Question

Five moles of nitrogen molecules have a mass of 140.07 g. What is the mass of 10 atoms of nitrogen?

Answer 1

Five moles of nitrogen molecules have a mass of 140.07 g

Therefore 10 moles of nitrogen atoms have a mass of 140.07 g (N₂ molecule has 2 nitrogen atoms)

Therefore 1 mole of nitrogen atom have a mass of 14.007 g..................(1)

Also we know that 1 mole of nitrogen has 6.022 X 10²³ nitrogen atoms in it. (Avogadro's number).............(2)

So from (1) and (2) 14.007g of nitrogen= 6.022 X 10²³ nitrogen atoms

x g = 10 nitrogen atoms

x = 14.007X10 / 6.022 X 10²³

  = 2.325 X 10 ^-22

Therefore mass of 10 atoms of nitrogen is 2.325 X 10 ^-22 g