Here is a problem involving nutritional Calories, which are actually kilocalorie

Question

Here is a problem involving nutritional Calories, which are actually kilocalories. Perhaps someone decided on this so that we don’t feel so bad about calorie intake – it seems better to eat something that is only 100 nutritional Calories, rather than thinking about the actual calorie content (100,000 calories)! You’ll notice below that in this case, the heat capacity of the calorimeter includes the water in it, so the (m s T) component of of qsystem = {(Ccalorimeter T) + (m s T)} can be ignored. When 1.0 g of snack cake is combusted in a constant-pressure bomb calorimeter with a heat capacity (including its water) of 10.0 kJ/°C, the temperature of the calorimeter rises by 2.24°C. How many nutritional calories (Calories) are in one serving (28 g) of this snack cake? (1 Calorie = 1000 calories and 1 calorie = 4.184 J

Explanation / Answer

The mass of snack cake = 28 g

Change in temperature = 2.24 oC

Heat capacity = 10 kJ/oC

The energy liberated = m*S*delta T

=28 g * 10 kJ * 2.24 oC

= 627.2 kJ

1 calorie =4.18 joules

627.2 kJ = 627.2 kJ/4.184 calories

=150 kCalories

1 nutrition calorie =1000 calories or 1 Kcalorie

So, total nutrition calories = 150 Calories

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