Day 27
This class period will be asynchonous. You don't have to join a discussion today. The homework is due at the end of our normal class period: 12:15. It is Class Review Homework Set #4, a quiz on Canvas. Here are the questions:
1. Describe, at the molecular level, how table salt, NaCl, is formed. Does table salt have molecules? Why do the atoms in table salt stay together?
2. What would the formulas be for the compounds that are formed between: (a) K and O, (b) Sr and I, (c) Li and Br? Give formulas for seven other ionic compounds (salts).
3. Many people believe that the number of electrons in an atom will identify an element, but Ar, K+, and Cl- all have the same number of electrons. Explain.
4. Fill in the following table:
| pH | H+ Concentration | Acidic/Basic |
|---|---|---|
| 3 | ||
| 9 | ||
| 7.3 | ||
| 10-2 | ||
| 10-12 |
5. Given that HCl turns a solution of water and Neutral Red (an acid-base indicator) the color red and that NaOH turns a solution of water and Neutral Red the color amber. What can you say about NaHCO3, which turns a solution of water and Neutral Red the color amber? Is NaHCO3 an acid or a base? Defend your choice.
6. Fill in the column labeled ?Acid/Base/Neutral? for each substance in the table below:
| Substance | pH | Acid/Base/Neutral |
|---|---|---|
| Stomach Contents | 1.5 | |
| Grapefruit | 3.1 | |
| Saliva | 6.8 | |
| Egg White | 7.8 | |
| Bleach | 12.5 |
7. In a video we saw that the light bulb did not go on when the wires were placed in tap water. Explain.
8. What is the main idea to keep in mind when explaining how salts, or ionic compounds, are formed? In other words: How do we determine what charge an ion will be when forming the ions in an ionic compound?