A0.50 g sample of vegetable oil gives out 19.9 kj of heat when burned. what is the caloric value of the oil in kcal/g?

Answer is 9.51 kCal/g

Explanation;

1 kJ = 1000 J

1 J = 0.239 Cal

Hence,

19.9 kJ = 19900 J

19900 J = (0.239 Cal / 1 J) x 19900 J

= 4756.1 Cal

1000 Cal = 1 kCal

Hence, 4756.1 Cal = 4.7561 kCal

Those calories are in 0.50 g of vegetable oil.

Hence, to find out the caloric value of the oil in kCal/g, we have to divide amount of Kcal by mass of the oil.

Then,

   caloric value of the oil = heat burned / mass

                                         = 4.7561 kCal / 0.50 g

                                         = 9.5122 kCal/g

                                        = 9.51 kCal/g

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"

there are two significant figures.