# What is the mole fraction of N2 when its 6.023*10^22 molecules are mixed (at NTP) with 2 g of He and 8g of O2? Please explain whats the use of NTP here. Also tell the difference between STP , NTP and RTP.

1
by shubhank

2015-04-10T17:02:19+05:30

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STP and NTP are same : standard temperature and pressure and normal temperature and pressure:  The temperature is 0 deg C and 1 atmospheric pressure.  This is a standard.  A gas occupies 22.4 liters at STP.

RTP is room temperature and pressure:  This is at room temperature 25 deg C.   The gas occupies around 24.1 litres at RTP.

1 mole of any gas contains 6.023 * 10^23 molecules at any temperature and pressure.  There is no use of  NTP  here for the calculation purposes.

N2 :  6.023 * 10^22 molecules = 0.1 moles
He : 2 gm = 1 mole
O2 :  8 gm   0.25 moles

Mole fraction of N2 :  0.1 /(0.1+1+0.25) = 0.1/1.35 = 20/27

Thanks.But you got the mole of helium wrong.No worries I got what I wanted.
Oh! it is 4 gm = 1 mole. then, answer is 0.1 / 0.85 moles = 2/17