📚 Topic Summary
In chemistry, $K_c$ and $K_p$ represent equilibrium constants. $K_c$ uses molar concentrations, while $K_p$ uses partial pressures. The relationship between them is given by the equation: $K_p = K_c(RT)^{\Delta n}$, where $R$ is the ideal gas constant, $T$ is the temperature in Kelvin, and $\Delta n$ is the change in the number of moles of gas during the reaction (moles of gaseous products minus moles of gaseous reactants). This conversion is essential when dealing with gaseous equilibria where partial pressures are known or easier to measure.
Understanding this conversion helps predict reaction direction and equilibrium composition under different conditions. Remember to always use consistent units for $R$ and ensure the temperature is in Kelvin!
🧪 Part A: Vocabulary
Match the terms with their definitions:
| Term |
Definition |
| 1. Equilibrium Constant ($K_c$) |
a. The change in the number of moles of gas in a reaction. |
| 2. Equilibrium Constant ($K_p$) |
b. A constant related to the ratio of partial pressures of products to reactants at equilibrium. |
| 3. R |
c. A constant related to the ratio of molar concentrations of products to reactants at equilibrium. |
| 4. T |
d. The ideal gas constant (0.0821 L atm / (mol K)). |
| 5. $\Delta n$ |
e. Temperature in Kelvin. |
(Answers: 1-c, 2-b, 3-d, 4-e, 5-a)
⚗️ Part B: Fill in the Blanks
Complete the following paragraph with the correct terms:
The conversion between $K_c$ and $K_p$ involves several factors. $K_c$ uses __________, while $K_p$ uses __________. The formula to convert between them is $K_p = K_c(RT)^{\Delta n}$, where R is the __________ and T is the __________ in __________. $\Delta n$ represents the change in the number of __________ of __________ in the reaction.
(Answers: molar concentrations, partial pressures, ideal gas constant, temperature, Kelvin, moles, gas)
🤔 Part C: Critical Thinking
Explain why it is important to use Kelvin for the temperature when converting between $K_c$ and $K_p$. What would happen if you used Celsius instead?