Question

How can I calculate the percentage by mass of sodium in sodium azide, NaN3(s); used in automobile air bags?

Answer 1

You can calculate the percentage thru the following formula

(mass of required atom/mass of compound)*100

Here, mass of Na is 23, mass of NaN3 is 23 + 3*14 = 23 + 42 = 65.

percent of Na in NaN3 is therefore

23*100/65 = 35.38%

Hope it helps ;-)