Q: Question 9Give equations for formation of two different acids from conc. H2SO4. State the property of sulphuric acid involved in the above formation.

NaNO3+H2SO4[conc.]→<200°CNaHSO4+HNO3\text{NaNO}_3 + \text{H}_2\text{SO}_4 [\text{conc.}]\xrightarrow{\lt 200 \degree\text{C}} \text{NaHSO}_\text{4} + \text{HNO}_3NaNO3+H2SO4[conc.]<200°CNaHSO4+HNO3NaCl+H2SO4[conc.]→<200°CNaHSO4+HCl\text{NaCl} + \text{H}_2\text{SO}_4 [\text{conc.}]\xrightarrow{\lt 200 \degree\text{C}} \text{NaHSO}_\text{4} + \text{HCl}NaCl+H2SO4[conc.]<200°CNaHSO4+HClThe property of being a non-volatile acid is used in the above reactions.

Q: Question 13State the observation seen when conc. H2SO4 is added to –(i) sucrose(ii) hydrated copper [II] sulphate.

(i) Conc. H2SO4 dehydrates sucrose to a black spongy charged mass of carbon sugar charcoal.C12H22O11→Conc. H2SO412C [sugar charcoal]+11H2O\text{C}_{12}\text{H}_{22}\text{O}_{11}\xrightarrow{\text{Conc. H}_2\text{SO}_4} \text{12C} \small{\space[sugar\space charcoal]} + \text{11H}_2\text{O}C12H22O11Conc. H2SO412C [sugar charcoal]+11H2O(ii) The blue coloured hydrous copper sulphate changes to white anhydrous copper sulphate as the water of crystallization is removed.CuSO4.5H2O→Conc. H2SO4CuSO4 [White Anhydrous]+5H2O\text{CuSO}_4\text{.5H}_2\text{O} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \text{CuSO}_4 \text{ [White Anhydrous]} + 5\text{H}_2\text{O}CuSO4.5H2OConc. H2SO4CuSO4 [White Anhydrous]+5H2O

Q: Question 14State how addition of –(i) copper(ii) NaClto hot conc. H2SO4 serves as a test for the latter.

(i) When Cu is added to hot conc. H2SO4, colourless suffocating (SO2) gas is evolved. The gas turns orange coloured acidified potassium dichromate solution to green colour.Cu + 2H2SO4 (conc.) →Δ\xrightarrow{\Delta}Δ CuSO4 + SO2 + 2H2O(ii) When NaCl is heated with conc. H2SO4, colourless pungent smelling HCl gas is evolved.NaCl+H2SO4[conc.]→<200°CNaHSO4+HCl\text{NaCl} + \text{H}_2\text{SO}_4 [\text{conc.}] \xrightarrow{\lt 200 \degree\text{C}} \text{NaHSO}_\text{4} + \text{HCl}NaCl+H2SO4[conc.]<200°CNaHSO4+HClDense white fumes are produced when a rod dipped in NH3 soln. is brought near the test tube containing HCl gas.

Q: Question 15Give two tests for dilute sulphuric acid with balanced equations. State why(i) BaCl2(ii) Pb(NO3)2are used for the above tests

(i) BaCl2 solution on treating with dilute sulphuric acid forms white ppt. of barium sulphate, which is insoluble in dilute sulphuric acid.BaCl2 + H2SO4 (dil) ⟶ 2HCl + BaSO4 ↓ [white ppt. formed](ii) Pb(NO3)2 on treating with dilute sulphuric acid gives white ppt of lead sulphate, which is insoluble in dil. H2SO4.Pb(NO3)2 + H2SO4 (dil) ⟶ 2HNO3 + PbSO4 ↓ [white ppt. formed]BaCl2 and Pb(NO3)2 are used for the above tests as they react with H2SO4 and form BaSO4 and PbSO4 respectively, which are the only compounds insoluble in dil. sulphuric acid.

Q: Question 1What property of conc. H2SO4 is made use of in each of the following cases? Give an equation for the reaction in each case:(a) in the production of HCl gas when it reacts with a chloride,(b) in the preparation of CO from HCOOH.(c) as a source of hydrogen by diluting it and adding a strip of magnesium.(d) in the preparation of sulphur dioxide by warming a mixture of conc. sulphuric acid and copper-turnings.(e) hydrogen chloride gas is passed through concentrated sulphuric acid.(f) it's reaction with (i) Ethanol (ii) Carbon.

