What is the molar mass of potassium nitrate, KNO3
The Correct Answer and Explanation is:
The molar mass of potassium nitrate (KNO₃) is 101.10 g/mol.
Explanation
Potassium nitrate (KNO₃) is a chemical compound composed of three elements: potassium (K), nitrogen (N), and oxygen (O). To calculate its molar mass, we need to sum the atomic masses of each element present in the compound, multiplied by the number of atoms of that element in one molecule.
Here are the atomic masses (rounded to two decimal places):
- Potassium (K): 39.10 g/mol
- Nitrogen (N): 14.01 g/mol
- Oxygen (O): 16.00 g/mol
KNO₃ contains:
- 1 atom of potassium (K)
- 1 atom of nitrogen (N)
- 3 atoms of oxygen (O)
So, the molar mass calculation is:Molar mass of KNO₃=(1×39.10)+(1×14.01)+(3×16.00)\text{Molar mass of KNO₃} = (1 \times 39.10) + (1 \times 14.01) + (3 \times 16.00)Molar mass of KNO₃=(1×39.10)+(1×14.01)+(3×16.00)=39.10+14.01+48.00=101.11 g/mol= 39.10 + 14.01 + 48.00 = 101.11 \, \text{g/mol}=39.10+14.01+48.00=101.11g/mol
(We often round this to 101.10 g/mol depending on significant figures used.)
Why Molar Mass Is Important
The molar mass is a key quantity in chemistry, especially for converting between grams and moles. It enables chemists to measure out substances accurately for reactions based on molar relationships from balanced chemical equations. For instance, if a reaction requires 1 mole of KNO₃, you would weigh out 101.10 grams.
In practical applications, potassium nitrate is commonly used in fertilizers, food preservation, and even pyrotechnics. Knowing its molar mass helps ensure that precise quantities are used in such applications, avoiding excess or deficiency.
By understanding how to calculate and use molar mass, chemists ensure proper stoichiometry, safe handling, and efficient chemical reactions.
