Question

What is the mass in grams of 3 moles of nitrogen?

Answer 1

Mole is a unit measurement. A mole corresponds to the mass of a substance that contains $6.023\;\times\;10^{23}$ particles of the substance. Its symbol is mol.

Complete step by step answer:

1 mole of any substance contains $6.023 \times {10^{23}}$ particles any macroscopic substance can’t be present in this amount so this number is used to measure microscopic particles like atomic or subatomic. Mass of 1 mole of a substance in grams is given by its molar mass also called gram molecular mass.
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.
Therefore
Mass in grams of 3 moles of nitrogen is 3 $\times$ 14 = 42 grams .

Hence the correct answer is 42 grams.

Additional information: Other units of measuring concentration are:
Molality - This can be determined by calculating number of moles of solute per kg solvent. It is represented by the symbol ‘m’.
Molarity - It is defined as the number of moles of solute dissolved in volume of solution of solution in litres. It is represented by the symbol ‘M’.

Note: While calculating the mass in grams we have to take into account the atomic mass of nitrogen not for the nitrogen molecule.