(a) The property of being a non-volatile acid is used.NaCl + H2SO4 [conc.] →<200°C\xrightarrow{\lt 200 \degree\text{C}}<200°C NaHSO4 + HCl(b) The property of being a dehydrating agent is used.HCOOH →Conc. H2SO4\xrightarrow{\text{Conc. H}_2\text{SO}_4}Conc. H2SO4 CO + H2O(c) The acidic property is used.Mg + H2SO4 [dil.] ⟶ MgSO4 + H2 ↑(d) The property of being an oxidizing agent is used.Cu + 2H2SO4 [conc.] ⟶ CuSO4 + 2H2O + SO2 ↑(e) The property of being a drying agent is used.Hydrogen chloride gas is dried by passing through conc. sulphuric acid as it does not react with conc. sulphuric acid.(f) (i) The property of being a dehydrating agent is used.C2H5OH ethyl alcohol→170°CConc. H2SO4[excess]C2H4ethene↑+H2O \underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170\degree\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} ↑ + \text{H}_2\text{O}\ ethyl alcoholC2H5OHConc. H2SO4[excess]170°CetheneC2H4↑+H2O (ii) The property of being an oxidizing agent is used.C + 2H2SO4 [conc.] ⟶ CO2 + 2H2O + 2SO2 ↑

Q: Question 16Assertion (A): Sulphuric acid when dissolved in water forms a basic saltReason (R): Sulphuric acid ionises in two stages, it is a dibasic acid.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

A is false but R is true.Explanation— Sulphuric acid when dissolved in water forms hydronium ion and shows acidic properties. Hence, the assertion (A) is false.Sulphuric acid ionises in two stages and is called dibasic acid. Hence, the reason (R) is true.H2SO4 + 2H2O ⇌\rightleftharpoons⇌ H3O+ + HSO4-HSO4- + 2H2O ⇌\rightleftharpoons⇌ H3O+ + SO42-

Q: Question 17Assertion (A): Pure sulphuric acid is almost a non-conductor of electricity.Reason (R): Dilute sulphuric acid is a good conductor of electricity.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Both A and R are true but R is not the correct explanation of A.Explanation— Pure (concentrated) H2SO4 is not ionized significantly because no water is present to dissociate it into ions. Therefore, it does not conduct electricity. Hence, the assertion (A) is true.When H2SO4 is diluted with water, it ionizes completely to give H- and SO42- ions, which are free to move. These ions carry electric current, making it a strong electrolyte. Hence, the reason (R) is true.However, reason (R) does not explain why pure sulphuric acid is a poor conductor of electricity. Hence, reason (R) is not the correct explanation of assertion (A).

Q: Question 18Assertion (A): Impurity of arsenic oxide must be removed before passing the mixture of SO2 and air through the catalytic chamber.Reason (R): Arsenic oxide poisons the catalyst.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Both A and R are true and R is the correct explanation of A.Explanation— In the manufacture of sulphuric acid, purification of gases is done by removing the impurity of arsenic oxide before passing the mixture of SO2 and air through the catalytic chamber. Hence, the assertion (A) is true.Purification of gases is done because arsenic oxide poisons the catalyst and the catalyst loses its efficiency. Hence, the reason (R) is true and it is the correct explanation of assertion (A).

Question 1

Question 6State the basic steps with reasons, involved in diluting a beaker of conc. H2SO4.

Accepted Answer

For dilution of conc. H2SO4, the conc. acid is added to water and not the water to the acid even though heat is evolved in both cases.If water is added to the acid : There is a sudden increase in the temperature and the acid being in bulk tends to spurt out.If acid is added to water : The water is in bulk and the acid being heavier settles down. The heat evolved is dissipated in the water itself and hence the spurting of the acid is minimized.

Question 2

Question 7Give reasons why dilute sulphuric acid:(i) behaves as an acid when dilute.(ii) is dibasic in nature.

