2 Gas Laws Flashcards by Sophie D

How is P₁and T₁ related to P₂ and T₂?

P₁ is pressure before

T₁ is temperature before

P₂ is pressure after

T₂ is temperature after

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Explain why a hot balloon expands

As temperature rises, the particles have more energy

Particles have more KE

Particles move faster

More collisions per unit time AND particles collide with more force

Pressure = force / area

Increased pressure on the inside of the balloon, with same pressure on the outside results in greater forces on inside compared to outside of balloon - balloon skin stretches outward

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What are the control variables for the Boyles’ Law investigation where the volume of a gas was measured as the pressure was varied?

Moles or mass of gas

Temperature of gas

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Use the equation below to calculate the new volume of a gas as its pressure increased from 100kPa to 200kPa.

Its initial volume was 50cm3.

P₂V₂ = P₁ V₁

V₂ = P₁V₁/P₂

V₂ = 100kPa x 50cm³ / 200kPa

V₂ = 25cm³

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Convert 373K to ºC

ºC = K - 273

373K = 100ºC

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How does a gas exert pressure of the inside of a balloon?

Gas particles are moving fast and freely
They collide with the walls of the balloon
They exert a force of the wall of the balloon
Pressure = force / area
Particles exerting a force on the area of the balloon creates a pressure.

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Convert 100K to ºC

ºC = K - 273

100K = -173ºC

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Name the independent and dependent variable for the Joly’s bulb experiment

Independent : temperature gas

Dependent : pressure of gas

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What happens to the pressure of a gas if the volume is halved?

Explain why this happens.

As volume is halved, pressure is doubled

There are the same number of particles as the volume is halved

OR double the number of particles per unit volume

Pressure = force / area

Double the number of collision per unit time per unit area.

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Name the independent and dependent variable for Boyle’s law experiment

Independent : pressure

Dependent : volume of gas

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What happens to the particles of a gas when they are heated?

The particles gain energy

KE of particles increases

Particles move faster

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Convert 100ºC to Kelvin

K = ºC + 273

100ºC = 373 K

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How would you represent the motion of a smoke particles in air? (Brownian motion)

Uses arrows of different length and directions to show continual random movement.

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What is the unit for volume of a gas?

cm³ or dm³

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How many Pa is a kPa?

1000 Pa = 1 kPa

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From the graph, how is pressure of a gas related to its volume at the same temperature and moles of gas?

Pressure is inversely proportional to volume at same temperature and moles of gas

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Convert -273ºC to Kelvin

K = ºC + 273

-273ºC = 0 K

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A pupils stated that as the temperature of a gas in degrees celsius is doubles, the kinetic energy of the gas must also double.

Is this statement true or false?

False

At t_emperature of a gas in kelvin doubled,_ the average kinetic energy of the particles doubles

Temperature must be in kelvins!!

How is P₁ and V₁ related to P₂ and V₂?

P₁ is pressure before

V₁ is volume before

P₂ is pressure after

V₂ is volume is after

Use the pressure-temperature equation to work out the new temperature for a gas where the pressure was decreased from 100kPa to 50kPa

Intial temperature was 40K.

T₂/P₂ = T₁/P₁

(write the equation with T2 first- this makes it easier to rearrange!!)

T₂= T₁P₂/P₁

T₂= 40K x 50kPa / 100kPa

T₂ = 20K

How can Brownian motion be observed?

Random jerky movement of smoke particles in a smoke cell through a microscope

What is the unit for pressure

Pascal (Pa)

kilopascal (kPa)

atmospheres (atm)

A pupils stated that as the temperature of a gas in kelvin is doubled, the average speed of the gas must also double.

Is this statement true or false?

False

At t_emperature of a gas in kelvin doubles,_ the average kinetic energy of the particles doubles, NOT the average speed

Why does an air balloon grow bigger when air is heated

As temperature of a gas increases, kinetic energy increases

particles move with greater speed and hit the sides of the balloon more frequently AND with more force

Pressure = force / area

Greater force on walls of balloon increases the pressure of the gas pushing the walls of the balloon outward.

From the graph, how is pressure related to temperature *_in kelvin_* of a gas - at the same volume and mole of gas?

Pressure is proportional to temperature in kelvin at the same volume and moles of gas

What is Brownian motion?

