Answer:
5.99 moles of [tex]UF_6[/tex]
Explanation:
In this case, we can start with the decomposition of [tex]UF_6[/tex], so:
[tex]UF_6~->~U~+~3F_2[/tex] (Reaction 1)
The [tex]F_2[/tex] can react with carbon to produce [tex]CF_4[/tex]:
[tex]CF_4~+~2F_2~->~CF_4[/tex] (Reaction 2)
If we 8.99 mol of [tex]CF_4[/tex], we can calculate the moles of [tex]F_2[/tex] that we need. In reaction 2 we have a molar ratio of 1:2 (2 moles of [tex]F_2[/tex] will produce 1 mol of [tex]CF_4[/tex]):
[tex]8.99~mol~CF_4\frac{2~mol~F_2}{1~mol~CF_4}~=~17.98~mol~F_2[/tex]
With this value and using the molar ratio in reaction 1 (3 moles of [tex]F_2[/tex] are producing by each mol of [tex]UF_6[/tex]), so:
[tex]17.98~mol~F_2\frac{1~mol~UF_6}{3~mol~F_2}~=~5.99~mol~UF_6[/tex]
So, we will need 5.99 moles of [tex]UF_6[/tex] to produce 8.99 mol of [tex]CF_4[/tex].
I hope it helps!
