Can you explain:
• How To Get A Egg Into A Bottle
• Rally Robin
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1. Students number off.
2. Teachers asks a question and gives “think time”. (30 seconds)
3. Students privately write own answers [solo time]. (30 seconds)
4. Students stand up, put heads together [huddle up], show answers,
discuss, and coach if necessary.
5. Students sit down when everyone knows the answer or has
something they can share.
6. Teacher calls a number; that numbered student
from each group stands and simultaneously
answers the teacher’s question.
7. Teammates praise [CELEBRATE] students who
responded.
What do you think? • Is there a lowest temperature that you
can reach?
• If there is, why?
• What is temperature? What does it describe?
• How can you convert between Kelvin and Celsius
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Aim • Understand how temperature, pressure and
volume are related
Key words
• Boyle’s Law
• Charles’ Law
• Temperature Law
• Combined Gas Laws
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Have you ever wondered?
If you pump up a tyre or ball, what happens to the amount of space the air takes up?
kT
PP
T
Temperature (K)
Pressure (torr)
k (torr/K)
248 691.6 2.79
273 760.0 2.78
298 828.4 2.78
373 1,041.2 2.79
Temperature Law
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How does temperature affect pressure? • The higher the temperature of a gas, the greater the kinetic energy
of the particles. • They move faster and collide with the walls of the container more
frequently and with greater force.
• This increases the pressure of the gas when volume is constant.
Pressure and temperature are directly proportional.
higher temperature higher pressure
pressure (Pa) temperature (K)
= constant P1
T1 =
P2
T2
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The Pressure-Temperature Law
A gas has a pressure of 1000 Pa at a temperature of 295 K.
What is the pressure when it is heated to 395 K?
P1
T1
P2 =
P2 =
P2 = 1339 Pa
P2
T2 =
× T2
P1
T1
1000 295 × 395
P
V PV = k
Volume (mL)
Pressure (torr)
k (mL·torr)
10.0 760.0 7.60 x 103
20.0 379.6 7.59 x 103
30.0 253.2 7.60 x 103
40.0 191.0 7.64 x 103
Boyle’s Law
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How does volume affect pressure?
P1 × V1 = P2 × V2
When the temperature of a gas is kept constant, a change in volume causes a change in pressure.
Particles collide more frequently with the container wall when the volume is smaller. This increases the pressure.
larger volume lower pressure
Pressure and volume are inversely proportional.
pressure (Pa) × volume (m3) = constant
Students take turns writing on own paper then pass it on
to teammates:
1. Teacher announces topic / gives “think time”.
2. Each teammate writes his/her short answer to
the topic on own paper then passes the paper
on to the next teammate.
3. Writing continues until the teacher
says stop.
Boyle’s Law
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• Can you explain why?
• Balloon in the vacuum pump.mp4
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Boyle’s Law Example:
A gas syringe contains 0.00005 m3 of CO2 at a pressure of
100 kPa. If the volume is reduced to 0.000035 m3, what is the
new pressure?
P1 × V1 = P2 × V2
P1 × V1
V2
100,000 × 0.00005 0.000035
P2 = 143 kPa
P2 =
P2 =
kT
V
V
T
Volume (mL)
Temperature (K)
k (mL/K)
40.0 273.2 0.146
44.0 298.2 0.148
47.7 323.2 0.148
51.3 348.2 0.147
Charles’s Law
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Charles’s Law
• Charles' Law
• Can you explain what happened?
• Simultaneous Round table
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How does temperature affect volume? • If a gas is in a container that does not have a fixed volume, then it
will expand as it is heated. • The pressure on the walls of the container will cause it to expand,
so pressure stays constant. higher temperature larger volume
Temperature and volume are directly proportional.
V1
T1
volume (m3) temperature (K)
= constant V2
T2
=
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Charles’ Law
Example:
A gas has an initial temperature of 300 K and initial volume of
0.2 m3. What is the volume when it is heated to 330 K?
V1
T1
V2 =
V2 =
V2 = 0.22 m3
= V2
T2
× T2
V1
T1
× 330 0.2
300
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The Combined Gas Law The Combined Gas Law brings together the Pressure-
Temperature Law, Boyle’s Law and Charles’ Law.
It is generally written as:
pressure × volume
temperature
To compare the behaviour of a gas in different conditions,
the following form of the equation is used:
P1V1 T1
It describes the relationship between volume, pressure and temperature, whether or not any variable is kept fixed.
= constant
P2V2 T2
=
Gas Law Problems • A gas has an initial temperature of 3 oC and occupies an initial
volume of 100 mL at 150kPa. Find its new volume when its pressure changes to 200 kPa and the temperature is changed to 8 oC.
Solution
• 𝑃1= 150kPa and 𝑃2 = 200 kPa
• 𝑇1 = 3 oC and 𝑇2 = 8 oC
• 𝑉1 = 100 mL and 𝑉2 = ?
•𝑃1𝑥𝑉1
𝑇1=
𝑃2𝑥 𝑉2
𝑇2 solve for 𝑉2
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𝑉2 =𝑃1𝑥𝑉1
𝑇1 x
𝑇2
𝑃2
Convert 𝐶0 𝑡𝑜 𝐾𝑒𝑙𝑣𝑖𝑛: 𝑇1 = 273 + 3 = 276K 𝑇2 = 273 + 8 = 281K
Plug in numbers:
𝑉2= 150𝑥100𝑥281
276𝑥200= 76.35 𝑚𝐿
Gas Law Problems
• A gas pressure is 765 torr at 296 K. At what temperature will the pressure be 560 torr if the volume is held constant?
Solution
•𝑃1
𝑇1=
𝑃2
𝑇2
• 𝑇2 = 𝑃2𝑥𝑇1
𝑃1
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𝑇2 =560𝑥296
765= 216.68𝐾
Given: 𝑃1 = 765 torr 𝑃2= 560 torr 𝑇1= 296 K 𝑇2 = ?
Key words • Boyle’s Law - For a fixed amount of an ideal gas kept at a fixed
temperature, pressure and volume are inversely proportional.
• Charles’ Law – "For a fixed mass of gas, at a constant pressure, the volume is directly proportional to the absolute temperature."
• Pressure - temperature Law – It states that, for a given mass and constant volume of an ideal gas, the pressure exerted on the sides of its container is directly to its absolute temperature.
• Combined Gas Laws - Pressure is inversely proportional to volume, or higher volume equals lower pressure. Pressure is directly proportional to temperature, or higher temperature equals higher pressure.
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