thermodymamics

Question 1

what is a Diathermic system?

Answer 1

a closed system only energy can be exchanged between the system and the surroundings

Question 2

ISOLATED (ADIABATIC)

Answer 2

neither matter or energy can be exchanged

Question 3

what is internal energy or U?

Answer 3

The Internal Energy is in very simple words the total of the kinetic
energy due to the motion of molecules (translational, rotational,
vibrational) and the potential energy (associated with the atoms within
molecules or crystals).

Question 4

what is the internal energy of an ideal gas?

Answer 4

For the simplest case of an ideal gas (no interactions between the
particles) all of the internal energy is present as the kinetic energy and
hence as the temperature is raised, the particles move more quickly and
the internal energy is therefore also raised.

Question 5

-q:

Answer 5

heat is given out by the system
(an exothermic process)

Question 6

+q:

Answer 6

the system absorbs heat
(an endothermic process)

Question 7

𝑤

Answer 7

work done on the system

Question 8

-w

Answer 8

work done by the system

Question 9

what happens if there is a vacuum on a gas?

Answer 9

no work is done by a gas expanding into a vacuum.

Question 10

if the pressure is constant we can pull it out of the integral and thus what do we end up with?

Answer 10

pext(vf-vi)

Question 11

the first law of thermodynamics?

Answer 11

Energy cannot be created or destroyed but is just
transformed from one form to another. delta U = UB
− UA

Question 12

if pv is the work on the system

Answer 12

d U = d q − d( pV)

Question 13

isochoric

Answer 13

A change at constant volume

Question 14

if only PV does the work

Answer 14

A change at constant volume (“isochoric”), (dV=0)
A change where the surroundings are at constant pressure
(dp=0)

Question 15

in a vacuum

Answer 15

dU = dq

Question 16

Exothermic reaction (-q):

Answer 16

ΔU is negative

Question 17

Endothermic reaction (+q):

Answer 17

ΔU is positive

Question 18

isobaric

Answer 18

A change where the surroundings are at constant pressure

Question 19

when is maximum work done by the gas?

Answer 19

Maximum work is done during a reversible process.

Question 20

Which is at equilibrium: reversible or irreversible work?

Answer 20

resrseable is at equilibrium

Question 21

At a constant volume

Answer 21

dU = dqV, In other words all the heat goes into
altering the internal energy.

Question 22

what is the formula for heat capacity?

Answer 22

dq = CdT

Question 23

can you describe the heat capacity relationship?

Answer 23

Substances with a high heat capacity (i.e. water) require larger
amounts of heat to bring a given rise in T than those with a small
heat capacity (i.e. air)

Question 24

under constant pressure conditions what is enthalpy

Answer 24

dH = qp

Question 25

at constant pressure what is the enthaply realted to the heat capacity

Answer 25

dH=CPDT

Question 26

if there are many processes how do we calcualte entropy?

Answer 26

ΔH(t2)=ΔH(t1)+ΔCP(t2-t1)

Question 27

The thermodynamic definition of entropy

Answer 27

is motivated by the idea that a change (energy is dispersed in a disordered fashion) depends on how much energy is transferred as heat which stimulates disordered motion in the surroundings.

Question 28

Boltzmann’s formula

Answer 28

s=KLNW k is 1.381x10-23

Question 29

third law of thermodynamics

Answer 29

The entropy of a perfect crystalline substance approaches zero as the temperature approaches absolute zero (0 K)

Question 30

what is about entropy and themp

Answer 30

In general, when T > 0, W> 1, ln W > 0, therefore: the entropy rises above zero ie if themp is grater than zero then entropy is greater than zero

Question 31

what should we take the residual energy of CO to be

Answer 31

sm(0)=5.8jk-1 mol

Question 32

piston example for irreverale

Answer 32

pext(vf-vi)

Question 33

process is reversible

Answer 33

nRTinvf/vi

Question 34

Endothemic systems do what for the entropy

Answer 34

Endothermic processes (that need heat to be supplied to the system) decrease the Entropy of the surroundings by taking in heat

Question 35

The work done reversibly and isothermally is equal to the area under the isotherm .

Answer 35

p=nRT/V

Question 36

what is the graph of pressure vs volume do for an adiabat

Answer 36

adiabate falls more steply then a isotherm

Question 37

the efficiency of the engine

Answer 37

e=/W/ /qh or 1-qc/qh

Question 38

when is the dependence of gm on p really intense

Answer 38

for a gas

Question 39

what does temp do to gibbs molar

Answer 39

general, because molar entropy is positive, an increase in temperature (ΔT > 0) results in a decrease in Gm (ΔGm < 0).

Question 40

what does the Clausius Clapeyron equation do?

Answer 40

derive an equation for the line between two phases in the phase diagram

Question 41

An ideal-dilute solution

Answer 41

is one in which the solvent obeys Raoult’s Law but the solute obeys Henry’s Law

Question 42

Therefore the mixing of ideal solutions is spontaneous in all proportions why?

Answer 42

As mole fractions are never greater than 1, the logarithmic terms are negative and hence delta Gmix < 0

Question 43

what is something to note about colligative properties?

Answer 43

These properties all stem from changes in the disorder of the solvent, and the increase in disorder is independent of the identity of the solid species we add.

Question 44

hypertonic solution

Answer 44

solute concentration outside the cell is greater than inside the cell)

Question 45

hypotonic solution

Answer 45

solute concentration outside the cell is less than that inside the cell

Question 46

The osmotic pressure of a solution is proportional to

Answer 46

the concentration of the solute

Question 47

what is a binary mixture

Answer 47

a mixture of only two components