Accepted Answer

(i) Acidic properties of sulphuric acid are due to the presence of hydronium ions [H3O+] formed when H2SO4 dissociates in aqueous solution. Hence, it behaves as an acid when dilute.(ii) Sulphuric acid dissociates in aqueous solution giving two hydrogen ions (H+) ions per molecule of the acid. Hence, it is dibasic in nature.H2SO4 ⇌ 2H+ + SO42-H2SO4 + 2H2O ⇌ 2H3O+ + SO42-

Question 3

Question 9Give equations for formation of two different acids from conc. H2SO4. State the property of sulphuric acid involved in the above formation.

Accepted Answer

NaNO3+H2SO4[conc.]→<200°CNaHSO4+HNO3	ext{NaNO}_3 + 	ext{H}_2	ext{SO}_4 [	ext{conc.}]\xrightarrow{\lt 200 \degree	ext{C}} 	ext{NaHSO}_	ext{4} + 	ext{HNO}_3NaNO3​+H2​SO4​[conc.]<200°C​NaHSO4​+HNO3​NaCl+H2SO4[conc.]→<200°CNaHSO4+HCl	ext{NaCl} + 	ext{H}_2	ext{SO}_4 [	ext{conc.}]\xrightarrow{\lt 200 \degree	ext{C}} 	ext{NaHSO}_	ext{4} + 	ext{HCl}NaCl+H2​SO4​[conc.]<200°C​NaHSO4​+HClThe property of being a non-volatile acid is used in the above reactions.

Question 4

Question 12Give the equation for the reaction of conc. sulphuric acid with –(i) glucose(ii) sucrose(iii) cellulose(iv) an organic acid containing one carbon atom and two hydrogen atoms(v) an organic acid containing two carbon and two hydrogen atoms(vi) an alcohol(vii) hydrated copper [II] sulphate

Accepted Answer

(i) Reaction of conc. sulphuric acid with glucose:C6H12O6→Conc. H2SO46C+6H2O	ext{C}_{6}	ext{H}_{12}	ext{O}_{6}\xrightarrow{	ext{Conc. H}_2	ext{SO}_4} 	ext{6C} + 	ext{6H}_2	ext{O}C6​H12​O6​Conc. H2​SO4​​6C+6H2​O(ii) Reaction of conc. sulphuric acid with sucrose:C12H22O11→Conc. H2SO412C [sugar charcoal]+11H2O	ext{C}_{12}	ext{H}_{22}	ext{O}_{11}\xrightarrow{	ext{Conc. H}_2	ext{SO}_4} 	ext{12C} \small{\space[sugar\space charcoal]} + 	ext{11H}_2	ext{O}C12​H22​O11​Conc. H2​SO4​​12C [sugar charcoal]+11H2​O(iii) Reaction of conc. sulphuric acid with cellulose:[C6H10O5]n→Conc. H2SO46[C]n+5[H2O]n[	ext{C}_{6}	ext{H}_{10}	ext{O}_{5}]	ext{n}\xrightarrow{	ext{Conc. H}_2	ext{SO}_4} 	ext{6[C]}_	ext{n} + 	ext{5[H}_2	ext{O}]_	ext{n}[C6​H10​O5​]nConc. H2​SO4​​6[C]n​+5[H2​O]n​(iv) Reaction of conc. sulphuric acid with formic acid [H.COOH]:H.COOH→Conc. H2SO4CO+H2O	ext{H.COOH}\xrightarrow{	ext{Conc. H}_2	ext{SO}_4} 	ext{CO} + 	ext{H}_2	ext{O}H.COOHConc. H2​SO4​​CO+H2​O(v) Reaction of conc. sulphuric acid with oxalic acid [H2C2O4]:H2C2O4→Conc. H2SO4CO+CO2+H2O	ext{H}_{2}	ext{C}_{2}	ext{O}_{4} \xrightarrow{	ext{Conc. H}_2	ext{SO}_4} 	ext{CO} + 	ext{CO}_{2} + 	ext{H}_2	ext{O}H2​C2​O4​Conc. H2​SO4​​CO+CO2​+H2​O(vi) Reaction of conc. sulphuric acid with ethyl alcohol:C2H5OH→Conc. H2SO4C2H4 [ethene−ethylene]+H2O	ext{C}_{2}	ext{H}_{5}	ext{OH}\xrightarrow{	ext{Conc. H}_2	ext{SO}_4} 	ext{C}_{2}	ext{H}_{4} \small{\space[ethene-ethylene]} + 	ext{H}_2	ext{O}C2​H5​OHConc. H2​SO4​​C2​H4​ [ethene−ethylene]+H2​O(vii) Reaction of conc. sulphuric acid with hydrated copper sulphate:CuSO4.5H2O→Conc. H2SO4CuSO4 [White Anhydrous]+5H2O	ext{CuSO}_4	ext{.5H}_2	ext{O} \xrightarrow{	ext{Conc. H}_2	ext{SO}_4} 	ext{CuSO}_4 	ext{ [White Anhydrous]} + 5	ext{H}_2	ext{O}CuSO4​.5H2​OConc. H2​SO4​​CuSO4​ [White Anhydrous]+5H2​O

