Answer: 120 grams of HF are needed to react with 3.0 moles of Sn
Explanation:
The balanced chemical equation is :
[tex]SnF_2+H_2\rightarrow Sn+2HF[/tex]
According to stoichiometry:
1 mole of [tex]Sn[/tex] reacts with 2 moles of HF
Thus 3.0 moles of Sn will react = [tex]\frac{2}{1}\times 3.0=6.0[/tex] moles of HF
Mass of [tex]HF=moles\times {\text {molar mass}}=6.0mol\times 20.01g/mol=120g[/tex]
Thus 120 grams of HF are needed to react with 3.0 moles of Sn
