A student investigates the combustion of dimethyl ether, CH3OCH3\text{CH}_3\text{OCH}_3CH3OCH3.
The equation for the complete combustion of dimethyl ether is:
CH3OCH3(g)+3O2(g)→2CO2(g)+3H2O(g) \text{CH}_3\text{OCH}_3(\text{g}) + 3\text{O}_2(\text{g}) \rightarrow 2\text{CO}_2(\text{g}) + 3\text{H}_2\text{O}(\text{g}) CH3OCH3(g)+3O2(g)→2CO2(g)+3H2O(g)The displayed formulae for dimethyl ether, oxygen, carbon dioxide, and water are shown below:
The table gives some average bond energies:
∣Bond∣Average bond energy in kJ/mol∣|\text{Bond}|\text{Average bond energy in kJ/mol}|∣Bond∣Average bond energy in kJ/mol∣ ∣:−−−:∣:−−−:∣|:---:|:---:|∣:−−−:∣:−−−:∣ ∣C−H∣412∣|\text{C}-\text{H}|412|∣C−H∣412∣ ∣C−O∣360∣|\text{C}-\text{O}|360|∣C−O∣360∣ ∣H−O∣463∣|\text{H}-\text{O}|463|∣H−O∣463∣ ∣O=O∣496∣|\text{O}=\text{O}|496|∣O=O∣496∣ ∣C=O∣743∣|\text{C}=\text{O}|743|∣C=O∣743∣
Use this information to calculate the enthalpy change (ΔH\Delta HΔH) when one mole of dimethyl ether is completely burned.
In a calorimetry experiment, a student burns 1.15 g1.15\text{ g}1.15 g of dimethyl ether (formula mass =46.0 g/mol= 46.0\text{ g/mol}=46.0 g/mol) and finds that 23.5 kJ23.5\text{ kJ}23.5 kJ of heat energy is released. Calculate the experimental energy given out by 1 mol1\text{ mol}1 mol of dimethyl ether.
