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Multiple Choice
What will be the change in enthalpy when 100.0 g of butane, C4H10, is burned in oxygen according to the thermochemical equation: 2 C4H10(l) + 13 O2(g) → 8 CO2(g) + 10 H2O(g) with ΔH rxn = −5271 kJ?
A
−1810 kJ
B
−5271 kJ
C
−905 kJ
D
−2635 kJ
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Verified step by step guidance
1
Determine the molar mass of butane (C4H10) by adding the atomic masses of its constituent atoms: 4 carbon atoms and 10 hydrogen atoms.
Calculate the number of moles of butane in 100.0 g using the formula: \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \).
Use the stoichiometry of the given thermochemical equation to find the relationship between moles of butane and the enthalpy change. The equation shows that 2 moles of butane release −5271 kJ.
Calculate the enthalpy change for the moles of butane you have by setting up a proportion: \( \frac{\Delta H}{2 \text{ moles of C4H10}} = \frac{\text{calculated enthalpy change}}{\text{moles of C4H10 from 100.0 g}} \).
Solve the proportion to find the enthalpy change for the combustion of 100.0 g of butane.