Question

QUESTION 2 A sample of nitrogen gas is sealed into a 18.6 L container at 715.2 torr and 146.8 °C. How many nitrogen molecules are in the container? (Enter your value in E-notation with three significant figures.]

Answer 1

We have

Pressure P = 715.2 torr

we know that

1 atm = 760 torr

hence 715.2 torr = 715.2 $\times$ 1/760 = 0.94 atm

Volume = 18.6 L

Temperature T = 146.8 ⁰C = 146.8 + 273.15 = 419.95 K

We know the ideal gas law equation

PV = nRT

where

R = 0.0821 L.atm/mol.K

n = number of moles of gas present in sample

hence by using given values and above formula we get

PV = nRT

n = PV / RT

= 0.94 atm $\times$ 18.6 L / ( 0.0821 L.atm/mol.K $\times$ 419.95 K)

= 0.512 moles of N₂  

Now we know that

1 mole of gas = Avogadros number of molecules = 6.022 $\times$10²³ molecules

hence

0.512 moles of N₂ = 0.512 $\times$ 6.022 $\times$ 10²³ molecules of N₂

= 3.08 $\times$ 10²³ molecules of N₂

In E-notaion our answer is 3.08e+23 molecules