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1.2.2: Avogadro’s Constant & The Mole - Coggle Diagram
1.2.2: Avogadro’s Constant
& The Mole
Amount of Masses
The quantity whose unit is the mole.
Chemist use it as a means of counting atoms
Avogadro's constant
The number of atoms per mole of the carbon-12 isotope
6.02x10^23 mol^-1
Mole
The amount of any substance containing as many elementary particles as there are carbon atoms in exactly 12g of the Carbon-12 isotope
Molar Mass
The mass per mole of a substance.
The units of molar mass is g mol^-1
Mr
Relationship of Mass, Molar Mass and Moles
Moles = Mass ÷ Molar Mass
n (mol) = m (g) ÷ Mr (g mol^-1)
Calculating the Mass of a substance
Mass of 0.05 moles of Sodium Thiosulfate
O=8 (16.00)=128.00
H=10 (1.01)=10.1
S=2 (32.06)=64.12
Mr=248.20
Na=1(22.99)=32.06
Mass= Moles x Molar Mass
Mass= 0.05 x 248.20
Mass= 1.2x10^1 g (2sf)
Calculating the number of moles in a substance
Number of moles in 560g of ethene
H=4(1.01)=4.04
Mr=28.06
C=2(12.01)=24.02
Moles=Mass/Molar Mass
Moles= 2.00x10^1 mol (3sf)
Moles=560/28.06
Significant Figures
5.000 x 21.9= 109.5 = 110 (3sf)
When multiplying or dividing in scientific notation the result will always be to 3 significant figure as both factor are to 3 sig figs.
When multiplying or dividing the answer should be to the lowest number of significant figures of the factors
3.50x10^1 x 2.11x10^1 = 7.385x10^2 = 7.39x10^2 (3sf)