To determine the calories of a food, the energy released is calculated based on the mass used in the calorimeter. If a 0.8 g nut is consumed in a bomb calorimeter and the resultant temperature change is 80.3 degrees C for 50 mL of water, what would be the energy in Calories per gram of nut? One joule = 2.39 x 10^-4 Calories.
If supposed to use qsoln = CxmxDt, C = 4.18J/gdegreesC.
qsoln = (4.18)(50)(80.3) = 16782.7J
qrxn = -16782.7 J
I know you get DHrxn from qrxn/moles, but do I need to find the moles? If so, how do I figure this out with the information given? Am I doing this problem wrong? If so, please explain.
Convert 16782.7 J to Calories and that will be calories per 0.8 gram. (Note: you may want to look at the number of significant figures if your prof is picky about that.) So this will give you calories/gram of nut and that's what the problem asks for.
To determine the energy in calories per gram of nut, you can start by calculating the energy released in joules.
Using the provided formula, qrxn = qsoln = C ∙ m ∙ ΔT, where C is the specific heat capacity of water, m is the mass of water, and ΔT is the change in temperature, you correctly calculated qsoln as 16782.7 J.
Next, you need to convert this energy from joules to calories. Given that 1 joule equals 2.39 x 10^-4 calories, you can calculate the energy in calories using the conversion factor:
qrxn (in calories) = qrxn (in joules) / conversion factor
= 16782.7 J / (2.39 x 10^-4 cal)
≈ 70171316.32 cal
Now, to find the energy in calories per gram of nut, you need to divide the energy obtained by the mass of the nut:
Energy per gram of nut (in calories) = qrxn (in calories) / mass of nut
= 70171316.32 cal / 0.8 g
≈ 87714145.4 cal/g
Therefore, the energy in Calories per gram of nut would be approximately 87714145.4 cal/g.
It seems like you are following the correct steps to solve the problem. Just make sure to use the correct conversion factor and perform the necessary calculations with the given values.
To determine the energy in Calories per gram of nut, you need to calculate the heat released by the nut in the bomb calorimeter. The heat released can be calculated using the formula q = C × m × ΔT, where q is the heat released, C is the specific heat capacity of water (4.18 J/g°C), m is the mass of water (50 g), and ΔT is the temperature change (80.3°C).
Plugging in the values, you get q = (4.18 J/g°C) × (50 g) × (80.3°C) = 16782.7 J.
Now, to convert this value to Calories per gram, you need to divide it by the mass of the nut consumed. In this case, the mass of the nut is 0.8 g.
To get the energy in Calories per gram, you can use the conversion factor of 1 joule = 2.39 x 10^-4 Calories.
So, the energy in Calories per gram of nut would be (16782.7 J) × (1 Cal / 2.39 x 10^-4 J) / (0.8 g).
To find the moles of the nut, you would typically need the molar mass of the nut. However, in this case, you do not need to calculate the moles since you are calculating the energy per gram of nut.
To recap, the correct steps to calculate the energy in Calories per gram of nut are:
1. Calculate the heat released using q = C × m × ΔT.
2. Convert the heat value from joules to Calories using the conversion factor.
3. Divide the converted value by the mass of the nut consumed (0.8 g).
I hope this explanation helps you solve the problem correctly.