Download Unit Conversion for Gas Laws Calculations

HONORS CHEMISTRY
May 7, 2012
Brain Teaser
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Turn in Titration Lab
Describe the characteristics or
properties of solid, liquid and gases
Agenda
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Brain Teaser
Unit 9 Acid/Base Test Result
Notes: Introduction to Gases and Gas Laws
Homework

Charles and Boyles Law Worksheet
Introduction to Gases

Earth is surrounded by a layer of
gaseous molecules - the atmosphere extending out to about 50 km.
Characteristics of Gases
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Gases
low density; compressible
 volume = shape of container
 expand when heated
 large distance between particles

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Model of a gas:
rapidly moving particles: vol. & shape of
container
12m05vd1
 no attraction between particles
 moving about freely
 large space between particles: low density &
high compressibility
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Liquids and Solids
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Liquids
higher density, lower compressibility
 characteristic volume; shape of container
 particles closer together; moving about;
experience attractive forces

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Solids
high density; low compressibility
 particles are close together; little empty
space; strong attractive forces
 characteristic volume and shape
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Atomic View of the States of
Matter
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Note distance between particles and
order of arrangement of particles
Figure 9.1
01m07an1
States of Matter
Pressure
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Pressure = force/area
Units: lb/ft2
Pa = N/m2 = kg/ms2
torr = mm Hg
atm
1 atm = 760 torr= 760 mm Hg
1 atm = 29.9 in Hg = 14.7 lb/in2
1 atm = 101.3 kPa
Measure pressure with barometer or Utube or manometer
Charles’ Law- Relationship between:
_________ and __________

Variables/Units
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T=K
V=L
P = atm
n = moles
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Direct
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As temperature increases,
volume increases
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Held Constant
Relationship (direct
or inverse)
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In words
Charles’ Law
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Graph of
Relationship
Charles’ Law
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V/T = m
m= constant
V1/T1 = V2/T2
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K = C + 273

C = 5/9(F-32)
K = C + 273
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Charles’ Law
Formula
How to convert
C to K
F to C to K

Charles’ Law
Convert 212 degrees F to K
Temperature
Conversion
Practice
Convert 50 degrees C to K
The volume of a sample of
Practice Problem gas is 2.50L at 45K. What
is the volume when it is
heated to 125K at a
constant pressure.
Pressure

Why does a pin hurt?

Why don’t snowshoes sink?
Boyle’s Law: The relationship
between _______ & ________
Variables/Units
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Held Constant
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Volume (L)
Pressure (atm)
Temperature (K)
Moles (n)
Boyle’s Law:
Relationship
(direct or
inverse)
Relationship in
words
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Inverse
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As pressure increases
volume decreases.
Boyle’s Law
Sketch Graph
Pressure vs.
Volume
Boyle’s Law
Sketch Graph
Pressure vs. 1/ V
Boyle’s Law Formula
Boyle’s Law Formula
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Pressure Units
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PV = m m = constant
P1V1 = P2V2
atm = atmospheres
mmHg = millimeters of
mercury
torr
Pa = Pascals
psi = pounds per square inch
1 atm = 101,325Pa = 760
mmHg = 760 torr = 14.70psi
Boyle’s Law Formula
Pressure Unit
Conversions
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1 atm = 101,325Pa = 760 mmHg = 760 torr = 14.70psi
Boyle’s Law
How to convert
from pressure
units to atm
Convert 458mmHg to atm
Convert 96.5 psi to atm
(use dimensional
analysis)
Convert 485kPa to atm
Boyle’s Law
Boyle’s Law Practice Problem
The pressure on 2.5L of anesthetic gas is
changed from 760mmHg to 304mmHg.
What will be the new volume of the gas?
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STP:
Standard Temperature and Pressure
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0
oC
(273 K) , 1 atm
HONORS CHEMISTRY (5/6)
Open Note Quiz (5/6)
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Place Homework on your desk
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Textbook Notes
Charles and Boyles’ Laws Worksheet
Time – 10 minutes
Unit Conversion for Gas
Laws Calculations
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Convert to the following units
P = atm
V = Liters
T = Kelvin (oC + 273)
Agenda
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Open Note Quiz
Grade Homework
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Charles & Boyles’ Laws Worksheet
Exploring Gas Behavior
Exploring Gas Behavior
Activity
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Refer to Handout
HONORS CHEMISTRY
May 11, 2012
Brain Teaser
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The pressure on 5.5 L gas is changed
from 3 atm to 5 atm. What will be the
new volume of the gas?
The volume of a sample of gas is 4 mL
at 40oC. What is the volume when it is
heated to 60 oC at a constant
pressure?
Agenda
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Brain Teaser
Grade Worksheet: Charles and Boyles’
Law Worksheet
Notes: Combined Gas law, Avogadro’s
Law and Ideal Gas Law
Homework
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Ideal Gas Law and Combined Gas Law
Worksheet
Combined Gas Law
Boyle’s Law
Charles’s
Combined
P1V1  P2V2
V1 V2

