Question

the heat of combustion of fructose,C6H12O6, is -2812 kJ/mol. if a fresh golden delicious apple weighing 4.23 oz (120g) contains 16.0 g of fructose, what caloric content(in Cal) does the fructose contribute to the apple?

Answer 1

To calculate the caloric content of fructose in an apple, convert the mass of fructose to moles, use the heat of combustion to find the energy released in kJ, and then convert that to dietary Calories.

The fructose in a 120g apple with 16g of fructose contributes approximately -59.7 dietary Calories.

Step-by-step explanation:

The student has asked about the caloric content of fructose in an apple, given the heat of combustion of fructose is -2812 kJ/mol. To calculate the caloric content (in Calories), first,

we convert the amount of fructose in the apple to moles using its molar mass (180.16 g/mol for C6H12O6). Then, the energy released by this amount of fructose in kJ is calculated. Finally, we convert this energy to dietary Calories (1 Calorie = 4.184 kJ).

Firstly, we calculate the moles of fructose in 16.0 grams:

Number of moles = mass (g) / molar mass (g/mol) = 16.0 g / 180.16 g/mol = 0.0888 mol

Then, we calculate energy in kJ:

Energy (kJ) = moles * heat of combustion (kJ/mol) = 0.0888 mol * (-2812 kJ/mol) = -249.7 kJ

Finally, we convert kJ to dietary Calories:

Caloric content (Cal) = Energy (kJ) / 4.184 kJ/Cal = -249.7 kJ / 4.184 kJ/Cal = -59.7 Cal

Therefore, the fructose in the apple contributes approximately -59.7 dietary Calories to the total caloric content of the apple, indicating that 59.7 Calories are released through the combustion of the fructose.