Unit 1: Gases And Gas Laws

Question 1

Would 2 grams of hydrogen gas have a larger volume or 32 grams of oxygen gas (assume they are in identical containers, under identical conditions)? Why?

Answer 1

They would occupy the same volume; both values in grams are equivalent to one mole of the gas. 1 mole of the gas would mean that there are 6.022x10^23 molecules of that gas. O2 is slower, but bigger. H2 is smaller, but faster. Since they have the same temperature, they have the same kinetic energy. Because they have the same kinetic energy, they exert the same amount of force against the inside of the container. Thus, they would have the same pressure, resulting in the same volume.

Question 2

What are the aspects of the kinetic molecular theory?

Answer 2

1) Elastic collisions between molecules (not gonna have strong force of attraction; this means that they bounce off of one another)

2) Random motion of molecules with high kinetic energy; this results in the molecules occupying the entire volume of the container.

3) Volume of the sample is much greater than the volume of an individual molecule/ion.

KMT-ERV

Question 3

What is a barometer used for?

Answer 3

Measuring pressure

Question 4

_____ mmHg/torr= 1 atm

Answer 4

760

Question 5

What is the formula for Force and what are the units?

Answer 5

Force= mass x acceleration (kg x m/ sec^2) FMA

Question 6

What is the formula for Pressure and what are the units?

Answer 6

Pressure= Force/ Area (Newtons/ Meter^2) PFA

Question 7

What is Newton/ meter^2 callled?

Answer 7

Pascal

Question 8

What is 1 atm equivalent to?

Answer 8

14.7 psi

Question 9

What is the equation for Absolute Pressure?

Answer 9

Absolute Pressure= Gauge Pressure + Atmospheric Pressure

Question 10

What is the formula for Kinetic Energy

Answer 10

KE= 1/2 mv^2 (m= mass ; v=velocity)

Question 11

What will happen to an aluminum soda can after water inside of the can is heated and then submerged in ice water? Why?

Answer 11

It will collapse and suck in water.

Submerging the can in ice water will lower the temperature of the water vapor. Kinetic energy of the water vapor will be lowered. The pressure exerted by the water vapor will be lowered. So, the volume of the vapor/gas decreases.

The rapid decrease in volume/pressure of the vapor inside of the can will result in the can getting crushed and sucking in water.

Question 12

What does Boyle’s Law demonstrate?

Answer 12

1/V vs. Pressure ; increased pressure on a gas will decrease its volume. The graph of 1/V vs P is linear. Volume and Pressure have an inverse relationship.

Question 13

What does Charles’ Law demonstrate?

Answer 13

Volume vs. Temperature; increased temperature leads to the increased volume of a gas. Volume and Temperature have a direct relationship; the graph is linear.

Question 14

What does Avogadro’s Law demonstrate?

Answer 14

Volume vs. Moles of Gas; increase the moles of a gas, increase the volume of a gas. The graph is linear; volume and moles of gas have a direct relationship. BCA-VTM (

Question 15

What is the Ideal Gas Law Equation?

Answer 15

PV= nRT

Pressure is in atm; n is in moles; Volume is in Liters; R= 0.08201 Latm/molK ; Temperature is in Kelvin

Question 16

How do you get Celsius from Fahrenheit?

Answer 16

C= 5/9 (F-32)

Question 17

What are the conditions of STP?

Answer 17

0 Degrees Celsius/ 273K; 1 atm

Question 18

What is the volume of 1 mole of an ideal gas at STP?

Answer 18

22.4 L

Question 19

What conditions make a gas ideal?

Answer 19

1) No IMFs/ negligible IMFs
2) Elastic Collisions
3) Constant Motion
4) Have negligible volume

Question 20

Other than mass divided by volume, what is the other formula for density?

Answer 20

Density= PM/RT (M being molar mass)

Question 21

Do all gas molecules/atoms have the same velocity/KE in a sample of gas stored at fixed volume and constant temperature?

Answer 21

No

Question 22

Define Diffusion

Answer 22

Mixing of gas molecules by random motion under conditions where molecular collisions occur.

Question 23

Define Effusion

Answer 23

The escape of has through a pinhole into a vacuum w/ molecular collisions.

Question 24

What is Graham’s Law?

Answer 24

Rate Gas 1/ Rate Gas 2= (MW Gas 2/MW Gas 1)^1/2 (the one with the smaller molecular weight should be placed on top—>left hand side of the reaction)

Question 25

What might make a gas behave in a non-ideal way?

Answer 25

Lower temperatures will allow the IMFs to be more prevalent and IMFs will overcome the KE of the gas molecules (atoms); if IMFs are strong enough, the pressure that will be exerted will be smaller than the pressure predicted by PV=nRT

Question 26

Define Molar Volume

Answer 26

The molar volume is the volume of one mole of a substance at a specified temperature and pressure.

Question 27

Why are many researchers and policy makers pursuing the use of hydrogen as a fuel for automobiles?

Answer 27

Hydrogen fuel has a very high energy density (hydrogen has a high energy produced per mass of substance ratio); hydrogen fuel is environmentally friendly since it only produces water as a product (assuming the hydrogen fuel is synthesized using a sustainable process).

Question 28

What are the limitations of using hydrogen fuel as a fuel for automobiles?

Answer 28

Storing hydrogen safely and efficiently in automobiles is technically challenging.