Asked my chemistry teacher (first year of highschool) this "Why do we use the mole (unit) instead of just using the mass (grams) isn't it easier to handle given the fact that we can weigh it easily? why the need to use the mole?" And he said he "doesn't answer to stupid questions" | AskScience Blog

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Saturday, January 19, 2019

Asked my chemistry teacher (first year of highschool) this "Why do we use the mole (unit) instead of just using the mass (grams) isn't it easier to handle given the fact that we can weigh it easily? why the need to use the mole?" And he said he "doesn't answer to stupid questions"

Asked my chemistry teacher (first year of highschool) this "Why do we use the mole (unit) instead of just using the mass (grams) isn't it easier to handle given the fact that we can weigh it easily? why the need to use the mole?" And he said he "doesn't answer to stupid questions"


Asked my chemistry teacher (first year of highschool) this "Why do we use the mole (unit) instead of just using the mass (grams) isn't it easier to handle given the fact that we can weigh it easily? why the need to use the mole?" And he said he "doesn't answer to stupid questions"

Posted: 19 Jan 2019 06:17 AM PST

Did I ask a stupid question?

submitted by /u/Onigiri22
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Is the distance between atoms in a molecule like hydrogen gas constant? If yes, how is it kept constant?

Posted: 19 Jan 2019 05:19 AM PST

I read in a high school chemistry textbook that the distance between the protons of a H2 (hydrogen-gas) molecule is constant. It didn't explain why. It confuses me, as I always thought, since the electrons are constantly moving the coloumbic force on the nuclei should force like a tandem motion. At least it's what I always imagined that they all hold each other in place like they're connected by jelly strings.

submitted by /u/anearneighbor
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Do people with CIPA (insensitivity to pain) not experience things such as headaches or stomach cramps that occur within the body or are they only immune to pain exerted by external factors?

Posted: 18 Jan 2019 03:56 PM PST

What position of earth relative to the sun has humanity deemed the end/beginning of a calendar year?

Posted: 18 Jan 2019 11:04 PM PST

Now I understand that we'll need another reference point so say you're looking at a top view of the solar system and "North" or 0° is pointing to the center of our galaxy, what is the relative position of earth to the sun on new years day? An obscure question that came into my head today that I'd thought I'd ask.

submitted by /u/jpettyjhawk
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simple questions regarding air pressure?

Posted: 19 Jan 2019 04:06 AM PST

📷

not sure if i understand air pressure properly can someone correct my statements below if they are wrong...

  1. air pressure is caused by air's instrinsic property of wanting to expand (much like water but it expands at a much faster rate).
  2. Cold air expands slower than warm air thus cold air has a lower pressure than hot air.
  3. in an experiment where you place an air balloon with in a fridge, the balloon becomes flaccid and deflates due to a decrease in the air's activity; however, when it returns to room temperature, the balloon eventually returns to its original shape; that i understand, however my problem is that within the fridge doesn't the external pressure decreases due to its coldness and this balance of temperature within and without would achieve a pressure equilibrium in & out of the balloon and would leave the balloon inflated? someone correct the way i think about this.

thanks

submitted by /u/HREisGrrrrrrrreat
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Why some stars in the night sky look like they are changing colours or flashing light rapidly?

Posted: 18 Jan 2019 07:17 PM PST

I just saw one today in the clear night sky and was wondering. Sorry if it's a silly question. Thanks!

submitted by /u/thearcher122
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If a neutron is more massive than a proton, and a proton turns into a neutron when shedding a positron, does that mean that a positron has negative mass?

