Question

For the given reactions
`SiO_(2) +4HF rarr SiF_(4) +2H_(2)O, DeltaH =- 10.17 kcal`
`SiO_(2) +4HCI rarr SiCI_(4) +2H_(2)O, DeltaH = 36.7 kcal`
It may be concluded that
A. `HF` will attack `SiO_(2)` and `HCI` will not
B. `HCI` will attack `SiO_(2)` and `HF` will not
C. `HF` and `HCI` both attack `SiO_(2)`
D. None attacks `SiO_(2)`

Answer 1

`DeltaG = DeltaH - T DeltaS =- ve`
All exothermic reactions are spontaneous, hence `HF` will attack `SiO_(2)`.