what are the products of this reaction?

Question

Lithium metal is burned in air.

gaseous hydrofluoric acid (HF) reacts with solid silicon dioxide.

and potassium dichromate added to acidified solution of sodium sulfite?

these are so tricky, i cant predict the correct answer.

Answer 1

Hi Kitty! Dr. J to the rescue with a full answer.

1) 4Li + O2 ---> 2Li2O

2) 4HF + SiO2 ---> SiF4 + 2H2O

3) It is simpler if we eliminate the K and the sodium and write the equation ionic because it is a redox reaction and we need to balance.

The overall redox equation will be:

Cr2O7(=) + SO3(=) + H(+) ---> Cr(+3) + SO4(=).

Now you balance by the half reaction method. The two reactions are:

6e(-) + Cr2O7(=) + 14H(+) ---> 2Cr(+3) + 7H2O
3SO3(=) + 3H2O ---> 3SO4(=) + 6H(+) + 6e(-)

Eliminating the electrons:

Cr2O7(=) + 3SO3(=) + 8H(+) ---> 2Cr(+3) + 3SO4(=) + 4H2O

This one was tough!!! Thumbs up!

If you want you could put the K and the Na back.

Best answer?

Answer 2

1/ 4Li + O2 => 2Li2O ; 2Li + H2 => 2LiH
2/ 4HF + SiO2 => SiF4 + 2H2O
the last one I dont know

Answer 3

I suggest that you go over it again and read it very carefully several or more times.