Solutions

Definition of solution

1. It is a mixture of liquid where the minor component is solute and is dissolved in the major component is solvent.
2. This solute and solvent are uniformly distributed.

• These are the formulas for the preparation of various solutions

Molar solution

1. It contains one mole as (molecular weight) of solute in a solution (solvent) making it equal to one liter.
2. Molar solution = Molecular weight in gram/liter in the solution.
3. Example:
4. I molar solution of sodium chloride (NaCl).

Sodium atomic weight = 23

Chloride atomic weight  = 35.5

Total molecular weight = 58.5 gram/mol

Now dissolve 58.5 grams of NaCl in distilled water and make the solution to one liter.

Normal solution

• The normal solution is defined as the gram equivalent weight per liter of the solution (solvent).
  • Normal solution  =  gram equivalent weight of solute/liter of the solution (solvent) = Eq.wt/L.
• These solutions are expressed as N.
  • Gram equivalent weight = Gram molecular weight/valency.
• Example of Gram equivalent weight  e.g NaCl
  • NaCl gram molecular weight = 58.5 g
  • Valency =1
  • 58.5/1 = 58.5 gram equivalent weight.

Example

To make a 1 N sodium chloride solution

• The molecular weight of NaCl is 58.5.
• Gram equivalent weight of NaCl =  molecular weight/1 (valency).
  • So dissolve 58.5 grams of NaCl in distilled water and makeup to one liter.
  • Dissolve 58.5 grams of NaCl in distilled water to make one liter.

Percent solution

1. This is per hundred part of the total solution.
2. There are three possibilities for a percent solution.
3. Weight/weight:
   1. It is a percentage of solute in 100 grams of final solution equal to solute + solvent.
   2. e.g.For the 5% solution take 5 grams of NaCl dissolved in 95 grams of water which is around 95 mL.
4. Weight/volume:
   1. 5 grams of NaCl dissolved in water and the volume is made 100 ml is called a 5% solution of NaCl.
5. Volume/volume:
   1. It is composed of two solutions. e.g. if we take 5 mL of acid and dilute it to 100 mL of water will be a 5% solution of that acid.

Dilution

1. This procedure is very common to prepare the dilution of the serum where there is a high concentration of chemicals like urea in the blood if it is above 300 mg/dL.
2. If we make a dilution of serum like this:
   1. Serum = 1 ml
   2. Diluting fluid 4 mL
   3. This will be a dilution of 1:5 (1+4 =5).