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How many molecules are there in 122.35 L of H2 gas?The information provided is molar...

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tamanim | Student, Grade 11 | Honors

Posted December 10, 2012 at 3:34 AM via web

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How many molecules are there in 122.35 L of H2 gas?

The information provided is molar volume is 24.27 at STP

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ncchemist | eNotes Employee

Posted December 10, 2012 at 5:38 AM (Answer #1)

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We can use the molar volume of a gas given above to convert the volume of H2 gas to moles of H2 gas.  Then we can use Avogadro's number to find the number of molecules of H2.  First we start with the moles of H2:

122.35 liters (mole/24.27 liters) = 5.04 moles H2

We know that by definition one mole of a substance is equal to 6.022 x 10^23 units of that substance.  So we multiply the moles of H2 by Avogadro's number to get the number of molecules of H2:

5.04 moles H2 (6.022 x 10^23 molecules/mole) = 3.04 x 10^24 molecules H2

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