Question

Finish the calculations for the following problems. pH=-log[H+]

Na2SO4 + CaCO3 + 2 C rightarrow Na2CO3 + 2 CO2 + CaS 2CU2S + 3 O2 rightarrow 2 Cu2O + 2 SO2 P2H4 rightarrow PH3 + P4H2 (+2) pH calculation: Finish the calculations for the following problems, pi 1 - -log [H Calculate: The pH of a 0.005M hydrofluoric acid solution. The concentration of hydrobromic acid in a solution of pH 1.2.

Answer 1

HF(aq) <--> H+ (aq) + F-(aq)

at eqilibrium [HF]= 0.005-X , [H+]=[F-] = X

Ka of HF = [H+][F-]/[HF]

6.76 x 10^ -4 = X^2 /( 0.005-X)

X = 0.00153 =[H+]

pH = -log [H+] = -log ( 0.00153) = 2.815

HBr is strong acid and hence [H+] =[HBr ]

we have pH = 1.2   hence -log [H+] = 1.2

[H+] = 10^ -1.2 = 0.0631 = [HBr]

hence concentration of HBr is 0.0631 M