help with chemistry homework....

hey im not sure if i can post this here, if not a mid can delete it or move it to a different section. i have been helping my friend with there chemistry and i am stuck on this one. maths is not my strong point... if anyone can help on this i would be grateful...

One cubic metre (1 m3) of atmosphere at sea level contains 3.80 × 102 ppm of CO2 and 5.00 × 103 ppm of water vapour.
If there is a total of 2.6 × 1025 molecules in 1 m3 of air, calculate how many molecules of CO2 and water vapour there are in 1 m3 of air. Give your answers to the appropriate number of significant figures.

thank you

kx

stoichiometry

and Alvagrado's number I believe you have to use.... Haven't done those problems in a while so....not tooo sure.

reply to post by purplemer


I believe you mean 3.8 x 10^2 and 5.00 x10^3
and
2.6 x 10^25 which is one atmo-meter.

If that is the case, find out how many millions are in 2.6 x 10^25.

Then find the percentage of 380 and 5000 in a million.

Then mulitply and you have the answer.

reply to post by purplemer


The whole point of homework is so that you learn the subject matter on your own. Moreso it is a tool to teach you how to find the answer to a subject that you need the answer for.

Chemistry is useless if you arent going to be a chemist or deal with chemistry in the work-force.

Prime example of how they should cut lots of highschool and allow kids to specialize at a way earlier age....

If you arent going to be a chemist.....then that time could be spent learning the social skills to greet people at Wal-mart...or whatever you fancy being when you get out of school.

In short.....FIGURE IT OUT on your own.

Originally posted by ATC_GOD
reply to post by purplemer

 

The whole point of homework is so that you learn the subject matter on your own. Moreso it is a tool to teach you how to find the answer to a subject that you need the answer for.

Chemistry is useless if you arent going to be a chemist or deal with chemistry in the work-force.

Prime example of how they should cut lots of highschool and allow kids to specialize at a way earlier age....

If you arent going to be a chemist.....then that time could be spent learning the social skills to greet people at Wal-mart...or whatever you fancy being when you get out of school.

In short.....FIGURE IT OUT on your own.

Which is exactly why I didn't do the math for him, just pointed him down the right path. The rest is up to the OP.

see above /delete

reply to post by Long Lance

your answer was helpful i was trying to understand it could you please put it back up. once i can understand the method i wil find my own way of understanding it....

kx

reply to post by ATC_GOD


There is no harm in asking for help when you are stuck on a problem. What good would it do him to not ask for help and never understand the problem.

The OP is asking for help on ONE problem...let's calm down a bit ok?

is this correct..?

Ii did 2.6x10^25 divided by 1,000,000 then multiply by 380 = 9.88x10^21 thefor carbon dioxide

Originally posted by purplemer
is this correct..?

Ii did 2.6x10^25 divided by 1,000,000 then multiply by 380 = 9.88x10^21 thefor carbon dioxide

Almost.

To get how many millions are in 2.6 x 10^25 is correct: 2.6 x 10^25 / 1,000,000= 2.6 x 10^19


Then to get the carbon dioxide, you first need to take 380 / 1,000,000 to get the percentage: 0.00038

Then you take 2.6 x 10^19 * 0.00038 = 9.88 x 10^15


Then do the same for the other.

EDIT: You know...after thinking about it...you may be right in your calculations I haven't done chemistry in about 10 years...and I always hated ppm. I'm starting to think you don't need to do the "380/1000000" step. Sorry if I am confusing you even more hopefully someone can clarify.

You would think with all the self-proclaimed geniuses on ATS...this thread would of been flooded with help

reply to post by MindSpin


thank you for your help....
still not sure which is right though...

kx

Originally posted by MindSpin


Then you take 2.6 x 10^19 * 0.00038 = 9.88 x 10^15

I got a similar answer as mindspin, but his percentage is off. If you want to have the decimal in there it should be 9.88 x 10^17.

It should be .038%

Here is a conversion table I found:

Ppm (parts per million) to % (parts per hundred)

Example:

1 ppm = 1/1,000,000 = 0.000001 = 0.0001%
10 ppm = 10/1,000,000 = 0.00001 = 0.001%
100 ppm = 100/1,000,000 = 0.0001 = 0.01%
200 ppn = 200/1,000,000 = 0.0002 = 0.02%
5000 ppm = 5000/1,000,000 = 0.005 = 0.5%
10,000 ppm = 10000/1,000,000 = 0.01 = 1.0%
20,000 ppm = 20000/1,000,000 = 0.02 = 2.0%

So therefore 2.6 x 10^19 * .038 = 988 x 10^15 molecules of CO2

The percentage of water vapor (H2O) is .5%

Now finish the math for that and you should be on your way.

Originally posted by MindSpin

You would think with all the self-proclaimed geniuses on ATS...this thread would of been flooded with help

You know, you are right, however, since we can't spin this into a left against right arguement it won't get as much notice. lol

Should be of interest to the chemtrail community though.

Well there you go...three different methods with three different answers.

I'm glad we could help confuse you, , I bet this is the last time someone asks for help with homework on ATS.

reply to post by MindSpin


Just goes to show that there is more than one way to solve a problem.

I hope we helped him though.

Originally posted by purplemer
reply to post by MindSpin

 

thank you for your help....
still not sure which is right though...

kx

I used to teach college students at the local university.

Unfortunately, nobody got it right.

Some people were partly on the right track, but the mistake made was accounting for the "parts per million" two times. If you do that, you're off by a factor of a million.

Just account for the "parts per million" one time, instead of twice, and you'll have the correct answer using the clues provided.

Originally posted by Arbitrageur

Originally posted by purplemer
reply to post by MindSpin

 

thank you for your help....
still not sure which is right though...

kx

I used to teach college students at the local university.

Unfortunately, nobody got it right.

Some people were partly on the right track, but the mistake made was accounting for the "parts per million" two times. If you do that, you're off by a factor of a million.

Just account for the "parts per million" one time, instead of twice, and you'll have the correct answer using the clues provided.

edit on 24-2-2011 by Arbitrageur because: clarification

Oh! I messed that up. You are right, I did the million part twice. Answer should be 988 x 10^21 molecules of CO2.

reply to post by tsawyer2
Thanks for agreeing, but we're supposed to help the OP figure it out so it becomes a learning experience, not give out the answer, right?

I was hoping my clue might be enough along with all the other clues.

Originally posted by Arbitrageur
reply to post by tsawyer2

 

Thanks for agreeing, but we're supposed to help the OP figure it out so it becomes a learning experience, not give out the answer, right?

I was hoping my clue might be enough along with all the other clues.

I just figured his homework was already overdue, so no harm there now.