Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Chemistry > Thermochemistry > Flashcards

Thermochemistry Flashcards

1
Q

System

A

the matter that is being observed; total amount of reactants and products in a chemical reaction

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

Surroundings/Enviornment

A

everything out side the system

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

If we are looking at the coffee as the system and the cup as the enviornment, what heat transfer are we studying?

A

Heat transfer between coffee and the cup

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

Isolated System

A

Environment and System do not exchange energy (heat/work) or matter

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

Closed System

A

System and Environment exchange energy but not matter

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

Open System

A

system and environment exchange both energy and matter

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

First Law of Thermodynamics

A

change in internal energy of a system is equal to the sum of heat added to the system minus work done by the system

U = Q - W

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

Isothermal Process

A

temperature is constant

Internal energy, U, is constant = 0

Work done by system = heat added to the system

Q = W

hyperbolic

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

Adiabatic Process

A

No heat exchange; Q = 0

change in internal energy of the system is opposite of work done by system

U = -W

extremely hyperbolic

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

Isobaric Process

A

Pressure is constant

no affect on first law

flat line

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

Isovolumetric/Isochoric Process

A

Volume is constant

no work is performed ; W = 0

change in energy is equal to energy placed into the system

U = Q

vertical line

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

Spontaneous Process

A

occurs by itself without having to be driven by energy from an outside source

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

State Functions

A

pressure, density, temperature, volume, enthalpy, internal energy, gibbs free energy, entropy

when the state of a system changes, one or more of these will change

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

Standard Conditions

A

298k

1 atm

1 M

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

Phase Changes

A

are reversible, and an equilibrium of phases will be given for a combination of temperature and pressure

ex: 0 degrees C and 1 atm pressure ic e and water are at equilibrium soice absorbs heat to become water but the water lsoes heat and becomes ice keeping relatively equal amounts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Phase equilibrium are analogous to the dynamic equilibrium of _________: the concentration of reactants and products are constant because the rates ____ and _____ are equal.

A

reversible chemical reactions

forward

reverse reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Not all molecules possess the same instantaneous speeds, meaning not the same instantaneous kinetic energy values. In the liquid phase, the molecules near the surface of the liquid have _________ to leave the liquid phase and enter the ______. This is known as _______.

A

enough kinetic energy

gas

evaporation/vaporization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Evaporation is an ________ process where the heat source is ______

A

endothermic process

liquid water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Boiling

A

a specific type of vaporization where the entire liquid bubbles and there is rapid release of liquid to gas particles once the BP is met

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Condensation

A

gas molecules forced back to liquid molecules based on pressure or low temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Vapor Pressure

A

pressure exerted on the liquid by the gas

increases as temperature increases because mroe liquid particles can escape into gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Boiling point

A

where vapor pressure is equal to the ambient/applied pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Whereas pure crystalline solids have ditinct _______, amorphous solids like glass, plastix, chocolate _______ over a _______ of temperatures due to their less ordered molecular structure

