You are so excited - your first summer job! You are a hot-tub maintenance assistant. You travel to homes, making sure the pH of their hot-tub water is correct (between 7 and 7.6), and adjusting and cleaning when necessary. But before you get started, you need to answer the following questions.

1. What is pH? What do you use to test it? Why would it be important to keep the pH of hot-tub water between 7 and 7.6? (4 points)

2. You test the pH of your first hot tub's water. You discover that its pH is 8.1. Is the water too acidic or too basic? How could this pH harm the hot tub and the people in it? (4 points)

3. What do you need to do to get the hot-tub water back to an acceptable pH? What specific substance might you use? What type of chemical reaction could occur when you add this substance? What would the products of this reaction be? (6 points)

4. You notice that there are deposits of calcium carbonate (a hard, white substance) along the inside walls of the hot tub. What type of reaction caused this? In this type of reaction, what would you call the calcium carbonate deposits? (4 points)

5. Your workday is over, and you are headed to a friend's house for a barbecue. You are in charge of cooking the hot dogs. You will be using a propane gas grill. When you ignite the grill, propane (C3H8) reacts with oxygen (O2) to produce carbon dioxide (CO2) and water vapor (H2O). (11 points)

a. Write a balanced equation for this reaction. Be sure to show your work. (8 points)

b. What type of reaction is this? What are the common reactants and products for this type of reaction? (2 points)

c. This reaction can be classified as another type of reaction. What is it? (1 point)

6. After cooking the hot dogs, your friend's mom reminds you not to leave the grill out, or the iron (Fe) in the grill will react with oxygen (O2) in the air to produce rust (Fe2O3). (11 points)

a. Write a balanced equation for this reaction. Be sure to show your work. (8 points)

b. What type of reaction is this? What are the common reactants and products for this type of reaction? (2 points) c. This reaction can be classified as another type of reaction. What is it? (1 point)

7. If the grill gets rusty, should you use an acid or base to clean it? Explain why you chose an acid or a base, and give an example of an acid or a base you might use. (2 points)

8. You are done with grill duty, so you wander into the kitchen, where your friend's mom is baking gingerbread cookies. She is using a recipe that requires vinegar (HC2H3O2) and baking soda (NaHCO3). The reaction between vinegar and baking soda looks like this: HC2H3O2(aq) + NaHCO3(aq) → NaC2H3O2(aq) + H2CO3(aq) (8 points)

a. Is vinegar an acid or a base? Is baking soda an acid or a base? (2 points)

b. This type of reaction can be classified at least two ways. What are they? Explain each. (4 points)

c. Describe how this reaction is different from a single-displacement reaction. Give details about each type of reaction. (2 points)