Solutions

 Solutions – homogeneous mixtures composed of two or

more substances. In such mixtures, a solute is dissolved

in another substance, known as a solvent.

 Solvent is that component in the solution, whose

physical state is the same as that of resulting solution.

For a solution in which both components have the same

physical state, the component which is in larger amount

is called solvent.

Types of solutions

 According to the particle size

 Suspensions ( >100 nm)

 Colloidal solution ( 1 - 100 nm)

 True solution ( <1 nm)

 According to the amount of solute

 Unsaturated

 Saturated

 Supersaturated

 The effect of the nature of the solvent

on solubility – “Like dissolves like”!!!

Concentration

 It shows exactly how much solute is dissolved in a certain

amount of solution. The quantities of the solute and the

solvent can be expressed by different measure units

(moles, grams, liters)

Medical chemistry, Assist. Prof. S. Ruseva 5

Concentration =

Amount of solute

Amount of solution

Types of concentrations

 Percent concentrations

 Weight/weight percent (w/w)%

 Volume/volume percent (v/v)%

 Weight/volume percent (w/v)%

 Volume concentrations

 Molarity (М)

 Titer (Т)

Percent concentrations

 (w/w)% - shows the grams of solute dissolved in 100 g of

solution.

 (v/v)% - shows the milliliters of solute dissolved in 100 mL

of solution.

 (w/v)% - shows the grams of solute dissolved in 100 mL

of solution.

(w/w)% = g solute/ g solution x 100

(v/v)% = mL solute/mL solution x 100

(w/v)% = g solute/mL solution x 100

 Molarity (М ) – shows the number of moles of solute

dissolved in 1 L of solution.

 Molar mass = mass (in grams) of 1 mole of substance

Mole

 The mole (abbreviated mol) is a measure unit in

chemistry.

 Defined as the number equal to the number of carbon

atoms in exactly 12 grams of pure 12C.

 One mole of any substance is that amount which

contains Avogadro's number of particles (atoms,

molecules, ions). Avogadro's number is 6,02x1023.

 Just like a dozen eggs is 12 eggs; a mole of eggs is

6,02x1023 eggs .

Volume concentrations

 Titer (Т) – shows the grams of solute dissolved in 1 mL of

solution.

T = g solute/mL solution

Dilution

C1 x V1 = C2 x V2

Dilute solutions are prepared by mixing extra solvent

with a more concentrated solution.

C1 – initial concentration

V1 – initial volume

C2 – final concentration

V2 – final volume

Saline solution

 Normal Saline Solution (saline) is a

mixture of sodium chloride NaCl in water

(concentration 0,9 %(w/v)).

 It is isotonic with human blood. (The

osmolarity of normal saline is a close

approximation to the osmolarity of

blood.)

 It is used to clean wounds, help remove

contact lenses, and help with dry eyes.

 By injection into a vein it is used to treat

dehydration such as from gastroenteritis

and diabetic ketoacidosis.

Measuring volume - liquids

 When water is in a thin glass tube, it does not have a flat

surface at the top. Instead, the top is curved inward.

 The curved surface at the top of a column of liquid is called

meniscus .

 The volume of the solution should be read from the bottom

of the meniscus.