View Full Version : The mole
beauty lux
Jan 10, 2009, 01:27 PM
I truly am confused by this question. It gives no specific details.
Here it is.
Calculate how long a chain of paper clips would be (in inches) if you had one mole of them.
Can someone please answer this question, or at least guide me in the direction?
Curlyben
Jan 10, 2009, 01:30 PM
Break it down into things you know.
How many atoms in a mole ?
AND
How long is an average paper clip ?
Hint: The answer is a VERY large number.
beauty lux
Jan 10, 2009, 01:44 PM
Yea I kind of figured that.
BUT
The big factor in this is that I just enrolled in chemistry..
Literally I don't know how to count atoms. How atoms are linked to moles or anything..
Curlyben
Jan 10, 2009, 01:51 PM
A Mole of atoms has a definition, what is it ?
Basically there are X atoms in a mole, what is X?
Have a read of this: http://en.wikipedia.org/wiki/Mole_(unit)
beauty lux
Jan 10, 2009, 02:00 PM
Okay.
6.02*10 to the 23?
Curlyben
Jan 10, 2009, 02:02 PM
yep that's it.
6.02*10^2^3
The rest is easy.
Isn't learning fun ;)
beauty lux
Jan 10, 2009, 02:03 PM
:)
What about the rest?
This is totally confusing
Curlyben
Jan 10, 2009, 02:05 PM
Well you know what value a mole is, so now multiply by the length of a paperclip.
Then BINGO...
beauty lux
Jan 10, 2009, 02:07 PM
Okay.one last thing.
I am truly asking this question
How do you count the ruler marks.
There's like 15marks and I thought a normal ruler was different.
Curlyben
Jan 10, 2009, 02:10 PM
Now there you've got me.
Normally the small marks are 1/16th's
To be honest the actual length isn't really that important.
What they are looking for here is that you have researched what a mole is.
After all paperclips come in tons of different sizes.
beauty lux
Jan 10, 2009, 02:13 PM
Okay
Thank you sooo much!
Curlyben
Jan 10, 2009, 02:16 PM
No worries.
Glad to help.
beauty lux
Jan 10, 2009, 02:16 PM
One more thing.
Okay so you helped me find the 6.02*10 23 thingy.
Now I have the measure of the paperclip.
1 4/16
Now how would I use the conversion chart to do that.
The answer has to be in inches.
Would it be a multiple step problem?
Curlyben
Jan 10, 2009, 02:19 PM
Well the paper clip is X inches
and a Mole (Mol) is 6*10^2^3
so it's simply
X*Mol Inches
Make sense ?
beauty lux
Jan 10, 2009, 02:22 PM
Lol sort of.. but then again the fraction is going to get me.
Would the answer be a mixed number or fraction or just a whole number?
I'm so annoying
Curlyben
Jan 10, 2009, 02:24 PM
Hey make it easy on yourself and say the paperclip is 2 inches ;)
Did they give you the paperclip to use or was it one you found in the house.
beauty lux
Jan 10, 2009, 02:27 PM
One I found in the house.
Curlyben
Jan 10, 2009, 02:30 PM
Cool, so juts say it was 2 inches.
Makes thing easier all round.
beauty lux
Jan 10, 2009, 02:31 PM
Okay. I think I have the answer.would the answer be 12.04*10 to the 23rd?
Curlyben
Jan 10, 2009, 02:35 PM
That's it.
Remember the answer isn't the whole problem.
You need to show you whole working as I laid out in #14 above.
That's how you get the full marks.
beauty lux
Jan 10, 2009, 02:39 PM
Okay.thank you
Can you stand for another question.(chemistry worksheet but this is the last question.) not about the same question though.
Curlyben
Jan 10, 2009, 02:40 PM
Post it up on a new thread and we'll see what can be done.
I don't mind guiding, but I won't do the work for you.
Show us what you have tried and we're all good.
beauty lux
Jan 10, 2009, 02:44 PM
Okay this question is even more confusing then the first one.
Here it is.
The distance around the earth to the sun is apporximately 25,000 miles. Calculate how many times your paper clip chain could wrap around the earth.
