Q. 2.31 P - Chemistry: Molecular Nature Of Matter And Change

Question

Use Dalton’s theory to explain why potassium nitrate from India or Italy has the same mass percents of K, N, and O.

Step-by-Step Solution

Answer

According to the Dalton, theory compounds result from the chemical combination of a specific ratio of atoms of different elements therefore whether the potassium nitrate is from India or Italy the mass percent of potassium, nitrogen and oxygen will always remain the same.

Step 1: Postulates Dalton’s atomic theory:

According to atomic theory:

• Atoms of an element are identical in mass and other properties and are different from atoms of any other element.
• Compounds resulting from the chemical combination of a specific ratio of atoms of different element

Step 2: Similar mass percents of K, N and O in potassium nitrate.

Potassium nitrate is a compound composed of potassium, nitrogen and oxygen atoms, so according to the Dalton atomic theory ratio of potassium, nitrogen and oxygen remain fixed in potassium nitrate irrespective of the place where they are found in India or Italy. 

Result: Elements present in compounds in fixed proportional to weight. Hence mass percent of potassium, nitrogen and oxygen remains the same in potassium nitrate whether it is found in India or Italy.