Lecture 14
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Ectotherms?
Absorb energy direcly from the sun’s radiation like lizards and reptiles as they have low metabolic rates
Endotherms?
Have intricate mechanisms for maintaining a constant body temperature, birds and mammals, with a high metabolic rate and fur/hair/feathers, and behavioral adaptations
2nd law of thermodynamics
when energy is transferred, there will be less energy avilable at the end of the transfer process than at the beginning.
How does the 2nd law of TD explain nature’s directionality?
It places severe restrictions on the way heat and other forms of energy can be transferred and used to work
What are the 3 logically equivalent statements about the 2nd law of TD?
Heat will not flow spontaneously from a cold to a hot body. You cannot construct an engine that does nothing but convert heat to useful work. Every isolated system becomes more disordered with time
What is a spontaneous process?
One that occurs naturally under certain conditions
What is a nonspontaneous process
Will not take place unless it is driven by the continual input of energy from an external source
Why will heat not spontaneously flow from a cold to hot body?
At the molecular level, faster moving objects (heat) tend to share their kinetic energy with slow moving ones (cold)
Whenever energy is transferred from heat to another type what happens to it?
Some of the heat must be dumped into the environment and is unavailable to do work, it is not lost or destroyed it just can’t be used to do useful work
You cannot convert energies with?
100% efficiency
Efficiency =
the amount of work you get from an engine / amount of energy you put into it
What is the difference between an ordered and disordered system?
An ordered system has a regular, predictable pattern. A disordered system is random, and things in an ordered state tend to move towards a disordered state
A system always spontaneously becomes more disordered because?
Nature prefers a more probable state and moves to achieve it
What is entropy?
The measure of disorder, how much energy is not available to do work.
The entropy of an isolated system?
remains constant or increases, as energy is transferred, entropy increases
The food chain
Living organisms are arranged in trophic levels according to how they obtain energy
As energy is transferred along food chains, the amount of available energy?
decreases from one trophic level to the next
The word atom comes from the greek word?
atomos
Ancient vs current belief of atoms
Ancient: all matter can be subdivided into atoms which cannot be subdivided further Modern: further subdivision is possible but the identity of the original element is lost
The atomic number tells you what?
The number of protons or electrons if neutral
The atomic mass tells you what?
The number of protons + the number of neutrons
Alkali metals are?
soft, silvery metals that are highly reactive and form salt compounts in 1 to 1 ratio with halogens
Alkaline Earth metals are?
reactive with oxygen forming colorless compounds
Noble gases are?
colorless, odorless gases that are inert