Solve an equilbrium problem (using an ICE table) to calculate the pH of each sol

ID: 784699 • Letter: S

Question

Solve an equilbrium problem (using an ICE table) to calculate the pH of each solution:

Part A: a solution that is 0.185M in HC2H3O2 and 0.110M in KC2H3O2

Part B: a solution that is 0.205M in CH3NH2 and 0.100 in CH3NH3Br

2) A buffer contains significant amounts of ammonia and ammonium chloride.

Part A: write an equation showing how this buffer neutralizes added acid (HCl) (Express your answer as a chemical equation)

Part B: write an equation showing how this buffer neutralizes added base (CsOH) (Express your answer as a chemical equation)

1. Part A)

HC3H3O2 <---> C3H3O2- + H+

I 0.185 0.110 0

C -x +x +x

E 0.185-x 0.110 +x x

1.8X10^-5 = (0.110+x)(x)/(0.185 - x)

Assume x is negligible

1.8X10^-5 = x*(0.110/0.185)

x = [H+] = 3.03X10^-5

-log[H+] = pH = 4.52

Part B)

CH3NH2 + H2O <---> HCH3NH3+ + OH-

I 0.205 --- 0.100 0

C -x +x +x

E 0.205 - x 0.100 + x x

Kb = 4.4X10^-4 = (0.100+x)(x)/(0.205 - x)

Assume x is negligible

4.4X10^-4 = x*(0.100/0.205)

x = [OH-] = 9.02X10^-4

-log[OH-] = pOH = 3.04

pH = 14 - 3.04 = 10.96

Part A) NH3 + HCl <----> NH4Cl

Part B) NH4Cl + CsOH <---> H2O + NH3 + CsCl

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