Question

77. In an experiment, 4.90 g of copper oxide was obtained from 3.92 g of copper. In another experiment, 4.55 g
of copper oxide gave, on reduction, 3.64 g of copper. Show with the help of calculations that these figures
verify the law of constant proportion.

Answer 1

Answer :

★ Law of constant proportion :

• The ratio of the masses of elements in any compound is constant regardless of its source or its preparation i.e., a given compound always contains exactly the same proportion of elements by weight.
• It sometimes referred to as law of definite composition.

★ In first experiment :

4.9g of copper oxide gave 3.92g of copper.

• Mass of copper oxide = 4.9g
• Mass of copper = 3.92g
• Mass of oxygen = 0.98g

Ratio of masses of copper and oxygen,

• 3.92/0.98 = 4 : 1

★ In second experiment :

4.55g of copper oxide gave 3.64g of copper.

• Mass of copper oxide = 4.55g
• Mass of copper = 3.64g
• Mass of oxygen = 0.91g

Ratio of masses of copper and oxygen,

• 3.64/0.91 = 4 : 1

The same ratio confirms that these experiment clarify Law of constant proportion$.$

Answer 2

Answer :

★ Law of constant proportion :

The ratio of the masses of elements in any compound is constant regardless of its source or its preparation i.e., a given compound always contains exactly the same proportion of elements by weight.

It sometimes referred to as law of definitecomposition.

★ In first experiment :

4.9g of copper oxide gave 3.92g of copper.

Mass of copper oxide = 4.9g

Mass of copper = 3.92g

Mass of oxygen = 0.98g

Ratio of masses of copper and oxygen,

3.92/0.98 = 4 : 1

★ In second experiment :

4.55g of copper oxide gave 3.64g of copper.

Mass of copper oxide = 4.55g

Mass of copper = 3.64g

Mass of oxygen = 0.91g

Ratio of masses of copper and oxygen,

3.64/0.91 = 4 : 1

The same ratio confirms that these experiment clarify Law of constant proportion..