Question 5

Question 13State the observation seen when conc. H2SO4 is added to –(i) sucrose(ii) hydrated copper [II] sulphate.

Accepted Answer

(i) Conc. H2SO4 dehydrates sucrose to a black spongy charged mass of carbon sugar charcoal.C12H22O11→Conc. H2SO412C [sugar charcoal]+11H2O	ext{C}_{12}	ext{H}_{22}	ext{O}_{11}\xrightarrow{	ext{Conc. H}_2	ext{SO}_4} 	ext{12C} \small{\space[sugar\space charcoal]} + 	ext{11H}_2	ext{O}C12​H22​O11​Conc. H2​SO4​​12C [sugar charcoal]+11H2​O(ii) The blue coloured hydrous copper sulphate changes to white anhydrous copper sulphate as the water of crystallization is removed.CuSO4.5H2O→Conc. H2SO4CuSO4 [White Anhydrous]+5H2O	ext{CuSO}_4	ext{.5H}_2	ext{O} \xrightarrow{	ext{Conc. H}_2	ext{SO}_4} 	ext{CuSO}_4 	ext{ [White Anhydrous]} + 5	ext{H}_2	ext{O}CuSO4​.5H2​OConc. H2​SO4​​CuSO4​ [White Anhydrous]+5H2​O

Question 6

Question 14State how addition of –(i) copper(ii) NaClto hot conc. H2SO4 serves as a test for the latter.

Accepted Answer

(i) When Cu is added to hot conc. H2SO4, colourless suffocating (SO2) gas is evolved. The gas turns orange coloured acidified potassium dichromate solution to green colour.Cu + 2H2SO4 (conc.) →Δ\xrightarrow{\Delta}Δ​ CuSO4 + SO2 + 2H2O(ii) When NaCl is heated with conc. H2SO4, colourless pungent smelling HCl gas is evolved.NaCl+H2SO4[conc.]→<200°CNaHSO4+HCl	ext{NaCl} + 	ext{H}_2	ext{SO}_4 [	ext{conc.}] \xrightarrow{\lt 200 \degree	ext{C}} 	ext{NaHSO}_	ext{4} + 	ext{HCl}NaCl+H2​SO4​[conc.]<200°C​NaHSO4​+HClDense white fumes are produced when a rod dipped in NH3 soln. is brought near the test tube containing HCl gas.

Question 7

Question 15Give two tests for dilute sulphuric acid with balanced equations. State why(i) BaCl2(ii) Pb(NO3)2are used for the above tests

Accepted Answer

(i) BaCl2 solution on treating with dilute sulphuric acid forms white ppt. of barium sulphate, which is insoluble in dilute sulphuric acid.BaCl2 + H2SO4 (dil) ⟶ 2HCl + BaSO4 ↓ [white ppt. formed](ii) Pb(NO3)2 on treating with dilute sulphuric acid gives white ppt of lead sulphate, which is insoluble in dil. H2SO4.Pb(NO3)2 + H2SO4 (dil) ⟶ 2HNO3 + PbSO4 ↓ [white ppt. formed]BaCl2 and Pb(NO3)2 are used for the above tests as they react with H2SO4 and form BaSO4 and PbSO4 respectively, which are the only compounds insoluble in dil. sulphuric acid.

