For RN H 2 ( g ) + H 2 O ( l ) ⇌ RN H 3 + ( aq ) + O H − ( aq ) , K = 2 × 1 0 − 6 . At equilibrium p RN H 2 = 0.5 bar; pH of water=6.5. Find equilibrium pH.

Question

For RN H 2 ​ ( g ) + H 2 ​ O ( l ) ⇌ RN H 3 + ​ ( aq ) + O H − ( aq ) , K = 2 × 1 0 − 6 . At equilibrium p RN H 2 ​ ​ = 0.5 bar; pH of water=6.5. Find equilibrium pH.

TestHub · Accepted Answer

Neutral water pH=6.5 implies pK_w=13 at the given temperature. With gas activity p/1 bar=0.5, K=[RNH₃⁺][OH⁻]/0.5=2×10⁻⁶. Equal base-generated concentrations give [OH⁻]≈10⁻³ M, pOH=3. Thus pH=13-3=10, C. Using 14 would ignore the supplied neutral-water pH.

Chemistry - Ionic Equilibrium Question with Solution | TestHub

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