Substance W contains 15.2% by mass of sodium and 53% by mass of bromine the rest is O2. When W is thermally decomposed, a white solid, X and oxygen are the only products. An aqueous solution of X gave a cream precipitate, Y, when aqueous silver nitrate and nitric acid are added.
a)Calculate empirical formula of W
b)Name X and Y
c)Work out the balanced equation for the thermal decomposition of W.
2006-10-03 07:12:20 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
Why do you divide them all by 0.66?
2006-10-03 07:58:48 · update #1
First, find the mass of oxygen in 100 g of substance W:
oxygen mass = 100 - 15.2 - 53 = 31.8 g
Divide each element mass by the relative Atomic mass (Ar or atomic weight) of the element:
Na: 15.2/23 = 0.66 mol
Br: 53/80 = 0.66 mol
O: 31.8/16 = 1.98 mol
Now divide each number by 0.66:
Na: 0.66/0.66 = 1, Br: 0.66/0.66 = 1, O: 1.98/0.66 = 3
So the empirical formula of W is NaBrO3
b. 2NaBrO3 -> 2NaBr + 3O2
NaBr + AgNO3 -> NaNO3 + AgBr
So, X is NaBr and Y is AgBr (precipitate)
c. Already answered in (b)
2006-10-03 07:34:11 · answer #1 · answered by Dimos F 4 · 1⤊ 0⤋
Oh my goodness!
I'm so glad I am out of school!!!
What are they teaching kids how to make bombs in school these days!?
2006-10-03 07:25:13 · answer #2 · answered by StarrLee 4 · 0⤊ 0⤋