Question

Determine the pH of a solution containing 0.050 M NaOH and 0.025 M KI neglecting activities. pH= Determine the pH of the same solution including activities. Activity coefficients at various ionic strengths can be found in this table, pH= contact u help terms of use privacy policy about us careers MacBook Pro DIl FB en F7 8

Answer 1

(1) Neglacting Activities :- [OH^-] = 0.050 M

P^OH = - log[OH^-] = 1.30

P^H + P^OH = 14

P^H = 14 - 1.30

P^H = 12.7

Ionic strength (μ) = 1/2 *(μ₁Z₁² +  μ₂ Z₂² +   μ₃ Z₃² +   μ₄ Z₄².)

= 1/2 * (0.035 X 1² + 0.035 X 1² + 0.025 X 1² + 0.025 X 1²)

= 0.06 M

μ = 0.05 r_OH^- = 0.81

μ = 0.1 r_OH^- = 0.76

μ = 0.06 r_OH^-​​​​​​​ = ?

Linear inter portion r_OH^- = 0.81 + (0.76 - 0.81) . (0.06 - 0.05) / (0.1 - 0.05)

formula y = y_o + [(y₁ - y_o) (x-x_o) / (x₁ - x_o)]

r_OH^- = 0.8 M

[H⁺]r_H⁺ = K_W / ( [OH^-] r_OH^-) = 10^-14 / (0.035 X 0.8) = 3.57 X 10^-13 M

p^H = - log [H⁺] = = log(3.57 X 10^-13 M)

p^H = 12.45

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Answer 2

1. 12.70

2. 12.63