Open Question
The value of ΔH° for the reaction 3 O2(g) ⇌ 2 O3(g) is +285 kJ. Does the equilibrium constant for this reaction increase or decrease when the temperature increases? Justify your answer using Le Châtelier’s principle.
Ch.15 - Chemical Equilibrium
Chapter 15, Problem 126
Methanol (CH3OH) is manufactured by the reaction of carbon monoxide with hydrogen in the presence of a Cu/ZnO/Al2O3 catalyst: CO(g) + 2H2(g) ⇌ CH3OH(g) ΔH° = -91 kJ. Does the amount of methanol increase, decrease, or remain the same when an equilibrium mixture of reactants and products is subjected to the following changes? (a) The temperature is increased. (b) CO is added. (c) Helium is added. (d) The catalyst is removed.
Verified step by step guidance1
Step 1: Consider the effect of temperature on the equilibrium. Since the reaction is exothermic (ΔH° = -91 kJ), increasing the temperature will shift the equilibrium to favor the endothermic direction, which is the reverse reaction. This will decrease the amount of methanol.
Step 2: Analyze the effect of adding CO. According to Le Chatelier's principle, adding more CO will shift the equilibrium to the right to counteract the change, increasing the amount of methanol produced.
Step 3: Evaluate the impact of adding helium. Adding an inert gas like helium at constant volume does not change the partial pressures of the reactants or products, so the equilibrium position remains unchanged, and the amount of methanol stays the same.
Step 4: Consider the role of the catalyst. Removing the catalyst will slow down the rate at which equilibrium is reached but does not affect the position of the equilibrium. Therefore, the amount of methanol at equilibrium remains the same.
Step 5: Summarize the effects: (a) Methanol decreases with increased temperature, (b) Methanol increases with added CO, (c) Methanol remains the same with added helium, (d) Methanol remains the same if the catalyst is removed.
Related Practice
Textbook Question
Consider the exothermic reaction
CoCl 2-1aq2 + 6 H O1l2 ∆ Co1H O2 2 + 1aq2 + 4 Cl-1aq2 which interconverts the blue CoCl 2- ion and the pink
Co 2 +CoCl 2- increase or decrease when the following changes occur?(c) The solution is diluted with water.
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Open Question
Consider the endothermic reaction Fe³⁺(aq) + Cl⁻(aq) ⇌ FeCl₂⁺(aq). Use Le Châtelier’s principle to predict how the equilibrium concentration of the complex ion FeCl₂⁺ will change when: (a) Fe(NO₃)₃ is added. (b) Cl⁻ is precipitated as AgCl by addition of AgNO₃. (d) A catalyst is added.
Open Question
In the gas phase at 400 °C, isopropyl alcohol (rubbing alcohol) decomposes to acetone, an important industrial solvent:
\[
\text{Isopropyl alcohol: }(\text{CH}_3)_2\text{CHOH(g)} \rightleftharpoons (\text{CH}_3)_2\text{CO(g) + H}_2\text{(g)} \\
\Delta H^\circ = + 57.3 \text{ kJ}
\]
Does the amount of acetone increase, decrease, or remain the same when an equilibrium mixture of reactants and products is subjected to the following changes?
(c) Argon is added.
(d) H₂ is added.
(e) A catalyst is added.
Textbook Question
The following reaction is important in gold mining: 4 Au1s2 + 8 CN-1aq2 + O21g2 + 2 H2O1l2 ∆ 4 Au1CN22-1aq2 + 4 OH-1aq2For a reaction mixture at equilibrium, in which direction would the reaction go to reestablish equilibrium after each of the following changes?
(a) Adding gold
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Open Question
For the following reaction catalyzed by iridium, which is endothermic at 700 K: CaO(s) + CH₄(g) + 2 H₂O(g) ⇌ CaCO₃(s) + 4 H₂(g), how would the following changes affect the total quantity of CaCO₃ in the reaction mixture once equilibrium is reestablished at 700 K? (a) Increasing the temperature (b) Adding calcium oxide (c) Removing methane (CH₄) (d) Adding iridium.