Agenda Jan 30th, 2018
Slip Quiz - from last time
And Dalton’s Law of Partial Pressure Slip Quiz for today
Lab: Pressure and volume of gases relationship - check data and review mathematical model
The Gas Laws Notes
Slip Quiz - from last time.
1. Name the two gases that make up most of
the mixture we call air.
Nitrogen 78% by volume;
Oxygen 21% by volume
Dalton’s Law of Partial Pressures
Each gas in a mixture exerts pressure independently of the other gases present.
The total pressure of a mixture of gases is equal to the sum of the pressures of all the gases in the mixture. The portion of the total pressure contributed by a single gas is called its
partial pressure.
(The partial pressure of a gas depends on the amount of it, the size of the container and the temperature of the mixture. It does not depend on the identity of the gas.)
Dalton’s Law of Partial Pressures
Can be summarized as
P
total= P
1+ P
2+ P
3+...P
nWhere P
totalrepresents the total pressure of a
mixture of gases. P
1,P
2, and so on represents
the partial pressures of each gas in the mixture.
Dalton’s Law of Partial Pressure Sample Problem
A mixture of oxygen (O2), carbon dioxide (CO2) and nitrogen (N2) has a total pressure of 0.97 atm. What is the partial
pressure of O2, if the partial pressure of CO2 is 0.70 atm and the partial pressure of N2 is 0.12 atm?
Using Dalton’s law of partial pressure Ptotal = Poxygen + Pcarbondioxide + Pnitrogen
Dalton’s Law of Partial Pressure Sample Problem
A mixture of oxygen (O2), carbon dioxide (CO2) and nitrogen (N2) has a total pressure of 0.97 atm. What is the partial
pressure of O2, if the partial pressure of CO2 is 0.70 atm and the partial pressure of N2 is 0.12 atm?
Using Dalton’s law of partial pressure Ptotal = Poxygen + Pcarbondioxide + Pnitrogen Poxygen = Ptotal - Pcarbondioxide - Pnitrogen
Dalton’s Law of Partial Pressure Sample Problem
A mixture of oxygen (O2), carbon dioxide (CO2) and nitrogen (N2) has a total pressure of 0.97 atm. What is the partial
pressure of O2, if the partial pressure of CO2 is 0.70 atm and the partial pressure of N2 is 0.12 atm?
Using Dalton’s law of partial pressure Ptotal = Poxygen + Pcarbondioxide + Pnitrogen Poxygen = Ptotal - Pcarbondioxide - Pnitrogen
Dalton’s Law of Partial Pressure Practice Problem (1)
What is the partial pressure of hydrogen gas (H2)in a mixture of hydrogen and helium if the total pressure is 600 mmHg and the partial pressure of helium is 439 mmHg?
Using Dalton’s law of partial pressure Ptotal = Phydrogen + PHelium
Dalton’s Law of Partial Pressure Practice Problem (1)
What is the partial pressure of hydrogen gas (H2)in a mixture of hydrogen and helium if the total pressure is 600 mmHg and the partial pressure of helium is 439 mmHg?
Using Dalton’s law of partial pressure Ptotal = Phydrogen + PHelium
Phydrogen = Ptotal - PHelium Phydrogen =
Dalton’s Law of Partial Pressure Practice Problem (1)
What is the partial pressure of hydrogen gas (H2)in a mixture of hydrogen and helium if the total pressure is 600 mmHg and the partial pressure of helium is 439 mmHg?
Using Dalton’s law of partial pressure Ptotal = Phydrogen + PHelium
Phydrogen = Ptotal - PHelium
Dalton’s Law of Partial Pressure Practice Problem (2)
Find the total pressure for a mixture that contains four gases with partial pressures of 5.00 kPa, 4.56 kPa, 3.02 kPa, and 1.20 kPa.
Using Dalton’s law of partial pressure Ptotal =
Dalton’s Law of Partial Pressure Practice Problem (2)
Find the total pressure for a mixture that contains four gases with partial pressures of 5.00 kPa, 4.56 kPa, 3.02 kPa, and 1.20 kPa.
Using Dalton’s law of partial pressure Ptotal = (5.00 + 4.56 + 3.02 + 1.20)kPa Ptotal = 13.78 kPa
Dalton’s Law of Partial Pressure Practice Problem (3)
Find the partial pressure of carbon dioxide in a gas mixture with a total pressure of 30.4 kPa if the partial pressures of the other too gases in the mixture are 16.5 kPa and 3.7 kPa.Using Dalton’s law of partial pressure
Dalton’s Law of Partial Pressure Practice Problem (3)
Find the partial pressure of carbon dioxide in a gas mixture with a total pressure of 30.4 kPa if the partial pressures of the other two gases in the mixture are 16.5 kPa and 3.7 kPa.Using Dalton’s law of partial pressure
Ptotal = 16.5 kPa + 3.7 kPa + Pcarbondioxide Pcarbon dioxide = Ptotal - (16.5 + 3.7)kPa
Slip Quiz for Jan 30, 2018
1. For the lab investigation you carried out on
Friday, what factors were kept constant during
the investigation?
2. Which factor did you manipulate (control) and
which factor did you measure?
Slip Quiz
1. During the investigation of the
relationship between gas pressure and
volume, we kept the temperature constant
(room temperature throughout) and the
initial volume of gas was the same each
time which means that the mass of gas used
was constant throughout the investigation.
