A solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is a substance dissolved in another substance called as the solvent. The concentration of a solute in a solution is a measure of how much of that solute is dissolved in a solvent.
Standard solutions are those in which the exact amount of a substance presents in a definite volume of solution. To prepare the standard solution, a known weight of solute is measured on a well-calibrated weighing scale and then dissolved in a solvent (usually distilled water) to make up a specific volume.
Normality (N) is one of the commonly used units that determine the concentration of the solution that expresses the gram equivalent weight of solute per liter of the solution. In other words, Normality is simply the number of active grams of a solute per liter of the solution.
The 2/3 N Sulfuric Acid solution is prepared as follows…..
- Measuring cylinder
- Volumetric flask / Beaker
- Distilled water
- Concentrated H2SO4 (97%)
CALCULATIONS FOR 2/3 N SULFURIc ACID SOLUTION…..
Molecular weight of H2SO4 = (2×1) + 32 + (4×16) = 2 + 32 + 64 = 98 gm
N = [Weight / Equivalent weight] × [1000 / Volume (in ml)]
2/3 = [X/98/2] × [1000/500]
X = 1/3 × 49 = 16.3 gm
X = 16.3 gms
Conversion of grams into volume (ml) –
Volume of acid needed = Grams of acid / (Concentration of acid + Specific gravity)
Specific gravity of H2SO4 = 1.94
Concentration of the acid = 97%
Volume of the acid needed to make 500 ml of 2/3 N H2SO4
(16.3 / 0.97) + 1.94 = 8.7 ml
Thus, 8.7 ml of 97% H2SO4 should be added to the 491.3 ml of Distilled water to make the 500 ml of 2/3 N H2SO4 Solution.
PROCEDURE FOR 2/3 N SULFURIC ACID SOLUTION…..
⇒ Take measuring cylinder and measure 8.7 ml of H2SO4 [sulfuric acid (97%)].
⇒ Take 250 ml of Distilled water in the Beaker or Volumetric flask.
⇒ Now add 8.7 ml of the H2SO4 slowly in the flask having distilled water.
⇒ Mix well using a stirrer (if you are making the solution in the beaker) or by swirling (in case you are making the solution in the volumetric flask).
⇒ Make the final volume 500 ml by adding the distilled water.
⇒ Mix well by stirring (in case of the beaker) or swirling (in case of the volumetric flask).
PRECAUTIONS TO BE TAKEN WHILE PREPARING SULFURIC ACID SOLUTION…..
⇒ Measure accurately the 8.7 ml of 97% concentrated sulfuric acid.
⇒ Always add acid to water and never water to the acid as dilution of acid is a highly exothermic reaction.
⇒ Work near a running supply of water. If the acid contacts the skin, it must be washed off rapidly with the copious amount of tap water.
⇒ Concentrated H2SO4 is highly corrosive so handle with care.