Question

How do you determine the molar mass of heptane?

Answer 1

. Molar mass of a chemical compound is calculated by the ratio of mass of the substance in grams to the number of moles of a substance. Molar mass is generally calculated in grams.

Complete step by step answer:
- Heptane is a carbon chain having seven carbon atoms connected by a single bond. The structural formula of heptane is ${{C}_{7}}{{H}_{16}}$ .
The number of carbon atoms = 7
Mass of single carbon atom = 12 g
The number of hydrogen atoms = 16
Mass of per hydrogen atom = 1 g
Molar mass of heptane = $7\times 12 + 1\times 16=84 + 16 = 100 g/mol$
Hence, the molar mass of heptane = 100g/mol

Additional information: To calculate the number of atoms first we have to calculate the number of moles of the given element as the number of moles is already given, then the number of atoms will be equal to the product of number of moles and Avogadro’s number. A mole is generally used as a unit for the number of atoms or molecules or particles of a material.

Note: 1 mole = $6.022\times {{10}^{23}}$ particles or atoms or molecules or electrons or protons etc. The number of the constituent particles of atoms such as molecules or atoms or ions present in a given sample is related with the mass of the substance present in the sample using Avogadro's number. The SI unit of Avogadro’s number is inverse of mole i.e. $mol{{e}^{-1}}$
- Avogadro’s number is dimensionless. It also helps to relate the molar volume of a substance to the average volume which is occupied by one of the particles.