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Flashcards in Thermo 1 Deck (35):
1

Work

Concerted energetic change

2

Compressive work

-PΔV

3

Ideal gas assumptions

Negligible volume
No interactions
Negligible collision time

4

Ideal gas equations

PV=nRT=NkT

5

Partial pressures

Normalised to atmospheric

6

Intensive properties

Do not depend on amount of material
Density

7

Extensive properties

Depend on amount of material
Mass, volume

8

System types

Isolated -no exchange
Closed- only energy
Open- mass and energy

9

Closed system types

Isobaric - pressure
Isochoric - volume
Isothermal - temperate - must have heat flow
Adiabatic - no heat flow

10

1st law

Energy of an isolated system is constant
Δsys + Δsurr = 0

ΔU = Δq + Δw

11

d to Δ

For state can be done directly
Where continual small changes must be integrated

12

H

U + PV

13

dH at constant pressure

dq

14

ΔH variable pressure and volume

ΔU + ΔngRT

15

ΔH at constant volume

Δq + ΔngRT

16

C
Cp
Cv

Δq/ΔT

dH/dT

dU/dT

17

ΔH or U from heat capacity

ΔH = CpΔT
ΔU = CvΔT

(Cm x n)
(c x m)

18

2nd law thermo

Entropy of an isolated system tends to increase
ΔSsys+ ΔSsurr> 0

19

Entropy and multiplicity

S= k ln(Ω)

20

dSsys

=dq/T

dSsurr= -dq/T

To find Δ must be integrated

21

dG

=dH - TdSsys

From dG=-TdStot

22

dA

dU - TsSsys

23

At thermal equilibrium

ΔG = 0

24

μa

μStandard + RTln[A]
+ RTln(Pa/pstand)

25

Free energy of mixtures

G= Σni μi

μi = dG/dni

dG = dH - TdS + Σμi dni

26

ΔrG

-RTln(k)

27

Temperature dependence of G

-RTln(K) = ΔH - TΔS
Plot ln(k) against 1/T
dln(K) /d(1/T) = ΔH/R

Ln(k1/k2)=ΔH/R (1/T1 -1/T2)

28

μa non ideal

μa standard + RTln(activity)

activity = γ [A]

29

pKw

14=pH+pOH

30

Strong acid pH

-log[HA]

31

Weak acid

Ka= ([H3O+]squared)/(c-[H3O+])

For very weak c>>h3o+
So quadratic solves for [h3o+]= 1/pKa -1/2log(c

32

KaKb

[oh-][h3o+]=Kw

33

Indicator eqm

Change over +-1 pKa range

-log(hin/in-) = pH-pKa

34

Buffer Ka

H3o(b+h3O)/a-h3o

35

Buffer pH

pKa- log(a-h3o/b+h3o)

Assuming weak = pKa-log(a/b)