Question

What is the pH of the resulting solution when equal volumes of 0.1 M NaOH and 0.01 M HCl are mixed?

विकल्प

• 2.0

• 3

• 7.0

• 12.65

Answer 1

12.65

Explanation:

x ml of 0.1 m NaOH + x ml of 0.01 M HCI

No. of moles of NaOH = 0.1 × x × 10⁻³ = 0.1x × 10⁻³

No. of moles of HCl = 0.01 × x × 10⁻³ = 0.01x × 10⁻³

No. of moles of NaOH after mixing = 0.1x × 10⁻³ – 0.01x × 10⁻³

= 0.09x × 10⁻³

Concentration of NaOH = `(0.09"x" xx 10^-3)/(2"x" xx 10^-3)` = 0.045

[OH^–] = 0.045

p^OH = –log (4.5 × 10⁻²)

= 2 – log 4.5

= 2 – 0.65

= 1.35
pH = 14 – 1.35 = 12.65