Chemistry 1-20-21 Chapter 7 Test Practice

CHEMISTRY: Here’s our practice with oxidation numbers and chemical formulas and a couple other things from Wednesday. What about polymers? Have you watched that vodcast? Super important!!

Are you using the Chapter 7 Stuff to Know sheet? Be sure and use it as a road map for your studying. I know it seems like a lot, but you can do it!

First priority – make sure that you have memorized EVERYTHING. Then, practice!!! Go to and make sure you can write and name chemical formulas. Practice, practice, practice!!! Then start practicing the different kinds of problems – do at least three of each one of them. And also try those on That’s always some good practice. And don’t forget about polymers!

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48 thoughts on “Chemistry 1-20-21 Chapter 7 Test Practice

  1. Question: How do you tell the difference between formula mass and molecular mass?

    Answer: The are the same except for the unit (formula=g, molecular=u)

  2. Q: Why do high density polymers melt more easily than low density polymers?

    A: The chains of a high density polymer can slide past each other much more easily than the cross linked low density chains can.

  3. Q: Why are environmentalists so concerned with carbon dioxide affecting the environment when it isn’t toxic?

    A: When carbon dioxide is released into the air, it undergoes a synthesis reaction with the water vapor in the air and/or in the ocean to produce carbonic acid. This carbonic acid can erode many things in the environment and can immensely affect life under the sea. Carbonic acid is also a component of acid rain, which can deprive trees and plants of their nutrients.

  4. Question: What is the first step of finding the molecular formula?

    Answer: You have to find the empirical formula first.

  5. Q: Why are lead pipes bad for water in homes, if lead doesn’t react with water.

    A: The lead will react with the water if it is slightly acidic, and that is toxic for humans to consume.

  6. Q: Why did/do people believe that the Hindenburg burned down from the hydrogen gas inside?

    A: A spark from static electricity could have ignited the hydrogen gas, which is extremely flammable and since there was metal framework it would have conducted the heat as well.

  7. Q: What is a catalyst and when would you use one?

    A: A catalyst is a substance that can be added to a reaction to speed it up by lowering the amount of energy you need from each substance to cause a reaction. You can use a catalyst when the alternative, waiting for the basic substances to react themselves, will take too long.

  8. Q: What term describes the formula that represents the smallest whole number ratio of the atoms of the elements in a compound?

    A: Empirical Formula

  9. Q: Why is potassium stored in airtight containers with a coating of oil?

    A: Potassium is highly reactive and will quickly react with water to form potassium hydroxide and hydrogen gas. When this reaction takes place, large amounts of energy and quickly transferred, causing an explosion.

  10. Q. What is the law of definite proportions/composition?

    A. A compound that always contains the same elements in the same proportions by mass, no matter where it’s found.

  11. Why should people be worried about CO2 emissions. CO2 can react with the water in the oceans or water vapor in the atmosphere and create carbonic acid which is corrosive

  12. Why should people be worried about CO2 emissions. CO2 can react with the water in the oceans or water vapor in the atmosphere and create carbonic acid which is corrosive

  13. Q. How do you get rid of a decimal in an empirical formula?

    A. You multiply all of the moles by the smallest number that will give you a whole number.

  14. Q: When you’re converting Molecules to grams can you go straight to grams?
    A: No, when using the Q formula you have to go from molecules to moles to grams.

  15. Ask – Write a deeper thinking question and answer from studying this chapter:

    Q: What is an example of a synthetic polymer and why is it considered synthetic rather that natural.

    A: Teflon is an example of a synthetic polymer because it is heat resistant and used in energy. This is also because they are bonded with carbon; making it highly resistant to items such as acids, bases and solvents.

  16. q: what’s the difference in formula and molecular mass?
    a: formula mass is measured in amu and molecular mass is in grams.

  17. Q: What is the law of definite proportions?

    A: A compound will always contain the same elements in the same proportions by mass, no matter where it’s found.

  18. Q: How can wheels be made out of rubber if it is a linear polymer?
    A: Goodyear found discovered vulcanization and it is where the rubber is cross-linked with sulfur so they will not easily melt or reshape.

  19. Q: Why does a baking soda (Sodium bicarbonate) volcano “erupt” once vinegar is added down the base of it?

    A: Acetic acid, also known as vinegar, reacts with sodium bicarbonate, a base, to form a neutralization reaction. This intern forms sodium acetate, water, and, most importantly carbon dioxide. This carbon dioxide is mostly responsible for the bubbling and eruption due to it expanding and leaving through the opening at the top of the volcano.

  20. Q: Why can’t you burn some polymers?

    A: Because sometimes the reaction will release chlorine gas, which is toxic

  21. Q:What affected the romans and may have poisoned them helping in the downfall of rome.

    A: The lead pipes and the cauldrens they used for their wine was lined with sugar of lead

  22. Q: Why won’t oxides of metals above iron in the activity series decompose with heat alone?
    A: The activity series is organized by the reactivity levels of metals, and the metals near the top are highly reactive. Since they are highly reactive, they readily form very strong compounds. As a result, during decomposition, heat alone is not sufficient enough to break apart these strong bonds. The more reactive a metal is, the more difficult it is to decompose its compounds.

  23. Question: On recycling how do you know if it is safe to recycle?

    Answer: There is a a number between one and six on the bottom. The lower the number the easier it is to recycle and the higher the number the harder it is to recycle.

  24. Why is there concern about carbon dioxide emissions, when carbon dioxide is not even toxic? There is concern because carbon dioxide can react with water in our environment to form carbonic acid, which is toxic to humans.

  25. Why is copper used for piping in homes? Copper does not readily react with oxygen, meaning it can’t form a toxic metal oxide. It is also corrosion resistant, so little bits won’t get into the water.

    • I forgot to put an answer!!! Lead is dangerous because it will break down in acidic conditions. It harms the production of red blood cells and the absorption of calcium.

  26. Question: What is the difference between an empirical formula and molecular formula?

    Answer: The empirical formula is the simplest form of a compound while the molecular formula is a multiple of it.

  27. Q: Why are metals near the top of the activity series never found free in nature?

    A: Metals near the the top are the most active meaning that they will react with a lot of things in nature causing them to always be in a compound rather than an uncombined element.

  28. What is the difference between thermosetting and thermoplastic?
    -thermoplastic can be remelted back to a solid but thermosetting is always a solid

  29. Q. What is a gun proof polymer that is commonly used in protective gear?

    A. Kevlar is the polymer that is used in those protective items.

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