Determine the mass(in grams) of each of the following compounds.

Question

a) 0.709 mol magnesium fluoride

i got 30.7grams but it was wrong.

id appreciate the help! thanks!

also if i end up getting the help i have a couple other questions

Answer 1

nevermind i got the answer but i do have another question:

A salt crystal has a mass of 0.40 mg. How many NaCl formula units does it contain?

Answer 2

moles = grams/molar mass
Substitute "number formula units" for moles. Substitute "mass formula unit" for molar mass. Solve for moles.
0.04/about 58.5 or so. You do it more precisely.

Answer 3

so do i have to convert .4 mg to grams first? that would be .0004 right?

so then i just divide .004/58.44 and that will be my answer?

Answer 4

Yes, and I notice I didn't see the decimal point.
0.4 mg = 0.0004 grams and that divided by 58.44 = ?? formula units.

Answer 5

so it would be .000006845 formula units?