Demonstrations for Chapter 11: Spontaneous Change and Equilibrium

70. Michael Flanders and Donald Swan, two British wits of the 1960s and 1970s, turned their understanding of the first and second laws of thermodynamics into a song which they sing for you. Their words and music summarize hundreds of years of experience which suggest the improbability of events to the contrary.

First and Second Law - Flanders and Swann

The First Law of Thermodymamics:
Heat is work and work is heat

Heat is work and work is heat
Very good!
The Second Law of Thermodymamics:
Heat cannot of itself pass from one body to a hotter body
(scat music starts)
Heat cannot of itself pass from one body to a hotter body
Heat won't pass from a cooler to a hotter
Heat won't pass from a cooler to a hotter
You can try it if you like but you far better notter
You can try it if you like but you far better notter
'Cos the cold in the cooler with get hotter as a ruler
'Cos the cold in the cooler with get hotter as a ruler
'Cos the hotter body's heat will pass to the cooler
'Cos the hotter body's heat will pass to the cooler

First Law:
Heat is work and work is heat and work is heat and heat is work
Heat will pass by conduction

Heat will pass by conduction
Heat will pass by convection
Heat will pass by convection
Heat will pass by radiation
Heat will pass by radiation
And that's a physical law

Heat is work and work's a curse
And all the heat in the Universe
Is gonna cooool down 'cos it can't increase
Then there'll be no more work and there'll be perfect peace

Really?
Yeah - that's entropy, man!

And all because of the Second Law of Thermodynamics, which lays down:
That you can't pass heat from the cooler to the hotter
Try it if you like but you far better notter
'Cos the cold in the cooler will get hotter as a ruler
'Cos the hotter body's heat will pass to the cooler
Oh, you can't pass heat from the cooler to the hotter
You can try it if you like but you'll only look a fooler
'Cos the cold in the cooler will get hotter as a ruler
That's a physical Law!

Oh, I'm hot!

Hot? That's because you've been working!
Oh, Beatles - nothing!
That's the First and Second Laws of Thermodynamics!

71. Spontaneous Endothermic Reactions: Exothermic reactions are sometimes beguilingly spontaneous while at the same time we are sometimes surprised to find endothermic reactions that are clearly spontaneous. Two examples from the previous chapter's demonstration included (1) using heat from the hydration of quicklime, producing "slaked" lime, to fry an egg, and (2) use of the reaction between ammonium thiocyanate and barium hydroxide to freeze water. Consider what might be driving the second reaction:

heat + NH4SCN (s) + Ba(OH)2 NH3 + 2 H2O + Ba(SCN)2 ; DH>0
The spontaneous decomposition of ammonium dichromate provides a spectacular example of another reaction in which gaseous products are produced from solid starting materials:
(NH4)2Cr2O7(s)<=> Cr2O3(s) + N2(g) + 4 H2O(g) ; DH<0

72. Carbon Dioxide Fire Extinguisher Demonstration: See CHEMBytes.

73. Irreversibility: Potassium Permanganate sprinkled into a water tank diffuses rapidly as the entropy of the system increases to a maximum. The process is clearly spontaneous and irreversible.

74. Chemiluminescence, or cold light, is produced in a complex set of chemical reactions involving, among other molecules and ions, an organic substance called luminol (which responds much as luciferin does when the firefly sends a glowing message to prospective mates) and a peroxide oxidizing agent - in this case, hydrogen peroxide. This reaction is spontaneous and irreversible.

75. Irreversibility: By slowly turning the inner drum an exact number of turns, and then reversing the operation by the exact same number of turns, the line of carbon black particles between the outer and inner drums can be returned to nearly their original position.

76. Predicting Chemical Reactions: A catalyst initiates the spontaneous decomposition of a hydrogen peroxide solution. In this case, the catalyst is finely divided iron(III) oxide.

77. The sublimation of solid iodine.

78. Operating heat engine - the "Sterling Engine."

79. The ammonia fountain is a demonstration of a the spontaneous nature of the dissolution of amonia in water. Calculate DG° for the process