Day 39
This class period will be asynchonous. You don't have to join a discussion today. The Class Review for the Final is due at the end of our normal class period: 12:15. Here are the questions.
1. What is in the air after water evaporates? Is this a physical or a chemical change? Explain.
2. Does the following argument lead to the truthfulness of the conclusion? Explain.
P1 If an acid is placed in water then the H+ concentration will increase.
P2 The H+ concentration increased.
C An acid is placed in water.
3. Does the following argument lead to the truthfulness of the conclusion? Explain.
P1 If an apple floats in water then the apple is more dense than water.
P2 An apple does float in water.
C The apple is more dense than water.
4. Does the following argument lead to the truthfulness of the conclusion? Explain.
P1 If electrons reside in discrete energy states then a line spectrum will be produced after the electrons have been excited.
P2 Electrons reside in discrete energy states.
C A line spectrum will be produced after the electrons have been excited.
5. What is the volume of an object that has a mass of 8 g and a density of 2 g/mL?
6. The density of an object was experimentally determined five times. The results were 1.8, 2.1, 1.99, 2.26, and 2.2 g/mL. What would you report as the density of the object?
7. Using the Gold Foil Experiment, write a sound conditional argument in the If-Then format that has the conclusion: The raisin pudding model must be discarded.
8. Why has the solar system model of the atom been discarded?
9. Explain what happens to the leaves of an electroscope and why it happens when a rod with a positive charge is placed next to the ball of the electroscope but doesn't touch it.
10. When a person holds on to a device that generates a charge, it is observed that their hair "stands on end," each hair getting as far away from other hairs as possible. Explain this observation.
11. (a) How are ionic bonds formed? (b) Write the formulas for four compounds that have ionic bonds.
12. An atom has 18 electrons and a -1 charge. (a) What element is it? (b) What is the symbol for the ion of this element? (c) Give the formulas for three salts that could be formed using this element.
13. A friend says that water is a good conductor of electricity. What would you tell them?
14. A solution was found to have an H+ concentration of 10-5. (a) Is this solution acidic or basic? (b) What is the pH of the solution? (c) What would be produced if an acid was added to this solution? (d) What would be produced if a base was added to this solution?
15. (a) How are covalent bonds formed? (b) What is the difference between polar and nonpolar covalent bonds?
16. (a) What are intermolecular forces? (b) Which has stronger intermolecular forces: polar molecules or nonpolar molecules? Explain.
17. Determine which liquid, A or B, will evaporate faster in each of the situations given below. If it can't be determined put "not conclusive."
| Situation # | Greater Polarity | Greater Mass | Evaporates Faster |
|---|---|---|---|
| #1 | A | A | |
| #2 | B | A | |
| #3 | A | B | |
| #4 | B | B |
18. Explain fully why the boiling point goes down in part (a) and up in part (b). (a) H2O (100 oC) to H2S (-60.7 oC), (b) H2S (-60.7 oC) to H2Se (-40 oC).
19. Consider the experiment in the video where some small pieces of paper were attracted toward a piece of charged cotton towel. Write a conditional argument with the following conclusion: The paper is attracted to the towel. Video
20. If a 2.5 kg ball is dropped from rest at a height of 2.0 m, how much kinetic energy does the ball have when at a height of 1.0 m? Assume no heat or other energy is produced.
21. What is the purpose of a college education? How can this course help to accomplish this purpose? Explain.