A student followed the procedure of this experiment to determine the Caloric con

Question

A student followed the procedure of this experiment to determine the Caloric content of a Planter's cocktail peanut. The peanut studied had a mass of 0.609 g before combustion and 0.053 g after combustion. The energy released during combustion caused a 14.2 degrees C increase in the temperature of 200.0 mL of water in the calorimeter.

1) Calculate the mass of peanut burned.

2) Calculate the mass, in kg, of water present in the calorimeter.

3) Calculate the amount of energy released, in Cal, from the burning peanut.

4) Calculate the amount of energy released per gram of peanut burned.

Explanation / Answer

1. Since we have a starting mass and ending mass, all we have to do is subtract the final from the initial:

0.609 g - 0.053 g = 0.558 g peanut burned

2. If there are 200 mL of H20 (volume) present in the calorimeter, we need to know the density of water to find out how much mass the water has. The relationship between mass and volume is described by density (d), or mass (m)/volume (v). m/v=d

Since we know the volume (200 mL) and can find the density (0.997 g/mL at room temp), we can solve for the mass.

m/v=d m/200 mL=0.997g/mL m= 199.4 g BUT this is in grams not kg, so we must divide by 1000 to get kg

m= 0.1994 kg

3. We can find the energy released by understanding what a Cal, or kcal is. A Cal is defined as the amount of energy it takes to heat one kg of water one degree Celsius.

The equation is therefore Cal=kg*degree Celsius

Since we know kg (0.1994 kg) and degree C (14.2) we can plug that into the equation:

Cal= 0.1994*14.2 = 2.83 Cal

4. The way to find out how much energy is in 1 g of peanuts, we simply divide Cal/mass burned and we will get a Cal/g value.

2.83 Cal/0.558 g = 5.07 Cal/ g peanut

This also stands up to the sniff test, because it seems reasonable that a handful of peanuts ~20 g is about 100 Calories.

I hope this helps.

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