# convert the mass of a compound to the number of particles( and vice versa)? For this type of problem, we use the molar mass and avogadros number in order to solve the question.

Mass of compound -> Moles compound -> number of particles

this step is vice versa.

Let me show you an example.

100 grams of NaCl

Solution:

100 grams NaCl -> moles...

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For this type of problem, we use the molar mass and avogadros number in order to solve the question.

Mass of compound -> Moles compound -> number of particles

this step is vice versa.

Let me show you an example.

100 grams of NaCl

Solution:

100 grams NaCl -> moles NaCl -> number of particles

`100 g NaCl x ((1mol NaCl)/(58.44gmol-1)) x ((6.022x10^23 particl es)/(1 mol NaCl))`

= 1.0305x10^24 particles

Now to work on from particles to the molar mass of compound, you just have to reciprocate the values. For example 2.00x10^24 atoms/particles of gold

`2.00x10^(24) particl es Au x ((1mol e Au)/(6.022x10^23 particl es)) x ((196grams)/(1mol e Au))`

= 654 grams of gold (Au)

Approved by eNotes Editorial Team