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what is the mass of 7.00 litres of neon gas if the volume is measured at 0 degrees...

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lisa2190 | Student | eNotes Newbie

Posted January 19, 2012 at 3:52 AM via web

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what is the mass of 7.00 litres of neon gas if the volume is measured at 0 degrees celcius and 101.3 kPa pressure?

 

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pacorz | High School Teacher | (Level 3) Educator

Posted January 19, 2012 at 4:44 AM (Answer #1)

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To answer your question, we need to use the universal gas law:

PV = nRT

Where P = pressure in atmospheres

V = volume in liters

n =  number of moles of gas

R = .0821 L atm/Mole Deg K which is a gas constant

T = temperature in Kelvin

Before you put the numbers in to this formula, you need to convert degrees C to K: 0C + 273 = 273K

and convert 101.3 kPa converts to 1 atmosphere

Then:

1 * 7 = n (.0821) 273

7 = 22.4 n

0.3125 = n

Which means you have 0.3125 moles of Neon

1 Mole of Neon weighs 20.2 grams, so 0.3125 * 20.2 = 6.3 grams of Neon

 

 

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ndnordic | High School Teacher | (Level 2) Associate Educator

Posted January 19, 2012 at 5:28 AM (Answer #2)

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Your gas sample, at 0 degrees C and 101.3 kPa, is at STP, standard pressure and temperature.  At STP, one mole of any gas has a volume of 22.4 L.  Since you have 7 liters, you have 7/22.4 = 0.3125 moles of Ne.

0.3125 * 20.17 g/mole of Ne = 6.3 g of Ne

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