Question

To begin the experiment, 1.11g of methane CH4 is burned in a bomb calorimeter containing 1000 grams of water. The initial temperature of water is 24.85oC. The specific heat of water is 4.184 J/g oC. The heat capacity of the calorimeter is 695 J/ oC . After the reaction the final temperature of the water is 35.65oC.
Using the formula waterq =m•c•ΔT ,calculate the heat absorbed by the water

Answer 1

In order to calculate the enthalpy of the reaction, we first calculate the heat released using the given formula.
Q = mcΔT
Q = 1000 x 4.184 x (35.65 - 24.85)
Q = 45187.2 J = 45.2 kJ

Now, we determine the moles of methane that were burned.
Moles = mass / Mr
Moles = 1.11 / (12 + 4)
Moles = 0.07

The enthalpy of a reaction is the energy released per mole, so the enthalpy in this case is:
ΔH = 45.2 / 0.07
ΔH = 645.7 kJ/mol