Calculate the mass of 120cc of nitrogen gas at ntp. How many number of molecules are present in it. Easy step of mole concept

Explanation:

The formula of nitrogen gas is given as;

          N₂

  Given volume of the gas = 120cm³

Now,

 We need to find the number of molecules and the mass of this compound

Solution:

At STP;

     1 mole of gas occupies a volume of 1dm³ ;

          1000cm³  = 1dm³

          120cm³  gives 0.12dm³;

Now;

              1dm ³ of gas contains 1 mole of substance at STP

             0.12dm³ will contain 0.12mole of nitrogen gas at STP

Mass of N₂ gas = number of moles x molar mass of N₂

    Molar mass of N₂ = 2(14)  = 28g/mol

    Mass of N₂  = 0.12 x 28  = 3.36g

1 mole of a substance contains 6.02 x 10²³ molecules

0.12 mole of N₂ will contain 0.12 x 6.02 x 10²³  = 7.22 x 10²²molecules

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