GAS LAWS

ANNOUNCEMENTS!

1.Housekeeping

■ Rules, Door, Attention signal

■ Quarter 4 assignments due by May 6th for ½

credit

– Unit 6 assessment & research paper will

not be accepted

– No additional copies will be made

■ EOC review sheet due for FULL credit 25th

Title Page #

Specific heat IP 75

Specific heat notes 76

Rotations 77-78

Equilibrium notes 79

Equilibrium IP 80

Acids and bases 81

Acids/Bases IP 82

Acid bases day 2 notes 83

Day 2 IP 84

Acids bases day 3 notes 85

Day 3 IP 86

Acid Bases Lab 87

Common Units of Measurement for Gas Law Equations

■ Pressure (P)

– the measure of force applied by another substance (such as a gas). It is commonly

abbreviated as “P” (a capital letter P). Pressure can be measured in millimeters of

Mercury (mmHg), torr, atmospheres (atm), Pascals (Pa), and kilopascals (kPa).

■ Volume (V)

– the by a solid, liquid, or gas. It is commonly abbreviated as “V” (a capital letter V).

Volume, in this situation, will be most often measured in liters, L.

■ Temperature (T)

– the in a solid, liquid or gas. It can be measured on three scales: Fahrenheit, Celsius

(sometimes referred to as Centigrade) and Kelvin. It is commonly abbreviated as “T” (a

capital letter T). Temperature, in this situation, will most often be measured in Kelvin, K.

Temperature Conversions

■ Celsius to Kelvin formula

– T(K) = T(°C) + 273.15

■ Example

– Convert 10 degrees Celsius to Kelvin:

– T(K) = 10°C + 273.15 = 283.15 K

Common Units of Measurement for Gas Law Equations

■ Moles of Gas (n)

– a lowercase “n” stands for the number of moles of a gas. This is a measurement in moles, so if you are given a mass in grams or kilograms, be sure to change it to moles first.

■ R is a Constant (R)

– when dealing with gas laws, R is a constant that means .0821 (L*atm)/(mol*K). The units are read as “liter-atmospheres per mole-Kelvin.” This label combines volume (measured in liters, L), pressure (measured in atmospheres, atm), mass (measured in moles, mol), and temperature (measured in Kelvins, K).

■ Standard Temperature and Pressure (STP)

– STP stands for “standard temperature and pressure” and refers to conditions of 273 K (0 degrees C) and 1 atm.

Temperature Conversions

■ Kelvin to Celsius formula

– The temperature T in Kelvin (K) is equal to the temperature T in degrees

Celsius (°C) minus 273.15

– T(°C) = T(K) - 273.15

■ Example

– Convert 283.15 Kelvin to degrees Celsius

– T(°C) = 283.15 - 273.15 K = 10°C

Boyles Law

Boyles Law

Definition Pressure and Volume are

inversely related.

Formula 𝑃1 × 𝑉1 = 𝑃2 × 𝑉2

Boyles LawBoyles Law

explanation Gases squeezed into a smaller volume will

exert more pressure (as the molecules hit the

walls with a greater force more often.)

CFU#1 - 2

A. WHAT TWO VARIABLES DOES BOYLES LAW DEAL WITH?*

B. Assume you had to solve for V1. How would you set up the

equation?

C. Assume you want to solve for P2. How would you set up the

equation?

𝑃1 × 𝑉1 = 𝑃2 × 𝑉2

𝑃1 × 𝑉1 = 𝑃2 × 𝑉2

3 minutes

Gay Lussac LawGay-Lussac Law

Definition Pressure will increase when

temperature increases (vice versa)

Formula

𝑃1

𝑇1=𝑃2

𝑇2

French, “Guy”

Gay Lussac LawGay Lussac Law

explanation Hot molecules move/spread faster and exert

more force especially when the container walls

are fixed (when they bounce off each other and

the walls of their container).

CFU#3 - 4

A. WHAT TWO VARIABLES DOES GAY-LUSSACS’ LAW DEAL WITH?*

B. Assume you had to solve for p2. How would you set up the

equation?

C. Assume you want to solve for T1. How would you set up the

equation?

𝑃1

𝑇1=𝑃2

𝑇2

𝑃1

𝑇1=𝑃2

𝑇2

3 minutes

Charles LawCharles Law

Definition As temperature increases, volume

increases (vice versa)

Formula

𝑉1

𝑇1=𝑉2

𝑇2

CFU#5 - 6

A. WHAT TWO VARIABLES DOES CHARLES’ LAW DEAL WITH?*

B. Assume you had to solve for V1. How would you set up the

equation?

C. Assume you want to solve for T1. How would you set up the

equation?

𝑉1

𝑇1=𝑉2

𝑇2

𝑉1

𝑇1=𝑉2

𝑇2

3 minutes

Charles LawCharles Law

explanation When you heat a certain amount of gas you will give it

energy to move/spread and increase the volume of a

container.

A sample of neon gas occupies a volume of 2.8 L at 1.8 atm. What would its volume be at 1.2 atm?

■ Looking for:

■ Given:

■ Relationship:

■ Solution:

WORD PROBLEM (on back!)

Try the last 3!

1. Circle and label all variables (V1, V2, T1, T2, P1, P2)

2. Decide who's law does the equation relate to

3. L – what are you looking for?

4. G –what variables where you given?

5. R – what equation should you use?

6. S – manipulate the equation and solve.

WORD PROBLEM (on back!)

10 minutes

Remember temperature should

be in Kelvin !

Formula

PV = nRTP

RE

SS

UR

E

VO

LU

ME

MO

LE

S

CO

NS

TAN

T

TE

MP

ER

ATU

RE

Formula and Constants @ STP

PV = nRT1 atm

22.41 L

1 mol

0.0821 atm*L

mol*K

273.15 K

Solve for the Variables

P =nRT

VR =

PV

nT

T =PV

nRV =

nRT

P

n =PV

RT

Ideal Gas LawExample Problems

Problem #1

A sample of argon gas at STP occupies

56.2 liters. Determine the number of

moles of argon and the mass in the

sample.

Problem #2

Determine the volume of occupied by

2.34 grams of carbon dioxide gas at

STP.

Independent Practice

Complete IP #1 and #2 by the end of class today

Make sure to show all work to receive full credit for the assignment.

DON’T FORGET YOUR UNITS

DONE?

• Get a laptop and complete EOC review sheet

• Complete any IP you have not done for Q4 (half credit)