Question

three sig figs please.

a) 0.19 M HCl

calculate [H3O+] , [OH-], and pH

b)1.5 x 10^ -2 M HNO3

calculate [H3O+] , [OH-], and pH

c) a solution that is 7.5×10⁻² M in HBr and 1.9×10⁻² M in HNO3

calculate [H3O+] , [OH-], and pH

d) a solution that is 0.780% HNO3 by mass (Assume a density of 1.01 g/mL for the solution.)

calculate [H3O+] , [OH-], and pH

Answer 1

a)     For 0.19 M HCl, [H⁺] or [H₃O⁺] = 0.19 M

pH = -log (0.19) = 0.721

[H⁺] [OH^-] = 1 x10^-14 M

[OH^-] = 5.26 x 10^-14 M

b)    For 1.5 x 10 ^-2 M HNO₃, [H⁺] or [H₃O⁺] = 1.5 x 10 ^-2 M

pH = -log (1.5 x 10 ^-2) = 1.824

[H⁺] [OH^-] = 1 x10^-14 M

[OH^-] = 6.6 x 10^-13 M

c)     HBr and HNO₃ both are strong acids so, [H⁺] or [H₃O⁺] = 7.5 x 10^-2 + 1.9 x 10^-2 = 9.4 x 10^-2 M
pH = -log (9.4 x 10^-2 ) = 1.026

[H⁺] [OH^-] = 1 x10^-14 M

[OH^-] = 1.06 x 10^-13 M

d)    0.780% HNO₃ by mass = (0.780 x 1010) / 100 = 7.878 g/L of HNO3

Molarity, [H⁺] or [H₃O⁺] = (7.878 g/L) /(63g/mol) = 0.125 M
pH = - log (0.125) = 0.903
[H⁺] [OH^-] = 1 x10^-14 M

[OH^-] = 0.8 x 10^-13 M