Ethanol (C₂H₅OH) burns according to the equation C₂H₅OH(l) + 3O₂(g) $\rarr$ 2CO₂(g) + 3H₂O(l), $\Delta$H^$\circ$_rxn = -1367 kJ/mol.How much heat is released when 35.0 g of ethanol is burned

Question

Quizplus · Accepted Answer

First, we need to convert the given mass of ethanol (35.0 g) to moles:

35.0 g C2H5OH x (1 mol C2H5OH/46.07 g) = 0.760 mol C2H5OH

From the balanced equation, we see that 1 mol of C2H5OH produces -1367 kJ of energy when burned. Therefore, we can calculate the amount of energy released by multiplying the number of moles of C2H5OH by the molar heat of combustion:

0.760 mol C2H5OH x (-1367 kJ/mol) = -1038 kJ

The negative sign indicates that the reaction releases energy (i.e. it is exothermic). We round our answer to 1,040 kJ since we are only given three significant figures. Therefore, the correct answer is B.

Ethanol (C2H5OH) Burns According to the Equation C2H5OH(l) + 3O2(g) →\rarr→

Ethanol (C₂H₅OH) Burns According to the Equation C₂H₅OH(l) + 3O₂(g) $\rarr$