# How many molecules are in 6.0 moles of NO_2?

Feb 18, 2016

There are $6.0 \times {N}_{A}$ individual $N {O}_{2}$ molecules in such a quantity.

#### Explanation:

${N}_{A}$ represents Avogadro's number $=$ 6.022140857(74)×10^23.

${N}_{A}$ is just a number; admittedly, it's a very large number. Why was it chosen? Well, it has the property that ${N}_{A}$ individual ""^1H atoms have a mass of $1$ $g$ PRECISELY. It is thus the link between the micro world of atoms and molecules, of which we can only conceive but about which we can theorize, with the macro world of grams and kilograms and litres and cubic metres, which we can conveniently measure.

Knowledge of Avogadro's number allows us to calculate equivalent weight. If I know the mass of an element OR a COMPOUND, I know precisely the number of elemental or molecular species, and I can measure out the mass of another reagent such that I have an equivalent amount of particles.

In terms of ${N}_{A}$, how many atoms are there in your quantity? What type are they?