Question

HL

Calculate the solutions of homogeneous equilibrium problems using the expression for Kc for a particular reaction
- Standard question

Answer 1

To calculate the solutions of homogeneous equilibrium problems using the expression for
`\( K_c \)` (equilibrium constant) for a particular reaction, we need to follow the below steps.

To calculate the solutions of homogeneous equilibrium problems using the expression for
`\( K_c \)` (equilibrium constant) for a particular reaction, we need to follow these general steps:

Step 1: Write the Balanced Chemical Equation:

Write the balanced chemical equation for the reaction. For example, let's consider the generic reaction:

`\[ aA + bB \rightleftharpoons cC + dD \]`

Step 2: Write the Expression for
`\( K_c \)`:

Write the expression for
`\( K_c \)` based on the balanced chemical equation.
`\( K_c \)` is the equilibrium constant for concentrations, and for the generic reaction above, the expression is:

`\[ K_c = ([C]^c [D]^d)/([A]^a [B]^b) \]`

Step 3: Determine Known Concentrations:

If we are given initial concentrations or equilibrium concentrations of some of the species (
`\([A]_0\), \([B]_0\), \([C]_0\), \([D]_0\)` or
`\([A]_{\text{equilibrium}}\), \([B]_{\text{equilibrium}}\), \([C]_{\text{equilibrium}}\), \([D]_{\text{equilibrium}}\)),` use those values.

Step 4: Set up the
`\( K_c \)` Expression:

Substitute the known concentrations into the
`\( K_c \)` expression.

Step 5: Solve for Unknowns:

If there are unknown concentrations, solve for them using the known values and the
`\( K_c \)` expression. This might involve rearranging the
`\( K_c \)` expression or using an ICE (Initial Change Equilibrium) table.

Step 6: Check the Units:

Ensure that the units for concentrations are consistent, typically in mol/L.

Step 7: Interpret the Results:

Analyze the results. If
`\( K_c \)` is much greater than 1, the equilibrium favors the products. If
`\( K_c \)` is much less than 1, the equilibrium favors the reactants. If
`\( K_c \)` is close to 1, the concentrations of products and reactants are comparable.