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