Tony D. answered • 03/10/16

former chemistry, physics , math teacher

by inspection, the balanced equation is Mg + 2 NaF --> MgF

_{2}+ 2 Na(forgive me for not knowing how to make a nice set up with this system, but it looks something like this

a) 5.5 g NaF (1 mol NaF/42.0 g NaF) (1 mol MgF

_{2}/2 mol NaF) (62.3 g MgF_{2}/1 mol MgF_{2}) = 4.1 g MgF_{2}b) 4,01 g MgF

_{2}(1 mol MgF_{2}/62.3 g MgF_{2}) (2 mol NaF/ 1mol MgF_{2}) ( 6.02 X 10^{23}form units/ 1 mole) = 7.75 X 10^{22}unitsc) 8.8 mol Mg (2 mol NaF / 1 mol Mg) ( 6.02 X 10

^{23}form units NaF/ 1 mol NaF0 = 1.1 X 10^{25}form units
Luis M.

This was perfectly set up thank you. But one question, do you divide the original mass by the molecular mass, then the bottom mole ratio, then multiply it by the molecular mass of the unknown substance? Ill use A.) as an example: 5.5g ÷ 42.0g ÷ 2*62.3g because I got 4.0791 for my answer and im confused if im doing it correctly. Any tips?04/10/19