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Pre-Pharm > Chemistry - Ch 5 > Flashcards

Chemistry - Ch 5 Flashcards

1
Q

Thermodynamics

A

the study of energy and its transformations; from Greek therme dynamis (heat power)

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2
Q

Thermochemistry

A

energy changes involving heat

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3
Q

Energy

A

the capacity to do work or to transfer heat

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4
Q

Work

A

the energy used to cause an object with mass to move against a force; w = force times distance

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5
Q

Heat

A

the energy used to cause the temperature of an object to increase; energy transferred from a hotter object to a colder one

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6
Q

Kinetic energy

A

the energy of motion; Ek = 1/2 mass times volume squared

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7
Q

Potential energy

A

arises when a force operates on an object by virtue of its position relative to other objects; Ep = mass times gravitational constant (9.8m per second squared) times height of the object relative to some reference height

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8
Q

Force

A

any kind of push or pull exerted on an object; F = mass times gravitational constant, 9.8m/s^2

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9
Q

Electrostatic potential energy

A

arises from the interactions between charged particles; Eel = k (constant of proportionality = 8.99 x 10^9 J-m/C^2 times the electrical charge on the two interacting objects, Q1 & Q2) divided by the distance separating them

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10
Q

Joule

A

SI unit for energy; 1 J = 1kg-m^2/s

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11
Q

calorie

A

non SI unit; =4.184 J; not the same as the nutritional Calorie (capitalized); 1 Cal = 1000 cal = 1kcal

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12
Q

System

A

the portion of the universe we single out for study; may be open, closed, or isolated

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13
Q

Surroundings

A

everything else that is not the system

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14
Q

Closed system

A

can exchange energy but not matter with its surroundings

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15
Q

Isolated system

A

one in which neither energy nor matter can be exchanged with its surroundings (ex. insulated thermos)

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16
Q

First Law of Thermodynamics

A

Energy is conserved; it can neither be created nor destroyed

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17
Q

Internal energy

A

sum of all the kinetic and potential energies of all its components

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18
Q

Change in internal energy

A

Delta E = E final - E initial; positive answer = system has gained energy from its surroundings; negative = system has lost energy to its surroundings; Delta E = q (heat added to or liberated from the system) plus w (work done on or by the system)

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19
Q

Endothermic

A

when a process occurs in which the system absorbs heat (endo = into)

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20
Q

Exothermic

A

process in which the system loses heat (exo = out of)

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21
Q

State function

A

a property of a system that is determined by specifying the system’s condition or state, in terms of temperature, pressure, etc.; the value of a state function depends only on the present state of the system, not on the path the system took to reach that state

22
Q

Pressure-volume work (P-V work)

A

the work involved in the expansion or compression of gases (w = - P times the change in volume of the system)

23
Q

Enthalpy

A

thermodynamic function that accounts for heat flow in processes occurring at constant pressure when no forms of work are performed other than P-V work; from the Greek, enthalpein, “to warm”); H (enthalpy) = E (internal energy) plus pressure times volume; a state function; extensive property

24
Q

Change in enthalpy

A

change in internal energy plus the product of the constant pressure times the change in volume (Delta H = Delta E + P times Delta V); heat gained or lost at constant pressure

25
Q

Enthalpy of reaction (heat of reaction)

A

enthalpy change that accompanies a reaction

26
Q

Thermochemical equations

A

balanced chemical equations that show the associated enthalpy change

27
Q

The enthalpy change for a reaction is ____ in magnitude but ____ in sign to the change in enthalpy for the reverse reaction

A

equal; opposite

28
Q

Calorimetry

A

the measurement of heat flow

29
Q

Calorimeter

A

a device used to measure heat flow

30
Q

Heat capacity

A

the temperature change experienced by an object when it absorbs a certain amount of heat; the heat capacity of an object is the amount of heat required to raise its temperature by 1K (or 1 degree Celsius)

31
Q

Molar heat capacity

A

the heat capacity of one mole of a substance (Cm)

32
Q

Specific heat capacity (specific heat)

A

the heat capacity of one gram of a substance (Cs); = quantity of heat transferred divided by (grams of substance times temperature change)

33
Q

Bomb calorimeter

A

device used to measure heat accompanying combustion reactions at constant volume

34
Q

Radiation

A

direct loss of heat from the body to cooler surroundings

35
Q

Convection

A

heat loss by virtue of heating air that is in contact with the body

36
Q

Evaporation

A

cooling that occurs when perspiration is generated at the skin surface by the sweat glands

37
Q

Hess’s Law

A

if a reaction is carried out in a series of steps, the change in enthalpy for the overall reaction will equal the sum of the enthalpy changes for the individual steps

38
Q

Enthalpies of vaporization

A

change in enthalpy for converting liquids to gases

39
Q

Enthalpies of fusion

A

change in enthalpy for melting solids

40
Q

Enthalpies of combustion

A

change in enthalpy for combusting a substance in oxygen

41
Q

Enthalpy of formation (heat of formation)

A

enthalpy change associated with the process of forming a compound from its constituent elements

42
Q

Standard state

A

defined set of conditions; pure form at atmospheric pressure

43
Q

Standard enthalpy change

A

enthalpy change when all reactants and products are in their standard state

44
Q

Temperature of interest

A

usually 298 K (25 degrees C)

45
Q

Standard enthalpy of formation

A

change in enthalpy for the reaction that forms one mole of the compound from its elements, with all substances in their standard states; standard enthalpy of formation of the most stable form of any element is zero b/c there is no formation reaction needed when the element is already in its standard state

46
Q

Fuel value

A

energy released when one gram of a material is combusted

47
Q

Fossil fuels

A

coal, petroleum, and natural gas; world’s major sources of energy

48
Q

Natural gas

A

consists of gaseous hydrocarbons (compounds of hydrogen and carbon); primarily methane, with small amounts of ethane, propane, and butane

49
Q

Petroleum

A

liquid composed of hundreds of compounds, most of which are hydrocarbons, with the remainder being chiefly organic compounds containing sulfur, nitrogen, or oxygen

50
Q

Coal

A

solid; contains hydrocarbons of high molecular weight as well as compounds containing sulfur, oxygen, or nitrogen

51
Q

Renewable energy

A

energy sources that are essentially inexhaustible

Pre-Pharm (182 decks)

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