Question

The thermochemical equation for the burning of ethyl alcohol is

C₂H₅OH(l) + 3O₂(g) --> 2CO₂(g) + 3H₂O(l) ΔH = -1,367 kJ

What is the enthalpy change (in kJ) for burning 8.35 g of ethyl alcohol?

Answer 1

The enthalpy change for burning 8.35 g of ethyl alcohol (ethanol) is approximately -247.6 kJ, calculated by finding the number of moles of ethanol in 8.35 g and using the provided thermochemical equation.

Step-by-step explanation:

The enthalpy change for burning 8.35 g of ethyl alcohol (ethanol) can be calculated using the given thermochemical equation and the molar mass of ethanol. First, we need to determine the number of moles of ethanol in 8.35 g. The molar mass of ethanol is approximately 46.07 g/mol. Using this we find:

Number of moles of ethanol = 8.35 g / 46.07 g/mol = 0.1812 mol.

Next, we use the provided thermochemical equation, which tells us that the combustion of 1 mole of ethanol releases 1367 kJ of energy. Therefore, the enthalpy change for 0.1812 moles would be:

Enthalpy change = -1367 kJ/mol × 0.1812 mol = -247.6 kJ.

Thus, the enthalpy change when burning 8.35 g of ethanol is approximately -247.6 kJ.