Organic hydrogenation reactions, in which H2 and an "unsaturated" organic compound combine, are used in the food, fuel, and polymer industries. In the simplest case, ethene (C2H4) and H2 form ethane (C2H6). If 132 kJ is given off per mole of C2H4 reacting, how much heat is released when 15.3 kg of C2H6 forms?
To solve this question, we need to first determine the amount of ethane formed when 15.3 kg of C2H6 is produced. Then, we can use the enthalpy change per mole of C2H4 to calculate the total heat released.
Step 1: Calculate the moles of C2H6 using its molar mass.
The molar mass of C2H6 (ethane) is:
2 * (atomic mass of C) + 6 * (atomic mass of H) = 2 * (12.01 g/mol) + 6 * (1.01 g/mol) = 30.07 g/mol
Now, we can calculate the number of moles by dividing the mass (15.3 kg) by the molar mass:
Moles of C2H6 = Mass / Molar mass = 15.3 kg / 30.07 g/mol = 509.95 mol
Step 2: Calculate the heat released using the given enthalpy change per mole of C2H4.
The enthalpy change per mole of C2H4 is given as -132 kJ/mol.
To find the heat released, we multiply the number of moles of ethane formed (509.95 mol) by the enthalpy change:
Heat released = Moles of C2H6 × Enthalpy change per mole of C2H4
Heat released = 509.95 mol × -132 kJ/mol
Step 3: Calculate the total heat released.
To find the total heat released, we need to convert the result from kilojoules (kJ) to joules (J). Since 1 kJ = 1000 J, we multiply the result by 1000:
Total heat released = Heat released × 1000
Total heat released = (509.95 mol × -132 kJ/mol) × 1000 = -67,348,400 J
Therefore, the total heat released when 15.3 kg of C2H6 forms is -67,348,400 Joules.