Chemistry 1-19-22 Chapter 7 Test Overview

CHEMISTRY: God bless you as you study! Here’s our great overview of the test from today and a look at some chemical names and formulas and oxidation numbers. Did you find 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 the Physics Classroom as a guest, 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!

HELP SESSION Thursday morning, 7:30 AM.

I’ll be praying for you! You can do it!!

Photo by Artem Bryzgalov on Unsplash

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41 thoughts on “Chemistry 1-19-22 Chapter 7 Test Overview

  1. I wanted to know why some plastics are dishwasher safe and some aren’t? It can go in the dishwasher if it’s thermosetting because it’s heat resistant. However if it’s thermoplastic it can’t because the plastic will melt under the heat.

  2. I have always wanted to know why you can only put certain plastics in a dish washer or microwave. It is because the heat resistant plastics are thermosetting polymers and won’t melt. And non microwave safe plastics are thermoplastic so they will melt under heat.

  3. Why don’t some plastics melt/burn? Some plastics do not burn because of the structure of the polymer. The structure of the specific polymer is called a chain linked polymer. The strands of monomers are attached in between. This causes them to be thermosetting because the strands of monomers do not slide past each other as easily as they would if the strands were not attached like they are in some polymers that are recyclable such as linear polymers.

  4. Question: What are some uses of thermoplastics in everyday life, that we may, or may not know about?
    Answer: Some examples of the uses of thermoplastics in everyday life is car parts, carpet, rope, different types of electronics, cookware, toilet seats, and many others.

  5. Why do some plastics have a higher melting point then others? There are some plastics that are cross linked and branched out to stop the plastic from melting and moving around. This is called Thermo Setting. There are also plastics that are thermo plastic, which melt at lower temps then the thermo setting plastics.

  6. Question: Why don’t all plastics melt?

    Answer: Some plastics, called thermosetting polymers, do not melt at all because it’s molecules are cross-linked, which causes a rigid molecular structure. The plastics that do melt, called thermoplastic polymers, are made up of linear molecular chains, which allows the polymer to soften into a liquid form.

  7. Question- why don’t all plastics melt?

    Different plastics melt at different temperatures and cannot be processed all in one settings. Some plastics don’t blend similar like oil and water and are not miscible in each other. But some plastics are thermosetting that are heat resistant.

  8. Why do some plastics melt in the microwave while others don’t?

    Some do not melt because the polymers are thermosetting which means they are cross linked which makes it heat resistant causing it to not melt.

    Some do melt because they are thermoplastic which means they are linear it causes it to melt when heated.

  9. Why are some polymers recyclable?

    Some polymers don’t melt when you heat them.Thermosetting polymers aren’t recycable because they tend to harden when heated.

  10. Question: what do the numbers mean in the inside of the recycle symbol on plastics?

    Answer: the numbers mean how recyclable that piece of plastic is. If it’s a low number it’s easily recyclable because it’s a linear polymer and when energy is added the polymer slides apart from each other and breaks. If it’s a high number it can’t be recycled as easy because it’s more than likely a branched or cross-linked polymer. This means when force is added to the polymers they stop from sliding away or breaking because they are either connected or there are branches stopping each other.

  11. Why did adding salt (NaCl) to water and Waterlock cause the substance to liquify?

    Waterlock is a cross-linked polymer so the salt went into the spaces and separated the cross-linked structure. This caused it to not be able to hold its shape, so the water inside began to leak out and the water-lock turned into a liquid like gel.

  12. Question: Why are some plastics flexible and some are not?

    Answer: Thermoplastics have weak polymer bonds. Thermosetting plastics are dense and retain their shape.

  13. Would a thermoplastic or thermosetting plastic be best used for a phone charger or laptop charger? A thermosetting plastic would be best for this since chargers are dealing with electricity. The thermosetting plastic would be resistant to burning, melting, or causing a fire.

  14. Question: How can you tell how recyclable a water bottle is?
    Answer: You can find out by looking at the number located on the bottom of the bottle. The lower the number, the more recyclable it is. The higher the number, the more recyclable it is.

  15. What plastic is not recyclable?

    The plastic number 3, polyvinyl chloride, is not recyclable in most cases and is harmful to the environment.

  16. Why does our brains only let us focus on one thing?

    This is because the brain can only use one sense at a time and this means that we can’t focus on more than one thing. This is why humans aren’t good multitaskers

  17. What are recycled plastics used for?
    Answer: Recycled plastic is good for the environment and saves money.
    Some of the uses are making clothes, blankets, rugs, and backpacks.

  18. Question: Why do some plastics melt when they are heated in the microwave?
    Answer: The ones that melt are thermoplastic polymers, which means that they will melt when heated

  19. Why are some plastics recyclable whereas others are not?

    It is because recyclable plastics are thermoplastic, meaning they melt when heated and are easier to reshape as a result.

