A 1.07g sample of sulfur was burned in a bomb calorimeter whose calorimeter constant is 2.03 k cal/C. If the resulting temperature change was 1.17 C, what is the molar heat of combustion for sulfur?
S + O2 ==> SO2
q = Ccal x delta T
q = 2.03 kcal/c x 1.17 = ?
That q is for 1.07.
To find per grams it is
q/1.07 = ? kcal/g
And q/1.07 x molar mass S gives kcal/mol.
To calculate the molar heat of combustion for sulfur, we first need to calculate the heat released in the combustion reaction using the following formula:
q = m × C × ΔT
Where:
q is the heat released in calories
m is the mass of the sample in grams
C is the calorimeter constant in cal/°C
ΔT is the temperature change in °C
Given:
Mass of the sample (m) = 1.07 g
Calorimeter constant (C) = 2.03 k cal/°C (Note: we must convert this to cal/°C by multiplying by 1000)
Temperature change (ΔT) = 1.17 °C
First, let's convert the calorimeter constant from kilocalories to calories:
C = 2.03 k cal/°C × 1000 cal/kcal = 2030 cal/°C
Now we can substitute the given values into the equation to calculate the heat released (q):
q = 1.07 g × 2030 cal/°C × 1.17 °C
Simplifying the equation, we get:
q = 2500.631 cal
Next, we need to calculate the moles of sulfur burned. Since the molar mass of sulfur is 32.07 g/mol, we can divide the mass of the sample by the molar mass:
moles of sulfur = 1.07 g / 32.07 g/mol
moles of sulfur ≈ 0.03336 mol
Finally, we can calculate the molar heat of combustion using the equation:
Molar heat of combustion = q / moles of sulfur
Molar heat of combustion = 2500.631 cal / 0.03336 mol
Molar heat of combustion ≈ 74926.5 cal/mol
Therefore, the molar heat of combustion for sulfur is approximately 74926.5 cal/mol.