One tablespoon of peanut butter has a mass of 15 g . it is combusted in a calorimeter whose heat capacity is 120 kj/∘c . the temperature of the calorimeter rises from 22.4 ∘c to 25.5 ∘c. find the food caloric content of peanut butter.

5927.3488 calorie/g

Explanation:

For peanut butter:

Mass = 15 g

Initial temperature = 22.4 °C

Final temperature = 25.5 °C

Specific heat of calorimeter, C = 120 kJ/°C

Considering

Also,

1 kJ = 239.006 calories

So, Heat = 372*239.006 calories = 88910.232 calories

15 g of the peanut butter gives 88910.232 calories

So, the food caloric content of peanut butter = 88910.232 calories/ 15 g = 5927.3488 calorie/g

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%