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Topic: Calculating density using temp. and pressure  (Read 27604 times)

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Offline jylxox

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Calculating density using temp. and pressure
« on: October 23, 2009, 08:55:07 PM »
Calculate the density, g/cm3, of carbon dioxide   at   98.0 oC   and   807 torr.

Offline Boosted55

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Re: Calculating density using temp. and pressure
« Reply #1 on: October 23, 2009, 09:06:30 PM »
First you need the formula to find density, which is d = PM / RT.
Convert 807 torrs to atm by dividing by 760 torr. 807 torr x (1 atm / 760 torr) = 1.06 atm
Then find the molar mass of carbon dioxide, which is ~44g.
R is a constant. (~0.0821)
Convert 98.0 degree C to K, with is 98 + 273.15 K.
The plug everything in and you are good to do. Also remember that mL=cm3.

Offline jylxox

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Re: Calculating density using temp. and pressure
« Reply #2 on: October 24, 2009, 12:57:42 PM »
That's what I did.
P= 1.06 atm
M = 44 g
R = .0821
T= 371

(1.06 times 44)/(.0821 times 371) = 1.53

And the system says that the answer is wrong.

Offline Borek

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Re: Calculating density using temp. and pressure
« Reply #3 on: October 24, 2009, 04:06:09 PM »
What units is your answer in?
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Offline jylxox

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Re: Calculating density using temp. and pressure
« Reply #4 on: October 24, 2009, 05:43:30 PM »
The units are supposed to be g/cm cubed.

The units are not included in the answer.

Offline Borek

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Re: Calculating density using temp. and pressure
« Reply #5 on: October 24, 2009, 06:46:51 PM »
I am not asking what they are supposed to be, but what they ARE. You have calculated density to be 1.53 - of what? Pounds per kilogalon? Stones per cubic meter? Ounces per pint?
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Offline jylxox

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Re: Calculating density using temp. and pressure
« Reply #6 on: October 25, 2009, 02:55:49 PM »

P= 1.06 atm
M = 44 g./mol
R = .0821
T= 371 K

(1.06atm times 44g/mol)/(.0821 times 371K) = 1.53g/cm cubed.

Offline Borek

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Re: Calculating density using temp. and pressure
« Reply #7 on: October 25, 2009, 03:49:04 PM »
No. Check your units, especially for R.
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Offline butterwings

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Re: Calculating density using temp. and pressure
« Reply #8 on: October 26, 2009, 10:24:05 AM »
the R is equal to 0.08206, but it still the similar answer.

i dont understand this problem too! someone plz help?!

Offline Borek

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Re: Calculating density using temp. and pressure
« Reply #9 on: October 26, 2009, 10:59:15 AM »
I am not asking about numerical value, I am asking about UNITS.

For example - molar mass has units [gram/mole]. What units is ideal gas constant in, when its value is 0.0821?

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Offline typhoon2028

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Re: Calculating density using temp. and pressure
« Reply #10 on: October 26, 2009, 11:26:27 AM »
He is asking for your units "1.53 what?"

HINT....
If you used an R value = 0.082, the your volume units should be in liters.

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