T1 T2
P1V1 P2V2

T1
T2
Avogadro’s Law

How can we change the volume of a gas in
a balloon?
Avogadro’s Law
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Why did the blimp deflate?
Avogadro’s Law
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If the pressure and temperature are held
constant,
V  m(n)the
 bvolume of a gas is directly
proportional to the number of moles (n).
b0
V
m
n
V1 V2

n1 n2
V
n
Gas Laws Part 2: Work on Gas Notes
Sheet instead of Brain Teaser
Avogadro’s Law
O2  O3
Suppose we have a 12.2 L sample containing 0.50
mol oxygen gas at a pressure of 1 atm and a
temperature of 25 ºC.
1) Balance the equation
2) If all this oxygen is converted to ozone at the same
temperature and pressure, what would be the volume
of the ozone?
• The total
pressure is the
sum of the
partial
pressures.
• Ptotal = P1 +
P2 + P3 + …..
Dalton’s Law Practice

A mixture of oxygen, carbon dioxide,
and nitrogen has a total pressure of
0.97atm. What is the partial pressure
of Oxygen, if the partial pressure of
carbon dioxide is 0.70atm and the
partial pressure of nitrogen is
0.12atm?
The Gas Laws
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Variables: V, P, T, n (or m and MM or d)
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Ideal Gas: properties are independent of the
identity of the gas
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What is the relationship between the variables
for an ideal gas?
Basketball
Bike Tire
5.3 Ideal Gas Law
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PV = nRT
P= pressure
V = volume
n = number of moles
R = ideal gas constant

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0.08206 L·atm/mol·K
T = temperature
STP
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Standard Temperature and Pressure
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0ºC and 1 atm
Use the Ideal Gas Law to calculate the
volume of 1.00 mol of gas at STP
Molar Volume at STP

We can show that 22.414 L of any gas
at 0C and 1 atm contain 6.02  1023
gas molecules.
Example
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A sample of Hydrogen gas has a
volume of 8.56 L at 0ºC and a pressure
of 1.5 atm. Calculate the moles H2
molecules present in this gas sample.
Practice Problem
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The volume of an oxygen cylinder is
1.85 L. What mass of oxygen gas
remains in the cylinder when it is
“empty” if the pressure is 755 torr and
the temperature is 18.1oC?
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Answer: 2.46 g
Gas Law Stoichiometry
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Quicklime (CaO) is produced by the
thermal decomposition of calcium
carbonate. Calculate the volume of
CO2 at STP produced from the
decomposition of 152 g of CaCO3 by
the reaction
CaCO3 (s) CaO (s) + CO2 (g)
Molar Mass and the
Ideal Gas Law
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If 0.126 g of a gas are contained in a
25mL tank at 25ºC and 3.25 atm, what
is the molar mass of the gas? What is
the gas?
Kinetic Molecular Theory
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A model that attempts to explain the behavior of an
ideal gas.
The particles are so small that compared with the
distances between them that the volume of the
individual particles can be assumed to be
negligible (zero).
The particles are in constant motion. The
collisions of the particles with the walls of the
container are the cause of the pressure exerted by
the gas.
Kinetic Molecular Theory
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The particles are assumed to exert no forces on
each other; they are assumed to neither attract nor
repel each other.
The average kinetic energy of a collection of gas
particles is assumed to be directly proportional to
the Kelvin temperature of the gas.
When does the Kinetic Molecular
Theory break down?

What conditions would cause our
assumptions to become in valid?
Derivations from the Ideal gas law:
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Derivations occur in non-ideal conditions such
as low temperature or high pressure:
At high density the volume of the particles
themselves become important.
Gas particles do attract each other when they are
close together.
Barometer

What is in a
vacuum?
What is the
weight of the
atmosphere?
Figure 9.3
Pressure

Lab: soft drink can
Charles’ Law
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As x increases, y stays
the same, no
relationship.
y = b y is constant
As x increases, y
increases
Y = mx + b
As x increases, y
decreases
Y = m(1/x) + b
Team
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A sample of nitrogen occupies a
volume of 250 mL at 25ºC. What
volume will it occupy at 95ºC.
Fluorine gas at 300 K occupies a
volume of 500 mL. To what
temperature should it be lowered to
bring the volume to 300 mL?
Boyle’s Law by the Book
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Lab investigation
Pop Quiz: Boyle’s Law

Sulfur dioxide, a gas that plays a central
role in the formation of acid rain, is found
in the exhaust of automobiles and power
plants. Consider a 1.53 L sample of
gaseous sulfur dioxide at a pressure of
5.6 x 103 Pa. If the pressure changed to
0.148 atm at a constant temperature,
what will be the new volume of gas?
GROUP WORK

Charles and Boyle’s Law Worksheet