Question

exercise 13.5
equilibrium & ice tables
name:
date:
per:
the equilibrium constant (k) is the ratio of the equilibrium concentration (or pressure) of product(s) to the equilibrium concentration (or pressure) of reactant(s). the same expression can be used to calculate the reaction quotient, (q):
2no₂(g) + 7h₂(g) ⇌ 2nh₃(g) + 4h₂o(l)
kc = nh₃²h₂o⁴ / no₂²h₂⁷ (at equilibrium) ; q = nh₃² / no₂²h₂⁷ (at any moment/point)
the coefficients from the balanced equation become exponents. liquids and solids never appear in the expressions, because their concentrations (or pressures) do not change throughout the reaction.
directions: write an equilibrium expression for each of the following. not all equations are balanced.

1. caso₄(s) ⇌ ca²⁺(aq) + so₄²⁻(aq)
2. _no(g) + _cl₂(g) ⇌ _nocl(g)

Explanation:

Step1: Determine the form of equilibrium expression

For a reaction \(aA + bB
ightleftharpoons cC + dD\), the equilibrium constant \(K_c=\frac{[C]^c[D]^d}{[A]^a[B]^b}\). Solids (\(CaSO_4\) in reaction 1) do not appear in the equilibrium expression.

Step2: Write equilibrium expression for reaction 1

For \(CaSO_4(s)
ightleftharpoons Ca^{2 +}(aq)+SO_4^{2 -}(aq)\), \(K_c = [Ca^{2+}][SO_4^{2 -}]\)

Step3: Balance reaction 6

First, balance \(NO(g)+Cl_2(g)
ightleftharpoons NOCl(g)\). The balanced equation is \(2NO(g)+Cl_2(g)
ightleftharpoons 2NOCl(g)\)

Step4: Write equilibrium expression for reaction 6

Using the formula \(K_c=\frac{[C]^c[D]^d}{[A]^a[B]^b}\), for \(2NO(g)+Cl_2(g)
ightleftharpoons 2NOCl(g)\), \(K_c=\frac{[NOCl]^2}{[NO]^2[Cl_2]}\)

Answer:

1. \(K_c = [Ca^{2+}][SO_4^{2 -}]\)
2. \(K_c=\frac{[NOCl]^2}{[NO]^2[Cl_2]}\)