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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)