May be solved by the molar volume method (Section 14.7 ) or...

May be solved by the molar volume method (Section 14.7 ) or by the ideal gas equation method (Section 14.8 ). In the answer section, the setups are given first for the molar volume method, printed over a tan background. Then, over a green back- ground, the answers are given for the ideal gas equation method. Check your work according to the section you studied. How many grams of iron are required to react completely with 5.49 L of oxygen gas at $41^{\circ} \mathrm{C}$ and 1.41 atm according to the reaction $2 \mathrm{Fe}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{FeO}(\mathrm{s}) ?$

May be solved by the molar volume method (Section 14.7 ) or by the ideal gas equation method (Section 14.8 ). In the answer section, the setups are given first for the molar volume method, printed over a tan background. Then, over a green back-
ground, the answers are given for the ideal gas equation method. Check your work according to the section you studied.
How many grams of iron are required to react completely with 5.49 L of oxygen gas at $41^{\circ} \mathrm{C}$ and 1.41 atm according to the reaction $2 \mathrm{Fe}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{FeO}(\mathrm{s}) ?$

Key Concepts

Molar Mass

Molar mass is the mass of one mole of a substance, usually expressed in grams per mole. Once the number of moles of a substance is determined (from gas law or stoichiometric calculations), the molar mass allows for conversion of this amount into grams. This concept is essential for translating theoretical calculations into measurable quantities in laboratory settings.

Stoichiometry

Stoichiometry involves the quantitative relationship between reactants and products in a chemical reaction. Using the coefficients from a balanced chemical equation, one can determine how many moles of a reactant are needed to completely react with a given number of moles of another substance. This is central to converting the moles of oxygen calculated from the ideal gas law into the moles and subsequently the mass of iron required.

Molar Volume

Molar volume is the volume occupied by one mole of an ideal gas at a given temperature and pressure. Under standard conditions, this is approximately 22.4 liters, but varying conditions alter this volume. Understanding molar volume allows one to directly relate a given volume of gas to its amount in moles, either through direct use of the gas law or by using standard molar volume values when applicable.

Ideal Gas Law

The ideal gas law, expressed as PV = nRT, is fundamental for relating the pressure, volume, temperature, and number of moles of a gas. It is used to calculate the number of moles of a gas under specific conditions, even when those conditions are not at standard temperature and pressure. This concept is crucial when converting the measured volume of a gas to moles, as seen in problems that involve gas reactions.

Transcript

00:01 Hello there.

00:03 For this problem, i am going to start off with the balanced equation that we are provided with in the problem.

00:10 2fe plus o2 produces 2feo.

00:22 The oxygen on the reactant side is of course a gas.

00:26 The problem is asking us how many grams of iron we need to react completely with 5 .49 liters of this oxygen.

00:44 The leaders of the oxygen are at 41 degrees celsius and 1 .41 atmospheres.

01:01 Starting right off, i am going to go ahead and convert my celsius to kelvin.

01:06 So i'm adding 273 to that, and i get 314 kelvin.

01:18 All right, let's plan this out a little bit.

01:22 First thing i need to do, well, if we think about what we need to ultimately, do this is a stoichiometry problem.

01:30 I'm trying to get from information about one reactant, and i'm trying to convert that to information about the other reactant.

01:39 So that is a stoichiometry problem.

01:41 However, i cannot get moles of oxygen directly by using 22 .4 because we are not at stp.

01:52 So what i'm going to have to do first is i am going to have to use the ideal gas.

01:58 Equation to determine how many moles of oxygen i have when i have 5 .49 liters under these conditions of temperature and pressure.

02:08 So to do that, taking the ideal gas equation and rearranging it to solve for n gives me pv over r t.

02:24 So let's go ahead and solve for number of moles of oxygen by plugging in my information.

02:30 The pressure is 1 .41 atmosphere...

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