Thermodynamics: introduction Flashcards Preview

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Flashcards in Thermodynamics: introduction Deck (23)
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1
Q

Define a system

A

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

2
Q

Define the surroundings

A

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

3
Q

Draw and describe an open system

A

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

4
Q

Draw and describe a closed system

A

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

5
Q

Draw and describe an isolated system

A

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

6
Q

Describe Temperature, T

A

Measured in Kelvin. 0°C = 273.15K

7
Q

Describe Volume, V

A

The SI unit for volume is m3

8
Q

Describe pressure, P

A

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

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

9
Q

Define one bar

A

1 bar = 105 Pa

10
Q

Define one atm

A

1 atm = 101.325 kPa

11
Q

Define the standard pressure in thermodynamics

A

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

12
Q

Give the equation linking amount of substance to mass

A
13
Q

Give the equation linking mole fraction and number of moles

A
14
Q

Describe Avogadro’s principle

A

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

15
Q

Describe Boyle’s law

A

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

16
Q

Describe Guy-Lussac’s law

A

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

17
Q

Describe how to derive the ideal gas law.

A

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
Q

Give the value for R, the gas constant

A
19
Q

Describe an ideal gas

A
  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
Q

Define an isothermic process

A

One which takes place at constant temperature

21
Q

Define an isochoric process

A

One which takes place at constant volume

22
Q

Define an isobaric process

A

One which takes place at constant pressure

23
Q

Describe Dalton’s law of partial pressures

A

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