PO4 + H2O

Ka1 = 7.5

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