A 4.5 g sample of glucose, a carbohydrate, is placed in a calorimeter. The water in the container has a mass of 1500 g and an initial temperature of 15°C. After all the glucose is burned, the water temperature is 27 °C. What is the caloric value for glucose?

Question

Answer: _____________ kcal/g of glucose

First find the heat the water gained....( q = sp ht × mass × ΔT ) but this value will be for the 4.5 g sample of glucose.....you are asked for kcal per gram of glucose......also, when determining the heat the water gains, the mass will be 1500 g, referring only to the mass of the water.

Answer 1

q for water = 1500 g x 1 cal/g x (27-15) = 18,000 cal or 18 kcal.
That's the heat generated for 4.5 g glucose. So 18 kcal/4.5 g = q for sugar/gram. I found the value of 15.6 kJ/g and those are close. You cana convert 15.6 kJ x 1 kcal/4.184 kJ = ? kcal