1st Year MBBS- Solution

Solution

A solution may be defined as a homogenous mixture consisting of two or more substances in different proportions forming a single phase depending upon temperature and pressure.

Example: Solution of sugar or salt in water.

Components of the solution: A solution consists of two parts- a) Solvent and

b) Solute.

Solvent: The substance which has the capability to disperse another substance in solution and has the same physical state as that of the resultant solution is called the solvent. Example: Water.

Solute: A solute is the substance that dissolves in the solvent and loses its physical state to form a solution. Example: Sugar, NaCl.

Classification

On the basis of their characteristics:

a)      Qualitative b) Quantitative

On the basis of their physical appearance:

a) Saturated b) Unsaturated c) Supersaturated.

3.On the basis of their permeability through cell membrane: a) Crystalloidal b) Colloidal.

4.On the basis of their concentration:

Percent solution. It is subdivided into three type’s A. percent by weight (wt/wt) B.percent by volume (wt/vol) C.percent by volume (vol/vol).

Molar solution

Molal solution

Normal solution

Osmolar solution.

Some Definitions:

1. Saturated solution: A saturated solution is one in which there is equilibrium between the solution and undissolved solute at the temperature of the solution.

2. Unsaturated solution: A solution in which the solvent is capable of dissolving more of the solute at a definite temperature of the medium is called an unsaturated solution.

3. Supersaturated solution: A solution containing more of the solid than the liquid which would ordinarily dissolve by the saturated solution at a given temperature is called supersaturated solution.

Crystalloidal solution: The solution, the solutes of which can pass through a semipermeable membrane is called crystalloidal solution.

Colloidal solution: The solution, the solutes of which fail to pass through a semipermeable membrane is called colloidal solution.

Percent solution: It is the solution whose relative strength is expressed in percentage. It is of three types;

Percent by weight (weight/weight solution) This indicates weight in grams of solutes per 100-gram solution, e.g.38% HCl by weight.

Percent by volume (weight/volume solution) This indicates the grams of solute per 100 ml of solution, e.g.5% NaCl in water.

Percent by volume (Volume/volume solution) This indicates the milliliters of solute per 100 ml of solution. e.g. 5% alcohol solution in water.

Molar solution: It is a solution which contains 1 gm molecular weight of solute per liter of solution e.g. gm molecular weight of HCl = 36.5 gm. Therefore, molar solution of HCl contains 36.5 gm/liter of solution.

Normal solution: It is a solution which contains one gm equivalent weight of solute per liter of solution e.g. gm equivalent wt of H₂SO₄ = 49. Therefore, normal solution of H₂SO₄ contains 49 gm/liter of solution.

Molal solution: A molar solution is one which contains one gm molecular weight of solute in 1000 gm of solvent. For example, molal solution of HCl contains 36.5 gm/kgm.

Osmolar solution: It is a solution where one osmole of solute is dissolve in one liter of solution.

Isotonic solution: The solution which has the same osmotic pressure as that of plasma is called isotonic solution. For example, a NaCl solution containing 0.9 gm of NaCl in each 100 ml of water (i.e.0.9% NaCl solution is isotonic with plasma).

Hypertonic solution: The solution which has greater osmotic pressure than that of plasma is called hypertonic solution. For example, a concentrated solution of NaCl (i.e. 1.5% NaCl solution).

Hypotonic solution: The solution which has less osmotic pressure than that of plasma is called hypotonic solution. For example, a NaCl solution containing less than 0.9 gm NaCl in each 100 ml of water (i.e. 0.3% NaCl solution).

Normal saline: 0.9gm% NaCl solution is known as normal saline as it does not change the volume of red blood cell.

Gram molecular weight: Molecular weight expressed in gram is known as gram molecular weight. Gram molecular weight of NaCl is 58.5 gm.

Gram equivalent weight: It is that weight of an element or compound which will combine with or replace 1.008 gm hydrogen.

Equivalent weight of an element= Molecular weight/valency.

Milliequivalent weight: The milliequivalent weight is one thousandth of the gram equivalent weight and is he same as millimol as long as the valence is one, i.e.

Milliequivalent weight= millimolecular weight/valency.