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Ch.16 - Chemical Equilibrium
Chapter 16, Problem 34b

 Calculate Kp for each reaction. b. CH4(g) + H2O(g) ⇌ CO(g) + 3 H2(g) Kc = 1.3×10^22 (at 298 K)

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Identify the relationship between Kc and Kp using the equation: Kp = Kc(RT)^(Δn), where Δn is the change in moles of gas, R is the ideal gas constant, and T is the temperature in Kelvin.
Calculate Δn for the reaction: Δn = (moles of gaseous products) - (moles of gaseous reactants). For the given reaction, Δn = (1 + 3) - (1 + 1).
Substitute the values into the equation: Kp = Kc(RT)^(Δn). Use R = 0.0821 L·atm/(mol·K) and T = 298 K.
Simplify the expression by calculating (RT)^(Δn) using the values of R, T, and Δn.
Multiply Kc by the result from the previous step to find Kp.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Equilibrium Constant (Kp and Kc)

The equilibrium constant (K) quantifies the ratio of the concentrations of products to reactants at equilibrium. Kp is used for gas-phase reactions and is expressed in terms of partial pressures, while Kc is based on molar concentrations. The relationship between Kp and Kc is given by the equation Kp = Kc(RT)^(Δn), where Δn is the change in moles of gas.
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Reaction Quotient (Q)

The reaction quotient (Q) is a measure of the relative amounts of products and reactants present in a reaction at any point in time. It is calculated using the same formula as K, but with current concentrations or pressures. Comparing Q to K helps determine the direction in which a reaction will proceed to reach equilibrium.
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Temperature Dependence of K

The value of the equilibrium constant (K) is temperature-dependent, meaning it can change with variations in temperature. For exothermic reactions, increasing temperature typically decreases K, while for endothermic reactions, it increases. Understanding this dependence is crucial for predicting how changes in temperature affect the position of equilibrium.
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