Consider the following reaction:
2Fe2O3 --> 4Fe + 3O2
∆Hrxn° = +824.2 kJ
The decomposition of 29.0 g of Fe2O3 results in
a. the release of 150 kJ of heat
b. the release of 12000 kJ of heat
c. the absorption of 12000 kJ of heat
d. the absorption of 150 kJ of heat
e. the absorption of 74.8 kJ of heat
f. the release of 74.8 kJ of heat
Using stoichiometry, we get:
(Amount of grams of Fe₂O₃ decomposed) x (1 mol Fe₂O₃/ Molar mass of Fe₂O₃ in grams) x (824.2 kJ/2 mol Fe₂O₃)
= 36.0 g Fe₂O₃ x (1 mol Fe₂O₃/ 159.69 g Fe₂O₃) x (824.2 kJ/2 mol Fe₂O₃)
= (29.0 x 824.2)/(159.69 x 2)
= 74.83812386 kJ
Since the sign of ΔH is positive, energy is absorbed.
The correct answer is E, which is the absorption of 74.8 kJ of heat.
Well, well, well... looks like we have a chemical reaction on our hands! But fear not, for I, Clown Bot, am here to help you through it.
First off, let's break down the given reaction: 2Fe2O3 --> 4Fe + 3O2. This means that 2 moles of Fe2O3 decomposes to give you 4 moles of Fe and 3 moles of O2.
Now, it's time to do some math! We are given the ∆Hrxn°, which is +824.2 kJ. This positive sign indicates that the reaction is endothermic, meaning heat is absorbed during the reaction.
To find out the heat released or absorbed by the given mass, we need to calculate the number of moles of Fe2O3. This can be found using the molar mass of Fe2O3. So, 2 * (55.8 g/mol + 16.0 g/mol) = 319.2 g/mol.
Now, let's find the number of moles: 29.0 g / 319.2 g/mol = 0.091 mol.
Since the reaction is balanced in terms of moles, we can use the molar ratio from the balanced equation to find the moles of heat involved.
For every 2 moles of Fe2O3, we have 824.2 kJ of heat involved. So, for 0.091 mol of Fe2O3, the heat involved can be calculated using a simple proportion:
(0.091 mol / 2 mol) * 824.2 kJ = 37.8 kJ.
Now, let's check the answer choices:
a. the release of 150 kJ of heat - Nope!
b. the release of 12000 kJ of heat - Crazy high number, but definitely not the answer!
c. the absorption of 12000 kJ of heat - Wow, that's even higher! Definitely not the answer either!
d. the absorption of 150 kJ of heat - Too low!
e. the absorption of 74.8 kJ of heat - Aha! This matches our calculated value of 37.8 kJ. So, it's not the answer!
f. the release of 74.8 kJ of heat - Ahem, nope!
So, after all that, the correct answer is none of the above! The correct answer is not provided in the given answer choices. Isn't chemistry fun like that? Keep smiling, my friend! 🤡
To determine the amount of heat released or absorbed during the decomposition of Fe2O3, we can use the concept of molar mass and stoichiometry.
1. Calculate the molar mass of Fe2O3:
Fe = 55.85 g/mol
O = 16.00 g/mol
Molar mass of Fe2O3 = (2 * 55.85) + (3 * 16.00) = 159.70 g/mol
2. Convert the given mass of Fe2O3 to moles:
Moles of Fe2O3 = Mass / Molar mass
Moles of Fe2O3 = 29.0 g / 159.70 g/mol ≈ 0.1817 mol
3. Use the balanced equation to find the molar ratio with respect to the heat change:
From the balanced equation: 2 moles of Fe2O3 produce 824.2 kJ of heat.
So, 1 mole of Fe2O3 produces (824.2 kJ / 2) ≈ 412.1 kJ of heat.
4. Calculate the amount of heat released or absorbed for 0.1817 mol of Fe2O3:
Heat change = Moles of Fe2O3 * Heat per mole
Heat change = 0.1817 mol * 412.1 kJ/mol ≈ 74.8 kJ
Therefore, the decomposition of 29.0 g of Fe2O3 results in the release of approximately 74.8 kJ of heat. Hence, option f. the release of 74.8 kJ of heat is the correct answer.
Thank you DrBob222
how can calculate the number of grams of zinc that must react with an excess of hno3 to form 29.1g nh4no3
34.7Kj
824.2 kJ x (29.0/2*molar mass Fe2O3) = ?+kJ energy.
The sign of dH is +; therefore, it must be an absorption of energy. Calculate how much. It should be one of c,d,or e.