The propane fuel (C3H8) used in gas barbeques burns according to the thermochemical equation: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g) ΔH°rxn = –2044 kJ If a pork roast must absorb 1.6×103 kJ to fully cook, and if only 10% of the heat produced by the barbeque is actually absorbed by the roast, what mass of CO2 is emitted into the atmosphere during the grilling of the pork roast?
Ch.6 - Thermochemistry
Chapter 6, Problem 61
Nitromethane (CH3NO2) burns in air to produce significant amounts of heat. 2 CH3NO2(l) + 3/2 O2(g) → 2 CO2(g) + 3 H2O(l) + N2(g) ΔH°rxn = –1418 kJ How much heat is produced by the complete reaction of 5.56 kg of nitromethane?
Verified step by step guidance1
Convert the mass of nitromethane (5.56 kg) to grams by multiplying by 1000.
Calculate the number of moles of nitromethane using its molar mass (CH3NO2). The molar mass is the sum of the atomic masses of all atoms in the molecule.
Use the stoichiometry of the balanced chemical equation to determine the relationship between moles of nitromethane and the enthalpy change (ΔH°rxn).
Calculate the total heat produced by multiplying the number of moles of nitromethane by the enthalpy change per mole of reaction (ΔH°rxn).
Ensure the units are consistent and convert the final answer to kilojoules if necessary.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Stoichiometry
Stoichiometry is the calculation of reactants and products in chemical reactions based on the balanced chemical equation. It allows us to determine the proportions of substances involved in a reaction, which is essential for calculating how much heat is produced when a specific amount of a reactant, like nitromethane, is consumed.
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Enthalpy Change (ΔH)
Enthalpy change (ΔH) represents the heat absorbed or released during a chemical reaction at constant pressure. In this case, the negative value of ΔH indicates that the reaction is exothermic, meaning it releases heat. Understanding ΔH is crucial for calculating the total heat produced from the combustion of nitromethane.
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Molar Mass
Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). To find out how much heat is produced from a given mass of nitromethane, we first need to convert the mass of nitromethane (5.56 kg) into moles using its molar mass, which is essential for applying stoichiometry in the heat calculation.
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Related Practice
Textbook Question
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Textbook Question
Charcoal is primarily carbon. Determine the mass of CO2 produced by burning enough carbon (in the form of charcoal) to produce 5.00×102 kJ of heat. C(s) + O2(g) → CO2(g) ΔH°rxn = –393.5 kJ
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Textbook Question
Titanium reacts with iodine to form titanium(III) iodide, emitting heat. 2 Ti(s) + 3 I2(g) → 2 TiI3(s) ΔH°rxn = –839 kJ Determine the mass of titanium that react if 1.55×103 kJ of heat is emitted by the reaction.
Textbook Question
Determine whether each process is exothermic or endothermic and indicate the sign of ΔH. a. dry ice evaporating b. a sparkler burning c. the reaction that occurs in a chemical cold pack used to ice athletic injuries
Textbook Question
What mass of natural gas (CH4) must burn to emit 267 kJ of heat? CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g) ΔH°rxn = –802.3 kJ