Question 8

Question 2Chemical properties of sulphuric acidSulphuric AcidComplete and balance the equationsAs an acid [dilute]   4. Forms hydronium ions in aq. soln.H2SO4 + 2H2O ⟶ ............... + SO42-Reaction with 5. Active metal [zinc]Zn + H2SO4 ⟶ ............... + ............... [g]6. Base [Sodium oxide]Na2O + H2SO4 ⟶ ............... + ...............7. Base [Sodium hydroxide]NaOH + H2SO4 ⟶ ............... + ...............8. Carbonate [Potassium carbonate]K2CO3 + H2SO4 ⟶ ............... + ............... + ............... [g]9. Sulphite [Sodium sulphite]Na2SO3 + H2SO4 ⟶ ............... + ............... + ............... [g]10. Bisulphite [Sodium bisulphite]NaHSO3 + H2SO4 ⟶ ............... + ............... + ............... [g]11. Sulphide [Iron [II] sulphide]FeS + H2SO4 ⟶ ............... + ...............As a dibasic acid 12. Basicity is twoH2SO4 ⇌ ............... + SO42-13. Dissociates in two stepsH2SO4 ⇌ ............... + ...............HSO4- ⇌ ............... + SO42-14. Forms two types of salts- acid salt- Normal saltNaOH + H2SO4 ⟶ ............... + ...............2NaOH + H2SO4 ⟶ ............... + ...............As a non - volatile acid [conc.]Displaces volatile acid from salt 15. Sodium chlorideNaCl + H2SO4 ⟶ ............... + ...............16. Sodium nitrateNaNO3 + H2SO4 ⟶ ............... + ...............As an oxidising agent [conc. acid]Oxidation of 17. CarbonC + H2SO4 ⟶ ............... + H2O + ...............18. SulphurS + H2SO4 ⟶ ............... + H2O19. PhosphorousP + H2SO4 ⟶ ............... + H2O + ...............20. CopperCu + H2SO4 ⟶ ............... + H2O + ...............21. ZincZn + H2SO4 ⟶ ............... + H2O + ...............22. Hydrogen iodideHI + H2SO4 ⟶ ............... + H2O + ...............23. Hydrogen sulphideH2S + H2SO4 ⟶ ............... + H2O + ...............As a dehydrating agent [conc. acid] 24. GlucoseC6H12O6 ⟶ ............... + H2O25. SucroseC12H22O11 ⟶ ............... + H2O26. Cellulose[C6H10O5]n ⟶ ............... + H2O27. Formic acidH.COOH ⟶ ............... + H2O28. Oxalic acidH2C2O4 ⟶ ............... + ............... + H2O29. Hydrated copper sulphateCuSO4.5H2O ⟶ ............... + H2O

