GAS LAWSChapter 14 in your book

Gas Laws Unit

How do gases respond to changes in pressure, volume, and temperature?

Why do you suppose we study ideal gases?

Why is the ideal gas law useful even though ideal gases do not exist?

Describe three factors that affect gas pressure

Explain the relationship and calculate problems between p, v, and t of a gas

Relate the total pressure to the partial pressures of gases contained in a mixture

Use Graham’s diffusion rate to calculate the rate of diffusion of given gases.

ESSENTIAL QUESTIONS OBJECTIVES

Chemcatalyst: ___.___

Write down 4 properties of gases:

Give me 2 examples of gases:

Pressure Conversions

1 atm = 101.3 kPa = 760 mmHg (torr) How can we write these as conversion factors?

Do you know why torr and mmHg are the same? Evangelista Torricelli

invented the first barometer using mercury!

Torr is in honor of his work with pressure and measuring it!

Pressure Conversions

1. Write what you are given with its units2. Write the conversion factor next

a. Be sure to make sure you’re units cancel out!

3. Multiply the top and multiply the bottom… then divide

4. Check SigFigs and units!!!

Let’s try this one together:

If you have 99.6 kPa, how many atm would that be?

Try this one on your own:

How many mmHg are in 0.983 atm?

WWLKD?

What would Lord Kelvin do? With Temperature…

Temperature Conversions

For gas laws, we will be using KELVINS The Kelvin scale is only positive! Absolute Zero = 0 K

K = oC + 273 oC = K - 273

Let’s try these:

How many kelvins are equal to 21.0 oC?

How many kelvins are equal to -10.0 oC

Volume Conversions

1000 mL = 1L

How many liters are in 545 mL?

STP

Standard Temperature and Pressure

Temperature: 0oC Pressure: 1.00 atm

Chemcatalyst:___.___

How many atmospheres are equivalent to 450 kPa?

Show work and units! Try your best on Sig Figs!

Peeps Demonstration/Video

Pressure & Volume

What happened to the peep’s volume when the air was sucked out?

What happened to the pressure as the air was being sucked out?

What happened to the peep’s volume when air was let back in?

Fill in the blanks:

As the pressure _______________, the volume _______________.

This is an ________ or ________ relationship.

Boyle’s Law

PV =K K is a constant; so we can say the initial and final

conditions are equal As P increases, V decreases; As P decreases, V increases

P1V1 = P2V2

P= Pressure (atm, Kpa, Pa, mmHg (torr)) V= Volume (mL or L)

Let’s try this one together:

5.00 L of a gas is at 1.08 atm. What pressure is obtained when the volume is 10.0 L?

Try this one on your own:

2.50 L of a gas was at an unknown pressure. However, at standard pressure, its volume was measured to be 8.00 L. What was the unknown pressure?

(x) (2.50 L) = (1.00 atm) (8.00 L) X = 3.20 atm

Boyle’s Law Practice

In small groups, no more than 3 complete problems in your packet on page 1

Must show work on a separate sheet of paper

What ever you do not finish is homework

Good Luck

Chemcatalyst:__.___

If a balloon has 30.0L of gas at 100.0 kPa, what is the volume, if the pressure is decreased to 25.0 kPa?

Show all work with units and try your best with Sig figs!

Liquid Nitrogen & balloons

Video!

What happen to the balloon in liquid nitrogen and after the liquid nitrogen?

What two factors were affected in this video?

Charles’ Law

V/T =K K is a constant; so we can say the initial and final

conditions are equal As V increases, T increases; As V decreases, T

decreases

V= Volume (mL or L) T= Temperature (K)

Let’s do this one together!

A balloon is inflated at 24oC and has a volume of 4.00 L. What is the volume when the balloon is heated to 58oC?

Try this one on your own:

If a sample gas occupies 6.80L at 325oC, what will the temperature be if the volume decreases to 3.39 L?

Charles’ Law Practice

In pairs complete 1-3 in your packet on page 2

Show work on a separate sheet of paper

You will have 10 minutes to complete these 3 problems!

AXE Can Video

What will happen to the AXE can when it is placed in a bon fire?

How to fix a ping pong ball with chemistry?!http://www.youtube.com/watch?v=HxSPdmvqstQ

Mini Lab

Follow the procedure!

