Calculate the energy generated in kilowatt-hours if the burning of 2.5 g of methane produces 125 kJ of heat.

Question

Quizplus · Accepted Answer

First, we need to convert the mass of methane from grams to moles using its molar mass:

1 mole of CH4 (16.04 g) = 1 mol CH4

2.5 g CH4 = (2.5 g CH4) / (16.04 g/mol CH4) = 0.156 moles CH4

Next, we can use the given heat of combustion (125 kJ) to calculate the energy generated per mole of CH4:

125 kJ / 0.156 mol CH4 = 801.28 kJ/mol CH4

Now we can convert the energy generated to kilowatt-hours (kWh):

801.28 kJ/mol CH4 × (1 kWh / 3.6 × 10^6 kJ) = 0.222022 kWh/mol CH4

Finally, we can multiply by the number of moles of CH4 (0.156 mol) to get the total energy generated:

0.222022 kWh/mol CH4 × 0.156 mol CH4 = 0.034632632 kWh

Rounded to two significant figures, the answer is 3.5 × 10^-2 kWh, which corresponds to choice C.

Calculate the Energy Generated in Kilowatt-Hours If the Burning of 2.5