Accepted Answer

Sulphuric AcidComplete and balance the equationsAs an acid [dilute]   4. Forms hydronium ions in aq. soln.H2SO4 + 2H2O ⟶ 2H3O+ + SO42-Reaction with 5. Active metal [zinc]Zn + H2SO4 ⟶ ZnSO4 + H2 [g]6. Base [Sodium oxide]Na2O + H2SO4 ⟶ Na2SO4 + H2O7. Base [Sodium hydroxide]2NaOH + H2SO4 ⟶ Na2SO4 + 2H2O8. Carbonate [Potassium carbonate]K2CO3 + H2SO4 ⟶ K2SO4 + H2O + CO2 [g]9. Sulphite [Sodium sulphite]Na2SO3 + H2SO4 ⟶ Na2SO4 + H2O + SO2 [g]10. Bisulphite [Sodium bisulphite]2NaHSO3 + H2SO4 ⟶ Na2SO4 + 2H2O + 2SO2 [g]11. Sulphide [Iron [II] sulphide]FeS + H2SO4 ⟶ FeSO4 + H2SAs a dibasic acid 12. Basicity is twoH2SO4 ⇌ 2H+ + SO42-13. Dissociates in two stepsH2SO4 ⇌ H+ + HSO4-HSO4- ⇌ H+ + SO42-14. Forms two types of salts- acid salt- Normal saltNaOH (insufficient) + H2SO4 ⟶ NaHSO4 + H2O2NaOH (excess) + H2SO4 ⟶ Na2SO4 + 2H2OAs a non - volatile acid [conc.]Displaces volatile acid from salt 15. Sodium chlorideNaCl + H2SO4 [conc.] ⟶ NaHSO4 + HCl (<200°C)16. Sodium nitrateNaNO3 + H2SO4 [conc.] ⟶ NaHSO4 + HNO3 (<200°C)As an oxidising agent [conc. acid]Oxidation of 17. CarbonC + 2H2SO4 [conc.] ⟶ CO2 + 2H2O + 2SO218. SulphurS + 2H2SO4 [conc.] ⟶ 3SO2 + 2H2O19. Phosphorous2P + 5H2SO4 [conc.] ⟶ 2H3PO4 + 2H2O + 5SO220. CopperCu + 2H2SO4 [conc.] ⟶ CuSO4 + 2H2O + SO221. ZincZn + 2H2SO4 [conc.] ⟶ ZnSO4 + 2H2O + SO222. Hydrogen iodide2HI + H2SO4 [conc.] ⟶ I2 + 2H2O + SO223. Hydrogen sulphideH2S + H2SO4 [conc.] ⟶ S + 2H2O + SO2As a dehydrating agent [conc. acid] 24. GlucoseC6H12O6 + H2SO4 [conc.] ⟶ 6C + 6H2O25. SucroseC12H22O11 + H2SO4 [conc.] ⟶ 12C + 11H2O26. Cellulose[C6H10O5]n + H2SO4 [conc.] ⟶ 6[C]n + 5[H2O]n27. Formic acidH.COOH + H2SO4 [conc.] ⟶ CO + H2O28. Oxalic acidH2C2O4 + H2SO4 [conc.] ⟶ CO + CO2 + H2O29. Hydrated copper sulphateCuSO4.5H2O + H2SO4 [conc.] ⟶ CuSO4 + 5H2O

Question 9

Question 1What property of conc. H2SO4 is made use of in each of the following cases? Give an equation for the reaction in each case:(a) in the production of HCl gas when it reacts with a chloride,(b) in the preparation of CO from HCOOH.(c) as a source of hydrogen by diluting it and adding a strip of magnesium.(d) in the preparation of sulphur dioxide by warming a mixture of conc. sulphuric acid and copper-turnings.(e) hydrogen chloride gas is passed through concentrated sulphuric acid.(f) it's reaction with (i) Ethanol (ii) Carbon.

Accepted Answer

(a) The property of being a non-volatile acid is used.NaCl + H2SO4 [conc.] →<200°C\xrightarrow{\lt 200 \degree	ext{C}}<200°C​ NaHSO4 + HCl(b) The property of being a dehydrating agent is used.HCOOH →Conc. H2SO4\xrightarrow{	ext{Conc. H}_2	ext{SO}_4}Conc. H2​SO4​​ CO + H2O(c) The acidic property is used.Mg + H2SO4 [dil.] ⟶ MgSO4 + H2 ↑(d) The property of being an oxidizing agent is used.Cu + 2H2SO4 [conc.] ⟶ CuSO4 + 2H2O + SO2 ↑(e) The property of being a drying agent is used.Hydrogen chloride gas is dried by passing through conc. sulphuric acid as it does not react with conc. sulphuric acid.(f) (i) The property of being a dehydrating agent is used.C2H5OH ethyl alcohol→170°CConc. H2SO4[excess]C2H4ethene↑+H2O \underset{	ext{ ethyl alcohol}}{	ext{C}_2	ext{H}_5	ext{OH}} \xrightarrow[170\degree	ext{C}]{	ext{Conc. H}_2	ext{SO}_4	ext{[excess]}} \underset{ 	ext{ethene}}{	ext{C}_2	ext{H}_4} ↑ + 	ext{H}_2	ext{O}\ ethyl alcoholC2​H5​OH​Conc. H2​SO4​[excess]170°C​etheneC2​H4​​↑+H2​O (ii) The property of being an oxidizing agent is used.C + 2H2SO4 [conc.] ⟶ CO2 + 2H2O + 2SO2 ↑

