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Question
Explain the term:
Mole
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Solution
The mole is a unit of measurement for the amount of substance. Moles give us a consistent method to convert between atoms/molecules and grams.
The mathematical expression for calculating moles is expressed as:
moles = mass / molar mass
We can express moles in terms of molecular mass, number of atoms/molecules and in terms of volume.
- 1 mole of a pure substance has a mass in grams equal to its molecular mass.
- 1 mole contains the same number of particles as there are in 12g of carbon-12 atoms. This number is called Avogadro’s number and is equal to 6.023 × 1023 particles.1 mole of a gas occupies a volume of: 22.4 litres at S.T.P.
For example: 1 mole of sodium atom has mass 23 g. It contains 6.023 × 1023 atoms and occupies 22.4 litres of volume at S.T.P.
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Fill in the missing data in the Table
| Species Property | H2O | CO2 | Na atom | MgCl2 |
| No. of moles | 2 | - | - | 0.5 |
| No. of particles | - | 3.011×1023 | - | - |
| Mass | 36g | - | 115 g | - |
