Question

2. Hydrogen and oxygen combine in
sodium et
dioxide + water
tech
ima
aton
the ratio of 1:8 by mass to form
water. What mass of oxygen gas
would be required to react
completely with 3 g of hydrogen
gas?
3. Which postulate of Dalton's
atomic theory is the result of the
law of conservation of mass?
4. Which postulate of Dalton's
atomic theory can explain the law
of definite proportions?​

Answer 1

Explanation:

Q 2

SOLUTION Your Answer

1 g of hydrogen reacts with = 8 g of oxygen

∴ 3 g of hydrogen reacts with = 8 × 3 = 24 g of oxygen

Thus, 24 g of oxygen gas would be required to react completely with 3 g of hydrogen gas.

Q 3.

SOLUTION:

The postulate that “atoms can neither be created nor destroyed in a chemical reaction” is the result of the law of conservation of mass.

Q 4.

SOLUTION:

The postulate that “A chemical compound always consists of the same elements combined together in the same proportion by mass” is the law of definite proportions..

Answer 2

Answer:

The law of constant proportions states that in a chemical substance, the elements are always present in definite proportions by mass. Hydrogen and oxygen combine in the ratio of 1:8 by mass to form water.

1g of hydrogen reacts with oxygen = 8g

Thus, in order to form water, 3 x 8 = 24 g of oxygen will react completely with 3 g of hydrogen gas.

Concept insight: Recall the law of constant proportions and then apply that in a chemical substance, the elements are always present in definite proportions by mass.

OR

2H

2

+O

2

→2H

2

O

4g 32g 36g

Since, 32 g of oxygen reacts with 4g of H

2

.

So, 3g of H

2

will require =

4

3×32

=24 grams of O

2