Q. What is law of definite proportions?

A given compound is forever composed of the same elements in the same proportion by mass. This fact is recognized as the law of definite proportions. For instance 100.00g of H₂O always contains 11.19g of hydrogen as well as 88.81g of oxygen no matter where the water came from. Compounds are habitually identifiable from their percentage composition the percent by mass of each element in a compound. The percent by mass of every element in a compound may be found by using the following equation.

Percent by mass of an element (%)= (mass of element/ mass of compound)*100%

For instance suppose you break a compound down into its elements and find that 25.00g of the compound is composed of 6.77g of tin and 18.23g of bromine. The percent through mass of tin in the compound can be determined as follows.

Percent by mass of tin = (mass of tin/ mass of compound) *100%

Percent by mass of tin = 6.77 g/25.00 g*100% = 27.1% tin