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### Topic: Chemistry homework help  (Read 19537 times)

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#### manjui

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##### Re: Chemistry homework help
« Reply #15 on: April 19, 2009, 01:06:07 PM »
Ok, sorry, the unit is grams. So 2.49*10^-4 grams.

#### ARGOS++

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##### Re: Chemistry homework help
« Reply #16 on: April 19, 2009, 01:08:15 PM »
Dear manjui;

Yes!, - You got:  n = 2.49 * 10-4 of what?   NO! - Its not gram!

Hint: Cancel out all possible units of your equation above.

Good Luck!
ARGOS++

#### manjui

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##### Re: Chemistry homework help
« Reply #17 on: April 19, 2009, 01:12:20 PM »
Ok, I am SO confused.
The answer of 2.49*10^-4 is not being accepted in my homework as the right answer. It says "Express your answer using two significant figures, m = ____ g"

#### ARGOS++

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##### Re: Chemistry homework help
« Reply #18 on: April 19, 2009, 01:20:31 PM »

Dear manjui;

If you do what I told you:
n =  2.6997 L * 1.75 Torr/62.363 L Torr K^1- mol^-1 * 304.15 K = 2.49 * 10^-4

What unit is now left ?

Good Luck!
ARGOS++

#### manjui

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##### Re: Chemistry homework help
« Reply #19 on: April 19, 2009, 01:22:48 PM »
mol^-1

#### ARGOS++

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##### Re: Chemistry homework help
« Reply #20 on: April 19, 2009, 01:29:42 PM »

Dear manjui;

A little more correct:  1 / mol-1  = mol!

Finally:  What is the weight of 1.0 mol Neon?;  -
- and what is the weight of 2.49 * 10-4 mol Neon?

Good Luck!
ARGOS++

#### sjb

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##### Re: Chemistry homework help
« Reply #21 on: April 19, 2009, 02:21:56 PM »
Your idea is correct!,  -  But the performance is wrong!     Sorry sjb!

The formula is: A =  r2 * pi * l  and not A = d2 * pi * l.
And take care for all Units!

Good Luck!
ARGOS++

My bad, thanks for the catch!

#### manjui

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##### Re: Chemistry homework help
« Reply #22 on: April 19, 2009, 03:23:53 PM »
ARGOS++, I have no idea

#### ARGOS++

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##### Re: Chemistry homework help
« Reply #23 on: April 19, 2009, 03:32:07 PM »

Dear manjui;

What is the molar mass, also called the molecular weight, of Neon?

Hint:
Use the periodic table and think about: 1.0 mole Carbon weights 12.011g and 1.0 mole Oxygen weights 16.0g, and 1.0 mole water weights 18.0g.

Good Luck!
ARGOS++

#### manjui

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##### Re: Chemistry homework help
« Reply #24 on: April 19, 2009, 04:00:19 PM »
Got it. Sorry, I was confused with where Neon came in! I got so caught up in the problem that I forgot I was dealing with the amount of Neon in the tube. Thank you for all your help.

#### ARGOS++

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##### Re: Chemistry homework help
« Reply #25 on: April 19, 2009, 04:05:55 PM »

Dear manjui;

You 're welcome!   ─   Soon again.

Good Luck!
ARGOS++