Is the system’s entropy change
positive or negative?
• Water vapor deposits as ice crystals on a cold
windowpane
• A can of carbonated beverage loses its fizz
(Consider the beverage but not the can as the
system.)
• A glassblower heats glass to its softening
temperature
• Water boils
• A teaspoon of sugar dissolves in a cup of
coffee. (The system consists of both sugar and
coffee.)
• Calcium carbonate precipitates out of water in
a cave to form stalactites and stalagmites.
(Consider only the calcium carbonate to be
the system.)
Which one has a higher entropy?
1 or 2
Be able to explain why
• Solid carbon dioxide at
-78C
• Carbon dioxide vapor at
0C
• Solid sugar
• Sugar dissolved in tea
• 100mL of water and
100mL of alcohol
• 100mL of water and
100mL of alcohol mixed
together
• Cl2 (g)
• P4 (g)
• NH4NO3(s)
• NH4NO3(aq)
• AsH3(g)
• Kr(g)
• CH3OH(l)
• C2H5OH(l)
Predict whether the entropy change
would be positive or negative
Be able to explain why
• C2H4(g) + H2(g)  C2H6(g)
• CH3OH(l)  CO(g) + 2H2(g)
• Ag+(aq) + I-(aq)  AgI(s)
• Br2(l) + H2(g)  2HBr(g)
• CaCO3(s)  CaO(s) + CO2(g)