Avogadro's law

[djmacarro]

In my chemistry clase I had to proform an experiement that proved avogadro's law

Equal volumes of gases under the same temperature and pressure contain equal numbers of molecules.

 

no i need ot know why this is significant in the relm of chemistry as a conclusion

 

i am not a chemist and have no idea why the volume of 1 mole at STP is 58.016 cm3 of Hydrogen gas is important

[niviene]

I still think it's more amazing that Avogadro did this nearly 200 years ago....

[djmacarro]

yes italians are amazing but this is do soon and i have no idea what to say, all i need i like a few sentences

[niviene]

What to say about what? You're asking us to do your homework for you? :Alien: Why not do a little internet research or something?

[djmacarro]

Yes, i did all i got was 6.3 times 10^23 (something liek that)

 

i have to get this done becuase my professor is CRAZY, littlerally he picked a student up and threw him for not covering a Silver Nitrate container

[Qfwfq]

Apart from the conceptual importance and the kinetic theory of gas, a great practical importance is that, if you need the right stechiometric proportions for a chemical reactions, when the ingredients are gasses at equal pressures, you can just use the volumes. Consider:

 

2 H2 + O2 --> 2 H2O

 

You want exactly twice the moles of hydrogen as oxygen. As long as they aren't at high enough density to deviate from the ideal gas behaviour, you can get the amounts right by volume.

 

I still think it's more amazing that Avogadro did this nearly 200 years ago....

:Alien: I don't find that so amazing, science was in full swing well before that.

[niviene]

:) I don't find that so amazing, science was in full swing well before that.

 

Yes, I should have been more specific. I find it amazing that 200 years ago he was capable of doing this without the equipment we have around today. I find this very impressive. :)

 

Also, if you have a professor putting his hands on his students, you need to tell someone. That is extremely illegal. :)

[Dark Mind]

I don't think it's very illegal in college. My current Physics teacher (in high school) enjoys reminiscing about how he used to wire his students (the ones that fell asleep often) chairs with electrical wires and give 'em a volt or two to wake them up :) . He also turned out all the lights in an underground detention room once, he told the students (the ones that were awake) to exit the room as quietly as possible first, he then slammed a book on a desk as hard as he could and the once sleeping student shot up out of his seat and after a couple of seconds screamed "I'm blind!!!". :)

[Qfwfq]

I find it amazing that 200 years ago he was capable of doing this without the equipment we have around today.

I'm not so sure he counted the number of atoms or molecules. He figured the same number of moles of different gases would have about the same volume. This can be verified without counting molecules but by using stechiometric ratios of reactions, when at least two of the substances involved are gasseous, such as the one I used as an example. At that time the atomic theory of chemistry wasn't yet fully verified and Avogadro's work was extra evidence for it. When atoms and molecules could be actually counted, the number in a mole was named in his honour because it's a relevant matter.

[niviene]

Ahh... I guess that kind of eliminates why it was so amazing to me :)

 

Dark Mind, yes, a professor hitting a student even in college is completely illegal, just as it is to hit anybody on the street, not to mention that you can forget about keeping your job. :) Although I think playing pranks is pretty funny and a lot of professors get away with it (I've seen some pretty good ones), threatening a student with violence is also assault, and once you actually put your hands on the student as he claims happened, then it becomes battery as well. If there are that many witnesses, it just isn't a real smart thing to do.... playing a joke is one thing, but beating up a student because of "not covering up a container" is a little over the line.... Not to mention that if you start talking about "in high school" it becomes even more complicated, and the public loves to hang teachers who physically abuse their students. I'm sure if some disgruntled parent or student went to the media saying his teacher was shocking him in class, they could have a field day with it, and it would turn into a huge, totally blown out of proportion ordeal, but that's just the way the public is anymore.... silly persons. :)

[Dark Mind]

Well that's not completely true either, about a month ago we had a substitute teacher on campus that physically threw a student into a seat, threw another out of the class, and refused to let the remaining, scared students leave the classroom. And he got away with it all because he was "Keeping the peace and maintaining order.". It turned out two of the students in a Culinary Arts class were arguing with raised voices in the back of the class and when the sub told them to cut it out they got out of their seats and one of the students pushed the other, and that was enough reason for the sub to think they were going to fight and he took action.