Posted: 19 Jan 2019 12:01 AM PST

When atoms shed a positron from the nucleus, one of the protons changes to a neutron, and the reverse happens when an electron is shed. If the latter reduces the mass of the atom by the mass of an electron, since the mass of a proton added to that of an electron equals the mass of a neutron, then does an atom that sheds a positron gain mass?

submitted by /u/PhenomenalPancake
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What happens to quarks and the nucleus after the quark escapes it? (QCD)

Posted: 19 Jan 2019 03:02 AM PST

Hi,

(Not a physicist by any means, just a fan)

After watching Dr. Don Lincoln's video about quantum chromodynamics I was left with a bunch of questions, was wondering if someone could please help clear a few things up :) :

  1. He describes the strong nuclear force as being similar to a rubber band in such a way that the farther the quarks get from each other the stronger the force pulling them back together becomes - is there a specific terminal distance where the force stops applying (or starts getting weakr again) ? Do we know how to calculate it?
  2. He talks about what happens when we knock a quark hard enough out of a nucleus, and as a result some energy becomes matter-anti matter pairs and a "jet" happens - I'm wondering what happens after?
    1. does one of those newly formed quarks get sucked in inside the nucleus making it stable (white) again? or does the original quark somehow return? I can't imagine the nucleus staying with only 2 quarks, can it?
    2. and what happens to the original knocked quark? does it get annihilated with one of the anti quarks created? or does it just go on? are lonely quarks outside of nucleus a thing we observe? if so how do they interact with other matter considering they have color charge?

Thanks!

submitted by /u/wutalman
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How does thermoacoustic engines work? How can they cool things down? Where does the excess heat go to?

Posted: 19 Jan 2019 06:27 AM PST

If there was a filter with holes the size of water molecules would water be able to go through the filter considering surface tension?

Posted: 19 Jan 2019 05:31 AM PST

Why does ”disturbing” near-freezing water cause an immediate phase change?

Posted: 18 Jan 2019 06:57 PM PST

I'm a biologist working in clinical research related to the abnormal microbiome in stem cell transplant patients.

In developing our current protocol, we've been freezing small plastic vials containing 1ml of water (in place of actual human bio matter, for the time being). Often I'll check on them after they've been in the freezer for hours, and they will be cold but not frozen — until I "disturb" the water by tilting the vial, at which point the water will immediately freeze. This is fascinating to me! What causes this?

And for bonus points, can anyone tell me how to calculate how long it should take for 1ml of fresh water to reach a frozen state in the average person's freezer? My physics is pretty rusty...

submitted by /u/vaginamancer
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why can many animals only mate during a specific time frame in the year, whereas humans can mate almost all year round?

Posted: 18 Jan 2019 05:12 PM PST

Title. Thanks :)

submitted by /u/hhitch_
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How did grass “colonize” the earth?

Posted: 18 Jan 2019 03:58 PM PST

In the example of a raised pendulum having potential energy and a swinging pendulum having kinetic energy...what happens to the stored energy if you never release the pendulum?

Posted: 18 Jan 2019 06:34 PM PST

I have always had trouble with this part of basic mechanics. I know that, in the case of pumping water up a hill, the stored potential energy is very close to literally storing energy. The amount of energy can be easily calculated, and the energy can be easily retrieved and used.

But the thing is...what if your water tank or your pendulum is raised up, but simply never allowed to fall again? Is the energy "locked" in the object forever, with the object literally having or possessing literal extra energy, stored by it having been lifted, which it just has forever? I would assume yes, if we're talking about a water tower that is filled, and then left alone for an arbitrary length of time. If the tank doesn't physically decay and leak, you could come back in a thousand years, and use the water pressure to do work. So, in that case, the energy really is stored forever.

But other versions of the analogy do not seem as clear. The very first time I heard of potential and kinetic energy, my elementary school textbook used an illustration of a guy preparing to swing on a rope, like Tarzan. The dude up on a tree limb, preparing to swing was the example of potential energy, and the motion-blurred picture of him actually swinging was the example of kinetic energy.

Here's the thought experiment that popped into my head, when I was nine (even though I didn't know that's what I was doing). Imagine that our Tarzan guy climbs up to his tree limb, to load up potential energy for his swing. He's getting ready to swing, all filled up with apparently literal potential energy...but then (just at the point where he's poised to initiate that transfer from potential to kinetic energy) he notices something behind him, at the exact same height as the tree limb he's perched on: a mesa or plateau, with a pretty little town just down a dirt road. All he has to do is decide to let go of the vine, step onto the road, and go for a short walk, to explore this village he's never seen.

