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EXPT. No. Date:

STUDY THE EFFECT OF TEMPERATURE SOLUBILITY OF INORGANIC SALT

Aim: To study the effect of temperature on the solubility of salts

Prini!"e: Solubility is an important phenomenon in pharmaceutical sciences. It plays a

very important role in the formulation of dosage form as a Preformulation factor.

Solubility of a compound in a particular solvent is defined as the concentration of the

solute in a saturated solution at a certain temperature. A true homogenous solution is

formed due to the interaction or two or more compounds to form a molecular dispersion.

E##et o# tem!erat$re on %o"$&i"it':

Generally in many cases solubility increases with the rise in temperature and decreases

with the fall of temperature but it is not necessary in all cases. However we must

follow two behaviors:

  In endothermic process solubility increases with the increase in temperature for 

eample: solubility of potassium nitrate increases with the increase in temperature. In

eothermic process solubility decrease with the increase in temperature. !or eample:

solubility of calcium oide decreases with the increase in temperature. Gases are more

soluble in cold solvent than in hot solvent.

Re($irement:

C)emia"% * rea+ent%

". Pure inorganic salts #$%l& 'a%l& 'a'() $*S(+ etc,

-. istilled water 

E($i!ment% an, +"a%%-are

". Theromostat

-. Thermometer 

). Pocelain dishes or watch glasses

+. Pipette

/. Hot plate

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Proe,$re:

". %lean all glassware using detergent solution or chromic acid solution

-. 0ash two to three times using purified water 

). Ta1e /2 ml of distilled water in a bea1er #"22 ml,

+. Add some amount of salt li1e potassium chloride or sodium chloride in distilled water

and stir using glass rod or by an electric motor driven sha1er

/. Increase the temperature to 3/2% with continuous stirring

4. 5aintain this temperature for few minutes and then cool down the solution

6. Ta1e sample at 322% using pipette with a piece of filter paper& tie at the tip of the

pipette& so that the insoluble in soluble salt is removed

3. 7emove the piece of filter paper from the tip of pipette and transfer "2 ml of thissolution in weighed porcelain dish or watch glass.

8. Allow the temperature to fall down slowly to 622%& 422%& /22%& +22%& )22%& and then

to room temperature.

"2. At each temperature ta1e sample of the solution and repeat the step 6 and step 3.

"". 9vaporate the solution of each porcelain dish or watch glass using direct heat or on

the water bath or put in the oven.

"-. ry the solution till constant weight.

"). Ta1e weight of the dish using double pan balance or chemical balance and calculate

the weight of the powder 

"+. 7ecord all the parameter in the form of table

O&%eration%

S/N Tem!erat$re

02%,

1ei+)t

o#

em!t'

Di%)

12 +

1ei+)t

o# ,i%)

3%o"$tio

n 14 +

1ei+)t

o# ,i%)

3

re%i,$e

15 +

1ei+)t

o#

re%i,$e

156-2

+

1ei+)t

o#

%o"ent

14615

+

So"$&i"it

' in

+/277+

" 32

- 62) 42

+ /2

/ +2

4 )2

6 7T

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%alculations:

Solubility of salt in solvent at temperature   2% is calculated by the following formula in

g;"22g

solubility of salt at 80 °C =w3−w1

w2−w3 x100

Re%$"t 

Solubility of the given salt at room temperature #considering the saturated solution atroom temperature, < =. Plot the graph between solubility and temperature.