Answer:
3 because it the element that combined the form
Since
21.2 g H2O was produced, the amount of oxygen that reacted can be obtained
using stoichiometry. The balanced equation was given: 2H₂ + O₂ → 2H₂O and
the molar masses of the relevant species are also listed below. Thus, the
following equation is used to determine the amount of oxygen consumed.
Molar mass of H2O = 18
g/mol
Molar mass of O2 = 32
g/mol
21.2 g H20 x 1 mol
H2O/ 18 g H2O x 1 mol O2/ 2 mol H2O x 32 g O2/ 1 mol O2 = 18.8444 g O2
<span>We then determine that
18.84 g of O2 reacted to form 21.2 g H2O based on stoichiometry. It is
important to note that we do not need to consider the amount of H2 since we can
derive the amount of O2 from the product. Additionally, the amount of H2 is in
excess in the reaction.</span>
<span>Compounds are composed of different elements in a fixed proportions. For example, 1 atom of oxygen (O) combines with 2 atoms of hydrogen (H) to form one molecule of water (H2O) compound. Similarly other numbers of atoms would produce other chemical compounds. Even adding 1 more atom of oxygen would convert the water (H2O) into hydrogen peroxide(H2O2). Even if we were only to list the ones we know there are over 20 million known compounds.
In order to list all possible compounds such a table would rapidly become combinatoric nightmare of such size that it would not be practical to use even with a computer database and it would consist of over 100 billion possible compounds containing only H, C, O and N.
Creating a table to handle all possible elements would mean a table of many trillions of compounds.</span>
7. a. I
8. c. 75 g/ml
9. b. .25g/cm3
10. b. the density decreases
