Question

Using enthalpies of combustion for fat, carbohydrate, and protein of -39kj/g, -16kj/g, and -23kj/g, respectively to estimate what the caloric content would be for Haagen-Dazs vanilla ice cream. Recall that nutritional calories, or kcal, are 1000 scientific calories, and that there are 4.18 joules in one scientific calorie. Haagen-Dazs vanilla ice cream has: 17g fat, 20g carbs, and 4g protein.

Answer 1

Given that;

enthalpies of combustion for fat = -39kj/g

carbohydrate = -16kj/g

protein -23kj/g,

here

17g = fat, 20g = carbs, and 4g = protein.

Total enery from fat = 17.0 g* -39kj/g

= -663 KJ

Total enery from carbohydrate = 20.0 g* -16 kj/g

=- 320 KJ

Total enery from protein = 4.0 g* -23 kj/g

=- 92 KJ

Total enegy = -663 KJ +(- 320 KJ) + (- 92 KJ) = -1075 KJ

there are 4.18 joules in one scientific calorie

1.00 scientific calorie = 4.18 J

1075000 J *1.00 scientific calorie / 4.18 J = 2.6*10^5 scientific calorie