How much energy is evolved during the reaction of 48.7 g of Al, according to the reaction below? Assume that there is excess Fe2O3.
Fe2O3(s) + 2 Al(s) → Al2O3(s) + 2 Fe(s), ΔH°rxn = -852 kJ
To calculate the energy evolved during the reaction, we need to use the given information and the stoichiometry of the reaction. Here are the steps to solve the problem:
Step 1: Determine the number of moles of Al
To find the number of moles of Al, divide the mass of Al by its molar mass.
Molar mass of Al = 26.98 g/mol
Number of moles of Al = mass of Al / molar mass of Al
= 48.7 g / 26.98 g/mol
Step 2: Use the balanced equation to determine the moles of Fe2O3 reacted
According to the balanced equation, 1 mole of Fe2O3 reacts with 2 moles of Al. Therefore, the moles of Fe2O3 reacted can be calculated using the ratio:
Moles of Fe2O3 reacted = (moles of Al) / 2
Step 3: Calculate the energy evolved per mole of reaction
The energy evolved per mole of reaction can be calculated by:
Energy evolved per mole of reaction = ΔH°rxn / moles of Fe2O3 reacted
Step 4: Calculate the total energy evolved during the reaction
To find the total energy evolved during the reaction, multiply the energy evolved per mole of reaction by the moles of Fe2O3 reacted:
Total energy evolved = Energy evolved per mole of reaction * moles of Fe2O3 reacted
Let's plug in the values:
Number of moles of Al = 48.7 g / 26.98 g/mol = 1.805 mol
Moles of Fe2O3 reacted = 1.805 mol / 2 = 0.903 mol
Energy evolved per mole of reaction = -852 kJ
Total energy evolved = -852 kJ * 0.903 mol = -769.857 kJ
Therefore, the energy evolved during the reaction of 48.7 g of Al is approximately -769.857 kJ.
To find out how much energy is evolved during the reaction, we need to calculate the energy change given the amount of aluminum (Al) used.
First, we'll calculate the moles of aluminum (Al) used in the reaction. We can use the molar mass of aluminum to convert the mass of aluminum (given as 48.7 g) into moles.
The molar mass of aluminum is 26.98 g/mol.
Moles of Al = Mass of Al / Molar mass of Al
Moles of Al = 48.7 g / 26.98 g/mol
Moles of Al ≈ 1.808 mol
Since the reaction equation shows that 2 moles of aluminum react to produce -852 kJ of energy change, we can set up a proportion to find the energy change for the given amount of aluminum.
Moles of Al / Moles of Al in the equation = Energy change / Energy change in the equation
1.808 mol / 2 mol = Energy change / -852 kJ
Now we can solve for the energy change:
Energy change = (1.808 mol / 2 mol) × -852 kJ
Energy change ≈ -771.196 kJ
Therefore, approximately -771.196 kJ of energy is evolved during the reaction of 48.7 g of aluminum (Al).
delta H rxn = -852 kJ.
That is for 2*atomic mass Al in grams.
You want to know for 48.7 g. Simple proportion.