Chemistry Quiz
Pharaohmagnetic just posted a chemistry quiz on Shiny Things Distract Us. So as not to spoil things for you, I'm going to answer the questions in the comments for this post, which has the added benefit of timestamping my answers. So, go answer the quiz yourself, then come back and see my answers.
Update: discussion about the answers here.
Update: discussion about the answers here.
posted by JeremyHussell @ 5:23 p.m.
29 comments
29 Comments:
1. Name ten elements besides the following three examples: carbon, aluminum, oxygen.
There's antimony, arsenic, aluminum, selenium, and hydrogen, and oxygen, and nitrogen and rhenium, nickle, neodymium, neptunium, germanium, and iron, americium, ruthenium, uranium, europium, zirconium, lutetium, vanadium, and lanthanum, and osmium, and astatine, and radium, and gold, protactinium, and indium, and gallium... GASP... and iodine and thorium and thulium and thallium. There's yttrium, ytterbium, actinium, rubidium, and boron, gadolinium, niobium, iridium, and strontium and silicon and silver and samarium, and bismuth bromine lithium beryllium and barium.
There's holmium, helium, halfnium, erbium, phosphorus, francium, fluorine, terbium, manganese, mercury, molybdenum, magnesium, dysprosium, and scandium, and cerium, and cesium, lead, praseodymium, platinum, plutonium, paladium, promethium, potassium, polonium, tantalum, technetium, titanium, tellurium... GASP... and cadmium and calcium and chromium and curium. There's sulfur, californium, fermium, berkelium, and also mendelevium, einsteinium, nobelium, and argon krypton neon radon zenon zinc and rhodium, and chlorine carbon cobalt copper tungsten tin and sodium.
These are all the ones of which the news has come to Harverd. There may be many others but they haven't been discoverd.
Since that song was written, lawrencium, bohrium, rutherfordium, seaborgium, meitnerium, hassium, dubnium, and darmstadtium have all been discovered.
Wait, what was the question?
2. Arrange in order from smallest (1) to largest (6):
millimiter _3_
nanometer _1_
kilometer _5_
centimeter _4_
megameter _6_
micrometer _2_
3. Name three particles smaller than an atom.
Proton, neutron, electron, the six flavours of quark, leptons, muons, neutrinos... wait, what was the question?
4. What is the chemical name of table salt?
Sodium Chloride.
5. What is an ion?
A charged particle. Usually an atom that has lost one or more electrons.
6. If I add 1 kilogram of hot water (at 90 ºC) to 1 kilogram of cold water (at 10 ºC) and stir it all together, what is the new temperature?
Hmm. ~50 ºC, I think.
7. Now if I add 1 kilogram of metal (say, copper) at 90 ºC to 1 kilogram of water at 10 ºC, what will the new temperature approximately be?
Well, I know water has a higher specific heat than just about anything else, and metal is fairly low, so the temperature would be between below 50 ºC, but above 10 ºC. I haven't got a clue how much below, though.
8. What is the composition of air?
About 80% N2 and 20% O2. Although on the streets of a big city the pollutants probably add up to a percent or so.
9. Name a place where you might find carbon dioxide (besides air, which is really only 0.03% carbon dioxide anyway)
Mountain dew.
10. What is the physical difference between red light and blue light?
Red light has lower energy and wavelength than blue light.
11. What is a crystal?
A substance in which the atoms are arranged in a homogeneous lattice.
12. When you rub a balloon against your hair for a few seconds, it will stick to the wall. Why?
Static electricity. When you rub the balloon on your hair, electrons get transfered from one to the other, so the balloon (and your hair) ends up charged. The charge causes the balloon to stick to the wall. However, I don't know whether the electrons get transferred to the balloon or your hair.
13. What is the sun made of?
Mostly hydrogen, with some helium, and tiny amounts of other elements.
14. What are the states of matter?
Plasma, plus the three states of a burrito: solid, liquid, and gas.
Sounds a lot like fire, earth, water, and air, which makes me think we misused the word "element".
16. What is fire?
A too rapid exothermic reaction.
