## Test 1 # 4

TimVintsDis4L
Posts: 104
Joined: Sat Aug 17, 2019 12:17 am

### Test 1 # 4

Can someone please explain how to do #4 on Test # 1. The questions states

There is an unknown quantity of Xenon in a 25 L container at .50 atm and 27 C. How many grams of Xenon are present?

ThomasNguyen_Dis1H
Posts: 102
Joined: Fri Aug 30, 2019 12:17 am

### Re: Test 1 # 4

You'd have to use the equation PV=nRT since we have pressure, temperature, gas constant R, and the volume. Solve for n which is the amounts of mols of xenon and convert to grams. Make sure your units cancel out and temperature is in kelvin

KnarGeghamyan1B
Posts: 102
Joined: Fri Aug 09, 2019 12:15 am

### Re: Test 1 # 4

You add 273 to the 27 to get temperature in 300 degrees Kelvin, and make sure the correct Rydberg constant is used so the units Kelvin, Liters, and atm cancel.

Emma Popescu 1L
Posts: 105
Joined: Wed Sep 11, 2019 12:16 am

### Re: Test 1 # 4

You use PV=nRT and then find the number of moles (n). They forgot to give us the molar mass of Xenon on the test but you have to multiply moles by molar mass and it will give you the mass.

Rodrigo2J
Posts: 102
Joined: Sat Jul 20, 2019 12:16 am

### Re: Test 1 # 4

You need to use PV=nRT to find the moles of Xe. Remember to convert your given information to the proper units. Then convert the moles to mass using the molar mass from the periodic table.

Vincent Leong 2B
Posts: 207
Joined: Fri Aug 09, 2019 12:15 am

### Re: Test 1 # 4

use PV = nRT to solve for n which are moles of the gas. Then use the molar mass and the moles you solved for to solve for grams of gas.

Posts: 100
Joined: Wed Sep 18, 2019 12:19 am

### Re: Test 1 # 4

Ideal gas law but make sure you use the value of R that allows you to cancel your units correctly.

805373590
Posts: 101
Joined: Wed Sep 11, 2019 12:17 am

### Re: Test 1 # 4

Use pV=nrt when plugged in you will then need to calculte the grams from the moles found using the equation

Orrin Zhong 4G
Posts: 51
Joined: Sat Jul 20, 2019 12:16 am

### Re: Test 1 # 4

Use PV=nRT by plugging in pressure, volume, temperature, and R (0.0821 Latm/(molK)). Isolate and solve for n, which will give you the moles of Xenon present, and you can convert to the grams of Xenon using the molar mass of Xenon.

Hope Hyland 2D
Posts: 50
Joined: Wed Feb 20, 2019 12:16 am

### Re: Test 1 # 4

This one tricked me too! You have to use the ideal gas law, so PV=nRT and just plug everything in. But make sure to convert everything to the right units.

kausalya_1k
Posts: 50
Joined: Wed Nov 14, 2018 12:23 am

### Re: Test 1 # 4

You use PV=nRT to solve for n. Then use molar mass of Xe to convert n from moles to grams using stoichiometry.