How can I Prepare and Standardization 0.5 M Sulfuric acid

by

Aim: To prepare and standardize 0.5 M sulfuric acid (0.5 M H2SO4).

0.5 M Sulfuric acid Preparation and Standardization

Principle:

1. This is carried out by aqueous acid-base titration based on a neutralization reaction.
2. This titration takes place between sulphuric acid (H2SO4) and sodium carbonate (Na2CO3).
3. Sodium carbonate, anhydrous is a primary standard substance that reacts with a secondary standard substance, H2SO4.
4. Anhydrous sodium carbonate is a strong base whereas sulphuric acid is a strong acid.
5. Hence, it is strong base-strong acid (SB – SA) type of neutralization titration.
6. Methyl red solution is used as an indicator. It is a preferred indicator for this type of neutralization titration.

Requirements for Preparation and Standardization of 0.5 M Sulfuric acid:

1. Apparatus: Beaker, conical flask, pipette, pipette filler, burette, measuring cylinder, burette stand and holder, glass funnel, white tile, bench mat.
2. Chemicals: Sodium carbonate solution, concentrated sulphuric acid, methyl red indicator solution.

Theory:

(A) Sodium carbonate (Primary standard):
(B) Sulphuric acid (Titrant):
1. Molecular formula: H2SO4
2. Molecular weight: 98.079
3. Equivalent weight: 49.03
4. It is a diprotic acid and contains two replaceable hydrogen ions, therefore its equivalent weight is half of its molecular weight.
5. Chemical names: Oil of vitriol. This name was given because pure sulphuric acid is a viscous clear liquid, like oil.

Description: It is clear, odorless, pungent-ethereal, colorless to slightly yellow viscous liquid, a highly corrosive strong mineral acid, and a powerful protonating agent. It is hygroscopic, readily absorbing water vapors from the air. The 98% grade is more stable in storage, and is usually referred to as “concentrated sulphuric acid”.

Safety:

  • The reaction, specifically a hydration reaction, between sulphuric acid (H2SO4) and water (H2O) is known to be highly exothermic, meaning it releases a significant amount of heat. Consequently, when diluting sulphuric acid, it is essential to follow a specific procedure for safety purposes.
  • Dilution should always be carried out by adding the acid to the water, rather than the water to the acid.
  • Sulphuric acid at a high concentration can cause very serious damage up; contact. It burns the cornea and can lead to permanent blindness if splashed onto the eyes.
  • Sulphuric acid must be stored carefully in containers made of non-reactive material (such as glass). Solutions equal to or stronger than 1.5 M are labeled as “CORROSIVE”, while solutions greater than 0.5 M but less than 1.5 M are labeled as ( “IRRITANT”. However, even the normal laboratory “dilute” grade (approximate) 1 M, 10%) solutions produce a charing effect by dehydration. if left in contact for sufficient time.
  • The standard first aid treatment if acid spills on the skin is irrigation with a large quantity of water for at least ten to fifteen minutes. Contaminated clothing was removed immediately and the underlying skin was washed thoroughly.

Preparation of Reagents/Solutions:

0.5 M sulphuric acid Preparation: Add slowly, with stirring, 30 ml of concentrated sulphuric acid to about 1000 mL of water, and allow to cool at 25°C.

Standardization of 0.5 M H2SO4:

  1. Weigh accurately about 1.5 g of anhydrous sodium carbonate (which is previously heated at about 270°C for 1 hour).
  2. Dissolve 1.5 g of anhydrous sodium carbonate in 100 mL of distilled water.
  3. Add 0.1 mL of methyl red solution as an indicator.
  4. Gradually add 0.5 M sulphuric acid from a burette into the solution while stirring continuously until the solution turns slightly pink.
  5. Next, heat the solution to a boiling point, allow it to cool down, and then proceed with the titration process.
  6. Heat the solution once again until it reaches the boiling point, and proceed to titrate it further as required until the faint pink color remains unaffected by the continued boiling.

Reaction:

0.5 M Sulfuric acid Reaction

Strong acid (Sulphuric Acid) reacts with a strong base (Sodium carbonate) to form N2SO4 salt and carbonic acid which further form water molecules and carbon dioxide on heating.

Factor calculation:

1 mole of H2SO4= 1 mole of sodium carbonate
1000 mL of 1M H2SO4= 106 g of Na2CO3
1000 mL of 0.5 M H2SO4= 53 g of Na2CO3
1 mL of 0.5 M H2SO44= 0.053 g of Na2CO3
1 mL of 0.5 M sulfuric acid is equivalent to 0.05299 g of Na2CO3

Calculation:

Equivanalt factor method:

1 mL of 0.5 M H2SO4= 0.05299 g of Na2CO3
X mL of y M H2SO4 = 1.5 g of Na2CO3

y= ………M

Formula Method:

y= ……M

Result: The molarity of sulfuric acid solution (Prepared, 0.5 M) was found to be …….M

Leave a Comment