17. I balance two almost-full cups of water on a ruler over a pencil as shown (side view), making a crude set of scales:
[Can't see the picture]
If I insert my finger into one glass of water without touching the sides, what will happen?
The water will surface-tension itself to your finger, and the scale will tip up. I think. That's a good question.
18. Give three examples of an alloy.
Brass, bronze, and steel. That's zinc and copper, tin and copper, and iron and carbon, respectively. If you add chromium to steel, you get stainless steel.
19. Why is the sky blue?
Air refracts blue light more than it does the rest of the visible spectrum. As a result, blue light is scattered across the sky and reflected down to us from all over the place, wheras the rest of the light tends to come to us on a direct line from the sun.
20. Give three examples of a common chemical reaction.
Photosynthesis, oxidative phosphorylation, and muscle contraction. Ok, so those are really whole series of chemical reactions, but they are common.
For simpler reactions, try frying an egg, adding vinegar to baking soda, or lighting a match.
21. What are the standard scientific units for the following physical properties?
Length _meter_
Mass _gram_
Time _second_
Speed _meter per second_
Force _newton_
Pressure _atmosphere_
Energy _joule_
Power _watt_
Electric Current _ampere_
Alright, I had to check I was right on that. Turns out they use kilogram instead of gram (what?) and pascal for pressure.
22. Arrange in order of melting point, from lowest to highest: wax, ice, tungsten, table salt, gold, plastic
Well, ice and wax are at the bottom, with ice lowest, and tungsten is on top. For the rest, I'm guessing table salt, plastic, gold.
23. How does a hot air balloon work?
Hot air expands, so the air inside the balloon is less dense than the air outside, and therefore floats because it displaces more than its own mass.
24. What do you weigh? Now, what is your mass?
About 170 pounds in the morning (assuming I'm standing on a bathroom scale in North America). About 77kg.
25. Name something that you would find in your household that is an acid.
Vinegar
26. About how many molecules are in a raindrop?
The mass of the raindrop divided by the mass of 1 mole of water then multiplied by Avogadro's number.
you missed a corner-case phase of matter: the Bose-Einstein condensate. And from what Pharaoh tells me, the glass you put your finger in actually goes *down*, because of hydrostatic pressure. One last thing -- plastic's melting point is below salt's, as you can prove to yourself by trying to burn salt with a lighter. (its melting point is ~1070K).
27. What is the most interesting thing you learned in last year’s science class?
Since I wasn't in school last year, I'm answering "What is the most interesting thing you learned in science last year?" instead.
Unfortunately, I learn so many interesting things in science that I can't remember them all, much less what year I learned them. Worse, I can't rank them all by interestingness in a meaningful way. Here are a few of the interesting things I've learned fairly recently: non-genetic factors affecting worm longevity, DTAM seismic maps and world map, and last week a prof in computer graphics mentioned that a lot of the algorithms that model light in a rendered scene turned out to be applicable to radio, so that the graphics algorithms were very helpful for figuring out wireless transmission strengths in a simulated building.
Bose-Einstein condensate isn't a state of matter, I think. You can only make it work with bosons (particles that have a net integer spin). Besides, if you include that, you have to include superfluid and other esoteric quantum states that never affect chemistry.
For the glass of water trick, I think the answer depends on how fast you put your finger in. If you were to just barely touch the surface of the water, who knows what would happen? But really, this is a case of my suspicious nature convincing me it was a trick question.
Melting points: conceded; however, there are a lot of different plastics with a lot of different melting points. Are there any with really high melting points? (Or really low, too, my curiosity extends both ways.)
For the glass of water trick, I eventually realized that the behaviour was due to hydrostatic pressure and pascal's law. But at first, I thought that the glass went down because my finger is more buoyant than water. Hence, to hold part of it underwater, I have to be exerting a downward force on the cup/water system. I tested this hypothesis by dangling a metal spoon into the water. Sure enough, that cup went down too. Then I realized that all objects immersed in water experience an upward "buoyant" force equal to the gravity on the water that they displace, no matter their density. This force is, of course, met with a reaction at the bottom of the cup, which tips the scales. Neat!
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