How would you begin this problem?
Curlyben
Jan 10, 2009, 02:47 PM
Right then
I have put these two together as they are a follow on.
Is that how the question is written as it's seems slightly confused.
After all it mentions earth to sun and then earth on it's own.
beauty lux
Jan 10, 2009, 03:11 PM
Yeah.. I accidentally looked on the other problem.
It is written without the sun stuff.
The distance around the earth is approximately 25,000 miles. Calculate how many times your paper clip chain could wrap around the earth.
That's how it is really written.
Curlyben
Jan 10, 2009, 03:12 PM
OK so again break it down.
Forget actual numbers for now as this will get slightly messy.
So how many inches in a mile ?
beauty lux
Jan 10, 2009, 03:14 PM
Honestly I don't know..
I do know that there is 5280ft in a mile and there's 12inches in a foot.. so would I mutliply 5280 and 12 or something else?
Curlyben
Jan 10, 2009, 03:16 PM
Yep that's dead right.
Here's a whole write up about it: inches (http://www.math.ucr.edu/home/baez/inches.html)
Interesting in a geeky kind of way ;)
So we then need to convert the Paperclip mole inches into miles.
beauty lux
Jan 10, 2009, 03:19 PM
Okay. So there's 63,360inches in a mile. So from there would I... okay.confused
Curlyben
Jan 10, 2009, 03:21 PM
Hint:
Inches/conversion = Miles
Make sense ?
beauty lux
Jan 10, 2009, 03:22 PM
Yeah but how would the paper clips fit into all of it?
Curlyben
Jan 10, 2009, 03:24 PM
Well we know the length, in inches, of a mole of paperclips.
So we need to convert that to miles and divide by the circumference of the earth.
You following this ?
Told you it gets messy
This is one reason the SI units of measure, e.g. cm, kg, km, etc...
http://en.wikipedia.org/wiki/Si_units
beauty lux
Jan 10, 2009, 03:29 PM
So would I multiply the paperclips to 25,000 and divide the answer by 63360?
Curlyben
Jan 10, 2009, 03:35 PM
almost.
You need to convert the paperclips to miles.
Paperclips/63360 = miles
Then divide the 25,000 by the paperclip miles above, or the other way round.
beauty lux
Jan 10, 2009, 03:39 PM
Okay I did that and it came up zero..
It started with .0001895*10 to the 23/25000
Would I take the leading zeros away or no?
Capuchin
Jan 10, 2009, 03:39 PM
You need to divied the length of your paperclips in inches by 63360 to get the length of your paperclips in miles.
THEN you divide that answer by 25,000 to get the number of times the paperclip chain will wrap around the Earth.
Once you've done that, sit back a little bit and make sure you understand why we're dividing here.
If you don't I could explain it a bit more in depth. (please ask! )
beauty lux
Jan 10, 2009, 03:47 PM
So, would I take 12.04/63360/25000?
beauty lux
Jan 10, 2009, 03:49 PM
Would the answer be .0327716*10 to the 23?
Curlyben
Jan 10, 2009, 03:52 PM
Remember the actual answer isn't all that important.
How you got there is what the teacher is looking for.
BTW, errr the number doesn't look right ;)
Capuchin
Jan 10, 2009, 03:53 PM
No, think about it, you're dividing by 10^5 twice, so the answer will be somewhere close to 10^{(23-5-5)} = 10^{13}.
Your answer is about 10^{21}.
It's important to use quick mental calculations like this to make sure your answer sounds sensible.
beauty lux
Jan 10, 2009, 03:56 PM
Can you explain?
I'm lost
Capuchin
Jan 10, 2009, 04:00 PM
I'm not sure where you're going wrong. You're right to perform ((12.04*10^23)/63360)/25000.
What do you get as an answer to this? It should be somewhere near 10^13,
beauty lux
Jan 10, 2009, 04:05 PM
I think my problem is the fact that I do not multiply the 10 to the 23 to 12.04... my answer was completely off. It was .0328535*10 to the 23...
Totally wrong I think..
