I got 0.907 KJ for ΔHcomb but I don't know if its correct. I also don't know how to write the equation.
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question:
A calorimeter is filled with 10.0 mole of methane gas and an excess of oxygen. When burned, the ignition wire releases 107.2 J of heat. The heat capacity of the calorimeter (including the bomb and water) is 4.319 kJ oC-1.
Calculate ΔHcomb for methane and determine the thermochemical reaction?
Don't you have some information about the increase in temperature?
Yes the initial temperature is 24.75 degrees celsius and the final temperature is 26.85 degrees celsius
To calculate ΔHcomb (the enthalpy change of combustion) for methane, you need to use the information given in the question. Here are the steps to find the value:
1. First, convert the given heat release of 107.2 J to kJ by dividing it by 1000:
107.2 J ÷ 1000 = 0.1072 kJ
2. Next, calculate the heat absorbed by the calorimeter (Q_calorimeter) using the heat capacity (C_calorimeter) and the temperature change (ΔT):
Q_calorimeter = C_calorimeter * ΔT
Since the temperature change is not given in the question, we will assume it to be zero since the reaction takes place at constant pressure:
Q_calorimeter = C_calorimeter * 0 = 0 kJ
3. The heat released by the combustion reaction is equal to the heat absorbed by the calorimeter:
Q_combustion = Q_calorimeter
Therefore, the heat released by the combustion reaction is also 0 kJ.
4. ΔHcomb is defined as the enthalpy change per moles of substance undergoing combustion. So, divide the heat released by the number of moles of methane gas burned:
ΔHcomb = Q_combustion / n_methane
In this case, 10.0 moles of methane gas were burned, so:
ΔHcomb = 0 kJ / 10.0 mol = 0 kJ/mol
Based on the calculations, it appears that your value of 0.907 kJ for ΔHcomb is incorrect.
To determine the thermochemical reaction for the combustion of methane, you need to write the balanced chemical equation. The balanced equation for the combustion of methane is:
CH4(g) + 2O2(g) -> CO2(g) + 2H2O(l)
This equation represents the complete combustion of methane gas, producing carbon dioxide gas and liquid water.