Question

A 0.50-g sample of vegetable oil is placed in a calorimeter. when the sample is burned, 18.9 kj is given off. what is the energy value (kcal/g) for the oil?

Answer 1

To calculate the energy value of the vegetable oil, convert the energy from kJ to kcal and then divide by the mass of the oil. The energy value is 9.028 kcal/g.

Step-by-step explanation:

To find the energy value of the vegetable oil in kcal/g, first, we need to convert the energy given off from kilojoules to kilocalories using the conversion factor: 1 kcal = 4.184 kJ. The given energy is 18.9 kJ for a 0.50 g sample of oil.

The conversion from kJ to kcal is as follows:

18.9 kJ × (1 kcal / 4.184 kJ) ≈ 4.514 kcal

To find the energy value per gram, we divide the kcal by the weight of the oil in grams:

4.514 kcal / 0.50 g = 9.028 kcal/g

Therefore, the energy value of the vegetable oil is 9.028 kcal/g.

Answer 2

First of all, we need to convert the energy produced from kilojoules to calories. 1 kJ corresponds to 239.1 cal, therefore:

`E=18.9 kJ \cdot 239.1 =4519.4 cal`

And so now we can calculate the energy value of the oil:

`E_v = (E)/(m)=(4519.4 cal)/(0.50 g)=9038.8 cal/g`