Chem1A

· Each question will be scored out of a possible 25 points.

· You can use any sources for information, including the textbook, the Internet, classmates and other teachers. For each question, you must LIST your sources as the FIRST PART of your answer. Please be specific – cite the book title, author, and page number, identify teachers by name and department, provide web page titles and URLs for Internet sources. For classmates, first names are fine, but be specific about information they shared with you. Then, write your answer in your own words. I won’t give credit for answers that are simply copied. If you copy anything, put it in “quotes” or indent it, and give the source.

· Sources counts for 5 points out of 25 for each question.

· You can prepare your answers either electronically or hand-written (your score will improve if I can read what you wrote!) Include drawings or diagrams if the question asks for them. Cite your sources any diagrams that you copy.

· Parts of these questions go beyond the topics covered in this course. You don’t have to answer all the questions, right? Pick at least four to work on. Good luck!

1. Sugar and Electrolytes in Drinks

Every drink sold in the grocery store is labeled with its key chemical components, including carbohydrates, salt, and calories. You can find this information on company web sites.

Your assignment:

· Compare the contents of a fruit juice, your favorite soda, and at least two “sport” or “vitamin” drinks.

· Find out as much as you can about their chemical composition. Use the available information to convert weight % composition to molarity for sugar, electrolytes, and other components.

· If possible, identify the actual compounds or other products used to make the soda and drink recipes.

· Which drinks have the most calories per liter?

2. Smog and California’s Air Pollution Standards

You probably know that California sets the strictest standards in the U.S. for air pollution from cars, trucks, and other combustion sources. California also regulates volatile organic compounds, or VOCs. Here’s your chance to learn more about gas-phase redox chemistry and smog. Your assignment: Learn about the chemical reactions that make smog.

· Which components come from combustion? What chemical reactions happen in the air?

· Which components come from other sources? What chemical reactions to them?

· What is the role of light energy in these reactions (photochemical smog)?

· How do pollution controls reduce smog?

3. The Bohr Atom vs. the Schrödinger Atom

The quantum atom model allows us to predict the chemical properties of elements and compounds from basic principles of physics. Bohr was the first to describe the quantized energy levels of the atom. He used data from spectroscopy to determine these energy levels.

Your assignment: review the Bohr and Schrödinger models of the atom.

· Use the appropriate diagrams and formulas to show how the Bohr model predicts the wavelengths of light emitted by the hydrogen atom.

· Which of these wavelengths are visible to the human eye? Identify the specific energy level level transitions that produce the visible wavelengths.

· How does the Schrödinger model differ from Bohr’s? What can it do that Bohr’s cannot?

4. Carbon Dioxide in the Atmosphere

You’ve surely heard that the concentration of carbon dioxide in the Earth’s atmosphere is going up. If you’re interested in climate change or the other effects of carbon dioxide, here’s your chance to do some research. Please answer the following questions:

· How much has the carbon dioxide concentration increased since 1900? How fast is it increasing now?

· Where does all of this carbon dioxide come from? How much is from burning fossil fuels, and how can we tell the difference between this carbon dioxide and carbon dioxide that comes from, say, forest fires?

· Where does all of this carbon dioxide go? Is it absorbed by plants, or does it end up in water or in soil? What are the key chemical reactions of carbon dioxide in these places? What chemical changes occur when carbon dioxide dissolves in seawater?

5. Batteries, Then and Now

· The first rechargeable battery, the lead-acid battery, was invented by Gaston Planté in 1859. What material functions as the anode, and what material functions as the cathode? What reactions take place? What should the potential (voltage) be? What are the advantages and disadvantages of this battery?

· Zinc electrodes are still used in most disposable batteries, but acidic electrolytes were replaced by alkaline electrolytes around 1900. What material functions as the anode, and what material functions as the cathode? What reactions take place? What should the potential (voltage) be? What are the advantages and disadvantages of this battery?

· Modern battery development has focused on lighter materials with higher energy density. Lithium ion batteries were developed in the 1980s and first commercialized in 1991. John Goodenough, Stanley Whittingham, and Akira Yoshino shared the 2019 Novel Prize in Chemistry for their contributions to this invention. Commercial lithium ion batteries all use the same anode material, but there are competing cathode materials. What material functions as the anode, and what material(s) function as the cathode? What reactions take place? What should the potential (voltage) be? What are the advantages and disadvantages of these batteries?

6. Portland Cement

Portland cement is part of just about every building, road, tunnel, or bridge in the world today. Time to learn more about it (for me, too :-). It was invented in England and Germany in the 19th century, and the name refers to a type of stone found on the island of Portland in SW England. Here are some definitions: