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Introduction to Chemistry > chapter 7: chemical energy > Flashcards

chapter 7: chemical energy Flashcards

1
Q

what is thermodynamics

A

the study of energy and its transformations

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2
Q

what is thermochemistry

A

relationship between chemical reactions and energy changes involving heat

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3
Q

what is energy

A 
the ability (or capacity) to do work or 
transfer heat.
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4
Q

what is work

A

Energy used to cause
an object that has mass
to move

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5
Q

what is heat

A

Energy used to cause
the temp of an object
to rise

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6
Q

what is force

A

any kind of push or pull exerted on an object

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7
Q

what is the formula for force

A

f = m x g

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8
Q

what does g stand for

A

acceleration due to gravity; 9.8 m/s^2

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9
Q

what is the magnitude of work formula

A 
w = F x d = m x g x d
d = distance
m = mass
F = force
g = gravity
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10
Q

what is another name for heat

A

thermal energy

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11
Q

what direction does heat flow

A

warmer objects to cooler objects

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12
Q

what are some characteristcs of heat and work

A
  • energy is being exchanged between two objects
  • energy can flow into or out of the subject studied
  • dont exist before or after the state of change
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13
Q

what types of energy are there

A

potential and kinetic

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14
Q

what is electrical energy

A

KE associated w/ flow of electrical charge

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15
Q

what is heat or thermal enrgy

A

KE associated w/ molecular motion

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16
Q

what is light or radiant energy

A

KE associated with energy transitions in an atom

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17
Q

what is nuclear energy

A

PE in the nucleus of atoms

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18
Q

what is chemical energy

A

PE due to the structure of the atoms

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19
Q

what is kinetic energy

A

energy that is being transferred (motion)

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20
Q

what is the kinetic energy formula

A

KE = 1/2mv^2

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21
Q

what does KE depend on

A

the mass and speed of the object

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22
Q

do atoms and molecules possess KE

A

yes

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23
Q

what is potential energy

A

energy that is stored in an object

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24
Q

when does PE arise

A

no force operating on the on

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25
Q

what does PE depend on

A

mass, height, the gravitational

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26
Q

what is the formula for PE

A

m x g x h

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27
Q

what is the unit for energy

A

Joule (J)

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28
Q

who was the energy SI unit named after

A

James Joule

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29
Q

what does 1 joule equal

A

1 kgm^2/ s^2

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30
Q

what is a non-SI unit that is still used

A

calorie (cal)

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31
Q

how many joules does one calorie equal

A

4.184 J

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32
Q

what is the value of the nutritional calorie

A

1000 cal (1kcal)

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33
Q

what is the system

A

included the molecules we want to study

34
Q

what are the surroundings

A

everything else

35
Q

what is temperature

A

measure of the kinetic energy,

thermal energy, within a sample of mater.

36
Q

what is thermal equilibrium

A

the flow of heat from high temp to low temp until both objects reach the same temp

37
Q

what does endothermic mean

A

heat is absorbed by the system from the surroundings

38
Q

what does exothermic mean

A

eat is released by the system to

the surroundings,

39
Q

what is the first law of thermodynamics

A

law of the

conservation of energy.

40
Q

the total energy of the universe it….

A

constant

41
Q

if the system loses energy…

A

it must be gained by the surroundings

42
Q

what are state functions

A

values that depend on the state of the substance, and not on how that state was reached.

43
Q

is delta E a state function

A

yes bc it depends on the specific amounts of q and w

44
Q

what is an example of a state function

A

water reached room temp from both directions

45
Q

are q and w state functions

A

no bc they are forms of energy in transit, don’t exist before or after the change of the state

46
Q

what does delta E equal

A

q + w

47
Q

when does E increase

A

when heat is added to a system or work is done on a system

48
Q

what does q represent

A

heat

49
Q

what does w represent

A

work

50
Q

what happens when q is +

A

system gains thermal energy

51
Q

what happens when q is -

A

system loses thermal energy

52
Q

what happens when w is +

A

work done on the system

53
Q

what happens when w is -

A

work done BY the system

54
Q

when do most of the chemical and physical changes occur

A

occur at constant atmospheric pressure

55
Q

what is the formula for pressure-work volume

A

w = -(P)(change in volume)

56
Q

what is the change in volume

A

Vfinal - Vinitial

57
Q

when gases expand what happens to the volume and work

A 
V = + 
w = -
58
Q

what is enthalpy

A

heat flow; s defined as the internal energy plus

the product of pressure and volume:

59
Q

what is the formula for enthalpy

A

H = E +PV

60
Q

what is the formula for enthalpy when system changes at constant pressure, the
change in enthalpy,

A

deltaH = q

61
Q

delta H is positive

A

endothermic

62
Q

delta H is negative

A

exothermic

63
Q

what is the formula for enthalpy of a reaction

A

deltaH = Hproducts - H reactants

64
Q

what is the delta H called

A

enthalpy of reactionb

65
Q

what are the rules of enthalpy

A

1.) extensive property

66
Q

what is heat capacity

A 
amount of energy required to 
raise the temp. of a substance by 
1 K (1 °C)
67
Q

what is specific heat capacity

A

amount of energy required
to raise the temperature of 1 g of
a substance by 1 K (1 °C)

68
Q

what is molar heat capacity

A

the heat capacity of one mole of

a substance is called its

69
Q

what is the formula for heat capacity

A

Cs = q/ m x deltaT

70
Q

what is the formula for q

A

m x Cs x change in temp

71
Q

what does Cs mean

A

specific heat

72
Q

what is calorimetry

A

measurement of heat flow

73
Q

what is a calorimeter

A

device used to measure heat flow

74
Q

what happens with the heat produced in a calorimetry reaction

A

the solution absorbs it

75
Q

what happens to heat in an exothermic reaction

A

heat is lost by reaction and gained by the solution

76
Q

what happens to heat in an endothermic reaction

A

heat is gained by the reaction and lost by the solution

77
Q

the heat gained by the solution is equal to…

A

the magnitude of qrxn

78
Q

what does qsoln =

A

m x s deltaT = -qrxn

79
Q

what is the constant pressure formula for metal

A

mass metal x Cs metal x change temp of metal = mass metal x Cs metal x change temp of metal

80
Q

what is the second rule of enthalpy

A

change of heat for a reaction in the forward direction is
equal in magnitude, but opposite in sign, to H
for the reverse reaction

81
Q

what is the third rule of enthalpy

A

H for a reaction depends on the state of the

products and the state of the reactants.

Introduction to Chemistry (12 decks)

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