Sulfuric Acid (H2SO4): Structure, Properties and Uses

Ans. Sulphuric acid is produced from sulphur. Sulphur dioxide is obtained by burning the molten sulphur in the presence of air. Sulphur dioxide is then converted to sulphur trioxide in the presence of a catalyst such as vanadium pentoxide.

Ans. The primary application of sulfuric acid is in fertilizer processing. It is commonly used in chemical processing, e.g. in the manufacture of nitric acid, dyes and pigments, explosives, and medicines.

Ans. As sulphuric acid is a strong acid, a sulphuric acid solution of 0.50 M has a pH near zero.

Ans. Aluminum is a highly reactive metal and will not dissolve in oxidizing acids like nitric acid, as a protective layer of aluminum oxide will grow on its surface. Thallium dissolves in sulphuric acid, but not in hydrochloric acid.

Ans. Pouring the baking soda directly into a spill of acid will neutralize light acids such as vinegar, strong acids such as muriatic and sulphuric acids. Douse with the baking soda the entire contaminated region to neutralize the acid.

Ans. The monoprotic acid is hydrobromic acid because of one proton (H) hydrogen. No monoprotic hydrogen exists. In the starting acid, sulphuric acid (H₂SO₄), there are two acid protons.

Ans. When you have a certain amount of concentrated sulphuric acid, you should pour it into a sodium hydroxide solution. Water dilutes and carries off some heat that the sodium carbonate produces when it neutralizes the acid.

Ans. Water forms a compromise between H₂O and H₃O⁺ and -OH. That doesn’t make anything ionic. Since all the bonds are covalent, It is a compound with covalence.

Ans. (a) The unknown salt present in a test tube is sodium nitrate and sulphuric acid evolves a brown gas that is NO₂ gets intensified when Cu turnings are added. 

NO₂ condenses as a brown liquid on cooling which again turns paler on cooling and eventually becomes a colourless solid due to the formation of dimerized NO₂ i.e., N₂O₄ (Dinitrogen tetraoxide).

(i) – Nitrogen Dioxide (NO₂)

(ii) – Dinitrogen tetraoxide (N₂O₄) 

(b) The structure of XeOF_4,

Ans. (i) As the standard reduction potential value of Fluorine is more than that of Chlorine, therefore Fluorine is a stronger oxidising agent. 

• Bond dissociation enthalpy of F₂ is less than that of Chlorine.
• The negative electron gain enthalpy of Fluorine is slightly less than that of Chlorine. 
• The hydration entahlapy of Floride ion is much higher than that of Chloride ion due to smaller size.

(ii) The favourable conditions for manufacturing sulphuric acid by contact process are as follows:

• There must be high pressure of about 2 bars.
• Low temperature of about 720 K.
• Presence of V₂O₅ catalyst. 

(iii) (a) H₃PO4 < H₃PO₃  <  H₃PO2

(b) BiH₃ < SbH₃ < AsH₃ < PH₃ < NH₃ 

Ans. (a) 

(b) The contact process of sulphuric acid are,

• Formation of sulphur dioxide by burning eithrr sulphur or iron pyrites excess in air. S + O₂ → SO₂ ; 4FeS₂ +11O₂  → 2Fe₂O₃ + 8SO₂
• Catalytic Oxydation of SO₂ into SO₃ with the help of V₂O₅ as catalyst.

(c)According to Le-Chatelier’s principle, the reaction conditions are as follows,

• High concentration of reactants.
• Low temperature (623 – 723 K).
• High pressure (2 bar).

The yeild of sulphuric acid by obeying the above conditions will be, 96 – 98%

(iii) The absorption of SO₃ in 98% H₂SO₄ gives Oleum (H₂S₂O₇)

SO₃ + H₂SO₄ → H₂S₂S₇ (Oleum)

(iv) Dilution of Oleum to give sulphuric acid. 

H₂S₂O₇  + H₂O = 2H₂SO4

Ans. (a) The contact process- burning sulphur in an excess of air,

S + O₂ → SO₂

or, by heating sulphide ores like pyrites in an excess of air,

4FeS₂ +11O₂  → 2Fe₂O₃ + 8SO₂

In any one of the two cases, an excess of air is used so that the SO₂ produces is already mixed with oxygen for the next stage. This is the reversible reaction and the formation of SO3 is exothermic in the presence of catalyst V₂O₅ at 720 K.

This can not be done by adding water to the SO3 . This reaction is so uncontrollable that it creates a fog of sulphuric acid. Instead the SO₃ is first dissolved in cone, H₂SO₄

H₂SO₄ + SO₃ → H₂S₂O₇

The product is the fuming sulphuric acid or oleum to which water is added to get H₂SO₄

H₂S₂O₇ +  H₂O  → 2H₂SO4

Ans. The three areas in which sulphuric acid plays an important role are,

• Sulphuric acid is used for manufacturing a number of chemicals like hydrochloric acid, phosphoric acid, nitric acid along with a large number of organic compounds.
•  A mixture of concentrated nitric acid and concentrated sulphuric acid is used in the manufacture of explosives like picric acid, dynamite, T.N.T and so on.
• Dilute solution of acid is employed in petroleum refining to remove the unwanted impurities of sulphur.

Ans. The key step in the manufacture of sulphuric acid is the oxidation of SO₂ to SO3 in the presence of the catalyst V₂O₅.

The reaction is reversible and at the same time, exothermic. Therefore, low temperature and high pressure are the favourable conditions for the maximum yeild of SO3. In practice a pressure of 2 bar and temperature of 720 K is maintained.