Chapter 5 Flashcards

1
Q

Thermodynamics

A

study of heat, work, energy and the changes they produce in the states of systems

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2
Q

Thermochemistry

A

Branch of thermodynamics, the study of heat changes in chemical reactions

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3
Q

Heat

A

(q) a form of energy transfer that can occur when there is a temp. difference between the system and its surroundings. an extensive property

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4
Q

Work

A

(w) a form of energy transfer that occurs when a macroscopic force acts between the system and its surroundings. an extensive property

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5
Q

Types of macroscopic energy

A
  1. kinetic: due to motion of an object
  2. Potential: due to position/arrangement

3 Mechanical energy

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6
Q

Internal energy

A

a state function, the sum of all the kinetic and potential energies in a system

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7
Q

Law of conservation of energy

A

Energy can not be created or destroyed, it can be converted from one form
to another

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8
Q

Thermal energy

A

Kinetic energy of atoms, ions and molecules

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9
Q

Pressure

A

Force per area. P=F/A, intensive property

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10
Q

System

A

The part of the universe that is the focus of a thermodynamic study

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11
Q

Surroundings

A

Parts of the universe that can interact with the system

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12
Q

Types of systems

A

Isolated: Does not interact with surroundings

Closed: Energy but not matter can be transferred with surroundings

Open: Both energy and matter can be transferred with surroundingd

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13
Q

Exothermic

A

energy flows out of system to surroundings, q<0

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14
Q

Endothermic process

A

energy flows into system from surroundings, q>0

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15
Q

Work formula and types

A

w=Fd, types of work are electrical, magnetic, nuclear and chemical

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16
Q

How can you find 🔼E without initial/final values?

A

🔼E=q+w in a closed system only

17
Q

Calorie

A

Amount of heat necessary to raise the temperature of 1 g of water by 1C

18
Q

Joule

A

SI unit of energy

19
Q

First law of thermodynamics

A

The total energy of the system and surroundings is conserved

🔼TE(sys)+🔼TE(surr)=0

20
Q

In what situation does TE=E

A

system is at rest(KE=0) and there are no external fields(PE=0)

21
Q

PV work(including 🔼V, Vfinal, Vinitial and W in each situation)

A

work associated with compression or expansion

compression: Work is done on the system. w>0, 🔼V<0, Vfinal(Vinitial, w=-P🔼V>0

Expansion: Work done by the system
w<0, 🔼V>0, Vfinal>Vinitial
W=-P🔼V<0

22
Q

Enthalpy

A

(H) A state function and extensive property, it is the sum of internal energy and PV product of a system.

H=E+PV

23
Q

🔼H

A

Closed system and constant P when only the PV work is allowed: 🔼H=Qp
Qp= Heat exchanged at constant pressure

Constant pressure: 🔼H=🔼E+P🔼V

Constant volume: 🔼H=🔼E+V🔼P

General change of state: 🔼H=🔼E+🔼(PV)

24
Q

H and 🔼H in endothermic and exothermic reactions

A

Endothermic: 🔼H>0, Hproducts>Hreactants

Exothermic: 🔼H<0, Hproducts

25
Q

Molar heat capacity

A

c(p) Quantity of energy required to raise the temperature of 1 mole of a substance by 1C
q=n•c(p)•🔼T

26
Q

Specific heat

A

(Cs) The energy required to raise the temperature of 1 gram of a substance by 1C at constant P

q=m•Cs•🔼T

27
Q

Heat capacity

A

(Cp) quantity of energy needed to raise the temperature of an object by 1C(at constant P)

28
Q

Molar enthalpy of fusion

A

(🔼Hfus) the energy required to convert 1 mole of a solid at its melting point into a liquid state

q=n•🔼Hfus

29
Q

Molar enthalpy of vaporization

A

(🔼Hvap) The energy required to convert 1 mole of a liquid at its boiling point to the vapor state

30
Q

Bomb calorimeter

A

A constant volume device used to measure energy released during a combustion reaction. Heat produced in reaction=heat gained by calorimeter

31
Q

Standard molar enthalpy of formation

A

enthalpy change for reaction in which one mole of a substance is formed from elements in their standard states(1 bar, usually 298K/25C)

32
Q

Fuel value

A

The energy released during complete combustion of 1g of a substance

33
Q

Fuel density

A

The energy released during complete combustion of 1L of a liquid fuel

34
Q

Food value

A

The quantity of energy produced when a material consumed by an organism for sustenance is burned completely, determined by bomb calorimetry