A

melting points

melt/solidify

range

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Sublimation

A

solid to gas directly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Deposition
gas to solid directly
26
Triple Point
temperature and pressure where all 3 phases are in equilibria
27
Critical Point
between liquid and gas phase where there is no distinction between liquid and gas called supercritical fluids density of liquid and gas are equal
28
Temperature
avg kinetic energy of particles in a substance
29
Enthalpy (Thermal ENergy)
heat under constant pressure
30
Heat
transfer of energy from one substance to another resulting from a difference in temperatures
31
Endothermic
process where system absorbs heat delta Q > 0
32
Exothermic
process where system releases heat delta Q < 0
33
q = m*c*deltaT
m = mass c = specific heat of substance q = heat absorbed or released
34
Specific Heat
amount of energy required to raise the temperature of one gram of substance by one degree Celsius/Kelvin
35
Heat capacities
reason why it is less heat to raise temp of glass of water than a pool = mass * specific heat
36
Constant Pressure Calorimeter
incident pressure (atmospheric pressure) is e kept constant temperature is measured as reaction progresses with no gain/loss of heat to the environment
37
Constant Volume Calorimetry
no work is done as W = p* delta V no heat is exchanged between the calorimeter and universe so Q calorimeter is 0 deltaUsys + deltaUsurr = deltaU cal = Q - W = 0 delta U sys = - delta U surr qsys = -qsurroundings
38
Heating Curves
When a compound is ehated, temperature rises until the melting/boiling point is reached. Here temp stays constant until all of the sample is converted to the next phase and then temp begins to rise again
39
When phase changes occur, the heat added does not change the _____ but is used to _____
temperature overcome the attractive forces holding the phase
40
Enthalpy of Fusion (latent heat of Fusion)
transition during solid-liquid boundary determines the heat transferred during phase change + when going from solid to liquid as heat is added - when going from liquid to solid as heat must be removed
41
Enthalpy of Vaporization (latent heat of vaporization)
transition during liquid-solid boundary determines the heat transferred during phase change + when going fromn liquid to gas as heat is added - when going from gas to liquid as heat is lost
42
q = mL
m = mass L - latent heat, enthalpy essentially of the process
43
The total amount of heat needed to cross multiple phase boundriesis a _____ of the heats for changing the temperature of each of the respective phases and the heats associated with phase changes.
summation ex: energy required to make ice cube melt at 40 degrees q1 = heating to the transition temperature (q=mcdeltaT) q2 = heat generated during phase change (q=mL) q3 = heat generated to a temperature(q=mcdeltaT)
44
Enthalpy Change of a Reaction
deltaH reaction = Hproducts - Hreactants + = endothermic process - = exothermic process
45
Enthalpy cannot be measured, only _______
deltaH
46
Standard Enthalpy of Formation (deltaHf)
enthalpy required to produce one mole of a compound from its elements in standard state
47
Standard Heat of a Reaction (deltaHrxn)
enthalpy change accompanying a reaction being carried out under standard conditions deltaHrxn = sum( deltaHf,prod ) - sum(deltaHf,react)
48
Hess's Law
states that enthalpy changes of reactions are additive deltaHrxn = deltaH(reactants->elements) + deltaH(elements->products) remember to add the deltaHrxns together and flip sign if flipping direction of the reaction (even multiply if need to) arrange to cross out uncessary atoms/elements
49
Bond Dissociation Energy
average energy required to break a particular type of bond between atoms in the gas phase (endothermic reaction
50
Bond breaking has the same enthalpy as bond formation but is _____
opposite
51
Standard Heat of Combustion (delta H combo)
enthalpy change associated with the combustion of a fuel
52
Second Law of Thermodynamics
energy is spontaneously dispered from being localized to becoming spread out when not hindered
53
Entropy
how spontaneous the dispersion of energy at a temperature is deltaS = Qrev/T Q rev = heat gained/lost in a reversible process delta S of products and reactants can be used to find deltaSrxn like entropy (products - reactants)
54
When energy is distributed into a system at a given temperature, its entropy _____ . When energy is distributed out of a system, its entropy _____ .
increases | decreases
55
Gibbs Free Energy
measure of the change in enthalpy and entropy as a system undergoes a process tells if a reaction is spontaneous or not deltaG = deltaH - T*deltaS T*deltaS represents the total amount of energy absorbed by a system when its entropy increases reversibly
56
Movement towards the equilibrium position is a _____ in Gibbs Free Energy (G <0) and is ______. The reaction RELEASES energy and is called ________. Movement away from the equilibrium position is an ____ in Gibbs free energy (G > 0) and is _______. The reaction is ___ and ABSORBS energy.
decrease, spontaneous, exergonic increase, nonspontaneous, endergonic
57
At equilibrium, deltaG is ______ and deltaH = T*deltaS
0
58
``` delta H delta S + + + - - + - - ```
1) spontaneous at HIGH Temperature 2) nonspontaneous always 3) spontaneous always 4) spontaneous at low temperature
59
Remember, rate of a reaction is dependent on Ea, _______, not delta G
activation energy
60
When a reaction occurs with a Kinetic and Thermodynamic product, at first the ____ product will be dominant due to the low _____. Over time, ____ will be apparent because of the low ____.
Kinetic, activation energy Thermodynamic, gibbs free energy
61
Free Energy of Reaction
deltaGrxn = deltaGproducts - deltaGreactants
62
Deriving standard free energy change from equilibrium constant
deltaGrxn = -RT ln Keq T in kelvins R is ideal gas constant greater the value of Keq, the more postive the ln and the more negative the deltaG
63
Determining Free Energy change for a reaction in Progress
deltaGrxn = deltaGrxn(standard) + RTlnQ = RTln(Q/Keq)
64
If Q/Keq is less than 1, then free energy will be ______ and ______ If Q/Keq is more than 1, then free energy will be more _____ and _____. If this were the case, the reaction will move in the ____ direction until ______ is reached. If Q/Keq is = 1, then free energy is ____ and ____ is met.
negative, spontaneous positive, nonspontaneous opposite , equilibrium 0, equilibrium

Chemistry (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions