Constant-volume calorimeters are sometimes calibrated by running a combustion reaction of known ΔE and measuring the change in temperature. For example, the combustion energy of glucose is 15.57 kJ/g. When a 2.500 g sample of glucose burns in a constant volume calorimeter, the calorimeter temperature increases from 21.45 to 23.34°C. Find the total heat capacity of the calorimeter (in kJ/K).
15.57 kJ/g x 2.5 g = Ccal x (Tfinal-Tinitial)
Substitute and solve for Ccal.
13.4 KJ
What is question all about. Please
To find the total heat capacity of the calorimeter, you need to use the formula:
Q = mΔT,
where:
Q is the heat transferred,
m is the mass of the substance,
ΔT is the change in temperature.
In this case, the substance is glucose, and we need to calculate the heat transferred (Q) when a 2.500 g sample of glucose burns in the calorimeter.
First, we need to calculate the amount of heat transferred by the combustion reaction. We can do this using the formula:
Q = ΔE/n,
where:
Q is the heat transferred,
ΔE is the combustion energy of glucose (15.57 kJ/g),
n is the number of moles of glucose.
To calculate the number of moles of glucose (n), use the formula:
n = mass/molar mass,
where:
mass is the mass of glucose (2.500 g),
molar mass is the molar mass of glucose (180.16 g/mol).
Now we can calculate the heat transferred by the combustion reaction:
Q = (15.57 kJ/g) * (2.500 g) / (180.16 g/mol).
Next, we need to calculate the change in temperature (ΔT) of the calorimeter. The change in temperature is the final temperature minus the initial temperature:
ΔT = 23.34°C - 21.45°C.
Finally, we can calculate the total heat capacity of the calorimeter using the formula:
Heat Capacity = Q / ΔT.
Substituting the values we've calculated:
Heat Capacity = (Q) / (ΔT).
When you compute these values, you will get the total heat capacity of the calorimeter in kJ/K.