Chapter 5: Thermochemistry Flashcards

1
Q

internal energy (E)

A

sum of heat added/released from a system
(sum of all kinetic and potential energies in the system)
ΔE= q+w
ΔE= Efinal-Einitial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

q (+)

A

head is transferred TO system FROM surroundings

-endothermic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

q (-)

A

heat leaves system

-exothermic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

w (+)

A

work is done ON system BY surroundings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

w (-)

A

work is done ON surroundings BY system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

enthalpy (H)

A

-flow of heat into/out of system under CONSTANT PRESSURE
H= E+PV
ΔH=ΔE+PΔV
ΔHrxn= Hproducts-Hreactants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

-ΔH

A

exothermic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

+ΔH

A

endothermic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

+ΔE

A

net GAIN of energy by system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

-ΔE

A

net LOSS of energy by system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When HEAT is added to a system, internal energy ____. ______.

A

increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When volume increases, work is ___.

A

negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

When volume decreases, work is ___.

A

positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

q soln

A
  • heat gained/lost by solution

- ΔT increase- exothermic (q rxn0)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

enthalpy of formation

A
  • the enthalpy change for the formation of a compound from its constituent elements
  • ∆Hf
  • f means substance is formed from its constituent elements
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

standard enthalpy change

A
  • the enthalpy change when all the reactants and products are in their standard states
  • ∆Hº
  • º means standard-state conditions
17
Q

standard state (of a substance)

A

Its pure form at 1 atm and 298 K/25 degrees celsius

18
Q

standard enthalpy (heat) of formation

A
  • change in enthalpy for the reaction that forms one mole of the compound from its elements
  • all substances are in their standard states
  • ∆Hºf
19
Q

kinetic energy

A

the energy of motion

20
Q

potential energy

A

energy stored by its position relative to other objects

21
Q

force

A

any push or pull exerted on an object

22
Q

heat

A

the energy transferred from a hotter object to a colder one

23
Q

first law of thermodynamics

A

1) Energy is conserved

24
Q

state function

A

function whose value depends ONLY on the present state of the system

25
non-state function
function whose value depends on the path the system took to reach the present state
26
pressure-volume work
The work involved in the expansion or compression of gases
27
The change in enthalpy (∆H) ALSO equals ____
- qp | - the heat qp gained or lost at constant pressure
28
State functions (examples)
1) enthalpy (H) 2) internal energy (E) 3) pressure 4) volume
29
Non-state functions examples)
-qp
30
enthalpy of reaction
- the enthalpy change that accompanies a reaction - ∆Hrxn or ∆H - also called 'heat of reaction'
31
calorimetery
the measurement of heat flow
32
heat capacity
- The amount of heat required to raise its temperature by 1 K/1 °C - determines the temperature change when an object absorbs a certain amount of heat - C
33
molar heat capacity
heat capacity of one mole of substance (Cm)
34
specific heat capacity/ specific heat
heat capacity of one gram of a substance (Cs)
35
bomb calorimeter
studies combustion reactions - Substance is placed in a small cup inside insulated vessel called 'bomb' - Heat released when combustion occurs is absorbed by water and other components of calorimeter, causing water temperature to rise - Will measure change in water temp.
36
Hess's law
If reaction is carried out in a series of steps, ∆H is the sum of the enthalpy changes of individual steps. (because enthalpy is state function)