Week 9

Question 1

What are the properties that are easily measured for gasses

Answer 1

• Volume (m^3)
  -Temperature ( K or °C)
  -Pressure (Nm^-2 or Pa or bars (10^5 Pa))

Question 2

What are the three Gas Laws

Answer 2

Boyles Law: pV = constant
Charles Law
Constant Volume Law

Question 3

What is Boyles Law?

Answer 3

For a fixed mass of gas at constant temperature, the product of absolute pressure and volume is a constant:

pV = constant.

Used if:
- Pressure and gas changes and temperature stays the same

Question 4

What is it called when temperature is kept constant?

Answer 4

Isothermal

Question 5

Draw a p - V diagram

Answer 5

Its like an exponential graph with P on the Y axis and V on the x axis

Question 6

What is Charle’s Law

Answer 6

For a fixed mass of gas at constant pressure, the volume divided by absolute temperature is a constant:

V/T = constant

Question 7

Explain Charle’s Law

Answer 7

For a mixed mass of gas at constant pressure. The volume/absolute temperature is a constant. Therefore: V/T = Constant

If temperature and volume changes and pressure is still kept constant. Then: V1 / T1 = V2 / T2

Question 8

What is isobaric change?

Answer 8

A change where the pressure is kept constant

Question 9

What is the V-T graph when p is constant (Volume - Time graph)

Answer 9

V is on the y-axis and T is on the X axis. The graph is a linear graph

Question 10

What is the Constant Volume Law

Answer 10

For a fixed mass of gas at constant volume, theabsolute pressure divided by absolute temperature is a constant

P/T = Constant

Question 11

Explain Constant Volume Law

Answer 11

If pressure and temperature change while the volume remains constant then:

P1/T1 = P2/T2

Question 12

What would a pressure over time graph look like when volume is constant

Answer 12

Pressure on the y-axis and temperature is on the x-axis. It is a linear graph

Question 13

Important notes to know about the gas laws

Answer 13

For Charles’ (isobaric) and the Constant Volume (pT) laws, the temperature must be absolute.
* For Boyle’s (isothermal) and the ConstantVolume (pT) laws, the pressure must be absolute.

Question 14

What is the equation of state of gas?

Answer 14

pV = nRT
p = Presure (Pa)
V = Volume (m^3)
n = Moles (mol)
R = Molar gas constant (JK^-1 mol^-1)
T = Temperature (K)

Question 15

What is the universal molar gas constant?

Answer 15

8.31 JK^-1 mol^-1

Question 16

At which point do gases not obey the gas laws entirely?

Answer 16

Well above their liquefaction point.

Question 17

What is the ideal gas?

Answer 17

A gas that obeys all gas laws exactly under all the conditions

Question 18

How many molecules is in 1 mole?

Answer 18

6.022 x 10^23, which is the number of molecules in 12 g of Carbon-12

Question 19

How to calculate number of moles?

Answer 19

n = m/M
Number of moles = mass / mass number

OR

n = N/Na
Number of moles = Number of gas molecules / Avogadro number

Question 20

What is molar mass?

Answer 20

The mass of 1 mole of that substance

Question 21

What is the standard temperature and pressure?

Answer 21

• Temperature of 0°C
  -Pressure of 101.3 kPa

Question 22

What is the normal temperature and pressure?

Answer 22

• Temperature at 20°C
  -Pressure is 101.3 kPa

Question 23

What are all the different forms of pV = nRT?

Answer 23

• pV = m/M x RT
  Pressure x Volume = mass/Molar mass x Molar gas constant x temperature

-pV = N/Na RT
Pressure x Volume = Number of molecules/Avagrados constant x Gas constant x Temperature

• p = p/M RT
  Pressure = density/Molar mass x Gas constant x Temperature

Question 24

How to find specific gas constants?

Answer 24

Rgas = R/M

Rgas = Specific gas constant (JKg^-1K^-1)
R = Gas constant
M = Molar mass

Question 25

What does the coefficient of volume expansion (𝛽) of a gas represent?

Answer 25

It represents how much the volume of a gas changes per unit temperature increase at constant pressure.

Question 26

How is the coefficient of volume expansion (𝛽) mathematically defined?

Answer 26

Understand ts dawg​