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 - 6.022 * 10^(23) -, which tells us how many molecules are in 1 mole of a substance.

(3.0 * 10^(25) mol ecu l e s)* (1 mol e)/(6.022 * 10^(23) mol ecu l es) = 49.8

moles; this means that 3.0 * 10^(25) molecules make up 49.8 moles of Ne gas.

We can now find out the volume by using

n_(Ne) = V/V_(mol ar) -> V = n_(Ne) * V_(mol ar)

V = 49.8 mol es * 22.4 L/( mol e) = 1100L -> rounded to two sig figs.

Dec 10, 2014

You can determine the volume of "3.0 x 10"^25" 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 10"^23. STP for gas laws is "0"^"o""C" 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 10"^25 "molecules Ne" x "1 mol Ne"/"6.022 x 10"^23 "molecules 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 K"^(-1) "mol"^(-1)
T = "0"^"o""C" + "273.15" = "273.15K"

Unknown:
Volume

Equation:
"PV" = "nRT"

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

"V" = "nRT"/"P"
"V" = "49.82 moles x 0.08205746 L atm K"^(-1) "mol"^(-1)" x "273.15K/1 atm" = "1100 L"
(The answer is rounded to two significant figures because "3.0 x 10"^25 has two significant figures.)

Answer:
The volume of "3.0 x 10"^25 "molecules Ne" at STP is "1100 L".