We all want to know that in a particular substance how many molecules are present. Molecules and atoms are very tiny, both in size and mass.

**What is a Mole?**

In a substance, the amount of entities present for e.g. atoms, molecules, ions, is defined as a mole. A mole of any substance is \(6.022×10^{23}\)

The amount of atoms present in 12g (0.012 kg) of the \({12}^C\)

To know the number precisely the mass of carbon-12 atom was calculated by using a mass spectrometer and it was found to be \(1.992648×10^{-3}g\)

As we know that one mole of carbon weighs 12g, the total no. of atoms in it is equal to \(6.0221367×10^{23}\)**Avogadro’s number**(N_{A}). From the above discussion, we can say that the number of atoms present in 1 mole of hydrogen is equal to \(6.022×10^{23}\)

**What is molar mass?**

A substance is something which has mass and occupies space. The molar mass/molecular weight is actually the sum of the total mass in grams of the atoms present to make up a molecule per mole. The unit of molar mass is grams/mole.

** What is percentage composition?**

We can find the percentage composition of a substance by dividing the mass of that substance to the total mass of the substance. Suppose we have to find out the percentage composition of hydrogen in butane(\(C_4H_{10}\)

Total mass of one mole of butane =58.123

Mass of hydrogen in one mole of butane = 10.0794

Therefore, mass percent of hydrogen in butane=\( \frac{10.079}{58.123}×100\)

These concepts play a very important role for studying the behaviour of matter under different conditions. Know more about mole concept and the related topics, for any further help contact the mentors at Byju’s.

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