Question

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

Answer 1

The mass percent of hydrogen in water is 11.1%.

Step-by-step explanation:

Water is composed of two hydrogen atoms and one oxygen atom. By looking at the molecular formula of water, H2O, we can see that the mass of hydrogen is 2 g/mol. The molar mass of water is 18 g/mol. To find the mass percent of hydrogen in water, we divide the mass of hydrogen by the molar mass of water and multiply by 100%.

Mass percent of hydrogen in water:
(2 g/mol / 18 g/mol) x 100% = 11.1%

Answer 2

11.19

Step-by-step 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