# How do you convert from mass to the number of representative 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.

50 grams of KCl

Solution:

50.0 grams KCl -> 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.

50 grams of KCl

Solution:

50.0 grams KCl -> moles KCl -> number of particles

`50 g KCl x ((1mol e KCl)/(74.55g KCl)) x ((6.022x10^23 particl es)/(1mol e KCl))`

= 4.04x10^23 particles of KCl

Now to work on from particles to the molar mass of compound, you just have to reciprocate the values. For example 4.00x10^23 atoms/particles of silver (Ag)

`4.00x10^23 particl es Ag x ((1mol e Ag)/(6.022x10^23 particl es)) x ((107.87 g Ag)/(1mol e Ag))`

=71.65 grams Ag

Approved by eNotes Editorial Team