Question

Two samples ‘m’ and ‘n’ of slaked lime were obtained from two different reactions. The details about their composition are as follows:
‘sample m’ mass : 7g
Mass of constituent oxygen : 2g
Mass of constituent calcium : 5g
‘sample n’ mass : 1.4g
Mass of constituent oxygen : 0.4g
Mass of constituent calcium : 1.0g
Which law of chemical combination does this prove? Explain.

Answer 1

Answer ⇒ Law of Definite Proportions. 

Explanation ⇒ 
According to the law of the Definite proportion, Compounds obtained from the different places or position contains the same element in the fixed ratio by mass. 

For example, If the Carbon dioxide is produced from 2 different reactions then the ratio of the Carbon and Oxygen by mass will be fixed ,i.e. 3 : 8


Now, Proof of that law from the given data. 

For Sample 'm'. 

Mass of the Oxygen = 2 g.
Mass of the Calcium = 5 g.
Thus, the ratio of the Calcium and Oxygen in the compound is 5/2 = 5 : 2


For sample 'n'. 

Mass of the Oxygen = 0.4 g. 
Mass of the Calcium = 1.0 g.

Thus, Ratio by mass of Calcium and Oxygen in the compound = 1/0.4
 = 10/4
 = 5/2
 = 5 : 2

Now, we can see that the ratio by mass in both the compounds is same. Hence it illustrates the law of Definite Proportions. 


Hope it helps.