For the reaction shown here, Kc = 0.513 at 500 K. N2O4(g) ⇌ 2 NO2(g) If a reaction vessel initially contains an N2O4 concentration of 0.0500 M at 500 K, what are the equilibrium concentrations of N2O4 and NO2 at 500 K?
Ch.15 - Chemical Equilibrium
Chapter 15, Problem 55
Consider the reaction: NiO(s) + CO(g) ⇌ Ni(s) + CO2(g) Kc = 4.0 * 10^3 at 1500 K. If a mixture of solid nickel(II) oxide and 0.20 M carbon monoxide comes to equilibrium at 1500 K, what is the equilibrium concentration of CO2?

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Identify the balanced chemical equation: NiO(s) + CO(g) ⇌ Ni(s) + CO2(g).
Recognize that solids do not appear in the equilibrium expression, so the equilibrium constant expression is K_c = [CO_2]/[CO].
Substitute the given equilibrium constant K_c = 4.0 \times 10^3 into the expression: 4.0 \times 10^3 = [CO_2]/[CO].
Let the change in concentration of CO be x, so at equilibrium, [CO] = 0.20 - x and [CO_2] = x.
Substitute these expressions into the equilibrium constant expression: 4.0 \times 10^3 = x/(0.20 - x) and solve for x, which represents the equilibrium concentration of CO_2.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Equilibrium Constant (Kc)
The equilibrium constant, Kc, quantifies the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature. For the reaction provided, Kc = [CO2]/[CO], indicating that at equilibrium, the concentration of CO2 is significantly influenced by the concentration of CO and the value of Kc.
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Le Chatelier's Principle
Le Chatelier's Principle states that if a system at equilibrium is disturbed, the system will adjust to counteract the disturbance and restore a new equilibrium. In this reaction, adding CO or changing the temperature could shift the equilibrium position, affecting the concentration of CO2 produced.
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Stoichiometry of the Reaction
Stoichiometry involves the quantitative relationships between reactants and products in a chemical reaction. In this case, the balanced equation indicates that one mole of CO reacts with one mole of NiO to produce one mole of CO2, which is essential for calculating the equilibrium concentrations based on the initial concentrations and the changes at equilibrium.
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Related Practice
Textbook Question
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Textbook Question
For the reaction shown here, Kc = 255 at 1000 K. CO(g) + Cl2(g) ⇌ COCl2(g) If a reaction mixture initially contains a CO concentration of 0.1500 M and a Cl2 concentration of 0.175 M at 1000 K, what are the equilibrium concentrations of CO, Cl2, and COCl2 at 1000 K?
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Textbook Question
Consider the reaction: HC2H3O2(aq) + H2O(l) ⇌ H3O+(aq) + C2H3O2-(aq) Kc = 1.8⨉10-5 at 25°C If a solution initially contains 0.210 M HC2H3O2, what is the equilibrium concentration of H3O+ at 25 °C?
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Textbook Question
Consider the reaction: SO2Cl2(g) ⇌ SO2(g) + Cl2(g) Kc = 2.99⨉10-7 at 227 °C If a reaction mixture initially contains 0.175 M SO2Cl2, what is the equilibrium concentration of Cl2 at 227 °C?
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