Answer
Sketch (c)
Work Step by Step
1. Count the atoms in the initial mixture:
2 $Br_2$
3 $NO$
20 $NOBr$
2. Now, assume these are the concentrations in the complete mixture, and find the equilibrium amounts.
3. Draw the ICE table for this equilibrium:
$$\begin{vmatrix}
Compound& [ NO ]& [ Br_2 ]& [ NOBr ]\\
Initial& 3 & 2 & 20 \\
Change& -2 x& -x& 2 x\\
Equilibrium& 3 -2 x& 2 -x& 20 + 2 x\\
\end{vmatrix}$$
- The exponent of each concentration is equal to its balance coefficient.
$$K_C = \frac{[Products]}{[Reactants]} = \frac{[ NOBr ] ^{ 2 }}{[ NO ] ^{ 2 }[ Br_2 ]}$$
4. At equilibrium, these are the concentrations of each compound:
$ [ NO ] = 3 - 2x$
$ [ Br_2 ] = 2 - x$
$ [ NOBr ] = 20 + 2x$
$$3.0 = \frac{(20 + 2x)^2}{(3-2x)^2(2 - x)}$$
5. Solve for x:
$x = -1.3$
$ [ NO ] = 3 - 2(-1.3) = 5.6$
$ [ Br_2 ] = 2 - (-1.3) = 3.3$
$ [ NOBr ] = 20+ 2(-1.3) = 17.4$
6. Find the diagram that better represents it. (c)
