# If a sample of LiF is found to contain 7.73 x 10^24 Li+ ions how many grams of LiF formula units are present?

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I tried to work this out and each time i got the incorrect answer. I know the answer is 332.959930255729 as Wiley gave me this however it didn't explain how. Any help would be very appreciated!!!

I tried to work this out and each time i got the incorrect answer. I know the answer is 332.959930255729 as Wiley gave me this however it didn't explain how. Any help would be very appreciated!!!

##### 1 Answer

Think about it in terms of Avogadro's number.

#### Explanation:

We know that Lithium fluoride is an ionic compound that contains negative fluoride ions and positive lithium ions in a 1:1 ratio.

1 mole of any substance contains

Divide your number of molecules with Avogadro's number.

As lithium ions exist in a 1:1 ratio, this amount of moles of Lithium ions also correspond to the number of moles of the substance-

Hence to find the mass in grams we multiply the number of moles with the molar mass to find the mass (According to

Which is consistent with what Wiley gave you :)