What is the heat of combustion of ethane, C2H6, in kilojoules per mole of ethane?
-1560.4 KJ
What is the change in enthalpy for the combustion reaction of butane, C4H10?
2C4H10(g) + 13O2(g) 10H2O(g) + 8CO2(g)
Given:
To calculate the heat of combustion of ethane, we need the balanced equation for the combustion of ethane:
C2H6 + 7/2 O2 -> 2 CO2 + 3 H2O
Next, we will need the standard enthalpies of formation for all the compounds involved in the reaction. The standard enthalpy of formation of a substance is the enthalpy change when one mole of the substance is formed from its elements in their standard states.
The standard enthalpy of formation for ethane (C2H6) is -84.7 kJ/mol.
The standard enthalpy of formation for carbon dioxide (CO2) is -393.5 kJ/mol.
The standard enthalpy of formation for water (H2O) is -285.8 kJ/mol.
Now we can calculate the heat of combustion of ethane:
ΔH = (2 × ΔHf CO2) + (3 × ΔHf H2O) - (ΔHf C2H6)
ΔH = (2 × -393.5 kJ/mol) + (3 × -285.8 kJ/mol) - (-84.7 kJ/mol)
ΔH = -787.0 kJ/mol + -857.4 kJ/mol + 84.7 kJ/mol
ΔH = -787.0 kJ/mol - 857.4 kJ/mol + 84.7 kJ/mol
ΔH = -1559.7 kJ/mol
Therefore, the heat of combustion of ethane (C2H6) is -1559.7 kJ/mol.
To find the heat of combustion of ethane, we need to refer to reliable sources or use computational methods. One reliable source is the National Institute of Standards and Technology (NIST) Chemistry WebBook.
Here's how you can find the heat of combustion of ethane on the NIST Chemistry WebBook:
1. Open your web browser and go to the NIST Chemistry WebBook website (https://webbook.nist.gov/chemistry/).
2. In the search box on the top right corner, enter "ethane" and press Enter or click the magnifying glass icon.
3. From the search results, click on "Ethane" under the Compound Name column.
4. On the Ethane page, scroll down to the "Gas phase thermochemistry data" section.
5. Look for the parameter called "Enthalpy of combustion (ΔcHo)" under the "Standard Thermodynamic Properties" table. The value given will be in units of kilojoules per mole (kJ/mol).
Please note that the values may vary depending on the temperature range and the specific experimental conditions specified.