Concentration. Concentration Particles per volume Can be in grams per litre but chemists usually...
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Transcript of Concentration. Concentration Particles per volume Can be in grams per litre but chemists usually...
Concentration
Concentration
V
nc
Particles per volume
Can be in grams per litre but chemists usually express concentration in moles per litre
This are related by the formula:
Where:n = molesV = volume in litresc = concentration in molL-1
Write the formula for:
1. Moles using mass and Molar mass
2. Concentration using Volume and Moles
)Mr(gmol(g) m
n 1-
Vn
c
Concentration Example15 grams of NaCl is dissolved in 1 litre of water, what is the concentration of the solution in moles per litre? (M NaCl = 58.5 gmol-1)
Find moles of NaCl
Divide moles by volume in litres
mol 0.2564 58.515
Mm
n
1molL256.0litre 1
0.2564mol
Vn
c
Concentration Example20 grams of NaOH is dissolved in 500mls of water, what is the concentration of the solution in moles per litre? (M NaOH = 40gmol-1)
Find moles of NaOH
Divide moles by volume in litres
mol 0.5 40gmol
20g
Mm
n1-
1 00.10.5litre
0.5mol molL
V
nc
Have a go
• Calculate the concentration of 18.0g of glucose (C6H12O6) dissolved in 200ml of solution.
• n=m/Mr• n=18.0g/180gmol-1
• n=0.100mol
• c=n/V• c=0.100mol/0.200L• c=0.500molL-1