1. An excess amount of cholorine gas is passed over hot iron fillings.
Cl2 + F --> FeCl3 , in this reaction, why does Fe have +3
charge in the product? Couldn't it have +2 ?
Yes, the two most common oxidation states of iron are +3 and +2. I don't know how you would tell which form gets created in your reaction (note, your reaction is not balanced).
2. Solid litium hydride is added to water
LiH + H2O -> Li+ + OH- + H2(g)
Would I be wrong to say if it just formed LiOH and more water instead of H2
gas? How can one know it forms H2?
This is an acid/base reaction. However, it is a strange acid/base reaction because the hydride ion (H
-) is acting as your base. As in a normal acid/base reaction, the base picks up the proton from your acid (H
2O), creating H
2. This leaves behind an Li
+ ion and a OH
- ion. The reaction you have written will not work (for example, try to balance the reaction that you have written).
3. A concentrated solution of ammonia is added to a solution of Zinc Iodide
NH3 + ZnI2 ---> Zn(OH)2 + NH4+
Where does OH come from?
In the presence of water, ammonia reacts to form NH
4OH.