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# Molar math

This article was originally written by [Lynda ABC] at chemistryiseasy.com. That website no longer exists.

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### One mole   = 602,200,000,000,000,000,000,000 of something

(Well, not exactly. It is really 602,214,179,300,000,000,000,000, but we round off.
We usually don’t need to know all the digits, in order to use it. If you care to look into it, there’s a reason why it is this seemingly weird number.  We can look at that later if you like.)

## Four Simple Steps to Mastering Molar Math

### 4. Know how to set up a series of ratios to cancel the units you DON’T want and end up with the units you DO want. T

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## (1) Find Starting and Ending Units in a Problem

### You may find other language variations in problems, but you should always be able to find the ending units and starting units and set up a structure as we have done above.

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### A “conversion ratio” is a ratio which converts one unit into another.

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### The second form of the ratio is used when we want to convert from inches to feet, instead of from feet to inches. We set up the structure to START with inches and END with feet, as shown below.

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### This keeps everything easy to see when you have a string of ratios in a problem.

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### (3) Be able to find any of the 4 ratios related to the mole listed below.

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### (My assumption is that you already understand scientific notation and significant figures.)

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