Compute the amount of heat released (absolute value) when 2.3 kg of liquid ethanol is burned in excess oxygen to make carbon dioxide and liquid water.
2C2H5OH + 6O2 ==> 4CO2 + 6H2O
Calculate delta H (DHrxn) for the reaction from
DHrxn = (n*DHf products) - (n*DHf reactants)
Then heat released = DHrxn x (2,300/2*molar mass C2H5OH)
To compute the amount of heat released when ethanol is burned, we need to use the concept of energy released in a chemical reaction, specifically the enthalpy of combustion (ΔH). The enthalpy of combustion is the heat released when one mole of a substance is completely burned in excess oxygen.
Here are the steps to calculate the amount of heat released:
Step 1: Write the balanced chemical equation for the combustion of ethanol.
C2H5OH + 3O2 -> 2CO2 + 3H2O
Step 2: Determine the molar mass of ethanol (C2H5OH).
C: 12.01 g/mol
H: 1.01 g/mol
O: 16.00 g/mol
Molar mass of C2H5OH = (2 * 12.01 g/mol) + (6 * 1.01 g/mol) + 16.00 g/mol = 46.07 g/mol
Step 3: Calculate the moles of ethanol burned.
moles of ethanol = mass of ethanol / molar mass
moles of ethanol = 2.3 kg / 46.07 g/mol
Convert the mass of ethanol to grams:
2.3 kg = 2300 g
moles of ethanol = 2300 g / 46.07 g/mol
Step 4: Calculate the heat released using the balanced chemical equation and the enthalpy of combustion of ethanol.
In this case, we will assume that the enthalpy of combustion for ethanol is -1368 kJ/mol.
Heat released = moles of ethanol * ΔH
Heat released = (moles of ethanol) * (-1368 kJ/mol)
Substitute the value of moles of ethanol calculated in Step 3 to get the final answer.
Please note that the heat released will be negative (-) since it is an exothermic reaction.
By following these steps, you can calculate the amount of heat released when 2.3 kg of liquid ethanol is burned in excess oxygen.