# According to the law of definite proportions any two samples of KCl have?

##### 1 Answer

The exact same proportion of potassium and chlorine by mass.

#### Explanation:

According to the Law of Definite Proportions, a chemical compound will always have exactly the same proportion of elements by mass.

This means that the elements that make up a compound will always have the same percent composition by mass, *regardless* of the actual mass of the sample.

In your case, potassium chloride has a molar mass of **74.551 g/mol**. The two elements that form potassium chloride are *potassium*, which has a molar mass of **39.0983 g/mol**, and *chlorine*, which has a molar mass of **35.4527 g/mol**.

This tells you that *every mole* of potassium chloride weighs 74.551 g, out of which 39.0983 g is potassium and 35.4527 g is chlorine.

Therefore, chlorine and potassium will **always** be in a ratio by mass of

Simply put, you get an *almost equal* contribution to the mass of the compound from both elements.

Another way of looking at this is by calculating each element's percent composition.

This means that **every sample** of potassium chloride, regardless of its mass, will contain **47.55%** chlorine and **52.45%** potassium.

So, as a conclusion, *any two samples* of potassium chloride will contain potassium and chlorine in a **0.9068 : 1**, or 52.55% to 47.55%, mass ratio.