Question

Fill the following blanks with suitable words (a) In water, the proportion of oxygen and hydrogen is ...................by mass.
(b) In a chemical reaction, the sum of the masses of the reactants and the products remains unchanged. This is called ....................

Answer 1

Answer:

a) 4:1

b) law of conservation of mass

Explanation:

a) Mass of oxygen = 8 atomic mass units

Mass of hydrogen = 1 atomic mass unit

The molecular formula of water is H20, that is, two hydrogen atoms to every one oxygen atom.

Therefore the ratio of oxygen:hydrogen is

8:(1*2)

= 8:2

Which can be simplified to:

4:1

Therefore the ratio of oxygen to hydrogen is 4 : 1.

b) The law of conservation of mass states that mass can neither be created nor destroyed.

Of course, this makes sense, since extra atoms cannot suddenly appear during a chemical reaction!