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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
How many moles are there in 34.5 g of sodium ? (Atomic mass of Na = 23 u)
What is the mass of 5 moles of sodium carbonate (Na2CO3) ?
(Atomic masses : Na = 23 u ; C = 12 u ; O = 16 u)
What is the value of Avogadro's number?
Fill in the blank.
One a.m.u. is the mass of ______ atom of C12.
Complete the following calculations. Show working for complete credit :
Calculate the mass of calcium that will contain the same number of atoms as are present in 3.2 gm of Sulphur. [Atomic masses : S = 32, Ca = 40]
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How many grams of CO2 is present in 0.1 mole of it?
What mass of Ca will contain the same number of atoms as are present in 3.2 g of S?
Compute the difference in masses of 103 moles each of magnesium atoms and magnesium ions.
(Mass of an electron = 9.1×10–31 kg)
The number of atoms present in 0.1 mole of P4 (at. mass = 31) is ______.
