Answer
$$K_c = 5.8 \times 10^{-2}$$
Work Step by Step
1. Write the equilibrium constant expression:
- The exponent of each concentration is equal to its balance coefficient.
$$K_c = \frac{[Products]}{[Reactants]} = \frac{[ PCl_3 ][ Cl_2 ]}{[ PCl_5 ]}$$
2. Substitute the values and calculate the constant value:
$$K_c = \frac{( 1.5 x 10^{-2} )( 3.2 x 10^{-2} )}{( 8.3 x 10^{-3} )} = 5.8 \times 10^{-2}$$