Acetic acid, HC2H3O2, is the sour constituent of vinegar (acetum is Latin for "vinegar" ). In an experiment, 3.76 g of acetic acid was burned.

HC2H3O2(l) + 2 O2(g) 2 CO2(g) + 2 H2O(l)

If 54.6 kJ of heat evolved, what is ÄH per mole of acetic acid?

1. Convert 3.76 g HC2H3O2 to moles.

2. Divide 54.6 kJ by the number of moles. Attach a negative sign to the answer. The answer is in kJ/mole

To calculate the change in enthalpy per mole of acetic acid (ΔH), we need to use the given mass of acetic acid and the amount of heat evolved in the reaction.

Step 1: Convert the mass of acetic acid to moles
The molar mass of acetic acid (HC2H3O2) can be determined by adding up the atomic masses of its elements.

The atomic masses are:
H: 1 g/mol (hydrogen)
C: 12.01 g/mol (carbon)
O: 16 g/mol (oxygen)

So, the molar mass of acetic acid (HC2H3O2) is:
(2 * 1) + (2 * 12.01) + (4 * 16) = 60.05 g/mol

Using the given mass of acetic acid (3.76 g) and the molar mass, we can calculate the number of moles:
Number of moles = Mass / Molar mass
Number of moles = 3.76 g / 60.05 g/mol
Number of moles ≈ 0.0625 mol

Step 2: Calculate the ΔH per mole of acetic acid
To find the change in enthalpy per mole (ΔH) of acetic acid, we can use the given amount of heat evolved (54.6 kJ) and the number of moles (0.0625 mol).

ΔH = Heat evolved / Number of moles
ΔH = 54.6 kJ / 0.0625 mol
ΔH ≈ 873.6 kJ/mol

Therefore, the ΔH per mole of acetic acid is approximately 873.6 kJ/mol.