I don't understand the 10th power at all.. super confusing
Capuchin
Jan 10, 2009, 04:10 PM
It's scientific notation, you can write 10^23, or you can write 100000000000000000000000 (23 zeros). It's just a more compact way of writing bigger numbers.
If you are using a calculator, it will have an Exp or E button. If you hit 12.04 [Exp] 23, then it should put the number in correctly. You should talk to your teacher about this. Learning about moles before you know about scientific notation is harsh!
beauty lux
Jan 10, 2009, 04:16 PM
No.
I know about scientific notation, and all that jazz.
But I didn't understand when you put 10(23-5-5)...
Why did you subtract 5?
And my calculator is very odd.
It doesn't have any "symbols" pertaining to EXP or E..
beauty lux
Jan 10, 2009, 04:23 PM
Are you familiar with the "log" button..
I came up with the answer 1.035050704*10 to the -3
Capuchin
Jan 10, 2009, 04:24 PM
because 10^23/10^5 = 10^23-5 = 10^18
You can also just enter 12.04*10^23. You should have ^ or x^y or some kind of similar button.
Capuchin
Jan 10, 2009, 04:26 PM
You don't want to use the log button, that's something a little different.
beauty lux
Jan 10, 2009, 04:30 PM
Okay.
I used one that has an "x" and it has like a blank next to it.
Would that be the right one?
The answer I received on the calculator with the "x" button was 7.151698532*10 to the 24
Capuchin
Jan 10, 2009, 04:32 PM
What model is your calculator? :)
beauty lux
Jan 10, 2009, 04:34 PM
It's a casio fx-115 ES
Capuchin
Jan 10, 2009, 04:42 PM
it has a x10^x button at the bottom, try using that.
just hit 12.04 [x10^x] 23
beauty lux
Jan 10, 2009, 04:45 PM
Okay.. I got 1.204*10 to the 24th
Capuchin
Jan 10, 2009, 04:47 PM
Yes, now divide by 63360, then again by 25000
beauty lux
Jan 10, 2009, 04:49 PM
Okay I got 7.601010101*10 to the 14th
Capuchin
Jan 10, 2009, 04:54 PM
that sounds right to me, it's close to 10^13 :)
beauty lux
Jan 10, 2009, 04:54 PM
Is that the final answer?
Or is it incorrect?
beauty lux
Jan 10, 2009, 04:55 PM
Okay.
Thank you!
I'm very grateful
beauty lux
Jan 10, 2009, 04:58 PM
Could you help me on this question?
The distance form Earth to the Sun is approximately 93,000,000 miles. Calculate how many times your paper clip chain could make it to the sun and back.
Would I start this problem by finding out how many inches goes into 93,000,000 miles?
Capuchin
Jan 10, 2009, 04:59 PM
Well, think about what you did in the last question!
beauty lux
Jan 10, 2009, 05:06 PM
In the last one.the first thing I did was convert inches to miles.
So would I take 1.204*10 to the 24/93,000,000/63360?
Or because the question is asking for me to calculate the distance there and back.would I take 93million times 2?
Or am I overthinking?
Capuchin
Jan 10, 2009, 05:11 PM
You do need to multiply it by 2, but 63360 is your conversion from inches to miles.
So 1.204*10 to the 24 is the length of your chain in inches
1.204*10 to the 24/63360 is the length of your chain in miles and
1.204*10 to the 24/63360/25000 is the number of times the chain goes aroudn the earth.
This should be very easy to alter for your current question.
beauty lux
Jan 10, 2009, 05:16 PM
okay. So the equation would look like this.
1.204/63360/186000000 would be the equation?
Capuchin
Jan 10, 2009, 05:31 PM
yeah but don't forget your 10^24
beauty lux
Jan 10, 2009, 05:34 PM
Okay.
So the answer I got was 1.021641143*10 to the 11th
Capuchin
Jan 10, 2009, 05:45 PM
Sounds about right.
I think the point your teacher is trying to get across is htat a mole is a large number :)
beauty lux
Jan 10, 2009, 05:47 PM
Thanks a bunch..