# How many mols are in 8.00 g #BeF_2#?

##### 1 Answer

There are approximately 0.170 moles of

#### Explanation:

We can determine the number of moles of a compound in a given number of grams of that compound (and vice versa) using dimensional analysis, or conversions.

If you are uncomfortable with conversions, perhaps the best way to look at them starting out is how you can arrange the ratios so that the units cancel appropriately and leave you with the units you're looking for on your final answer.

In this case, we are looking for an answer with units of moles. We're starting with 8.00 grams of

In nearly every case you will need the molecular weight of the compound you are dealing with, and this one is no different, so the first step is to calculate the molecular weight of

From the periodic table, we can see that the molecular weight of one Be atom is 9.012 g/mol, and one fluorine atom has a molecular weight of 18.998 g/mol. Thus, the molecular weight of

We can now use dimensional analysis to determine how many moles of

8.00 grams

If we multiply, "grams

These types of problems can take some getting used to, but with enough practice, it will become second nature! Being able to quickly convert between grams and moles of a compound is an invaluable skill in chemistry.

tl;dr:

1. Determine molecular weight of

2. Use conversions with g/mol