 

Super Sub to the rescue!!

[Biochemist]

Ahh... I guess that kind of eliminates why it was so amazing to me :)

Well, Avogadro became more famous by being the main ingredient in guacamole dip.

[Qfwfq]

Ahh... I guess that kind of eliminates why it was so amazing to me

I think I may well suppose that what you found amazing was the idea that he had counted the actual number of atoms or molecules before lab instrument technology was up to today's standards.

 

My reason for not finding it so amazing is radically different. It isn't because he didn't count the actual number, it's because the technology that he did use is as old as homo sapiens sapiens. Thanks to this technology he didn't need to actually count the number, in order to show that the number is the same for different gasses. I would also have found his achievement amazing, 200 years ago, if the human brain had developed mostly in the past century or two, like other technologies, but it hasn't. It's been around for some time, many scientific achievements have depended more on it than on other technologies. :xx:

[niviene]

Well that's not completely true either, about a month ago we had a substitute teacher on campus that physically threw a student into a seat, threw another out of the class, and refused to let the remaining, scared students leave the classroom. And he got away with it all because he was "Keeping the peace and maintaining order.". It turned out two of the students in a Culinary Arts class were arguing with raised voices in the back of the class and when the sub told them to cut it out they got out of their seats and one of the students pushed the other, and that was enough reason for the sub to think they were going to fight and he took action.

 

Super Sub to the rescue!!

 

 

Dark Mind - this is still illegal. I deal with this often. :( Any time anything physical is involved - ESPECIALLY when high school students are involved - it's against the law to put your hands on them. Even Correctional Officers working in Juvie Detention centers can't even stop children from beating others up even if it looks like they might kill the kid - they are trained to stand there and yell "stop" (yea... sounds real effective... :(). Once they put their hands on the offender or even try to pry them apart, (and the children know this, so they take advantage of it) they are held accountable and open to lawsuits. Of course, it all depends on one of the kids pressing charges, which obviously hasn't happened in your class, but regardless, I can tell you that charges could be pressed against your sub teacher for his actions. ...Unless you are in a different country. :( Not to mention that refusing to allow students to leave the classroom is considered illegal detention. Of course, if a school board were to stand behind the teacher's actions, he might have a better chance of getting off the hook....

[niviene]

Well, Avogadro became more famous by being the main ingredient in guacamole dip.

 

LOL

mmm... guacamole dip

[TeleMad]

In my chemistry clase I had to proform an experiement that proved avogadro's law Equal volumes of gases under the same temperature and pressure contain equal numbers of molecules.

 

no i need ot know why this is significant in the relm of chemistry as a conclusion

 

i am not a chemist and have no idea why the volume of 1 mole at STP is 58.016 cm3 of Hydrogen gas is important

 

I can think of a couple of reasons it comes into play. Consider the hypothetical reaction:

X(g) <-> 2Y(g) + Z(g)

 

1) The reaction has 1 mole of a gas as a reactant but 3 moles of gases as products, and thus will be accompanied by a volume expansion in the forward direction: three times the number of gas molecules takes up three times the volume (if volume is fixed, as in a closed reaction vessel, then the pressure will increase instead).

 

2) LeChatelier's principle. When the system of gases is at equilibrium and you increase the pressure, the applied stress will drive the reaction to the left: from the side with a higher number of gas molecules – 3 – to the side with a lower number of gas molecules – 1. If you decrease the pressure when the system is at equilibrium, you will drive the reaction to the right.

[niviene]

I can think of a couple of reasons it comes into play. Consider the hypothetical reaction:

X(g) <-> 2Y(g) + Z(g)

 

1) The reaction has 1 mole of a gas as a reactant but 3 moles of gases as products, and thus will be accompanied by a volume expansion in the forward direction: three times the number of gas molecules takes up three times the volume (if volume is fixed, as in a closed reaction vessel, then the pressure will increase instead).

 

2) LeChatelier's principle. When the system of gases is at equilibrium and you increase the pressure, the applied stress will drive the reaction to the left: from the side with a higher number of gas molecules – 3 – to the side with a lower number of gas molecules – 1. If you decrease the pressure when the system is at equilibrium, you will drive the reaction to the right.

 

Wow.. finally a real answer, and not an allusion to guacamole dip. Brilliant! :hihi: