How can I find the volume of 3.0 x 10(25) molecules of Neon gas at STP?

2 Answers
Dec 10, 2014

The answer is 1100L.

In order to determine the volume of Ne gas at STP, you need to know that at STP (standard temperature and pressure), 1 mole of any ideal gas occupies exactly 22.4L.

We must however find out how many moles of Ne we are dealing with. We do this by using Avogadro's number - 6.0221023 -, which tells us how many molecules are in 1 mole of a substance.

(3.01025molecules)1mole6.0221023molecules=49.8

moles; this means that 3.01025 molecules make up 49.8 moles of Ne gas.

We can now find out the volume by using

nNe=VVmolarV=nNeVmolar

V=49.8moles22.4Lmole=1100L -> rounded to two sig figs.

Dec 10, 2014

You can determine the volume of 3.0 x 1025 molecules of Neon at STP using the ideal gas law: PV = nRT, solving for V. You must convert the molecules of Neon to moles using Avagadro's number, 6.022 x 1023. STP for gas laws is 0oC and 1 atm. You will need to convert the Celsius temperature to Kelvins, which is the temperature scale used in the gas laws.

Convert molecules of Neon to moles.

3.0 x 1025 molecules Ne x 1 mol Ne/6.022 x 1023molecules Ne = 49.82 moles Ne
(I'm leaving some guard units to reduce rounding errors.)

Given/Known:
P = 1 atm
n = 49.82 moles
R = 0.08205746 L atm K1mol1
T = 0oC+273.15=273.15K

Unknown:
Volume

Equation:
PV = nRT

Solution:
Divide both sides of the equation by P. Solve for V.

V = nRTP
V = 49.82 moles x 0.08205746 L atm K1mol1 x 273.15K/1 atm = 1100 L
(The answer is rounded to two significant figures because 3.0 x 1025 has two significant figures.)

Answer:
The volume of 3.0 x 1025 molecules Ne at STP is 1100 L.