Warm Up – WSHT #1 OUT!!! 1.When you increase the number of gas particles, does pressure increase, decrease or stay constant? 2.When you increase the volume

Warm Up – WSHT #1 OUT!!!1. When you increase the

number of gas particles, does pressure increase, decrease or stay constant?

2. When you increase the volume of a gas, does pressure increase, decrease or stay constant?

3. When you increase the temperature of a gas, does increase, decrease or stay constant?

Essential Questions

EQ: How do we quantitatively describe the effects of changing the P, V, T, or n of a gas? HOT Q1: How do we convert between units of pressure?HOT Q2: How do we find the new pressure of a gas when volume changes?HOT Q3: What is the combined gas law?

Agenda• Warm-Up• Pressure conversions• Gas Equations

– Combined Gas Law

• Exit Ticket

HOMEWORK: WORKSHEET #2 QUIZ TOMORROW!!!

Graph of relationship between the two variables

Key concept

3 particles diagrams to represent 3 diff. locations on graph

Real world example

Pressure vs. Number of Particles

Pressure vs. Temperature

Pressure vs. Volume




Real world example

Real world example

Key concept

Key concept


Your “Discussion”

section!

Consensus

Gas Conversions

We have learned the relationship between pressure, volume, number of particles, and temperature, But how do we measure pressure exactly?!!

• There are several units for pressure, and we can use their equal values to convert from one to the next.

• These units include:

Notes: Gas Conversions DateFIVE UNITS OF PRESSURE:

kPa kilopascals– Used frequently by meteorologists

• torr Torr – Named after the Italian scientist Evangelista Torricelli

• atm atmospheres– Sea level is 1 atm

• mmHg millimeters of Mercury – Hg is the atomic symbol for Mercury

• psi pounds per square inch– This is the what is usually used to measure the air pressure in a car

tire!

How do they relate?

1 atm = 760 torr = 101.3 kPa = 760 mmHg = 14.7 psi

WRITE THESE IN YOUR NOTES!!

Got it?• Let’s use the values you just copied down to

convert!

Convert 12 psi to torr.Step 1 – Write out your units

Step 2 – Fill in the numbers

THAT’S IT!

Still scratching your head?Convert 2.2 atm to kPa.Step 1 – Write out your units

Step 2 – Fill in the numbers

WRITE THIS IN YOUR NOTES!!

Uno mas?Convert 844 torr to atm:

Convert 10,450,217 mmHg to torr:

Partner Practice

Convert 185 kPa to psi

Convert 912 mmHg to atm

Convert 20.7 psi to torr

Convert 3.6 atm to kPa

Strong People?

Demo: King Kong’s Hand

You do not have to write this down…• Eye Level

• Particle Level

Consensus

Conceptual vs. Math

• Now that we have learned the relationship between pressure, volume, number of particles, and temperature, let’s look at the mathematical applications.

Notes: Combined Gas LawNotes: Combined Gas LawFour variables used in gas law

problems:• V = volume of the gas (L)• T = temperature (K)

–K stands for Kelvin. –K = oC+273

• n = number of particles (moles)• P = pressure

(atmospheres)

Notes: Combined Gas LawNotes: Combined Gas LawEarlier, we found the relationship between

all these variables. 1) Pressure and Temperature are

POSITIVELY related (when one goes up, so does the other).

2) Pressure and the number of particles (n) are POSITIVELY related.

3) Pressure and volume are NEGATIVELY related (when one goes up, the other goes down)!!

What does this all boil down to?

• THE COMBINED GAS LAW!!!

2

22

1

11

T

VP

T

VP

ALERT!!! P and V may be in any appropriate units as long as the same units are used on both sides of the equation

T must ALWAYS be in Degrees KELVIN(ie celsius +273)

Process of solving a problem

• Step 1: Identify which variables the problem gives you.– For some problems this will be easy, but you really

have to look through word problems!!

• Step 2: Cross out any variables you don’t need

• Step 3: Solve the remaining equation

ExamplesThe pressure inside of a 5.1 L container is 3.2 atm. The

container expands to a volume of 8.8 L. What is the new pressure inside the balloon?

1)P1 = 3.2 atm V1 = 5.1 L P2 = ? V2 = 8.8 L

Step 1: Identify which variables the problem gives you.

Step 2: Cross out any variables you don’t need

Step 3: Solve the remaining equation

ExamplesBria has a 3.2L balloon of hydrogen gas at 23 K. She

leaves the balloon in her blazing hot car, and the temperature increases to 72 C. What is the new volume of the balloon?

1) V1 = 3.2 L T1= 23 C V2 = ? T2 = 72 C

You must convert to Kelvin!!!

You must convert to Kelvin!!!

Partner Practice

The pressure inside a .83 L hot air balloon is 4.31 atm. If the volume increases to 1.44 L, what is the new pressure inside the balloon?

P1 = 4.31 atm V1 = .83 L P2 = ? V2 = 1.44 L

Partner PracticeA sample of gas occupies of volume of 5.5 L.

After being compressed to a volume of 3.9 L, the new temperature of the sample of gas is 273 K. What was the initial temperature of the gas?

V1 = 5.5 L T1= ? V2 = 3.9 L T2 = 273K

Example

• The temperature inside my refrigerator is about 40 Celsius. If I place a balloon in my fridge that initially has a temperature of 220 C, a volume of 0.5 liters, and a pressure of 3 atm, what will be the volume of the balloon when the pressure decreases to 2 atm and the temperature decreases to 40 Celsius?

