Determining Heat Given Off in Chemical Reaction

Calculation 1:

Final answer: The heat given off when 9.0g of Aluminium reacts with ample amount of Iron(III) Oxide according to the given equation is 140.75 kJ.

Explanation: In order to calculate the heat given off, we first need to convert the mass of Aluminum to moles using its molar mass which is 26.98 g/mol. 9.0 g Aluminum divided by 26.98 g/mol gives us 0.333 moles. The enthalpy change (ΔH°rxn) given in the question is for the reaction as written, which involves the reaction of 2 moles of Aluminum with Iron(III) Oxide. So, for 0.333 moles, we can just divide the ΔH°rxn by 2 and then multiply it with the moles of aluminum used. That is, (-849 kJ/mol ÷ 2) x 0.333 mol = -140.75 kJ. This means, when 9.0 g of aluminum reacts with ample amount of Iron(III) oxide according to the given equation, 140.75 kJ of heat is given off to the surroundings.

Calculation 2:

Final answer: The given reaction is exothermic and will release approximately 280 kJ of heat to the surroundings when 9.0 g of Aluminum reacts according to the specified equation.

Explanation: The question asks for the heat given off to the surroundings when 9.0 g of aluminum reacts according to the equation 2Al + Fe2O3 → Al2O3 + 2Fe, with a reaction enthalpy (ΔH°rxn) of -849 kJ/mol. This is a chemistry question related to thermochemical equations and exothermic reactions. In this case, the negative enthalpy change (-849 kJ/mol) indicates that the reaction is exothermic, i.e., it releases heat to the surroundings. The enthalpy change is specified per mole of aluminum, so we first calculate how many moles are present in 9.0 g of Aluminum. For Aluminum, the molar mass is approximately 27 g/mol, so 9.0 g is approximately 0.33 mol. To calculate the heat released to the surroundings during the reaction, we multiply the moles of Aluminum by the enthalpy change of the reaction. The result is approximately -280 kJ, indicating that 280 kJ of heat is released to the surroundings during the reaction.

Determine the heat given off to the surroundings when 9.0 g of aluminum reacts according to the equation 2Al + Fe2O3 → Al2O3 + 2Fe, ΔH°rxn= -849 kJ/mol.

The heat given off when 9.0g of Aluminium reacts with ample amount of Iron(III) Oxide according to the given equation is 140.75 kJ in Calculation 1 and approximately 280 kJ in Calculation 2.