1. Write down the balanced chemical reaction .
5 F2 (g) + 2 NH3 (g) → N2F4 (g) + 6 HF (g)
2. Determine mole proportions , then solve
From the above balanced reaction, we can see that :
5 moles of F2 reacts to form : 6 moles of HF ,
so, 7.78moles F2 will give :x moles of HF
Therefore,x mole HF =( 6 moles HF * 7.78 mole F2)/ 5 mole F2
= 6 * 7.78/5
=9.336
≈9.34moles HF
• This means that , if you reacted 7.78 moles of F2 , ,9.34 moles of HF would be produced,.