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When 3.6 g of butanal (mass of one mole = 72 g) was burned, 124 kJ of energy was released - Scottish Highers Chemistry - Question 16 - 2018

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Question 16

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When 3.6 g of butanal (mass of one mole = 72 g) was burned, 124 kJ of energy was released. What is the enthalpy of combustion of butanal, in kJ mol⁻¹? A -6 kJ B +6... show full transcript

Worked Solution & Example Answer:When 3.6 g of butanal (mass of one mole = 72 g) was burned, 124 kJ of energy was released - Scottish Highers Chemistry - Question 16 - 2018

Step 1

Calculate the number of moles of butanal burned

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Answer

To find the number of moles, use the formula:

t = \frac{mass}{molar \ mass}

In this case:

t = \frac{3.6 \ g}{72 \ g/mol} = 0.05 \ mol

Step 2

Determine the enthalpy of combustion per mole

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Answer

The energy released for burning 0.05 moles is 124 kJ. To find the enthalpy change per mole:

[ \Delta H = \frac{energy}{moles} = \frac{-124 \ kJ}{0.05 \ mol} = -2480 \ kJ/mol ]

Thus, the enthalpy of combustion of butanal is -2480 kJ/mol.

Step 3

Select the correct answer from the options

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Answer

Based on the calculation, the answer is C: -2480 kJ.

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