Question

Potassium has a mass of $39.1$ amu. Chlorine has a mass of $35.45$ amu. By the law of conservation of mass, what is the mass of potassium chloride, when these two ions combine?

Answer 1

Potassium is a chemical element with atomic mass of $39.1$ amu and chlorine is a chemical element with atomic mass of $35.45$ amu. According to the law of conservation of mass, the mass of the reactants and mass of the products in the chemical reaction are equal. Potassium chloride has the atomic mass equal to the sum of the atomic masses of the potassium and chlorine.

Complete answer:
Chemical elements are the purest form of atoms. Atoms combine with each other to form molecules. Potassium and chlorine combine with each other to form a molecule known as potassium chloride.
Potassium is a chemical element with atomic mass of $39.1$ amu and chlorine is a chemical element with atomic mass of $35.45$ amu. Chlorine is a chemical element with atomic mass of $35.45$ amu.
According to the law of conservation mass, the atoms or compounds reacted to atomic mass is equal to the atomic mass of the formed products.
When these two atoms combine, potassium chloride forms with atomic mass of $39.1 + 35.45 = 74.6$ amu.
Atomic mass of potassium chloride is $74.6$ amu.

Note:
Potassium is an alkali metal and can lose electrons easily. Chlorine is a halogen and can be considered as a non-metal, it can attract electrons from another atom. Thus, potassium donates electrons and chlorine accepts electrons forms an ionic salt known as potassium chloride.