When 114 g of fresh strawberries are burned in a bomb calorimeter, the temperature rises from 24.2 to 28.6 oC. If the heat capacity of the calorimeter is 80.7 kJ/oC, what is the fuel value for this food sample? [Find the change in energy for the reaction in kcal/g... 4.184 J = 1 cal]
To find the fuel value for the food sample, we need to calculate the change in energy for the reaction.
First, we need to convert the given temperature change from 28.6 °C to 24.2 °C to Kelvin:
ΔT = 28.6 °C - 24.2 °C = 4.4 °C = 4.4 K
Next, we multiply the change in temperature by the heat capacity of the calorimeter:
ΔE = 4.4 K * 80.7 kJ/°C = 353.16 kJ
Next, we convert from kilojoules to calories using the conversion factor 1 cal = 4.184 J:
ΔE_cal = 353.16 kJ * (1 cal/4.184 J) = 84.36 kcal
Finally, we need to find the fuel value per gram:
Fuel value = ΔE_cal / mass of strawberries burned = 84.36 kcal / 114 g = 0.74 kcal/g
Therefore, the fuel value for this food sample is 0.74 kcal/g.