Question
Carbon and oxygen are known to form two compounds. The carbon content in one of these is 42·9% while in the other it is 27·3%. Show that this data is in agreement with the law of multiple proportions.
Solution
In first compound:
Weight percent of carbon = 42.9
Weight percent of oxygen = 100 - 42.9 = 57.1
In second compound:
Weight percent of carbon = 27.3
Weight percent of oxygen = 100 - 27.3 = 72.7
Now in first compound:
57.1 parts by weight of oxygen combine with 42.9 parts by weigh of carbon
1 part by weight of oxygen will combine with
Now in second compound:
72.7 parts by weight of oxygen combine with 27.3 parts by weight of carbon
1 part by weight of oxygen will combine with 
parts of carbon.
The weights of carbon which combine with same weights of oxygen in two compounds bear a ratio 0·751 : 0·375 or 2 : 1. This is a simple ratio. Hence, the data illustrates the law of multiple proportion.
Weight percent of carbon = 42.9
Weight percent of oxygen = 100 - 42.9 = 57.1
In second compound:
Weight percent of carbon = 27.3
Weight percent of oxygen = 100 - 27.3 = 72.7
Now in first compound:
57.1 parts by weight of oxygen combine with 42.9 parts by weigh of carbon
1 part by weight of oxygen will combine withNow in second compound:
72.7 parts by weight of oxygen combine with 27.3 parts by weight of carbon
1 part by weight of oxygen will combine with parts of carbon.The weights of carbon which combine with same weights of oxygen in two compounds bear a ratio 0·751 : 0·375 or 2 : 1. This is a simple ratio. Hence, the data illustrates the law of multiple proportion.
