A sample of natural gas is 80.0% CH4 and 20.0% C2H6 by mass. What is the heat from the combustion of 1.00 g of this mixture?
add heats from each part
heat from methane: .80*Hc (you may have to convert Hc to joules/gram)
heat from Ethane: .20*Hc ibid.
To calculate the heat from the combustion of a mixture, we need to consider the individual heat of combustion for each component in the mixture. It is important to note that combustion reactions involve the reaction of the compound with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O) as the products. Here's how you can calculate the heat from the combustion of the given natural gas mixture:
1. Determine the molecular formula of each compound:
- CH4: methane
- C2H6: ethane
2. Write the balanced combustion equation for each compound:
- CH4: CH4 + 2O2 -> CO2 + 2H2O
- C2H6: C2H6 + 7/2O2 -> 2CO2 + 3H2O
3. Calculate the molar mass of each compound:
- CH4: 12.01 g/mol (C) + 4 * 1.008 g/mol (H) = 16.04 g/mol
- C2H6: 2 * (12.01 g/mol (C) + 6 * 1.008 g/mol (H)) = 30.07 g/mol
4. Calculate the moles of each compound in the 1.00 g sample:
- Mass of CH4: 80.0% * 1.00 g = 0.80 g
- Moles of CH4: 0.80 g / 16.04 g/mol = 0.0500 mol
- Mass of C2H6: 20.0% * 1.00 g = 0.20 g
- Moles of C2H6: 0.20 g / 30.07 g/mol = 0.00665 mol
5. Calculate the heat of combustion for each compound:
- Heat of combustion of CH4: -891 kJ/mol
- Heat of combustion of C2H6: -1560 kJ/mol
6. Calculate the total heat of combustion by multiplying the moles of each compound by their respective heat of combustion and summing them:
- Total heat of combustion = (0.0500 mol CH4 * -891 kJ/mol) + (0.00665 mol C2H6 * -1560 kJ/mol)
7. Calculate the heat from the combustion of the 1.00 g mixture by dividing the total heat of combustion by the total mass of the mixture:
- Heat from the combustion = (Total heat of combustion) / (1.00 g)
By following these steps, you can calculate the heat from the combustion of 1.00 g of the given natural gas mixture.