# Chapter 15 - Questions and Problems - Page 709: 15.44

$[I_2] = 0.194 \space M$ $[I] = 8.58 \times 10^{-4} M$

#### Work Step by Step

- Calculate all the concentrations: $$[I_2] = ( 0.0456 )/(2.30) = 0.0198 M$$ 1. Write the equilibrium constant expression: - The exponent of each concentration is equal to its balance coefficient. $$K_c = \frac{[Products]}{[Reactants]} = \frac{[ I ]^{ 2 }}{[ I_2 ]}$$ 2. At equilibrium, these are the concentrations of each compound: $[ I_2 ] = 0.0198 \space M - x$ $[ I ] = 0 \space M + 2x$ $$3.80 \times 10^{-5} = \frac{(2x)^2}{(0.0198 - x)}$$ x = $4.29 \times 10^{-4}$ $[I_2] = 0.0198 - 4.29 \times 10^{-4} = 0.194 \space M$ $[I] = 2(4.29 \times 10^{-4}) = 8.58 \times 10^{-4} M$

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