What mass of natural gas (CH 4 ) must burn to emit 267 kJ of heat? CH 4 (g) + 2 O 2 (g) → CO 2 (g) + 2 H 2 O(g) ΔH° rxn = –802.3 kJ

Hey everyone in this example, we need to find the mass of carbon monoxide produced if the reaction absorbs 32.11 kg of heat. So that's what we're going to begin our equation with 32.11 kg joules. And we're going to recognize that according to the given equation for our reaction, We have an entropy value of 42 kg jewels. So we're going to say that for 42 kg jules, looking at the stock geometry of our carbon monoxide, we have one mole of carbon monoxide that is produced. And so now we can cancel out our units of kilo jewels. And now that we're at moles of carbon monoxide, we want to get two g of carbon monoxide. And so we're going to recall from the periodic table are molar mass for carbon monoxide, Which we see as 28.01 g of carbon monoxide for one mole of carbon monoxide. So this allows us to cancel out moles leaving us with grams of carbon monoxide, which is what we want. And so when we type this into our calculators, we get a value equal to 21.41 g of carbon monoxide that is produced from the given reaction. When it absorbs 32.11 kg joules of heat. And so this will be our final answer to complete this example. So, I hope that everything we reviewed was clear. If you have any questions, please leave them down below and I will see everyone in the next practice video

Ch.6 - Thermochemistry

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Tro 4th Edition

Ch.6 - Thermochemistry

Problem 60

Chapter 6, Problem 60

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

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Identify the given information: The reaction is CH₄(g) + 2 O₂(g) → CO₂(g) + 2 H₂O(g) with ΔH°rxn = -802.3 kJ.

Understand that the negative sign in ΔH°rxn indicates that the reaction is exothermic, meaning it releases 802.3 kJ of heat per mole of CH₄ burned.

Set up a proportion to find the moles of CH₄ needed to release 267 kJ of heat: (1 mole CH₄ / 802.3 kJ) = (x moles CH₄ / 267 kJ).

Solve the proportion for x to find the moles of CH₄ required to release 267 kJ of heat.

Convert the moles of CH₄ to mass using the molar mass of CH₄ (16.04 g/mol): mass = moles × molar mass.

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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. It involves using balanced chemical equations to determine the relationships between the amounts of substances consumed and produced. In this case, stoichiometry will help relate the amount of CH4 burned to the heat emitted based on the reaction's enthalpy change.

Enthalpy Change (ΔH)

Enthalpy change (ΔH) is a measure of the heat absorbed or released during a chemical reaction at constant pressure. A negative ΔH indicates that the reaction is exothermic, meaning it releases heat. For the combustion of methane (CH4), the given ΔH of -802.3 kJ indicates that burning one mole of CH4 releases 802.3 kJ of heat, which is crucial for calculating the mass needed to emit a specific amount of heat.

Molar Mass

Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). For CH4, the molar mass is approximately 16.04 g/mol. Knowing the molar mass is essential for converting between moles of CH4 and grams, allowing us to determine how much mass is required to produce the desired heat output based on the stoichiometric calculations.

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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?

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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

Verified video answer for a similar problem:

Key Concepts

Stoichiometry

Enthalpy Change (ΔH)

Molar Mass

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