Textbook Question
Without referring to tables, predict which of the following has the higher enthalpy in each case: (c) 1 mol I2(g) and 1 mol H2(g) at 25 °C or 2 mol HI(g) at 25 °C (d) 1 mol H2(g) at 100 °C or 1 mol H2(g) at 300 °C.
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Ch.5 - Thermochemistry
Chapter 5, Problem 44c
Consider the following reaction: 2 CH3OH(g) → 2 CH4(g) + O2(g) ΔH = +252.8 kJ (c) For a given sample of CH3OH, the enthalpy change during the reaction is 82.1 kJ. How many grams of methane gas are produced?
Verified step by step guidance1
Identify the stoichiometry of the reaction: 2 moles of CH3OH produce 2 moles of CH4 and 1 mole of O2.
Understand that the given enthalpy change (ΔH = +252.8 kJ) is for the reaction as written, which involves 2 moles of CH3OH.
Determine the proportion of the reaction that corresponds to the given enthalpy change of 82.1 kJ. Use the ratio: (82.1 kJ / 252.8 kJ) to find the fraction of the reaction that has occurred.
Calculate the moles of CH4 produced using the stoichiometry of the reaction. Since 2 moles of CH3OH produce 2 moles of CH4, the moles of CH4 produced will be the same as the moles of CH3OH reacted.
Convert the moles of CH4 to grams using the molar mass of CH4 (16.04 g/mol). Multiply the moles of CH4 by the molar mass to find the mass of CH4 produced.
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Related Practice
Open Question
Consider the following reaction: 2 Mg(s) + O₂(g) → 2 MgO(s) ΔH = -1204 kJ (b) Calculate the amount of heat transferred when 3.55 g of Mg(s) reacts at constant pressure. (d) How many kilojoules of heat are absorbed when 40.3 g of MgO(s) is decomposed into Mg(s) and O₂(g) at constant pressure?
Textbook Question
Consider the following reaction: 2 CH3OH(g) → 2 CH4(g) + O2(g) ΔH = +252.8 kJ (b) Calculate the amount of heat transferred when 24.0 g of CH3OH(g) is decomposed by this reaction at constant pressure.
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Textbook Question
Consider the following reaction: 2 CH3OH(g) → 2 CH4(g) + O2(g) ΔH = +252.8 kJ (d) How many kilojoules of heat are released when 38.5 g of CH4(g) reacts completely with O2(g) to form CH3OH(g) at constant pressure?
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Textbook Question
When solutions containing silver ions and chloride ions are mixed, silver chloride precipitates Ag+(aq) + Cl-(aq) → AgCl(s) H = -65.5 kJ (a) Calculate H for the production of 0.450 mol of AgCl by this reaction. (b) Calculate H for the production of 9.00 g of AgCl. (c) Calculate H when 9.25⨉10-4 mol of AgCl dissolves in water.
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Textbook Question
At one time, a common means of forming small quantities of oxygen gas in the laboratory was to heat KClO3: 2 KClO3(s) → 2 KCl(s) + 3 O2(g) ΔH = -89.4 kJ For this reaction, calculate H for the formation of (a) 1.36 mol of O2
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