Question

Calculate the mass of:
a) 3 moles of nitrogen gas
b) 0.5 mole of nitrogen atom
c)0.2 mole of oxygen atom


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Answer 1

Answer:

The mass of 3 moles of nitrogen gas is 42 g.

The mass of 0.5 mole of nitrogen atom is 7 g.

The mass of 0.2 mole of oxygen atom is3.2 g.

Explanation:

• We are given with the moles of nitrogen (N) is 3 moles.  

       Molar mass of nitrogen is 14 amu or 14 grams.  

       Thus 28 grams of nitrogen occupies 22.4 litres at STP and is 1 mole.

       Mass in grams of 3 moles of nitrogen is 3 × 14 = 42 grams .

• Number of moles (n)= molecular weight/weight​  

       Weight= n × Molecular weight=0.5×14

       Mass=7g

• The atomic mass of oxygen (O) = 16 u.

        The mass of 1 mole of oxygen atoms = 16g.

        Now, 1 mole of oxygen atoms = 16g

        So, 0.2 mole of oxygen atoms = 16 x 0.2g = 3.2g

         Hence, 0.2 mole of oxygen atom = 3.2 g.