The Gas Laws!

1 / 19

The Gas Laws! - PowerPoint PPT Presentation

The Gas Laws!. Ch 14 Notes. Properties of Gases. Gases are compressible because of the space between particles. Factors that affect gases: Pressure Volume Temperature # of moles present. Boyle’s Law. P 1 V 1 = P 2 V 2 Inverse Relationship T is constant

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

PowerPoint Slideshow about 'The Gas Laws!' - kedma

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

The Gas Laws!

Ch 14 Notes

Properties of Gases
• Gases are compressible because of the space between particles.
• Factors that affect gases:
• Pressure
• Volume
• Temperature
• # of moles present
Boyle’s Law
• P1V1 = P2V2
• Inverse Relationship
• T is constant
• If one goes up, the other goes down
• If one goes down, the other goes up
Boyle’s Law Sample Prob
• You and your crazy friend want to make funny voices using helium. You obtain a helium tank….

The volume of the gas in the tank is 2 L, but can fill over 200 L at room pressure. Room pressure is 1 atm, what was the original pressure?

Charles’ Law
• V1/T1 = V2/T2
• Direct Relationship
• P is constant
• Temp in Kelvin!!! (°C + 273)
• As one goes up, so does the other
• As one goes down, so does the other
• higher temp = more kinetic energy, more collisions, so volume increases
Charles’ Law Sample Prob
• The temperature in the supermarket is a frosty 15 °C. When you buy your bag of chips it occupies 1 L of space. You leave the chips in your car for 1 hour and it reaches a temperature of 27 °C. what is the new volume of the bag?
Gay-Lussac’s Law
• P1/T1 = P2/T2
• Direct Relationship
• Temp in Kelvin!!!
• Volume is constant
• Sample: The temperature of a gas goes from 30 °C to 50 °C. The starting pressure is 760 mm Hg, what is the ending pressure?
Combined Gas Law
• P1V1/T1 = P2V2/T2
• Combines Boyle’s, Charles’, and Gay-Lussac’s Laws
• Sample: Your mom gives you a balloon that says “I love you!” (awh!). When she hands it to you it has a pressure of 1.5 atm and is at 295 K. The next morning it is at 290 K, has a pressure of 1.2 atm and has a volume of 1.5 L. What was the original volume of the balloon?
Molar Volume
• At STP, 1 mole of any gas occupies 22.4 L
• STP = 0 °C (273 K) and 1 atm
• What will the volume of 5 moles of gas be at STP?
• A sample of gas occupies 11.2 L at STP, how many moles is in the sample?
• How many atoms are in 5 L of gas at STP?
Ideal Gas Law
• relates P, V, T, and number of moles (n)
• PV = nRT
• R = 0.0821 (L*atm)/(mol*K) = “ideal gas law constant”
• ‘ideal’ gases - particles have no volume & no attractive forces
• real gases are ‘ideal’ gases under all conditions except very high pressure or very low temperature

go to animation

Sample Problems…
• You have 4 moles of helium gas at 1.5 atm and 25 L, what is the temperature?
• How many moles of argon gas are present in 500 mL at 3 atm and 30 ºC?
Gas Stoichiometry
• Coefficients in balanced reaction equations are mole ratios AND gas volume ratios!
• Can do “vol to vol” stoichiometry when P and T are constant
Volume - Volume Gas Stoich

(These are just like mole to mole

problems - one conversion!)

How many liters of NH3 will be produced if 10 liters of N2 are consumed according to the following reaction:

N2 (g) + 3H2 (g) -----> 2NH3 (g)

Volume-Mass Gas Stoich Example

N2 (g) + 3H2 (g) -----> 2NH3 (g)

How many grams of hydrogen gas are required to create 20 L of ammonia gas if the above reaction occurs at STP?

*do volume to volume stoich, then molar volume, then molar mass.

Mass-Volume Gas Stoich Example

N2 (g) + 3H2 (g) -----> 2NH3 (g)

How many liters of ammonia gas can be created from 50 grams of nitrogen gas at STP?

*mass to mole stoich, then molar volume