It is the _continuous_ and _random zig zag movement_ of microscopic particles in a fluid, as a result of continuous bombardment from molecules of the surrounding medium. (pollen in water)

Use the equation below to calculate the original pressure of a gas as its volume increased from 50cm³ to 100cm³ Its final pressure was 40kPa.

**P₁V₁**= P₂ V₂ P₁ = P₂V₂/V₁ P₁ = 40kPa x 100cm³ / 50cm³ P₁ = 80kPa

Use the equation below to calculate the **_new pressure_** of a gas as its volume decreased from 100cm³ to 50cm³. Its **_initial pressure_** was 1atm.

P₂V₂ = P₁ V₁ P₂ = P₁V₁/V₂ P₂ = 1atm x 100cm³ / 50cm³ P₂ = 2atm

How is **pressure** of a gas related to its **volume**? What would a graph of pressure against volume look like?

Pressure is **_inversely proportional_** to volume As pressure doubles, volume halves (For same moles of gas and temperature)

State Boyle's Law

**Pressure is inversely proportional to volume**- at a **constant temperature**. If pressure of a gas is doubled, its volume would halve

A pupils stated that as the temperature of a gas in kelvin is doubles, the average speed of the gas must also double. Is this statement true or false?

False At t_emperature of a gas in kelvin doubles,_ the average _**kinetic energy** of the particles doubles_, NOT the average speed

How is **temperture** related to the **average KE of particles**

Temperature is **proportional** to the *_average_* KE of the particles NOTE: Temperature **_is not proportional_** to the average velocity of the particles!!

What happens to the pressure inside a tyre in the summer?

1. As _temperature increases,_ _energy of gas particles increases_ 2. In_crease in KE_ of particles means particles _move more quickly_ 3. Particles _collide with the wall more frequently_ AND _with more force_ 4. _Pressure = Force / area_ 5. More _force_ on the _same area_ results in more _pressure._

What are the control variables for the investigation where pressure of a gas was measured as temperature was varied?

Moles/mass of gas Volume of gas

Use the pressure-temperature equation to work out the **_initial pressure_** for a gas where the temperature was increased from 100K to 200K **_Final pressure_** was 5 atm.

P₁/T₁ = P₂/T₂ (write the equation with P1 first- this makes it easier to rearrange!!) P₁= P₂T₁/T₂ P₁= 5atm x 100K / 200K P₁ = 2.5atm

How does the pressure of a gas relate to it temperature *_in kelvin_*? What would a graph of pressure against temperature look like?

Pressure is **proportional** to temperature *_in kelvin_* (For same moles of gas and volume) Straight time through the origin

How many cm³ in a dm³?

1 dm³ = 1000 cm³

What happens to the pressure inside a tyre in the winter?

1. As _temperature decreases,_ _energy of gas particles decreases_ 2. _Decrease in KE_ of particles means particles _move more slowly_ 3. Particles _collide with the wall less frequently_ AND _with less force_ 4. _Pressure = Force / area_ 5. _Less force_ on the _same area_ results in _less pressure._

How is pressure related to temperature *_in degrees celsius_*?

Pressure is **linearly** related to temperature *_in degrees celsius_*. (For same moles of gas and volume) It is a straight line but does not go through the origin.

Convert 0ºC to Kelvin

K = ºC + 273 0ºC = 273 K

Convert 0K to ºC

ºC = K - 273 0K = -273ºC

Use the pressure-temperature equation to work out the **_initial temperature_** for a gas where the pressure was decreased from 100Pa to 50Pa **_final temperature_** 15K.

T₁/P₁ = T₂/P₂ (write the equation with Ti first- this makes it easier to rearrange!!) T₁= T₂P₁/P₂ T₁= 15K x 100Pa /50Pa T₁ = 30K

Use the pressure-temperature equation to work out the **_new pressure_** for a gas where the temperature was increased from 100K to 200K **_Intial pressure_** was 3 atm.

P₂/T₂ = P₁/T₁ (write the equation with P2 first- this makes it easier to rearrange!!) P₂= P₁T₂/T₁ P₂= 3 atm x 200K / 100K P₂ = 6atm

Describe the movement of particles in a gas

Fast, freely and randomly