a student burns a peanut in a calorimeter. she places 10 ml of water in a test tube. she weighs a peanut before and after burning it. It weighs 3 grams before and 1 gram after burning. She determines that the temperature was at 20 degrees C before and 70 degrees C afterwards. How many kcals/g did the peanut contain?
11 years ago
11 months ago
To determine the energy content of the peanut in kcal/g, we can use the formula:
Energy content = (Temperature change) x (Volume of water) x (Specific heat capacity of water) / (Change in mass of the peanut)
Let's calculate the variables step by step:
1. Temperature change = Final temperature - Initial temperature
= 70 °C - 20 °C = 50 °C
2. Volume of water = 10 ml = 10 g (since the density of water is approximately 1 g/ml)
3. Specific heat capacity of water = 1 calorie/g°C (or 1 kcal/kg°C)
4. Change in mass of the peanut = Initial mass - Final mass
= 3 g - 1 g = 2 g
Now, plug these values into the formula:
Energy content = (50 °C) x (10 g) x (1 calorie/g°C) / (2 g)
= 250 calories / 2 g
= 125 calories/g
So, the peanut contained approximately 125 calories per gram (kcal/g).