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Flashcards in Thermodynamics: introduction Deck (23)
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1

Define a system

The system is what we are interested in, ie the reaction vessel

 

2

Define the surroundings

The surroundings describes all space that is not the system in question 

3

Draw and describe an open system 

Matter and energy can be exchanged with the surroundings. Eg an open beaker left to evaporate

4

Draw and describe a closed system 

Only energy can be exchanged with the surroundings, eg a reaction in a sealed tube 

5

Draw and describe an isolated system 

Neither energy nor matter can be exchanged with the surroundings eg hot liquid in a thermos 

6

Describe Temperature, T

Measured in Kelvin. 0°C = 273.15K

7

Describe Volume, V

The SI unit for volume is m3

8

Describe pressure, P

Force, F (N) per area, A (m2)

The SI unit is Pa but there are many other units of pressure 

9

Define one bar

1 bar = 105 Pa 

10

Define one atm

1 atm = 101.325 kPa

11

Define the standard pressure in thermodynamics

1 bar (105 Pa) is defined as the standard pressure, p0

12

Give the equation linking amount of substance to mass

13

Give the equation linking mole fraction and number of moles 

14

Describe Avogadro's principle 

For a system in which temperature and volume are fixed, pressure increases as gas is fed into the system. 

15

Describe Boyle's law

For a system where n and T are fixed, volume and pressure are inversely proportional. ie pV = constant 

16

Describe Guy-Lussac's law

For a system in which n and V are fixed, pressure increases as temperature increases 

17

Describe how to derive the ideal gas law. 

By combining Avogadro's principle (p ∝ n), Boyle's law (p ∝ 1/v) and Guy-Lussacs law (p∝T) we can get the ideal gas law: 

18

Give the value for R, the gas constant

19

Describe an ideal gas

  1. The volume of the gas molecules = 0 (negligible)
  2. There are no interactions between molecules
  3. The gas does not become a liquid or solid upon cooling

20

Define an isothermic process

One which takes place at constant temperature 

21

Define an isochoric process

One which takes place at constant volume 

22

Define an isobaric process

One which takes place at constant pressure

23

Describe Dalton's law of partial pressures

If we have a mixture of gases A and B, their partial pressures can be worked out. 

total p = pA + pB 

Mole fractions can be worked out using partial pressures: 

nA/(nA + nB) = pA/p