Question

for each strong acid solution determine [H3O+] [OH-] ans pH

112. For each strong acia and pt. (a) o. Biso M HCl (6) 1.9810-14m HI (c).0.0226 m HBr (d) 1.78103 M NHINO

Answer 1

All are strong acids dissociates completely into ions . As all are monoprotic acids, the concentration of hydronium ion formed on dissociation is equal to concentration of acid. That is

[H₃O⁺] = [acid]
pH is given as

pH = -log [H₃O⁺]

At 25^oC    [H₃O⁺] [OH^-] = 10^-14

[OH^-] = 10^-14/[H₃O⁺]

On the basis of above formula let us do calculation for each part

a) [H₃O⁺] = 0.0150 M

pH = -log (0.0150) = 1.82

[OH^-] = 10^-14/0.0150 = 6.6 x 10^-13 M

b ) Here the concentration of [H₃O⁺] from acid is very less than the hydronium ions from water so the concentration of hydronium ion is given as [H₃O⁺] ~ 10^-6.99 M

pH = -log (10^-6.99) = 6.99

[OH^-] = 10^-14/10^-6.99= 9.78 M

c) [H₃O⁺] = 0.0226 M

pH = -log (0.0226) = 1.64

[OH^-] = 10^-14/0.0226 = 4.4 x 10^-13 M

a) [H₃O⁺] = 0.0017 M

pH = -log (0.0017) = 2.77

[OH^-] = 10^-14/0.0017 = 5.8 x 10^-12 M