V1 = 0.5 L T1=220 C P1= 3 atm V2 = ? T2 = 40 C

P2=2 atm

Partner Practice

• The pressure in a 3.0L bicycle tire is 2.08 atm at 25˚C in Fresno. You take the bicycle up to Huntington, where the temperature is 0oC. The tire shrinks to a volume of 2.0 L. What is the final pressure in the tire?

V1 = 3.0 L T1=250 C P1= 2.08 atm

V2 = 2.0 L T2 = 00 C P2=?

Example – Word ProblemsA sample of xenon gas in a 6.1 L container initially has a pressure of .85 atm. If the pressure of the gas increased to 1.9 atm, what is the new volume of the container?

Step 1: Identify which variables the problem gives you.CIRCLE KEY FACTS. CROSS OUT EVERYTHING YOU DON’T

NEED.

Step 2: Cross out any variables you don’t need

Step 3: Solve the remaining equation

Examples

In a thermonuclear device, the pressure of .050 liters of gas within a bomb casing reaches 4000000 atm. When the explosion destroys the bomb casing, the gas is released into the atmosphere where it reaches a pressure of 1.00 atm. What is the volume of the gas after the explosion.

Partner Practice

A sample of gas at 288 K occupies a volume of 52.9 L. The gas is compressed to a volume of 41.9 L. What is the new temperature of the gas?

Partner Practice

Synthetic diamonds can be manufactured at pressures of 60,000 atm. If we took 2.0 liters of gas at 1.0 atm and compressed it to a pressure of 60,000 atm, what would the volume be?

Exit Ticket1) Convert 42 psi to torr.

2) A sample of gas at 42°C occupies a volume of 34 L. The gas is compressed to a volume of 28 L. What is the new temperature of the gas?

• HOMEWORK: WORKSHEET #2! Quiz tmrw!• Tutoring after school today!• Unit 1 Grades posted, Unit 1 Packet and Unit 1

Warm Ups posted

Warm Up – WSHT #2 OUT!!!

1. Convert 3.6 atm to kPa 2. A sample of gas

occupies of volume of 5.5 L. After being compressed to a volume of 3.9 L, the new temperature of the sample of gas is 273 K. What was the initial temperature of the gas?

Essential Questions

EQ: How do we quantitatively measure the P, V,T, or n of a gas? HOT Q1: What is the Ideal Gas Law?HOT Q2: When do we use the Ideal Gas Law, and when do we use the Combined Gas Law? HOT Q3: What should I do I finish my quiz early?

Agenda• Warm-Up – 10 min• Gas Equations (45) • Quiz! (25)

HOMEWORK: WORKSHEET #3!!!

I can show you the world…(of gas laws)… shining, shimmering, splendid…

Notes: Ideal Gas LawPV = nRT“piv nert”

This equation is used to predict any of these variables when the others are held constant.• P = pressure (atm)• V = volume (L)• n = number of particles (moles)• T = temperature (KELVIN!)• R = gas constant - 0.0821 L atm

mole K

ExamplesEquation: P*V = n*R*TA gas under a pressure of 2.3 atm and at a

temperature of 293 K occupies a 500.0 L container. How many moles of gas are in the container?

1)P = 2.3 atm V = 500.0 L n = ? T = 293 K

R = gas constant - 0.0821 L atm

Kmole

Examples.89 moles of a colorless gas occupy a volume of 84.1

L and a pressure of 3.6 atm. What is the temperature of the gas?

P = 3.6 atm V = 84.1 L n = .89 mol T = ?

When Do I Use Which?

Use “Ideal Gas Law” when solving for a variable and everything is held constant… used “Combined Gas Law” when something is changing and you are asked for “new” pressure, for example.

Example

The temperature inside my refrigerator is about 40 Celsius. If I place a balloon in my fridge that initially has a temperature of 220 C and a volume of 0.5 liters, what will be the volume of the balloon when it is fully cooled by my refrigerator?

Are you changing pressure, volume, temperature, or # of particles?

Ideal or Combined?

Example

If I have 4 moles of a gas at a pressure of 5.6 atm and a volume of 12 L, what is the temperature?


Ideal or Combined?

Flash!

• 1.0 L of a gas at 1 atm is compressed to .473L. What is the new pressure of the gas?


Ideal or Combined?

Flash!• Synthetic diamonds can be manufactured at

pressures of 60,000 atm. If we took 2.0 liters of gas at 1.0 atm and compressed it to a pressure of 60,000 atm, what would the volume be?


Ideal or Combined?

Flash!

• If I have 4 moles of a gas at a pressure of 5.6 atm and a volume of 12 L, what is the temperature?


Ideal or Combined?

Flash!

• If I have an unknown quantity of gas held at a temperature of 1195 K in a container with a volume of 25 liters and a pressure of 560 atm, how many moles of gas do I have?


Ideal or Combined?

Exit Ticket

1) 0.8 moles of an ideal gas are stored in a 5L container at 1.5atm. What is the Temperature of the gas?

2) A gas in a solid 8L container is initially at 32 C and 3.5 atm. The gas is cooled to 10 C what is the new pressure of the gas? YOU HAVE TO

CONVERT TO K!

Quiz!

• No talking• Only logistical questions will be answered• If you finish early, start your homework

(worksheet #3)

HOMEWORK: WORKSHEET #3

Documents

Warm Up – WSHT #1 OUT!!! 1.When you increase the number of gas particles, does pressure increase, decrease or stay constant? 2.When you increase the volume