Slip Quiz for Jan 30, 2018
2. Which factor did you manipulate (control) and
which factor did you measure?
We manipulated the volume of the mass of gas
we had, and measured the resulting pressure for
each volume we selected.
Data - check sig digs
Volume of air Pressure (kPa) 1 2 3 Average pressure (kPa) PV 20.0 mL xx xx 18.0 mL xx 16.0 mL xx 14.0 mL xx 12.0 mL xx 10.0 mL xx 8.0 mL xxUsing Desmos for Analysis of data
Sign in using your gusd email - I think this
should then give you a google + sign in for
desmos.
Enter your volume and average pressure data -
try some mathematical relationships
(equations) to find line that fits best.
Record your equation on the
whiteboard.
Data - check sig digs
Volume of air Pressure (kPa) 1 2 3 Average pressure (kPa) VxPav kPamL 20.0 mL xx 18.0 mL 16.0 mL 14.0 mL 12.0 mL 10.0 mL 8.0 mLStart with 2 sig digs here for pressure
End with 2 sig digs for volume
Data - check sig digs
Volume of air Pressure (kPa) 1 2 3 Average pressure (kPa) V x Pav 20.0 mL 96 18.0 mL 16.0 mL 14.0 mL 12.0 mL 10.0 mL 8.0 mL 20.0mL x 96kPa = 1920 mLkPa = 1900 mLkPa 2 sig digsAnalysis of data
What do you notice about V x P values (don’t
forget the units)?
The Gas Laws
Boyle’s Law
For a fixed mass of gas at a particular
temperature, as the volume decreases the
pressure increases. Volume is inversely
Boyle’s Law
P
inverse relationship
P = constant
mathematical model
V
PV = constant
confirmed by data
1
V
The Gas Laws
Charles’s Law
(Charles, 1746 - 1823)
States that the volume of a given mass of gas is
directly proportional to its kelvin temperature
at constant pressure.
V
T
V = const. T
const. = V
The Gas Laws
Gay-Loussac’s Law
States that the
pressure of a given mass of gas is directly
proportional to its kelvin temperature at a
fixed volume.
P
T
P = const. T
const. = P
The Combined Gas Law
Boyle’s, Charles’ and Gay-Loussac’s Laws are
parts of the same relationship and can be
combined into a single mathematical model.
const. = PV
T
The Combined Gas Law
Since
const. = PV
T
For a fixed mass of gas at pressure P
1and
volume V
1and temperature T
1if its conditions are changed to P
2, V
2, and
T
2- then the relationships will be
The Combined Gas Law
For a fixed mass of gas at pressure P
1and
volume V
1and temperature T
1if its conditions are changed to P
2, V
2, and
T
2- then the relationship will be constant.
Hence P
1V
1= P
2V
2Combined Gas
Gas Law Worksheet (1)
Each time write out and fill in what you know. Measurements - not counting numbers. Question 1. (Done for you)
P1 = 400 mmHg P2 = unknown
V1 = 400mL V2 = 200 mL
T1 = constant T2 = same as initial T1
Use combined gas law: Rearrange each time to isolate the missing value. P1V1 = P2V2 T1 400mmHg 400mL = P2 P2= 800 mmHg
Gas Law Worksheet (1)
Each time write out and fill in what you know. Measurements - not counting numbers. Question 2.
P1 = 200 mmHg P2 = unknown
V1 = 800mL decreased to V2 = 200 mL
T1 = constant T2 = same as initial T.
Use combined gas law: Rearrange each time to isolate the missing value. P1V1 = P2V2
2. The volume of 800 mL of chlorine gas at 200 mm
Hg is decreased to 200 mL at
constant temperature
.
What is the new gas pressure?
•
V
1= 800 mL
V
2= 200 mL
•
P
1= 200 mm Hg
P
2= ? mm Hg
• T1= T2 (Constant, stays the same, doesn’t change)
•
Combined gas Law
P
1V
1= P
2V
2T
1T
2P
2= P
1V
1= 200mmHg 800mL = 800mmHg
3. The volume of 200 mL of [you name it] gas at 400 mm Hg is
increased to 400 mL at constant temperature. What is the new gas pressure?
•
V
1= 200 mL
V
2= 400 mL
•
P
1= 400 mm Hg
P
2= ? mm Hg
• T1= T2 (Constant, stays the same, doesn’t change)
•
Combined gas Law
P
1V
1= P
2V
2T
1T
2P
2= P
1V
1= 400mmHg 200mL = 200mmHg
V
2400 mL
4.
•
V
1= 400 L
V
2= 200 L
•
P
1= 2 atm
P
2= ? atm
• T1= T2 (Constant, stays the same, doesn’t change)
•
Combined gas Law
P
1V
1= P
2V
2T
1T
2P
2= P
1V
1= 2atm 400L = 4atm
V
2200L
5.
•
V
1= 500mL
V
2= 200 mL
•
P
1= 300 mmHg
P
2= ? mmHg
• T1= T2 (Constant, stays the same, doesn’t change)
• Combined gas Law P1V1 = P2V2
T1 T2
P2 = P1V1 = 300mmHg 500mL = 750mmHg V2 200mL
6.
•
V
1
= 1000L
V
2= 2300 L
•
P
1= 15atm
P
2= ? atm
• T1= T2 (Constant, stays the same, doesn’t change)
