Question

When 1.550 g of liquid hexane (C6H14) undergoes combustion in a bomb calorimeter, the temperature rises from 25.87°C to 38.13°C. Find ΔErxn for the reaction in kJ/mol hexane. The heat capacity of the bomb calorimeter is 5.73 kJ/°C.

Options:
a) -352.4
b) -210.8
c) 144.6
d) 278.9

Answer 1

To find the ΔErxn for the combustion of hexane, first calculate the heat released by the combustion using the formula q = CT. Convert the mass of hexane to moles using the molar mass of hexane. Finally, divide the heat released by the moles of hexane to find the ΔErxn in kJ/mol hexane.

Step-by-step explanation:

To find the ΔErxn for the combustion of hexane in kJ/mol hexane, we need to first calculate the heat released by the combustion reaction using the formula:

q = CT

Where q is the heat released, C is the heat capacity of the bomb calorimeter, and T is the change in temperature.

Given that the temperature change is from 25.87°C to 38.13°C and the heat capacity of the bomb calorimeter is 5.73 kJ/°C, we can calculate:

q = 5.73 kJ/°C * (38.13°C - 25.87°C) = 69.2541 kJ

Next, we need to convert the mass of hexane to moles using the molar mass of hexane, which is 86.18 g/mol:

moles of hexane = 1.550 g / 86.18 g/mol = 0.01796 mol

Finally, we can calculate ΔErxn by dividing the heat released by the moles of hexane:

ΔErxn = 69.2541 kJ / 0.01796 mol = 3853.48 kJ/mol hexane