Questions: What is the equilibrium expression for the reaction below? CaCO3(s) ⇌ CaO(s) + CO2(g) A. (CaCO3)/(CaO) B. [CO2] C. (CaCO3)/([CaO]+[CO2]) D. ([CaO][CO2])/(CaCO3)

Transcript text: What is the equilibrium expression for the reaction below? \[ \mathrm{CaCO}_{3}(s) \rightleftarrows \mathrm{CaO}(s)+\mathrm{CO}_{2}(g) \] A. $\frac{\left[\mathrm{CaCO}_{3}\right]}{[\mathrm{CaO}]}$ B. $\left[\mathrm{CO}_{2}\right]$ C. $\frac{\left[\mathrm{CaCO}_{3}\right]}{[\mathrm{CaO}]+\left[\mathrm{CO}_{2}\right]}$ D. $\frac{[\mathrm{CaO}]\left[\mathrm{CO}_{2}\right]}{\left[\mathrm{CaCO}_{3}\right]}$

Solution

Solution Steps

Step 1: Identify the Reaction Type

The given reaction is: \[ \mathrm{CaCO}_{3}(s) \rightleftarrows \mathrm{CaO}(s) + \mathrm{CO}_{2}(g) \] This is a heterogeneous equilibrium involving solids and a gas.

Step 2: Understand the Equilibrium Expression

For a heterogeneous equilibrium, the concentrations of pure solids and pure liquids are not included in the equilibrium expression. Only the concentration of gases and aqueous species are included.

Step 3: Write the Equilibrium Expression

Since $\mathrm{CaCO}_{3}(s)$ and $\mathrm{CaO}(s)$ are solids, they are not included in the equilibrium expression. The only species to include is $\mathrm{CO}_{2}(g)$.

The equilibrium expression is: \[ K = [\mathrm{CO}_{2}] \]