Substance x has a molar mass of 107.6 g/mol. when 2.50 g of substance x burns in an iron calorimeter the temp. of calorimeter and water (2.000Kg)increases from 25.8 d Celsius to 38.7 d celsius. What is the molar heat of combustion of substance x in kJ/mol. the heat capacity of the calorimeter is 0.555 kj/d celsius.
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To calculate the molar heat of combustion of substance X, we can use the equation:
q = mcΔT
Where:
q is the heat released or absorbed (in joules),
m is the mass of the substance being heated or cooled (in grams),
c is the specific heat capacity of the substance (in J/g·°C), and
ΔT is the change in temperature (in °C).
First, let's calculate the heat released by substance X during combustion. We know the mass of substance X burned is 2.50 g.
q (substance X) = m (substance X) * c (calorimeter) * ΔT (calorimeter)
q (substance X) = 2.50 g * 0.555 J/g·°C * (38.7 - 25.8) °C
Now, let's convert the heat from joules to kilojoules by dividing by 1000:
q (substance X) = (2.50 g * 0.555 J/g·°C * (38.7 - 25.8) °C) / 1000
To find the heat released per mole of substance X, we need to divide the heat released by the number of moles of substance X.
Number of moles of substance X = mass of substance X / molar mass of substance X
Number of moles of substance X = 2.50 g / 107.6 g/mol
Finally, let's calculate the molar heat of combustion by dividing the heat released by the number of moles:
Molar heat of combustion = q (substance X) / number of moles of substance X
Molar heat of combustion = [(2.50 g * 0.555 J/g·°C * (38.7 - 25.8) °C) / 1000] / (2.50 g / 107.6 g/mol)
Calculating this expression will give you the molar heat of combustion of substance X in joules per mole. To convert it to kilojoules per mole, divide the result by 1000.
Molar heat of combustion = [(2.50 g * 0.555 J/g·°C * (38.7 - 25.8) °C) / 1000] / (2.50 g / 107.6 g/mol) / 1000
Simplifying the expression will give you the final answer.