NEET Equilibrium — Set 10

Question 1

For $ \ce{A2(g) <=> 2A(g)} $, $ K_c = 0.36 $ at 300 K. If 0.5 mol $ \ce{A2} $ is in a 1 L vessel, what is the degree of dissociation?

Accepted Answer

Initial: $ [\ce{A2}] = 0.5 \, \text{M} $, $ [\ce{A}] = 0 $. Let $ \alpha $ be the degree of dissociation, $ [\ce{A2}] = 0.5 (1 - \alpha) $, $ [\ce{A}] = \alpha $. $ K_c = \frac{[\ce{A}]^2}{[\ce{A2}]} = \frac{(\alpha)^2}{0.5 (1 - \alpha)} = 0.36 $, $ \alpha^2 = 0.18 (1 - \alpha) $, $ \alpha \approx 0.36 $.

Question 2

The solubility of $ \ce{Ag2S} $ in 0.01 M $ \ce{Na2S} $ is $ 2.0 \times 10^{-16} \, \text{M} $. What is its $ K_{sp} $?

Accepted Answer

For $ \ce{Ag2S <=> 2Ag+ + S^{2-}} $, $ [\ce{Ag+}] = 4.0 \times 10^{-16} $, $ [\ce{S^{2-}}] \approx 0.01 $, $ K_{sp} = (4.0 \times 10^{-16})^2 \times 0.01 = 1.6 \times 10^{-33} $.

Question 3

For $ \ce{Ag2S(s) <=> 2Ag+(aq) + S^{2-}(aq)} $, $ K_{sp} = 6.0 \times 10^{-50} $. If $ [\ce{Ag+}] = 1.0 \times 10^{-15} \, \text{M} $ in a saturated solution, what is $ [\ce{S^{2-}}] $?

Accepted Answer

$ K_{sp} = [\ce{Ag+}]^2[\ce{S^{2-}}] = 6.0 \times 10^{-50} $. Given $ [\ce{Ag+}] = 1.0 \times 10^{-15} $, $ (1.0 \times 10^{-15})^2 [\ce{S^{2-}}] = 6.0 \times 10^{-50} $, $ 1.0 \times 10^{-30} [\ce{S^{2-}}] = 6.0 \times 10^{-50} $, $ [\ce{S^{2-}}] = 6.0 \times 10^{-20} \, \text{M} $.

NEET Chemistry: Equilibrium — Practice Set 10

Q1. For \( \ce{A2(g) <=> 2A(g)} \), \( K_c = 0.36 \) at 300 K. If 0.5 mol \( \ce{A2} \) is in a 1 L vessel, what is the degree of dissociation?

Q2. The solubility of \( \ce{Ag2S} \) in 0.01 M \( \ce{Na2S} \) is \( 2.0 \times 10^{-16} \, \text{M} \). What is its \( K_{sp} \)?

Q3. For \( \ce{Ag2S(s) <=> 2Ag+(aq) + S^{2-}(aq)} \), \( K_{sp} = 6.0 \times 10^{-50} \). If \( [\ce{Ag+}] = 1.0 \times 10^{-15} \, \text{M} \) in a saturated solution, what is \( [\ce{S^{2-}}] \)?

Q4. For the reaction \( \ce{A(g) + 3B(g) <=> 2C(g)} \), \( K_c = 125 \) at 400 K. If 1 mole of \( \ce{A} \) and 4 moles of \( \ce{B} \) are placed in a 2 L vessel, what is \( [\ce{C}] \) at equilibrium?

Q5. For \( \ce{2NO2(g) <=> 2NO(g) + O2(g)} \), \( K_p = 0.05 \) at 600 K. If 1 mole of \( \ce{NO2} \) is placed in a 2 L vessel, what is \( P_{\ce{O2}} \) at equilibrium (\( R = 0.0831 \, \text{bar L/mol K} \))?

Q6. A weak base \( \ce{NH3} \) (\( K_b = 1.8 \times 10^{-5} \)) is mixed with 0.1 M \( \ce{NH4Cl} \) in equal volumes. If the final \( [\ce{NH3}] = 0.05 \, \text{M} \), what is the pH?

Q7. The solubility of \( \ce{AgBr} \) is \( 7.1 \times 10^{-7} \, \text{M} \). What is its \( K_{sp} \)?

Q8. Which species can act as both a Bronsted-Lowry acid and base?

Q9. For the reaction \( \ce{2A(g) <=> B(g) + C(g)} \), if \( K_c = 0.25 \) and at equilibrium \( [\ce{B}] = 0.1 \, \text{M} \), \( [\ce{C}] = 0.1 \, \text{M} \), what is \( [\ce{A}] \)?

Q10. For the equilibrium \( \ce{P(g) + Q(g) <=> R(g)} \), if \( K_c = 2.0 \) and initial moles of \( \ce{P} \) and \( \ce{Q} \) are 1 each in a 1 L vessel, what is \( [\ce{R}] \) at equilibrium?