need help A.) Find the [OH] of a 0.46 M methylamine (CH3NH2) solution. (The valu

Question

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A.) Find the [OH] of a 0.46 M methylamine (CH3NH2) solution. (The value of Kb for methylamine (CH3NH2) is 4.4×104.) Express your answer to two significant figures and include the appropriate units. answer is not 0.015M

B.)Determine the [OH] of a 0.30 M solution of NaHCO3. Express your answer using two significant figures. Answer is not 3.3x 10^-14

C.)Determine the pH of this solution in part B.). answer is not 3.4

D.) Find the pH of a 0.338 M NaF solution. (The Ka of hydrofluoric acid, HF, is 3.5×104.) Express your answer using two decimal places. answer is not 8.96

Explanation / Answer

(A) [OH] = sqrt( kb x c) == square root ( 0.46 x 4.4 x10-4 ) == 1.42 x 10-2

(B) [H+] = sqrt (ka x c) ==  square root ( 0.30 x 4.3 x10-7 ) == 3.59 x 10-4

  [OH] = 10-14 / 3.59 x 10-4 = 2.78 x 10-11

(C) pH = -log  [H+] ==-log (3.59 x 10-4 ) == 3.44

(D) [H+] = sqrt (ka x c) ==  square root ( 0.338 x 3.5 x10-4 ) == 1.088 x 10-2

  pH = -log  [H+] ==-log (1.088 x 10-2 ) == 1.963

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