For the reaction 2 + 2, the units of Kc are — Chemical Equilibrium Chemistry Question

💡 Solution & Explanation

# Finding Units of Kc for: $2SO_2 + O_2 \rightarrow 2SO_3$ **Step 1: Write the equilibrium constant expression** $$K_c = \frac{[SO_3]^2}{[SO_2]^2[O_2]}$$ **Step 2: Identify units of concentration terms** Each concentration term has units of $\text{mol/L}$ or $\text{M}$ **Step 3: Substitute units into the expression** $$[K_c] = \frac{(\text{mol/L})^2}{(\text{mol/L})^2 \times (\text{mol/L})}$$ **Step 4: Simplify** $$[K_c] = \frac{(\text{mol/L})^2}{(\text{mol/L})^3} = (\text{mol/L})^{-1} = \text{L/mol}$$ **Answer:** The units of $K_c$ are **L·mol⁻¹** or **L/mol** (equivalent to **M⁻¹**) This occurs because there are more moles of gaseous reactants (3 total) than products (2 total), resulting in a net negative exponent in the units.