question_answer 88)

  Define the law of multiple proportions. Explain it with two examples. How does this law point to the existence of atoms?

Answer:

  Law of multiple proportion: This law was put forward by Dalton in 1808. According to this law if two elements combine to form more than one compound, then the different masses of one element which combine with a Fixed mass of the other element, bear a simple ratio to one another. Hydrogen and oxygen combine to form two compounds \[{{H}_{2}}O\] (water) and \[{{H}_{2}}{{O}_{2}}\](hydrogen peroxide). In water, Hydrogen 2 parts Oxygen 16 parts In hydrogen peroxide. Hydrogen 2 parts Oxygen 32 parts. The masses of oxygen which combine with same mass of hydrogen in these two compounds bear a simple ratio 1 : 2. Nitrogen forms five stable oxides. \[{{N}_{2}}O\]    Nitrogen 28 parts     Oxygen 16 parts \[{{N}_{2}}{{O}_{2}}\] Nitrogen 28 parts       Oxygen 32 parts \[{{N}_{2}}{{O}_{3}}\] Nitrogen 28 parts       Oxygen 48 parts \[{{N}_{2}}{{O}_{4}}\] Nitrogen 28 parts       Oxygen 64 parts \[{{N}_{2}}{{O}_{5}}\]  Nitrogen 28 parts      Oxygen 80 parts The masses of oxygen which combine with same mass of nitrogen in the five compounds bear a ratio \[16:\text{ }32\text{ }:48\text{ }:64:\text{ }80\text{ }or\text{ }1\text{ }:\text{ }2\text{ }:\text{ }3\text{ }:\text{ }4\text{ }:\text{ }5.\]