A 0.50 {\rm g} sample of vegetable oil is placed in a calorimeter. When the sample is burned, 18.9 {\rm kJ} are given off.
To calculate the heat of combustion of the vegetable oil, we can use the formula:
Heat of combustion = Energy released / Mass of the sample
Given:
Energy released = 18.9 kJ = 18.9 × 10^3 J
Mass of the sample = 0.50 g = 0.50 × 10^−3 kg
Now, let's plug in these values into the formula:
Heat of combustion = 18.9 × 10^3 J / 0.50 × 10^−3 kg
To simplify the calculation, we divide the numerator and denominator by 10^−3:
Heat of combustion = 18.9 × 10^3 J / (0.50 × 10^−3 kg × 10^−3 / 10^−3)
Simplifying further:
Heat of combustion = 18.9 × 10^3 J / (0.50 kg)
Finally, we can calculate the heat of combustion:
Heat of combustion = 37.8 × 10^3 J/kg
Therefore, the heat of combustion of the vegetable oil sample is 37.8 × 10^3 J/kg.