**The Equilibrium Expression, K _{eq} – Practice**

**Questions:**

1) Write the equilibrium expression for the following reactions:

a) 2HI_{(g)} ⇌ H_{2(g) }+ I_{2(g)}

b) H_{2}O_{(g)} + C_{(s)} ⇌ H_{2(g) }+ CO_{(g)}

2) Nitrosyl Chloride decomposes according to the following equation:

2NOCl_{(g)} ⇌ 2NO_{(g)} + Cl_{2(g)}

At equilibrium the concentrations of these three gases were: [NOCl] = 0.00043, [NO] = 0.0072, [Cl_{2}] = 0.0016. Calculate K_{eq} for this equilibrium system:

3) 0.050 moles of SO_{2(g)} was reacted with 0.040 moles of oxygen to produce SO_{3(g)} in a 1L container. At equilibrium there was 0.024 moles of SO_{2(g) }remaining. Use an ICE table to calculate K_{eq} for this system:

4) Under certain conditions the equilibrium constant for the decomposition of dinitrogen tetraoxide to form nitrogen dioxide is 12.2. In a closed vessel, the concentration of N_{2}O_{4(g) }was 0.04M and the concentration of NO_{2(g) }was 0.03M. Determine if this system is at equilibrium and if not, which way the system will shift to reach equilibrium:

**Quick Answers:**

1) a) { K }_{ eq }=\cfrac { { [{ H }_{ 2 }] }[{ I }_{ 2 }] }{ { [HI] }^{ 2 } }

b) { K }_{ eq }=\cfrac { { [{ H }_{ 2 }] }[CO] }{ { [{ H }_{ 2 }O] } }

2) K_{eq} = 0.45

3) K_{eq} = 43.5

4) Q = 0.0225. Q < K_{eq}, system will shift right to produce more NO_{2}

**Worked Answers:**