stoichiometry problem

Question

Mg + NaF → MgF2 + Na

-If you start with 5.5 grams of sodium fluoride, how many grams of magnesium fluoride will be produced if there is no error?
-Determine how many formula units of sodium fluoride are needed if 4.01 grams of magnesium fluoride are produced and there is no error and 100% yield is achieved.
-How many formula units of sodium fluoride are needed to react with 8.8 moles of magnesium?

Answer 1

by inspection, the balanced equation is    Mg + 2 NaF --> MgF₂ + 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 MgF₂/2 mol NaF) (62.3 g MgF₂/1 mol MgF₂) = 4.1 g MgF₂

 

b) 4,01 g MgF₂ (1 mol MgF₂/62.3 g MgF₂) (2 mol NaF/ 1mol MgF₂) ( 6.02 X 10²³ form units/ 1 mole) = 7.75 X 10²² units

 

c) 8.8 mol Mg (2 mol NaF / 1 mol Mg) ( 6.02 X 10²³ form units NaF/ 1 mol NaF0 = 1.1 X 10²⁵ form units