How to prepare 1 molar solution

April 24, 2022Chemical pathologyLab Tests

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.

Molar solution

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).

Procedure for dilution

1. This dilution can be made from the stronger solution by this formula:

Solution diluting formula

1. Example dilution of sodium hydroxide 1:
   1. To make 250 mL of sodium hydroxide solution 0.25 mol/L from a solution of 0.4 mol/L solutions.
      1. C = o.25 mol/L
      2. V = 250 mL
      3. S = 0.4 mol/L
      4. Calculation = 0.25 x 250 / 0.4 = 156.25 mL
2. Example dilution of HCL 2:
   1. Make 500 ml of HCL acid , 0.01 mol/L from a 1 mol/L acid.
      1. C = 0.01
      2. V = 500
      3. S = 1
      4. Calculation = 0.01 x 500 / 1 = 5 mL of HCL acid.
3. Example for dilution of the body fluids:
   1. To make a 5 ml of 1 in 10 dilutions of the serum.
      1. C = 1:10
      2. Volume = 5 mL
      3. S = 1
      4. Calculations = 1/10 x 5 / 1 = 0.5 mL of the serum and 4.5 mL of the saline = 0.5 : 4.5 = 1:10 dilution

Question 1: What is the difference between the molar and normal solution?

Molar solution is gram molecular weight/L and the normal solution is gram equivalent weight/L.

Question 2: What is formula for the dilution of various fluids?

Volume mL of the strong fluid = C x V / S

Question 3: What are types of % solution?

There are possibilities of = 1. weight/weight 2. weight/volume 3. Volem /volume

Molarity is another standard expression of solution concentration. Molar solutions use the gram molecular weight of a solute in calculating molar concentration in a liter (L) of solution.

The gram molecular weight (GMW) of a substance (sometimes called the "formula weight") is the sum of the combined atomic weights of all atoms in the molecule expressed in grams. For example, the GMW of NaCl is equal to the atomic weight (these atomic weights may be found on a periodic table or as a formula weight on the bottle of substance) of Na (22.99) and the atomic weight of Cl (35.45) for a total of 58.44 g.

A 1 molar (M) solution will contain 1.0 GMW of a substance dissolved in water to make 1 liter of final solution. Hence, a 1M solution of NaCl contains 58.44 g.

HCl is frequently used in enzyme histochemistry. The GMW of HCl would be the atomic weight of H added to the atomic weight of Cl: H = 1 + Cl = 35.45 = 36.45 g. A liter of 1M solution of HCl would contain 36.45 g.

Monosodium dihydrogen phosphate (NaH2PO4) buffer is also used in enzyme histochemistry. A liter of 1M solution of NaH2PO4 would contain Na (22.99) + 2 H (1x2=2) + P (30.97) + 4 O (16x4=64) for a total GMW of 119.98 g.

To simply calculate the amount or weight of a substance needed for a desired molar solution, the following formula may be used:

Weight in grams = desired molarity x volume needed in liters x GMW

500 mL of a 0.1M solution of NaOH is needed for a procedure. Calculate the amount of solute (NaOH) needed to prepare the solution. (atomic weights: Na = 22.99; O = 16; H = 1)

How do you make a 1M molar solution?

What is 1 molar of a solution?

How do you make a 1 molar solution of NaCl?

How do you make a 1 molar solution of NaOH?