this heat release about 50% of the energy available can be used to per-
form work when organisms metabolize glucose.
Research direction: global climate change
Consider the Earth as a system that can be characterized with certain
thermodynamic parameters. The Earth is a closed system since matter
does not leave or enter, neglecting satellites, meteorites, and the escape of
light gases such as hydrogen and helium. The Earth does experience an
energy flow from the surroundings, namely heating from the Sun. Due
to its size and complex composition, the Earth does not have simple, unique
properties such as a uniform temperature. However, we can still apply
basic thermodynamic ideas using average values.
Let us examine the heat flow into the system. The Earth experiences
a certain amount of incoming solar energy that does vary with the time
40 PARTI THERMODYNAMICS AND KINETICS
Table 2.1
Standard enthalpies of formation (1 atm, 25°C).
Substance ΔΔH° (kJ mol−−^1 )
Simple molecules
CO (gas) −110.5
CO 2 (gas) −393.5
O 2 (gas) 142.3
H 2 O (gas) −241.8
H 2 O (liquid) −285.84
Carbohydrates
Glucose −1273.2
Sucrose −2225.9
Alcohols
Acetic acid −484.5
Ethanol −277.8
Glycerol −668.6
Amino acids
Alanine − 563
Cysteine − 534
Glutamic acid − 1010
Leucine − 647
Serine − 726
Tyrosine − 672
Fatty acids
Palmitic acid −891.6
Stearic acid −947.7
