Question

In an experiment 0.2430 gm of magnesium on burning with oxygen yielded 0.4030 gm of magnesium oxide. In another experiment 0.1820 gm of magnesium on burning with oxygen yielded 0.3020 gm of magnesium oxide. Show that the data explain the law of definite proportions.

Answer 1

Hint: Magnesium oxide is a compound in which there are two elements present: magnesium and oxygen. If the ratio of the percentage of magnesium and oxygen is the same in both the experiments then the data will explain the law of definite proportions.

Complete step by step answer:
Let us find out the ratio of the percentage of magnesium and oxygen in both the experiments.
In experiment 1, the magnesium oxide formed is equal to 0.4030 gm. In this experiment, the amount of magnesium used is 0.2430 gm. The amount of oxygen can be calculated as:
$0.4030-0.2430=0.16$
So, the amount of oxygen used is 0.16 gm.
The ratio of magnesium and oxygen is:
$0.2430:0.16=1.52:1$
In experiment 2, the magnesium oxide formed is equal to 0.3020 gm. In this experiment, the amount of magnesium used is 0.1820 gm. The amount of oxygen can be calculated as:
$0.3020-0.1820=0.12$
So, the amount of oxygen used is 0.12 gm.
The ratio of magnesium and oxygen is:
$0.1820:0.12=1.52:1$
In both, the experiment the ratio of magnesium to the oxygen is the same so it follows the law of definite proportions.
As the law of definite proportion states that “A chemical compound is always found to be made up of the same elements combined together in the same fixed proportion by mass”.

Note: Since this law is followed by most of the compounds but this law is not applicable in the formation of the compounds having different isotopes and the compounds are different but the elements combine in the same proportion.