Question

Calculate the percentage of sodium in sodium aluminium fluoride (Na₃AlF₆) correct to the nearest whole number. (F = 19; Na = 23; Al = 27)

Answer 1

Molecular mass of Na₃AlF₆ = 3Na + Al + 6F

= 3 × 23 + 27 + 6 × 19

= 69 + 27 + 114

= 210

Percentage of Na in Na₃(AlF₆) = `"mass of sodium"/("mass of Na"_3"AlF"_6) xx 100`

= `6/210 xx 100`

= `(69 xx 10)/21`

= `(23 xx 10)/7` 

= `230/7`

= 32.9%