# Ideal Gas Law Lab: Finding R with PV = nRT

• mirandasatterley
In summary, the lab involves measuring pressure and temperature, and pressure and inverse volume, in order to find the value of the gas constant, R. The values of n, the number of moles, and V, the initial volume, are kept constant in both parts of the lab. To find n, the gas must be weighed, and using the fact that 1 mole occupies 22.414 L at STP, the value for R can be indirectly calculated.
mirandasatterley
For the first part of my lab, I have a graph with pressure(atm) as a function of temperature(K).

For the second part of my lab, I have a graph with pressure(atm) as a function of inverse volume(mL^-1)

For both of these, i am supposed to find the value for R, the gas constant.

So far far part a i have: PV = nRT
P = (nR/V)T (in the form y = mx +b),
So the slope of my graph is nR/V
I also know that n is kept constant, because it was a closed system and 1mol= 22.4L. And that the initial volume is 20mL.
And i think I should I pick two points on the line to find the slope and set that equal to nR/V.

And this is where I'm having trouble, i get some value for the slope, m, so
m = nR/V
R = mV/n, here I'm confused at how to find V and n in order to solve for R.

For part b; PV = nRT
P = (nRT) 1/V
So the slope of my graph is nRT
I did the same thing as part one;
m = nRT
R = m/nT, since T was not chnged, I can do that part, but once again, I am confused by finding n.

mirandasatterley said:
For the first part of my lab, I have a graph with pressure(atm) as a function of temperature(K).

For the second part of my lab, I have a graph with pressure(atm) as a function of inverse volume(mL^-1)

For both of these, i am supposed to find the value for R, the gas constant.

So far far part a i have: PV = nRT
P = (nR/V)T (in the form y = mx +b),
So the slope of my graph is nR/V
I also know that n is kept constant, because it was a closed system and 1mol= 22.4L. And that the initial volume is 20mL.
And i think I should I pick two points on the line to find the slope and set that equal to nR/V.

And this is where I'm having trouble, i get some value for the slope, m, so
m = nR/V
R = mV/n, here I'm confused at how to find V and n in order to solve for R.

For part b; PV = nRT
P = (nRT) 1/V
So the slope of my graph is nRT
I did the same thing as part one;
m = nRT
R = m/nT, since T was not chnged, I can do that part, but once again, I am confused by finding n.
As I understand your lab experiment you are doing the following:

1) You keep Volume constant, and take measurements of Pressure at various Temperatures. A plot of P as a function of T should be a straight line P = nRT/V with slope m = nR/V and y intercept b=0.

2) Keeping T constant, take measurements of Volume at various Pressures. A plot of P as a function of 1/V should be a straight line: P = nRT(1/V) with slope m = nRT and y intercept b=0.

In 1) you determine V by measurement. You just have to keep n and V constant while you change the temperature.

In 2) you just have to keep n and T constant as you change the volume.

To find n, you have to weigh the gas. If you use the fact that 1 mole occupies 22.414 L at STP you are indirectly using the known value for R:

R = PV/nT = 101325*.022414/1*273.15 = 8.3145 J/mol K

AM

Last edited:

Thank you for sharing your lab results with me. It seems like you have a good understanding of the Ideal Gas Law and how to use it to calculate the gas constant, R. In order to solve for R, you will need to know the values of n, the number of moles, and V, the volume.

For part a, you mentioned that n is kept constant and is equal to 1 mole. This means that you can use this value in your calculation for R. As for V, you mentioned that the initial volume is 20mL. This value should be used in your calculation as well. So, your final equation for R should be R = m(20mL)/1 mole.

For part b, the same approach can be used. You mentioned that n is once again constant and equal to 1 mole. This value can be used in your calculation for R. As for V, you mentioned that it is the inverse of volume, so you will need to use the inverse value of the initial volume (20mL) in your calculation. Your final equation for R should be R = m/20mL.

I hope this helps clarify the steps needed to solve for R in both parts of your lab. Keep up the good work in your scientific experiments!

## 1. What is the purpose of the Ideal Gas Law Lab?

The purpose of the Ideal Gas Law Lab is to experimentally determine the value of the gas constant, R, using the Ideal Gas Law equation, PV = nRT. This lab allows us to explore the relationship between pressure, volume, temperature, and moles of a gas, and how they are affected by changes in these variables.

## 2. What materials are needed for the Ideal Gas Law Lab?

The materials needed for the Ideal Gas Law Lab include a gas collection apparatus (such as a gas syringe or eudiometer), a gas source (such as a gas cylinder or reaction flask), a pressure sensor, a temperature sensor, a ruler, and a calculator. You will also need the gas being studied, as well as a container to house the gas.

## 3. What are the steps involved in conducting the Ideal Gas Law Lab?

The steps involved in conducting the Ideal Gas Law Lab are as follows:

• Set up the gas collection apparatus, ensuring that it is airtight.
• Measure the initial volume of gas in the apparatus.
• Record the initial pressure and temperature of the gas.
• Introduce a known amount of gas into the apparatus.
• Record the final pressure and temperature of the gas.
• Calculate the change in pressure, volume, and temperature of the gas.
• Use the Ideal Gas Law equation, PV = nRT, to calculate the value of the gas constant, R.

## 4. What are some potential sources of error in the Ideal Gas Law Lab?

Some potential sources of error in the Ideal Gas Law Lab include air leaks in the gas collection apparatus, inaccuracies in measuring the volume of gas, and inconsistencies in temperature and pressure readings. Environmental factors such as humidity and altitude can also affect the results. It is important to carefully control and monitor these variables to ensure accurate data.

## 5. How is the Ideal Gas Law used in real-world applications?

The Ideal Gas Law is used in many real-world applications, such as in the design and operation of engines, refrigeration systems, and other industrial processes. It is also used in weather forecasting and in the study of atmospheric gases. Additionally, the Ideal Gas Law is a fundamental concept in the field of chemistry, allowing scientists to understand and predict the behavior of gases in various situations.

Replies
2
Views
1K
Replies
2
Views
2K
Replies
6
Views
1K
Replies
2
Views
2K
Replies
5
Views
3K
Replies
14
Views
1K
Replies
3
Views
545
Replies
4
Views
1K
Replies
9
Views
360
Replies
18
Views
1K