Steam can be as harmful as boiling water

Chemcatalyst: __.__

What’s happening in this video?

https://www.youtube.com/watch?v=GcCmalmLTiU

Gay-Lussac’s Law

P/T =K K is a constant; so we can say the initial and final

conditions are equal As P increases, T increases; As P decreases, T

decreases

P= Pressure (Kpa, atm, or mmHg (torr) T= Temperature (K)

Let’s try this one together!

An aerosol can has a pressure of 103 kPa at 25oC, if the can reaches a temperature of 928oC within a fire, what is the new pressure?

Try this one on your own:

The pressure in a car tire is 198 kPa at 27oC. After a long drive, the pressure is 225 kPa. What is the temperature in the tire?

T2 = 340 K

Mini lab

Egg in a bottle

Chemcatalyst: ___.___

Write down the 3 gas laws and their equations

Write each relationship too (Ie: pressure does this when volume does this)

A given sample of air has a volume of 6.00 L at 101 kPa, what volume would it occupy at 25.0 kPa?

Let’s combine them

What do each one of these equations have in common?

Do the places where P, V, T switch or change?

Combined Gas Law

Red- Boyle’s Law Blue- Charles’ Law Green- Gay-Lussac’s Law Orange- the COMBINED Gas Law

How many “knowns” will you have to have?

Combined gas Laws

The volume of a gas-filled baggie is 30.0 L at 313 K and 153 kPa, what would the volume be at STP?

Combined gas law worksheet

Work on Page 3’s chart on the combined gas law in pairs or threes!

Prepare for Quiz on:- Pressure conversions- Named Gas Laws - Combined Gas Laws**Can use given sheet with formulas!

Chemcatalyst: ____.____

What does it mean for something to be ideal?

Ideal Gases

The named gas laws had P, T, and V, but what about moles and mass?

Does gas have mass?

http://www.youtube.com/watch?v=_p--sGYfGnU

Moles and Gases

Chemist needed an equation with mass or moles!

Introducing the…. (drum role)

IDEAL GAS LAW

Ideal Gas Law

PV = nRTP= Pressure ( MUST be in atm or kPa)V= volume (MUST be in LITERS!)n= Number of moles (mols)R= Gas constant

For Atm = 0.0821 For kPa = 8.314

T= Temperature (MUST be in KELVIN (K))

Let’s do this one together:

At 34oC, the pressure inside a nitrogen-filled tennis ball with a volume of 0.148 L is 212 kPa. How many moles of nitrogen are in the tennis ball?

Try this one on your own:

When the temperature of a hollow sphere containing 685 L of helium is held at 621 K, the pressure is 1890 kPa. How many moles of helium are in this sphere?

Ideal Gas Law Practice

Work in small groups (2-3 people) and complete the back page in your packet #’s 1-3

Complete on a separate sheet of paper, show all work

You have 10 minutes to complete!!!

Molar Mass Reminder:

Calculate the molar mass for:

1. CaCO3

2. Mg(NO3)2

100.09 g/mol

148.33 g/mol

Ideal Gas Law with mass!

A steel cylinder that has a volume of 20.0L with nitrogen gas inside has a pressure of 200. kPa and 28oC, how many grams is that nitrogen (N2)?

WOOHOO WE DID IT!

Ideal Gas Law

Try the mass problems on the ideal gas law worksheet, page 4

Chemcatalyst ___.___

How do we smell things across the room?

Diffusion

Tendency for molecules to move towards areas of lower concentration until uniform throughout

Move from high concentration to lower ones

http://www.youtube.com/watch?v=_oLPBnhOCjM

Did you know?

Dif in latin means “apart”

Effusion

The process in which a gas escapes through a small hole

The flow of a gas

https://www.youtube.com/watch?v=GRcZNCA9DxE

Grahams Effusion Equation

a) the rate of effusion of gases at the same temperature and pressure are inversely related to the square root of their molar masses.

Rate of A = √mmB

Rate of B √mmA

Did you know?

In Latin the prefix eff, means exit

Effusion that gas is exiting through a small hole or one concentrated area!

Try this together:

How much faster does helium (He) effuse than nitrogen (N2) at the same temperature?

Try these on your own:

Calculate the rate of effusion between oxygen (O2) and carbon dioxide (CO2)

Reach question:

If an unknown gas diffuses 5 times faster than Argon, what is the molar mass of the unknown gas?