11.2.1 Effect of Temperature on Kc and Kp

• The equilibrium constants $K_{c}$ and $K_{p}$ are used to understand the position of equilibrium.
• Enthalpy change (ΔH) determines whether a reaction is exothermic or endothermic.
• Le Chatelier's Principle explains the effect of temperature on equilibrium systems.
• Steps to describe the effect of temperature on $K_{c}$ for exothermic reactions.


  1️⃣ Increase in temperature

  2️⃣ $K_{c}$ decreases

  3️⃣ Equilibrium shifts towards reactants
• Steps to describe the effect of temperature on $K_{c}$ for endothermic reactions.


  1️⃣ Increase in temperature

  2️⃣ $K_{c}$ increases

  3️⃣ Equilibrium shifts towards products
• $K_{p}$ is defined as the ratio of partial pressures of products to reactants at equilibrium.
• The effect of temperature on $K_{p}$ for gaseous equilibria is similar to its effect on $K_{c}$.
• The van't Hoff Equation is used to quantify the effect of temperature on equilibrium constants.
• Match the equilibrium constant with its definition.

  $K_{c}$ ↔️ Concentration ratio at equilibrium

  $K_{p}$ ↔️ Partial pressure ratio at equilibrium
• In an exothermic reaction, increasing temperature decreases $K_{c}$ and $K_{p}$.
• In an endothermic reaction, increasing temperature increases $K_{c}$ and $K_{p}$, shifting equilibrium towards products.
• $K_{c}$ is applicable to aqueous and gaseous systems, while K_{p}</latex> is only applicable to gaseous systems.
• Steps to describe the effect of temperature on an exothermic reaction.

  1️⃣ Increase in temperature

  2️⃣ $K_{c}$ and $K_{p}$ decrease

  3️⃣ Equilibrium shifts towards reactants
• For endothermic reactions, increasing temperature increases both $K_{c}$ and $K_{p}$, shifting equilibrium towards products.
• Match the reaction type with the effect of increasing temperature on $K_{c}$ and $K_{p}$.


  Exothermic reaction ↔️ $K_{c}$ and $K_{p}$ decrease

  Endothermic reaction ↔️ $K_{c}$ and $K_{p}$ increase
• Enthalpy change (ΔH) is the heat absorbed or released during a reaction at constant pressure.
• In an exothermic reaction, ΔH is negative and heat is released.
• In an endothermic reaction, ΔH is positive and heat is absorbed.
• Match the temperature change with its effect on equilibrium for exothermic and endothermic reactions.

  Increase in temperature ↔️ Exothermic: Shifts towards reactants

  Decrease in temperature ↔️ Endothermic: Shifts towards reactants
• For exothermic reactions, increasing temperature causes both $K_{c}$ and $K_{p}$ to decrease.
• In endothermic reactions, increasing temperature leads to higher values of $K_{c}$ and $K_{p}$.
• $K_{c}$ applies to aqueous and gaseous systems, while $K_{p}$ is only for gaseous
• A higher $K_{c}$ or K_{p}</latex> indicates that products are favored at equilibrium.
• Match the type of reaction with the effect of increasing temperature on $K_{c}$ and $K_{p}$:


  Exothermic (ΔH < 0) ↔️ $K_{c}$ and $K_{p}$ decrease

  Endothermic (ΔH > 0) ↔️ $K_{c}$ and $K_{p}$ increase
• Enthalpy change is defined as the heat absorbed or released during a chemical reaction at constant pressure
• Understanding enthalpy change helps predict whether a reaction requires energy input or releases energy.
• Match the reaction type with the sign of $ΔH$ and the type of heat flow:


  Exothermic ↔️ Negative (-), Heat released

  Endothermic ↔️ Positive (+), Heat absorbed
• Le Chatelier's Principle states that if a change in condition is applied to a system in equilibrium, the system will shift to counteract the change
• In an exothermic reaction, increasing the temperature shifts the equilibrium towards the reactants.
• When the temperature of an endothermic system in equilibrium decreases, the equilibrium shifts towards the reactants.
• For exothermic reactions, increasing temperature reduces the value of K_{c}</latex>
• At high temperatures, the $K_{c}$ for an exothermic reaction is low.
• For endothermic reactions, increasing temperature increases the value of $K_{c}$
• At low temperatures, the $K_{c}$ for an endothermic reaction is low.
• Match the equilibrium constant with its definition or suitability:

  $K_{c}$ ↔️ Ratio of concentrations of products to reactants

  $K_{p}$ ↔️ Only applicable to gaseous reactions
• A lower $K_{c}$ value indicates that the reaction favors the reactants.
• Enthalpy change is the heat absorbed or released during a chemical reaction at constant pressure
• Match the reaction type with the sign of ΔH</latex>:

  Exothermic ↔️ Negative (-)

  Endothermic ↔️ Positive (+)
• The formula for enthalpy change is $ΔH =$$H_{\text{products}} - H_{\text{reactants}}$, where $H$ represents enthalpy
• Arrange the effects of temperature on equilibrium shift in exothermic and endothermic reactions:

  1️⃣ For exothermic reactions, increasing temperature shifts towards reactants

  2️⃣ For exothermic reactions, decreasing temperature shifts towards products

  3️⃣ For endothermic reactions, increasing temperature shifts towards products

  4️⃣ For endothermic reactions, decreasing temperature shifts towards reactants