History Bookmarks Window Help Assignment 3 (Chapter 14) Problem 14.92 c) 7of9 Pa

Question

History Bookmarks Window Help Assignment 3 (Chapter 14) Problem 14.92 c) 7of9 Part A The arpoludant NOed ulsmoble engnes from the high-Hemperatne Calculate the equilbrium concentration of [Nal i the intial concentrations are 2.21 M N and 0.59 M 02 (This N/02 concentration ratio is the ratio found in air) Express your answer to three significant figures and include the appropriate units eest Ans Part B Calculate the equlbrium concentraton of O Express your answer to two signtant figures and ielude the appropriate . 02 An

Explanation / Answer

Equilibrium reaction looks like this

N2(g)+O2(g)2NO(g)

You know that the equilibrium constant for this reaction is

Kc=1.7103

Right from the start, the fact that Kc<1 should tell you that when equilibrium is reached, the reaction vessel will contain significantly higher concentrations of nitrogen gas and oxygen gas.

In other words, at this particular temperature, the equilibrium lies to the left.

Set up your ICE table and plug in your values to find the equilibrium concentrations of the three species

N2(g) + O2(g) 2NO(g)

2.24 0.55 0
x x +2x
2.24x 0.55x 2x

By definition, the equilibrium constant will be equal to

Kc=[NO]2  /[N2]x[O2]

In this case, you will have

Kc=(2x)2 /(2.24x)x(0.55x)=4x2  /( 2.24x)x(0.55x)

Now, because the value of Kc is very small, you can use the approximations

2.24x2.24 and 0.55x0.55

This will get you

1.7103=4x22.240.55

x=2.24x0.55x1.7x103 /4=0.0223

The equilibrium concentrations of the three chemical species will thus be

[N2]=2.240.0223=2.2 M

[O2]=0.550.0223=0.53 M

[NO]=2×0.0223=0.045 M

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