6. What is the mass percent of hydrogen in water?

11.19

Explanation:

Since water is

H

2

O

(molar mass is

18.015 g/mol

), it implies we have a percent composition of

H

and one for

O

.

Given that chemical formula, we have two equivalents of

H

, for which we can use its molar mass,

M

H

=

1.0079 g/mol

. We also have one equivalent of

O

, for which we can use its molar mass,

M

O

=

15.999 g/mol

.

The percent composition (by mass) of

H

is written in terms of a unified ratio of the molar masses is

%

H

=

2

×

M

H

M

H

2

O

×

100

%

=

2

×

1.0079 g/mol

18.015 g/mol

×

100

%

≈

11.19

%

H

answer: - 3.) the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

solution: - as per the rules, oxidation number of oxygen in its compounds is -2. the sum of oxidation numbers of all the elements of a molecule or compound is zero.

also, the oxidation number in elemental form is zero.

in no, the oxidation number of o is -2 so the oxidation number of n is +2 so that the sum is zero.

similarly, the oxidation number of c in co is +2 and o is -2.

on product side the oxidation number of n is 0 as it is in the elemental form() .

oxidation number of c in carbon dioxide is +4 as there are two oxygen in it and we know that each oxygen is -2.

so, oxidation number of n is changing from +2 to 0 and the oxidation number of c is changing from +2 to +4.

since nitrogen is reduced and hence no is acting as an oxidizing agent. carbon is oxidized and so co is acting as a reducing agent.

so, the right choice is number 3.)the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.