Thermodynamics

Question 1

Thermodynamics

Answer 1

the study of energy and its transformations

Question 2

Energy

Answer 2

the capacity to do work or transfer heat

Question 3

work

Answer 3

the movement of an object abasing some force; force is a push or pull exerted on an object

Question 4

heat

Answer 4

flow of energy from a body at higher temp. to one at a lower temp when they are placed in thermal contact

Question 5

kinetic energy

Answer 5

the energy an object has due to its motion

Question 6

potential energy

Answer 6

stored energy that results from the position

Question 7

system

Answer 7

part of the universe we single out

Question 8

surroundings

Answer 8

everything that exist outside the system

Question 9

open system

Answer 9

can exchange both energy and matter with surroundings. ex chem Rxn in open flask

Question 10

closed system

Answer 10

a system can exchange energy but not matter with surroundings. ex. chem rxn in stoppered flask

Question 11

isolated system

Answer 11

can exchange neither matter nor energy with its surroundings. ex. sealed flask that is thermally, electrically, mechanically insulated

Question 12

internal energy (U)

Answer 12

the sum of all kinetic and potential energy contribution

Question 13

ΔU= w + q

Answer 13

equation for finding internal energy of a system. w=work q=heat

Question 14

If w done onto system

Answer 14

w is greater than 0

Question 15

If w done by system

Answer 15

w is smaller than 0

Question 16

if q is absorbed from the surroundings, q>0 and the process is

Answer 16

endothermic

Question 17

if q is released to the surroundings, q<0 then the process is

Answer 17

exothermic

Question 18

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

Answer 18

its internal energy (U) increases

Question 19

First law of thermodynamics

Answer 19

Energy can be transferred and transformed, but it cannot be created or destroyed.

Question 20

Internal energy of an isolated system is

Answer 20

constant

Question 21

3 examples of forms of energy

Answer 21

work, heat and light

Question 22

Enthalpy (H)

Answer 22

related to the internal energy of a system plus the product of the pressure and volume of system
H= U + PV

Question 23

Constant pressure w

Answer 23

-P∆V

Question 24

when the reaction is not kept at a constant volume this equation is used for enthalpy

Answer 24

ΔH=ΔU + PΔV

Question 25

When change in ΔH is positive, the process is

Answer 25

endothermic, it gained heat from the surroundings

Question 26

ΔH<0 the process is

Answer 26

exothermic, it released heat to the surroundings

Question 27

the process by which a drug particle dissolves is called

Answer 27

dissolution

Question 28

breaking solute-solute attractions is

Answer 28

endothermic

Question 29

breaking solvent-solvent attractions is

Answer 29

endothermic

Question 30

forming solute-solvent attractions is

Answer 30

exothermic

Question 31

Enthalpy change

Answer 31

sum of endothermic and exothermic interactions

Question 32

spontaneous processes

Answer 32

- occur without outside assistance - occurs in a definite direction - they are spontaneous in one direction and non spontaneous in the reverse

Question 33

NaOH dissolving in water

Answer 33

- Heat is liberated (exothermic) | - ∆H is negative

Question 34

NaNO3 dissolving in water

Answer 34

- Solution becomes cooler - Heat is absorbed ( endothermic) - ∆H is positive

Question 35

reversible process

Answer 35

a system can be completely restored to its original condition with no net change to system or surroundings

Question 36

irreversible process

Answer 36

can't be reversed to restore the system and surroundings to original state. all real processes that occur on their own are irreversible

Question 37

spontaneous processes are

Answer 37

irreversible: even if the system is restored to the original condition, the surroundings will have changed

Question 38

Entropy

Answer 38

measurement of randomness or disorder | - when a system becomes more chaotic, its entropy increases

Question 39

Second law of thermodynamics

Answer 39

any irreversible process results in an increase in entropy

Question 40

Primary reason for Micelle formation

Answer 40

- attainment of a state of minimum free energy | - ex of thermodynamics

Question 41

Surface tension

Answer 41

- force per unit length that must be applied parallel to the surface as to counterbalance the net inward pull

Question 42

Contraction

Answer 42

is spontaneous and the contracted surface represents a minimum free energy state

Question 43

Surfactants are

Answer 43

- amphiphilic molecules ( have hydrophobic and hydrophilic parts) - orient themselves at the surface to remove the hydrophobic group from the aqueous environment

Question 44

Micelles form when

Answer 44

the surface layer is saturated with surfactant molecules and no further decrease in surface tension is possible

Question 45

which is most important in determining the free energy change

Answer 45

entropy | - in solution, hydrophobic molecules are surrounded by structured water

Question 46

What results in an increase in entropy

Answer 46

- loss of ordered structure of the water molecules when the hydrophobic regions of the surfactant are removed

Question 47

Third Law of Thermodynamics

Answer 47

- entropy of a perfectly organized crystal at absolute zero is zero

Question 48

In any dissolution, the entropy of a system

Answer 48

increases

Question 49

Gibbs free energy equation

Answer 49

ΔG = ΔH - TΔS

Question 50

Total entropy change

Answer 50

∆Stotal= ∆S+∆Ssurroundings

Question 51

For a spontaneous change, S is

Answer 51

positive, >0

Question 52

At constant Temperature and pressure, if ΔG>0 (positive) the reaction is

Answer 52

non spontaneous in the forward direction but spontaneous in the reverse rxn

Question 53

At constant Temperature and pressure, if ΔG<0 (negative) the reaction is

Answer 53

spontaneous in the forward reaction

Question 54

At constant Temperature and pressure, if ΔG=0 the reaction is

Answer 54

at equilibrium

Question 55

Equilibrium expression. K=

Answer 55

[C]^c[D]^d / [A]^a[B]^b

Question 56

If K and lnK <0 (negative), then ∆G is

Answer 56

positive

Question 57

If K and lnK >0 (positive), then ∆G is

Answer 57

negative

Question 58

If K and lnK =0, then ∆G is

Answer 58

=0

Question 59

The more negative ∆G,

Answer 59

the larger the equilibrium constant

Question 60

Oth Law

Answer 60

If two systems are at the same time in thermal equilibrium with a third, then all three are in thermal equilibrium