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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.
RELATED QUESTIONS
A gas cylinder can hold 1 kg of hydrogen at room temperature and pressure
1) Find the number of moles of hydrogen present.
2) What weight of CO2 can the cylinder hold under similar conditions of temperature and pressure? (H = 1, C = 12, O = 16)
3) If the number of molecules of hydrogen in the cylinder is X, calculate the number of CO2 molecules in the cylinder under the same conditions of temperature and pressure.
4) State the law that helped you to arrive at the above result.
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Correct the statement, if required.
One mole of chlorine contains 6.023 x 1010 atoms of chlorine.
Correct the statement, if required.
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