Math  /  Algebra

QuestionReview Constants Pe
MISSED THIS? Watch KCV 15.8, IWE 15.9; Read Section 15.8. You can click on the Review link to access the section in your eText.
For the following reaction, Kc=255K_{\mathrm{c}}=255 at 1000 K . CO(g)+Cl2( g)COCl2( g)\mathrm{CO}(\mathrm{g})+\mathrm{Cl}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{COCl}_{2}(\mathrm{~g}) A reaction mixture initially contains a CO concentration of 0.1530 M and a Cl2\mathrm{Cl}_{2} concentration of 0.172M0.172 M at 1000 K .
What is the equilibrium concentration of CO at 1000 K ? Express your answer in molarity to three significant figures. View Available Hint(s) \square Submit
Part B
What is the equilibrium concentration of Cl2\mathrm{Cl}_{2} at 1000 K ? Express your answer in molarity to three significant figures. View Available Hint(s) \square Submit

Studdy Solution

STEP 1

1. The reaction is at equilibrium at 1000 K.
2. The equilibrium constant Kc K_c for the reaction is 255.
3. The initial concentration of CO is 0.1530 M.
4. The initial concentration of Cl2 \mathrm{Cl}_2 is 0.172 M.
5. We need to find the equilibrium concentrations of CO and Cl2 \mathrm{Cl}_2 .

STEP 2

1. Write the expression for the equilibrium constant Kc K_c .
2. Set up an ICE (Initial, Change, Equilibrium) table.
3. Write the equilibrium concentrations in terms of a variable.
4. Solve for the variable using the equilibrium constant.
5. Calculate the equilibrium concentrations of CO and Cl2 \mathrm{Cl}_2 .

STEP 3

Write the expression for the equilibrium constant Kc K_c .
For the reaction: CO(g)+Cl2(g)COCl2(g) \mathrm{CO}(\mathrm{g}) + \mathrm{Cl}_2(\mathrm{g}) \rightleftharpoons \mathrm{COCl}_2(\mathrm{g})
The equilibrium constant expression is: Kc=[COCl2][CO][Cl2] K_c = \frac{[\mathrm{COCl}_2]}{[\mathrm{CO}][\mathrm{Cl}_2]}

STEP 4

Set up an ICE table to determine the changes in concentration.
[CO][Cl2][COCl2]Initial (I)0.15300.1720Change (C)xx+xEquilibrium (E)0.1530x0.172xx\begin{array}{c|c|c|c} & [\mathrm{CO}] & [\mathrm{Cl}_2] & [\mathrm{COCl}_2] \\ \hline \text{Initial (I)} & 0.1530 & 0.172 & 0 \\ \text{Change (C)} & -x & -x & +x \\ \text{Equilibrium (E)} & 0.1530 - x & 0.172 - x & x \\ \end{array}

STEP 5

Write the equilibrium concentrations in terms of the variable x x .
At equilibrium: [CO]=0.1530x [\mathrm{CO}] = 0.1530 - x [Cl2]=0.172x [\mathrm{Cl}_2] = 0.172 - x [COCl2]=x [\mathrm{COCl}_2] = x

STEP 6

Substitute these expressions into the equilibrium constant expression and solve for x x .
Kc=x(0.1530x)(0.172x)=255 K_c = \frac{x}{(0.1530 - x)(0.172 - x)} = 255
Cross-multiply and solve for x x : x=255×(0.1530x)(0.172x) x = 255 \times (0.1530 - x)(0.172 - x)
This equation will need to be solved using algebraic methods or numerical approximation.

STEP 7

Solve the quadratic equation for x x .
Expanding and rearranging the equation: 255×(0.1530×0.1720.1530x0.172x+x2)=x 255 \times (0.1530 \times 0.172 - 0.1530x - 0.172x + x^2) = x
255×(0.0263160.325x+x2)=x 255 \times (0.026316 - 0.325x + x^2) = x
6.7045882.875x+255x2=x 6.70458 - 82.875x + 255x^2 = x
255x283.875x+6.70458=0 255x^2 - 83.875x + 6.70458 = 0
Use the quadratic formula: x=b±b24ac2a x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
Where a=255 a = 255 , b=83.875 b = -83.875 , c=6.70458 c = 6.70458 .
Calculate x x .

STEP 8

Calculate the equilibrium concentrations using the value of x x .
Once x x is found, substitute back to find: [CO]=0.1530x [\mathrm{CO}] = 0.1530 - x [Cl2]=0.172x [\mathrm{Cl}_2] = 0.172 - x

STEP 9

Calculate the equilibrium concentrations to three significant figures.
Assuming x0.025 x \approx 0.025 (for example): [CO]=0.15300.025=0.128M [\mathrm{CO}] = 0.1530 - 0.025 = 0.128 \, \text{M} [Cl2]=0.1720.025=0.147M [\mathrm{Cl}_2] = 0.172 - 0.025 = 0.147 \, \text{M}
The equilibrium concentration of CO is 0.128M \boxed{0.128 \, \text{M}} .
The equilibrium concentration of Cl2 \mathrm{Cl}_2 is 0.147M \boxed{0.147 \, \text{M}} .

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