Question

For the ionisation reaction-
$\left(\left(\text{RNH}\right)_{2}\right)_{\left(\text{g}\right)}+\left(\text{H}\right)_{2}\left(\text{O}\right)_{\left(\textit{l}\right)}\rightleftharpoons\left(\text{RNH}_{3}^{+}\right)_{\left(\text{aq}\right)}+\left(\left(\text{OH}\right)^{-}\right)_{\left(\left(\text{aq}\right)_{}\right)}\left(\text{ K}\right)_{e q}\left(\text{= 8 x 10}\right)^{\text{-6 }}$
Find the pH of a solution at equilibrium when pressure of RNH₂(g) is 0.5 bar :

• A. $≈ 12.3$
• B. $≈ 11.3$
• C. $≈ 11.45$
• D. None

Answer 1

Answer: (B)

$8 \times 1 0^{- 6} = \frac{\text{x}^{2}}{\text{0.5}}$
$⇒ \, \, \text{x} = 2 \times 1 0^{- 3}$
$∴ \, \, \text{pOH} = \text{2.7}$
$\text{So, pH} = 11.3$