Okay, so let's imagine that he not only lets go of the vine, and walks to the town, let's say that he really likes the town, gets a job, takes a wife, raises children, grows old, dies, and gets buried on that mesa, never once coming down from the height he originally climbed to, either by swinging vine, or by any other means.

Okay, so precisely what happened to that potential energy that was going to be kinetic energy when he was going to swing on the vine, but decided not to actually do it?

Did it dissipate as heat or sound? Did he literally carry it with him, as some kind of theoretical (or literal???) energy, all his life? Is it still there in his corpse, buried beside his wife, on the mesa? I kind of feel that answer has merit, because if you dug him up and tied his remains to the vine, he would totally swing off. And where else could the energy for swinging have come from, but from when he carried himself up onto the mesa, to begin with? Or is this all a stupid analogy, because gravity is accelerating us, and it isn't the climb up the hill that "gives" the energy to the swinger, but gravity pulling him down? In that case, it wouldn't be the energy he "brought" with him up the hill that would allow his dead body to swing off of it, 50 years later. See how confused I am? Help. I've been confused about this for pretty much all my life now, and it's starting to irritate me.

Can you clear this up for me? I want to have a better understanding of kinetic and potential energy, before my child-self's thought experiment becomes literally 30 years old.

submitted by /u/Noxalk
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Why are most of the biggest land animals herbivores?

Posted: 18 Jan 2019 03:35 PM PST

Elephants must spend like 80% of their lives just eating because the foot they eat is so low in calories. Meat is a lot more nutrient-dense than plants and high in calories and protein. So why are so many of the largest animals that need the most sustenance herbivores?

submitted by /u/FeelThePower999
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During a glacial period, when sea levels are dropping, would ocean salinity be significantly higher?

Posted: 18 Jan 2019 04:05 PM PST

Assuming my understanding of glaciation is correct. When sea water evaporates the salt is deposited. Because that water is lost to snow and ice, sea levels drop. That would seem to imply that ocean salinity should be higher given a reduced volume of water.

If that's the case...

  • Is that increase significant?
  • Is there any geological or biological evidence of this?
  • Would the opposite be true as glaciers continue to retreat and the global sea level rises? Would the effects be more or less significant?
submitted by /u/Ampatent
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Does compression effect the electrical conductivity of a material?

Posted: 18 Jan 2019 06:04 PM PST

Not necessarily to the point of trauma, but does pressure alter the flow of electrons through, let's say, copper in any meaningful way?

submitted by /u/Kirbs_McGurbs
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Why is the joint near your fingernail not considered a knuckle? What defines a knuckle?

Posted: 18 Jan 2019 03:45 PM PST

Does the placebo effect work in reverse?

Posted: 18 Jan 2019 07:43 AM PST

If you were to strongly believe that a functional medicine would not work, would it be less effective?

submitted by /u/Grindylow2
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Is E=MC(2) a vector? In other words does it require Motion to work?

Posted: 19 Jan 2019 05:09 AM PST

Does a group of people yelling at the same time make the sound travel farther than one person yelling?

Posted: 18 Jan 2019 11:02 AM PST

If yes, if everyone in the U.S. were all to gather on the beaches of Miami and all yell at the same time, will it travel far enough that people in Cuba will hear it?

submitted by /u/aktright
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How do centrifugal governors regulate speed to a constant rather then oscillating speed?

Posted: 18 Jan 2019 09:57 AM PST

Shouldn't a centrifugal governor constantly be oscillating around a stable point but not actually achieve it? If that were the case why don't tractor engines that use these sound like engines that are revving and releasing?

https://en.wikipedia.org/wiki/Centrifugal_governor

submitted by /u/Towns10
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