NAME:______
Properties of Water and pH
1. Write the chemical equation for water, and draw a Stick model of a water molecule. Show polarity by label positive and negatively charged regions of the molecule.
3. What kind of bond holds the Hydrogen to the oxygen in ONE water molecule?
4. What kind of bonds can hold two separate water molecules together?
5. What is a polar molecule?
6. The polarity of water allows it to ______most substances. Because of this it is referred to as the ______.
7. Water molecules stick to other water molecules. This property is called ______.
8. Water molecules stick to other water molecules. This property is called
______.
9. Why does ice float on water?
10. Why is it important that water resists temperature changes?
Critical Reading: pH
When some substances dissolve in water they break up into ions. A compound that releases a hydrogen ion (a proton) when it dissolves in water is an acid. Bases are compounds that remove, or accept, hydrogen ions. A solution’s acidity, or its hydrogen ion concentration, is measured on the pH scale. An acid has a low pH (pH below 7)and a high hydrogen ion concentration. A base has a high pH (pH above 7) and a low hydrogen ion concentration. Organisms must maintain a stable pH. Even a small changein pH can disrupt many biological processes.
11. Describe what the pH of a substance is measuring.
12. Draw the pH scale and label acid, neutral, and base.
13. What has more hydrogen ions, acids or bases?
14.A student mixes strawberry koolaid and water. A pH meter is used to measure pH of 5.4. What kind of solution is strawberry Koolaid?
15.In the koolaid mixture, what must there be more of, hydrogen ions or hydroxide ions?
16. A student adds an alka-seltzer to the koolaid and stirs. The pH meter now reads 8.3. What was released by the alka-seltzer tablet to cause this change?
17. Bromthymol blue is a chemical indicator that is blue in basic and neutral solutions, and turns greenish and then yellow as the solution becomes more and more acidic. Fill in what color you think bromthymol blue would be in each of the situations in the chart.
Situation Ph Bromthymol blue indicator color
Water directly out of tap / pH =7.2pH after exhaled air is blown through a straw into water for 5 min. / pH=5.1
pH after a snail has lived in water for three days / pH=5.8
pH with 2mL of bleach added to the water / pH=9.4
pH with instant coffee added to the water / pH=5.0
pH after an aquatic plant is grown in water for three days in bright sunlight / pH=7.7
- What effect does carbon dioxide have on tap water?
- Is bleach an acid or a base?
- Is coffee an acid or a base?