The Reaction Quotient Video Lessons

Example

# Problem: For the reaction system      H2(g) + X2(g) ⇌ 2 HX(g)Kc = 24.4 at 300 K. If the reaction is set up with the following initial concentrations, what will the equilibrium concentration of X2 be? initial H2 = 0.150 M          initial X2 = 0.200 M          initial HX = 0.600 MA. 0.0365 M B. 0.114 M C. 0.164 M D. 0.0730 ME. 0.500 M

###### FREE Expert Solution

We are being asked to calculate the equilibrium concentration of X2 for the given equilibrium reaction:

H2(g) + X2(g) ⇌ 2 HX(g)            Kc = 24.4 at 300 K.

When dealing with equilibrium and Kc:

Kc → equilibrium units are in molarity
Kc is an equilibrium expression:

$\overline{){{\mathbf{K}}}_{{\mathbf{c}}}{\mathbf{=}}\frac{\mathbf{products}}{\mathbf{reactants}}}$

only aqueous and gaseous species are included in the equilibrium expression
▪ the coefficient of each compound in the reaction equation will be the exponent of the concentrations in the equilibrium expression

Given:

Initial Concentrations:

initial H2 = 0.150 M

initial X2 = 0.200 M

initial HX = 0.600 M

Let’s calculate the Reaction Quotient (Q) using the given initial concentration to determine which direction the equilibrium will proceed:

$\overline{){\mathbf{Q}}{\mathbf{=}}\frac{\mathbf{products}}{\mathbf{reactants}}}$

94% (58 ratings)
###### Problem Details

For the reaction system      H2(g) + X2(g) ⇌ 2 HX(g)
Kc = 24.4 at 300 K. If the reaction is set up with the following initial concentrations, what will the equilibrium concentration of X2 be?

initial H2 = 0.150 M          initial X2 = 0.200 M          initial HX = 0.600 M

A. 0.0365 M

B. 0.114 M

C. 0.164 M

D. 0.0730 M

E. 0.500 M