A 3.78 g sample of ethanol (C2H5OH) was burned completely in a bomb calorimeter. The temperature of the calorimeter plus the contents increased from 25.6oC to 35.2oC.

Knowing that ethanol's heat of combustion is -3600 kJ/mol, calculate the total heat capacity ( in kJ/oC ).

C2H5OH + 3O2 ==> 2CO2 + 3H2O

heat of combustion ethanol = 3600 kJ/mol x (3.78/molar mass ethanol) = ?
? = Ccal(Tfinal-Tinitial)

To calculate the total heat capacity of the calorimeter, we need to know the amount of heat transferred (q) during the reaction and the change in temperature (∆T).

The heat transferred (q) can be determined using the equation:
q = m × C × ∆T

where:
m is the mass of the substance (in grams) being burned,
C is the specific heat capacity (in kJ/g·°C) of the substance being burned, and
∆T is the change in temperature (in °C).

In this case, the substance being burned is ethanol (C2H5OH) and the heat of combustion for ethanol is given as -3600 kJ/mol. We need to convert the mass of ethanol to moles using the molar mass.

The molar mass of ethanol (C2H5OH) can be calculated as follows:
C = 12.01 g/mol (atomic mass of carbon)
H = 1.01 g/mol (atomic mass of hydrogen)
O = 16.00 g/mol (atomic mass of oxygen)

Molar mass of ethanol (C2H5OH) = (2 × C) + (6 × H) + O
= (2 × 12.01) + (6 × 1.01) + 16.00
= 46.07 g/mol

Now, we can calculate the number of moles of ethanol burned:
moles = mass / molar mass
= 3.78 g / 46.07 g/mol
≈ 0.082 moles

To find the heat transferred (q), we multiply the number of moles of ethanol burned by its heat of combustion:
q = moles × heat of combustion
= 0.082 moles × -3600 kJ/mol
≈ -295.2 kJ

Finally, we can calculate the total heat capacity of the calorimeter using the formula:
Heat capacity = q / ∆T

∆T = (35.2°C - 25.6°C) = 9.6°C

Therefore, the total heat capacity of the calorimeter is:
Heat capacity = -295.2 kJ / 9.6°C
≈ -30.625 kJ/°C.