Question

A chemical reaction gives off 1,500 kj of heat energy. about how many calories is this? (1 calorie = 4.18 joules)

a. 3.6 x 10^5 calories
b. 3.6 x 10^2 calories
c. 3.6 x 10^3 calories
d. 3.6 x 10^4 calories

Answer 1

1500kj = 15x 10^5 j
1 calorie = 4.18 j
(15 x 10^5)/4.18= 3.58 x 10^5

Answer is a

Answer 2

Answer is: a. 3.6 x 10^5 calories.

E = 1500 kJ; heat energy.

E = 1500 kJ · 1000 J/kJ.

E = 1500000 J = 1.5·10⁶ J.

E = 1.5·10⁶ J ÷ 4.18 J/cal.

E = 3.6·10⁵ cal.

Calorie (cal), or small calorie, is the amount of energy needed to heat one gram of water by one degree Celsius.

One small calorie is approximately 4.18 joules.

A calorie is a unit of energy.