Judy Lehmberg (FLC I) - Lee College

degrees C. Beaker C had 10 ml of water boiled away. And during that same time, the 100 ml of water in
Beaker A increased by _______________ degrees C.
4. How many calories of heat were required to evaporate the 10 ml of water in Beaker C? (Remember: You
must consider both how much water is in Beaker A and how much its temperature increased while Beaker C
boiled away.)
_____________ calories.
5. So, how many calories would be required to evaporate only 1 ml of water?
_____________ calories.
6.What does this exercise tell you about calories, exercise, and sweating?
As you exercise your body temperature increases. Some of that heat can be released as water molecules leave
your body.
Practice 6 - What the Heck is pH?
HYDROGEN IONS An ion is an atom that has lost or gained electrons, and thereby has become electrically
charged (either + or -). They act differently than uncharged atoms. (It's like comparing magnets with nonmagnets.)
These ions are very important in out life processes, and we would die without them. Table salt is an example of
two essential ions -- sodium and chloride.
Of all the ions in your body, none is more important than the hydrogen ion, H+. The term "pH" refers to the
concentration of H+ ions in water. Biologists are interested in H+ concentration because it affects chemical
reactions so greatly.
A small change in this ion can dramatically affect life. Acid rain and stomach acid are two expressions of the
concentration of H+ ions. Also, the blood of a human is so sensitive to H+ concentration that a small pH
change from your normal of 7.4 can result in your death.
We monitor the pH of our fish aquariums and our swimming pools in order to avoid potential problems. In the
case of the aquarium, we are trying to maintain a good environment for micro-organisms, whereas, in the
swimming pool, we are trying to prevent micro-organisms from growing.
QUESTIONS:
1. Knowing how important pH can be to living organisms, what would be the effect of acid rain on the
ecosystem?
It can have devastating effects on organisms, especially aquatic organisms. There are many bodies of water
that are now biologically dead due to low pH as a result of acid rain.
2. What does the "p" stand for in pH?
Potential, it is the potential of hydrogen.
The pH scale ranges from 1 to 14. Each step up the pH scale means that there is 10x more OH- (base) and less
H+ (acid) than the step below.
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