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2. How many molecules are contained in 25 L of N₂ at S. T.P.?

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12 votes

Answer:

6.721 x 10 ^23 molecules

Step-by-step explanation:

At STP an ideal gas has 22.4 liters per mole

25 liters / 22.4 liters/mole = 1.11607 moles

1.11607 moles * 6.022 x 10^23 molecules/mole = 6.721 x 10^23 molecules

User Harmelodic
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Step-by-step explanation:

How many nitrogen molecules are in 1 liter of nitrogen gas at STP?

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Pete Gannett

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Ph.D. Chemistry, University of Wisconsin-Madison, (1982)2y

Seems to be an ideal gas law question. The relevant equation is:

PV = nRT

where P is the pressure in atmospheres, V is the volume in liters, n is the number of moles of gas, R is the gas constant (0.082 atm-L/mole-deg K), and T is temperature in Kelvins. STP means standard temperature and pressure and this is taken as 1 atm and 0º C or 273 K.

To calculate the number of molecules we will use the constant 6.023 * 10^23 molecules/mole and, therefore, we will need to know the number of moles (n). So, first we’ll rearrange the gas law equation, isolating ’n’ and then put the numbers in.

n = PV/RT = 1 * 1 / (0.082)(273) = 0.0447 moles

So, to calculate the number of molecules, multiple this by the number of molecules in a mole and you get:

# molecules of nitrogen in 1 Liter at STP = 6.023 * 10^23 molecules/mole * 0.0447 moles = 2.6905 * 10^22 molecules

Note, it does not matter what the gas is.

User Matheus Araujo
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