State and explain law of multiple proportion with example.
The Correct Answer and Explanation is:
Law of Multiple Proportion:
The Law of Multiple Proportion states that if two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in the ratio of small whole numbers.
Explanation:
This law was proposed by John Dalton in the early 19th century. It supports Dalton’s atomic theory, which assumes that atoms are indivisible units that combine in simple ratios to form compounds.
To understand this law, imagine that element A combines with element B to form two different compounds. If the mass of element A is kept constant in both compounds, then the masses of element B that combine with the same mass of A will be in a simple whole-number ratio.
This law shows that elements do not combine randomly. Instead, they react in definite proportions based on the number of atoms, which are fixed and indivisible in chemical reactions.
Example:
Consider carbon and oxygen forming two compounds:
- Carbon monoxide (CO)
- Carbon dioxide (CO₂)
In carbon monoxide (CO), 12 grams of carbon combine with 16 grams of oxygen.
In carbon dioxide (CO₂), 12 grams of carbon combine with 32 grams of oxygen.
Let us fix the mass of carbon to 12 grams in both cases. Then, the masses of oxygen combining with this fixed mass are 16 grams and 32 grams.
Now, compare these two oxygen masses:
16 : 32 = 1 : 2
This is a simple whole-number ratio.
Conclusion:
The Law of Multiple Proportion confirms that chemical compounds are formed by the combination of atoms in fixed, simple numerical ratios. It provides strong evidence for the existence of atoms and supports the idea that chemical reactions involve the rearrangement of atoms in fixed ratios.
