A standard solution is a solution whose concentration is accurately and well known, that is a solution that contains a known mass of a solute dissolved in a known volume of Solvent.
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For example, a solution that contains 22g of Sodium Chloride (NaCl) in 1dm3 of a solution is a Standard solution. A solution containing 3.2g of Potassium trioxocarbonate (IV) salt in 250cm3 of a solution of water is also a Standard solution.
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In order to prepare a Standard solution in the laboratory, you must understand vividly the disparity or differences that exist between Molarity and Volume of a solution after it has been diluted.
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Molarity according to Molar concept can be defined as the Moles of a solute per unit Volume of a solution when dissolved in 1dm3 of the solution. A concentrated solution is one that contains a large amount of solute dissolved in its solvent while a dilute solution is one that contains a small amount of the solute particles dissolved in its solvent. When water is used to dilute a concentrated solution, the concentration of the solution actually experience a decrease, but the amount or mole of the dilute solution remains the same with the amount or moles of the concentrated solution.
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Therefore,
The number of moles in Concentrated solution =======The number of moles in dilute solution |
That’s okay. Let’s move on. For any dilution of any concentrated solution, the relationship between the concentration and volume of the concentrated and dilute solution is
C1V1 ====C2V2
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Before Dilution ======= After Dilution
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Now having learnt the above, let’s have a simple problem;
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1. Calculate the volume of 0.07mol/dm3 solution obtained when 200cm3 of 0.5 mol/dm tetraoxosulphate (VI) acid is diluted.
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SOLUTION
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C1V1=======C2V2
Concentration before Dilution
C1=0.5
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Volume before Dilution
V1=200cm3
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Concentration after dilution
C2=0.007mol/dm3
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Volume after dilution——————–?
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Therefore formularly, C1V1====C2V2
0.5 X 200 === 0.07 X V2
V2 ======= 0.5 x200 ÷ 0.07
V2============1428.6cm3
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I hope you enjoyed the lesson, comment below for improvement to serve you better. Thanks.
