Westonci.ca is the best place to get answers to your questions, provided by a community of experienced and knowledgeable experts. Our platform connects you with professionals ready to provide precise answers to all your questions in various areas of expertise. Get quick and reliable solutions to your questions from a community of experienced experts on our platform.

Consider the equilibrium system described by the chemical reaction below. At equilibrium, a sample of gas from the system is collected into a 5.00 L flask containing 25.3 g of [tex]H_2[/tex]. What is the value of [tex]K_c[/tex] for this reaction?

[tex] CH_4(g) + CO_2(g) \rightleftharpoons 2 CO(g) + 2 H_2(g) [/tex]

1. Based on the given data, set up the expression for [tex]K_c[/tex]. Each reaction participant must be represented by one tile. Do not combine terms.

2. Once the expression is constructed, solve for [tex]K_c[/tex].

[tex] K_c = \square [/tex]


Sagot :

Let's work through the problem step by step to find the equilibrium constant, [tex]\( K_c \)[/tex], for the reaction

[tex]\[ CH_4(g) + CO_2(g) \rightleftharpoons 2 CO (g) + 2 H_2(g) \][/tex]

### Step 1: Calculate the moles of [tex]\( H_2 \)[/tex]

We are given the mass of [tex]\( H_2 \)[/tex] as 25.3 g. First, we need to find the number of moles of [tex]\( H_2 \)[/tex].

1. The molar mass of H[tex]\(_2\)[/tex] is approximately 2 g/mol.
2. The formula to calculate the number of moles is:

[tex]\[ \text{moles of } H_2 = \frac{\text{mass of } H_2}{\text{molar mass of } H_2} \][/tex]

3. Thus:

[tex]\[ \text{moles of } H_2 = \frac{25.3 \, \text{g}}{2 \, \text{g/mol}} = 12.65 \, \text{mol} \][/tex]

### Step 2: Calculate the concentration of [tex]\( H_2 \)[/tex]

The next step is to determine the concentration of [tex]\( H_2 \)[/tex] in the flask.

1. We are given the volume of the flask as 5.00 L.
2. Concentration is calculated using the formula:

[tex]\[ \text{Concentration of } H_2 = \frac{\text{moles of } H_2}{\text{volume}} \][/tex]

3. Thus:

[tex]\[ \text{Concentration of } H_2 = \frac{12.65 \, \text{mol}}{5.00 \, \text{L}} = 2.53 \, \text{M} \][/tex]

### Step 3: Set up the expression for [tex]\( K_c \)[/tex]

The balanced chemical equation for the reaction is:
[tex]\[ CH_4(g) + CO_2(g) \rightleftharpoons 2 CO (g) + 2 H_2(g) \][/tex]

The expression for the equilibrium constant [tex]\( K_c \)[/tex] based on the given reaction is:
[tex]\[ K_c = \frac{[CO]^2 [H_2]^2}{[CH_4][CO_2]} \][/tex]

### Step 4: Determine the concentrations needed for the [tex]\( K_c \)[/tex] expression

Assuming the concentrations of [tex]\( CH_4 \)[/tex] and [tex]\( CO_2 \)[/tex] are each 1 M (as simplest assumption is made for the purpose of this problem), we need the concentration of [tex]\( CO \)[/tex] at equilibrium.

1. From the stoichiometry of the reaction, for every 2 moles of [tex]\( H_2 \)[/tex] formed, 2 moles of [tex]\( CO \)[/tex] are also formed.
2. Hence, the concentration of [tex]\( CO \)[/tex] will be half of that of [tex]\( H_2 \)[/tex] as:

[tex]\[ \text{Concentration of } CO = \frac{\text{Concentration of } H_2}{2} = \frac{2.53 \, \text{M}}{2} = 1.265 \, \text{M} \][/tex]

### Step 5: Plug the concentrations into the [tex]\( K_c \)[/tex] expression and solve

[tex]\[ K_c = \frac{(1.265 \, \text{M})^2 \cdot (2.53 \, \text{M})^2}{(1 \, \text{M}) \cdot (1 \, \text{M})} \][/tex]

Performing the calculation:

[tex]\[ K_c = \frac{(1.265)^2 \cdot (2.53)^2}{1 \cdot 1} \][/tex]

Calculate individually first:
1. [tex]\( (1.265)^2 = 1.600225 \)[/tex]
2. [tex]\( (2.53)^2 = 6.4009 \)[/tex]

So,

[tex]\[ K_c = 1.600225 \times 6.4009 = 10.2428802025 \approx 10.24 \][/tex]

### Final Answer

Thus, the equilibrium constant [tex]\( K_c \)[/tex] for the reaction is:

[tex]\[ K_c = 10.24 \][/tex]