How do I go about doing this question?
How much heat energy is involved when 5.58g of Fe metal reacts with excess oxygen to produce Fe2O3? Do you need the equation, and if so, what would tha be? Fe + O2 > Fe2O3? I don't think that is right though. And also, do you find moles of Fe? Thanks.
L
Yes, you need the equation. The one you wrote is a start, but you need to BALAMCE it. Do you know how to do that?
I do, but I wasn't sure if I even was doing the right thing, so I didn't bother. But ok so, the equation would be: 2 Fe + 1/2 O2 > Fe2O3 right...and then what do I do? Heat of formation and do the Hess' law equation of products-reactants? Thanks.
L
The way you have it written the oxygens do not balance. It is actually:
4Fe + 3O2 > 2Fe2O3. (or, 2Fe + 1.5O2 > Fe2O3.
So, basically 2 moles of Fe goes to form one mole of Fe2O3. Then, you must calculate how many moles of Fe you start with, and then you know how many moles of Fe2O3 you form. Then you can use the standard enthalpy of formation of Fe2O3, which is per mole.
To solve this question, we need to follow a few steps. Here's how you can go about it:
1. Determine the balanced chemical equation: The equation you provided, Fe + O2 > Fe2O3, is not balanced correctly. The balanced equation for the reaction between Fe metal and oxygen to produce Fe2O3 is:
4 Fe + 3 O2 -> 2 Fe2O3
2. Calculate the molar mass of Fe: The molar mass of Fe (iron) is found on the periodic table. The atomic mass of Fe is approximately 55.845 g/mol.
3. Determine the moles of Fe: Since we are given the mass of Fe (5.58 g), we can use the formula:
Moles = Mass / Molar mass
Moles of Fe = 5.58 g / 55.845 g/mol
Calculate this division to find the moles of Fe.
4. Determine the heat involved using the stoichiometry of the balanced equation: The balanced equation tells us the stoichiometric ratio, which is the ratio of moles between the reactants and products. In this case, the ratio is 4:2 between Fe and Fe2O3.
Moles of Fe2O3 produced = (Moles of Fe / 4) * 2
This calculation gives you the moles of Fe2O3 formed from the given moles of Fe.
5. Use the heat of reaction to find the heat energy involved: If the heat of reaction (ΔH) for the given reaction is given, multiply it by the moles of Fe2O3 to find the heat energy involved. The heat of reaction is usually given in kJ/mol.
Heat energy involved = ΔH * moles of Fe2O3 produced
Substitute the values and calculate the heat energy involved.
If the heat of reaction is not provided, you will need to find the enthalpy change (ΔH) for the reaction through other means, such as using thermodynamic data or experimental values.