Question

2. A sample of neon gas has a volume of 87.6 L at STP. How many moles are present?

Answer 1

Answer:

                      3.91 moles of Neon

Explanation:

According to Avogadro's Law, same volume of any gas at standard temperature (273.15 K or O °C) and pressure (1 atm) will occupy same volume. And one mole of any Ideal gas occupies 22.4 dm³ (1 dm³ = 1 L).

Data Given:

                 n = moles = ???

                 V = Volume = 87.6 L

Solution:

               As 22.4 L volume is occupied by one mole of gas then the 16.8 L of this gas will contain....

                          = ( 1 mole × 87.6 L) ÷ 22.4 L

                          = 3.91 moles

2nd Method:

                     Assuming that the gas is acting ideally, hence, applying ideal gas equation.

                              P V  =  n R T      ∴  R  =  0.08205 L⋅atm⋅K⁻¹⋅mol⁻¹

Solving for n,

                              n  =  P V / R T

Putting values,

                              n  =  (1 atm × 87.6 L)/(0.08205 L⋅atm⋅K⁻¹⋅mol⁻¹ × 273.15K)

                              n  =  3.91 moles

Result:

          87.6 L of Neon gas will contain 3.91 moles at standard temperature and pressure.