7.00 g of a certain Compound X, known to be made of carbon, hydrogen and perhaps oxygen, and to have a molar mass of 70. g/mol, is burned completely in excess oxygen, and the mass of the products carefully measured. 21.96 g of carbon dioxide and 8.99 g of water are formed as products. a) How much carbon, hydrogen and oxygen is in 7.00 g of Compound X

5.993 g C

1.01 g H

0 g O

Explanation:

Let's consider the combustion of the unknown compound X.

X + O₂ = CO₂ + H₂O

Due to the law of conservation of mass, all the C in CO₂ and all the H in H₂O come from X.

In CO₂, there are 12.01 g of C per 44.01 g of CO₂. The mass of C in 21.96 g of CO₂ is:

21.96 g CO₂ × (12.01 g C/44.01 g CO₂) = 5.993 g C

In H₂O, there are 2.02 g of H per 18.02 g of H₂O. The mass of H in 8.99 g of  H₂O is:

8.99 g H₂O × (2.02 g H/ 18.02 g H₂O) = 1.01 g H

If we sum the mass of H and the mass of C, we get

5.993 g + 1.01 g = 7.00 g

which is the mass of X. Then, X has no oxygen

explanation:

two years ago, when picking flowers in the mountains back of yosemite valley, i found a book. it was blotted and storm-beaten; all of its outer pages were mealy and crumbly. the paper seemed to dissolve like the snow beneath which it had been buried, however; many of the inner pages were well preserved. and although all were more or less stained and torn, whole chapters were easily readable. this is the condition of the great open book of yosemite glaciers today; its granite pages have been torn and blurred by the same storms that wasted the castaway book.

two years ago, when picking flowers in the mountains back of yosemite valley; i found a book. it was blotted and storm-beaten, all of its outer pages were mealy and crumbly. the paper seemed to dissolve like the snow beneath which it had been buried, however, many of the inner pages were well preserved. and although all were more or less stained and torn; whole chapters were easily readable. this is the condition of the great open book of yosemite glaciers today, its granite pages have been torn and blurred by the same storms that wasted the castaway book.