Question

1. list 5 ways that water helps to maintain homeostasis. 15. what property of water causes surface tension? 16. give an example that you observed of surface tension (think penny lab). 17. define cohesion in your own words. give an example. 18. define adhesion in your own words. give an example. 19. write the dissociation equation for water (when water breaks into hydrogen ions and hydroxide ions). 20. draw a ph scale. a. on the scale, label 1 - 14. b. label neutral. c. label the basic side and identify the direction that is increasingly basic d. label the acidic side and identify the direction that is increasingly acidic. e. identify 2 strong acids and put them on the scale in the appropriate place. f. identify 2 strong bases and put them on the scale in the appropriate place. 21. describe a buffer using your own words. why are they important to all living things?

Explanation:

1. In the penny - lab, you can observe surface tension when you carefully add water droplets to the surface of a penny. The water forms a dome - like shape on the penny's surface instead of immediately spilling over, due to the cohesive forces between water molecules creating surface tension.
2. Cohesion is the attraction between molecules of the same substance. For example, water molecules stick together, which is why water forms droplets.
3. Adhesion is the attraction between molecules of different substances. An example is water climbing up the sides of a glass tube (capillary action), where water molecules are attracted to the glass molecules.
4. A pH scale ranges from 0 - 14. 7 is neutral. The basic side is from 7 - 14, and the direction of increasing basicity is from 7 to 14. The acidic side is from 0 - 7, and the direction of increasing acidity is from 7 to 0. Examples of strong acids are hydrochloric acid (HCl) with a pH around 0 - 1 and sulfuric acid (H₂SO₄) with a pH around 0 - 2. Examples of strong bases are sodium hydroxide (NaOH) with a pH around 13 - 14 and potassium hydroxide (KOH) with a pH around 13 - 14.
5. A buffer is a solution that resists changes in pH when small amounts of an acid or a base are added. They are important to all living things because they help maintain a stable internal pH environment. Many biological processes are very sensitive to changes in pH, and buffers ensure that the pH remains within an optimal range for these processes to occur properly.

Answer:

1. In the penny - lab, water forms a dome on the penny's surface due to surface tension.
2. Cohesion is the attraction between like - molecules. Example: water droplets.
3. Adhesion is the attraction between different - molecules. Example: water climbing in a glass tube.
4. pH scale: 0 - 14; neutral at 7; basic side 7 - 14 (increasing basicity from 7 to 14); acidic side 0 - 7 (increasing acidity from 7 to 0); strong acids: HCl (pH 0 - 1), H₂SO₄ (pH 0 - 2); strong bases: NaOH (pH 13 - 14), KOH (pH 13 - 14).
5. A buffer resists pH changes. It's important for living things to maintain a stable internal pH for proper biological processes.