Question

Tin(II) fluoride, formerly found in many toothpastes, is formed by the reaction:Sn(s) + 2HF(g) → SnF2(s) + H2(g) What volume of HF is needed to produce 14.2 L of H2 gas?

Answer 1

28.22L of HF are needed.

Step-by-step explanation:

1st) It is necessary to convert the 14.2L H2 to moles, using the relation for gases that 22.4L is equal to the volume of 1 mole:

`\begin{gathered} 22.4L-1mol \\ 14.2L-x=(14.2L*1mol)/(22.4L) \\ x=0.63moles \end{gathered}`

2nd) Now, with the stoichiometry of the balanced reaction (we know that 1 mole of H2 is formed from 2 moles of HF), and the 0.63 moles of H2, we can calculate the moles of HF needed:

`\begin{gathered} 1molH_2-2molHF \\ 0.63molH_2-x=(0.63molH_2*2molHF)/(1molH_2) \\ x=1.26molHF \end{gathered}`

Now we know that 1.26 moles of HF can produce 14.2L (0.63moles) of H2 gas.

3rd) Finally, we have to convert the 1.26 moles of HF to liters:

`\begin{gathered} 1mole-22.4L \\ 1.26moles-x=(1.26moles*22.4L)/(1mole) \\ x=28.22L \end{gathered}`

So, 28.22L of HF are needed.