  20. How Charles Goodyear know to mix sulfur with rubber? He accidentally spilt sulfur on a hot stove that combined it with rubber causing the rubber to be vulcanized.

  21. How are some plastics safe in a microwave and others aren’t? It is because some plastics are thermoplastic and melt when placed in heat. The ones that are safe are most likely thermosetting which means they are heat resistant.

  22. Q. What type of polymer would be best suited for making components for train wheels? Why?
    A. A cross-branched, thermosetting polymer, because the components would likely be heated by the friction of the wheels moving and possibly under stress in the event that the train has to brake.

  23. Why can some plastics be microwaveable and some melt in the microwave?
    The ones that are heat resistant are thermosetting and cross linked, which means the polyatomic bonds are held together and durable through heat. The ones that aren’t heat resistant are thermoplastic and linear which means, the polyatomic bonds slide past eachother and melt.

  24. What causes the composition of a polymer to be thermoplastic or thermosetting? It all depends on the elements that make up the polymer and how they are placed.

  25. Why are only some polymers recyclable? Polymers that are crossed linked have a stronger bond so they tend not to melt. If the polymer is linear then the strands tend to slide so they can melt and can then be recycled. This is why linear polymers are thermoplastic.

  26. I had always wondered why I could microwave some plastics without the plastic melting while others I couldn’t. This is because the ones that can melt are linear bonded, but the plastics that won’t melt are cross linked. The linear ones are called thermoplastic and the polymers will slide around easier causing it to melt. The cross linked ones are called thermosetting and the polymers will not slide around which causes the plastic not to melt.

  27. Why are some polymers recyclable and some aren’t. Because the linear type can’t hold itself together making it easier to Melt or ryciclable.but the ones like cross linked are all holding themselves together make it harder to not melt but to just catch flame.

  28. Why can some items be placed in the dishwasher while some can not? It can go in the dishwasher if it’s thermosetting due to it being heat resistant and cross-linked. However if it’s thermoplastic it can’t be placed in there because the plastic will melt under the heat since it’s linear.

  29. Why is polysnow bad to inhale? Polysnow can be bad to inhale because it can absorb the water in your lungs making it difficult and painful to breathe.

  30. Why can some polymers be used in plastic bags and others used in hard plastic crates? Plastics such as crosslinked polymers are used for hard plastic crates because their shape allows them to be stronger. Crosslinked polymers are long lines of linear monomers connected by other lines of linear monomers. Because they are connected, when pressure is added they don’t break as easily. On the other hand, linear polymers are used in plastic bags. This is because they are very flimsy and breakable. Linear polymers are made of lines of linear monomers stacked on each other. When pressure is applied they break very easily and heat up very easily. Branched polymers can also be used in stronger plastics like milk jugs because of their shape. They are designed like crosslinked polymers, except for the fact that the lines of monomers do not connect to each other. They do though, have branches of monomers coming off the sides of them. This causes them to act much like cross linked polymers when pressure is added.

  31. How do you know if something plastic is recyclable?

    Locate the number on the item 1-6. 1 being most recyclable and 6 being least recyclable.

  32. Why are some polymers thermosetting while others are thermoplastic? The make up of the polymer decides wether or not it will be. When it’s cross linked it’s thermosetting which means it’s heat resistant while linear polymers are thermoplastic they slide when heated.

  33. Question: Why are some plastics recyclable and others aren’t?
    Answer: Some plastics are thermoplastic, meaning that they melt when heated and are easy to shape into new products. Others are thermosetting, which means they are heat resistant and would not be recyclable.

  34. Why does a milk carton have a recycling symbol with a 2 inside it, while a mustard bottle has the same symbol with a 1?-Because the lower the number inside the symbol, the easier and more efficiently it can be recycled.

  35. Why do some polymers not melt? It is because of their structure. They are cross linked which means branches attach together and make it harder to pull apart. This results in them not melting as easily. They are also thermosetting which makes them heat resistant

  36. Why can some polymers hold so much heat while others can’t . The reason is the type of polymer that it is made out of of. Cross-linked can not hold as much as heat as linear. Linear polymers has room for the heat to wiggle through cross-linked can not.

  37. Why did all of the water spill out of the polymer when salt was sprinkled on it?

    The water took up space between the crosslinks of the polymer, which caused it to expand so much. Salt, similar to when ingested in the body, caused the water to spill out of the absorbent polymer.

  38. Why are some plastics able to melt so easily while others aren’t? The reason why some plastics melt is because they are made of linear polymers which melt easily because the polymers slide right past each other while plastics made out of cross-linked polymers don’t melt because they are stronger and won’t slide past each other

  39. I wonder why the polymer reacted that way when sodium was added to it. The polymer already had sodium in it so i don’t understand why it collapsed. I guess it probably breaks down the polymer causing the water to go everywhere.

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