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Ch.10 - Gases
Brown - Chemistry: The Central Science 14th Edition
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
All textbooksBrown 14th EditionCh.10 - GasesProblem 72a3
Chapter 10, Problem 72a3

(a) What are the mole fractions of H2 in a mixture of 15.08 g of O2, 8.17 g of N2, and 2.64 g of H2?

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Step 1: The first step is to convert the mass of each component to moles. This is done by dividing the mass of each component by its molar mass. The molar mass of O2 is 32.00 g/mol, N2 is 28.01 g/mol, and H2 is 2.02 g/mol.
Step 2: After converting the mass of each component to moles, add up the total number of moles in the mixture. This is done by adding the number of moles of O2, N2, and H2 together.
Step 3: The mole fraction of a component in a mixture is the number of moles of that component divided by the total number of moles in the mixture. So, to find the mole fraction of H2, divide the number of moles of H2 by the total number of moles in the mixture.
Step 4: The result from step 3 is the mole fraction of H2 in the mixture. This value is a ratio and does not have units.
Step 5: Remember that the mole fraction is a way of expressing the concentration of a component in a mixture. It tells us what fraction of the total number of moles in the mixture is made up by a particular component.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Mole Concept

The mole concept is a fundamental principle in chemistry that relates the mass of a substance to the number of particles it contains. One mole of any substance contains Avogadro's number (approximately 6.022 x 10²³) of entities, whether they are atoms, molecules, or ions. This concept is essential for converting grams of a substance to moles, which is necessary for calculating mole fractions.
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Mole Fraction

Mole fraction is a way of expressing the concentration of a component in a mixture. It is defined as the ratio of the number of moles of a specific component to the total number of moles of all components in the mixture. Mole fractions are dimensionless and provide a useful means of comparing the relative amounts of different substances in a mixture.
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Mass to Moles Conversion

To calculate mole fractions, it is necessary to convert the mass of each component in the mixture to moles. This is done using the formula: moles = mass (g) / molar mass (g/mol). Knowing the molar masses of O₂, N₂, and H₂ allows for the determination of the number of moles of each gas, which is crucial for finding the total moles and subsequently the mole fractions.
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Related Practice
Textbook Question
A rigid vessel containing a 3:1 mol ratio of carbon dioxideand water vapor is held at 200 °C where it has a total pressureof 202.7 kPa. If the vessel is cooled to 10 °C so that all of thewater vapor condenses, what is the pressure of carbon dioxide?Neglect the volume of the liquid water that forms on cooling.
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Textbook Question

A sample of 3.00 g of SO2(g) originally in a 5.00-L vessel at 21 °C is transferred to a 10.0-L vessel at 26 °C. A sample of 2.35 g of N2(g) originally in a 2.50-L vessel at 20 °C is transferred to this same 10.0-L vessel. (a) What is the partial pressure of SO2(g) in the larger container? (b) What is the partial pressure of N2(g) in this vessel?

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Textbook Question

(a) What are the mole fractions of N2 in a mixture of 15.08 g of O2, 8.17 g of N2, and 2.64 g of H2?

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Textbook Question

(b) What is the partial pressure in atm of each component of this mixture if its held in a 15.50-L vessel at 15 °C?

Textbook Question
At an underwater depth of 100 m, the pressure is 1.106 MPa.What should the partial pressure of oxygen be in the divinggas for the mole fraction of oxygen in the mixture to be 0.21,the same as in air?
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Textbook Question
A quantity of N2 gas originally held at 531.96 kPa pressurein a 1.00-L container at 26 °C is transferred to a 12.5-L containerat 20 °C. A quantity of O2 gas originally at 531.96 kPaand 26 °C in a 5.00-L container is transferred to this samecontainer. What is the total pressure in the new container?
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