Question 10

Question 16Assertion (A): Sulphuric acid when dissolved in water forms a basic saltReason (R): Sulphuric acid ionises in two stages, it is a dibasic acid.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

A is false but R is true.Explanation— Sulphuric acid when dissolved in water forms hydronium ion and shows acidic properties. Hence, the assertion (A) is false.Sulphuric acid ionises in two stages and is called dibasic acid. Hence, the reason (R) is true.H2SO4 + 2H2O ⇌\rightleftharpoons⇌ H3O+ + HSO4-HSO4- + 2H2O ⇌\rightleftharpoons⇌ H3O+ + SO42-

Question 11

Question 17Assertion (A): Pure sulphuric acid is almost a non-conductor of electricity.Reason (R): Dilute sulphuric acid is a good conductor of electricity.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true but R is not the correct explanation of A.Explanation— Pure (concentrated) H2SO4 is not ionized significantly because no water is present to dissociate it into ions. Therefore, it does not conduct electricity. Hence, the assertion (A) is true.When H2SO4 is diluted with water, it ionizes completely to give H- and SO42- ions, which are free to move. These ions carry electric current, making it a strong electrolyte. Hence, the reason (R) is true.However, reason (R) does not explain why pure sulphuric acid is a poor conductor of electricity. Hence, reason (R) is not the correct explanation of assertion (A).

Question 12

Question 18Assertion (A): Impurity of arsenic oxide must be removed before passing the mixture of SO2 and air through the catalytic chamber.Reason (R): Arsenic oxide poisons the catalyst.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true and R is the correct explanation of A.Explanation— In the manufacture of sulphuric acid, purification of gases is done by removing the impurity of arsenic oxide before passing the mixture of SO2 and air through the catalytic chamber. Hence, the assertion (A) is true.Purification of gases is done because arsenic oxide poisons the catalyst and the catalyst loses its efficiency. Hence, the reason (R) is true and it is the correct explanation of assertion (A).

Question 13

Question 20Assertion (A): Sulphuric acid acts as an oxidising agent.Reason (R): Sulphuric acid produces hydrogen on reacting with zinc.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true but R is not the correct explanation of A.Explanation— Sulphuric acid acts as an oxidising agent due to the fact that on thermal decomposition, it yields nascent oxygen [O]. This nascent oxygen oxidises non-metals, metals and inorganic compounds. Hence, the assertion (A) is true.H2SO4 ⟶ 2H2O + SO2 + [O]Dilute sulphuric acid reacts with metals like zinc, that is present above hydrogen in the activity series to form metallic sulphate and hydrogen at ordinary temperature. Hence, the reason (R) is true.Zn + H2SO4 ⟶ ZnSO4 + H2 ↑But, reason (R) doesn't explain the reason behind oxidising property of sulphuric acid. Hence, reason (R) is not the correct explanation of assertion (A).

Question 14

Question 4State your observation when –(a) Sugar crystals are added to a hard glass test tube containing conc. sulphuric acid.(b) Conc. H2SO4 is added to a crystal of hydrated copper sulphate.

Accepted Answer

(a) Steam is evolved from the test tube and it becomes very hot. Black spongy mass of carbon is formed.C12H22O11Cane Sugar (s)→Conc. H2SO412C (s)Sugar Charcoal+11H2O\underset{	ext{Cane Sugar}}{	ext{C}_{12}	ext{H}_{22}	ext{O}_{11}} 	ext{ (s)} \xrightarrow{	ext{Conc. H}_2	ext{SO}_4} \underset{	ext{Sugar Charcoal}}{12	ext{C (s)}} + 11	ext{H}_2	ext{O}Cane SugarC12​H22​O11​​ (s)Conc. H2​SO4​​Sugar Charcoal12C (s)​+11H2​O(b) The blue coloured hydrous copper sulphate changes to white anhydrous copper sulphate as the water of crystallization is removed.CuSO4.5H2O→Conc. H2SO4CuSO4 [White Anhydrous]+5H2O	ext{CuSO}_4	ext{.5H}_2	ext{O} \xrightarrow{	ext{Conc. H}_2	ext{SO}_4} 	ext{CuSO}_4 	ext{ [White Anhydrous]} + 5	ext{H}_2	ext{O}CuSO4​.5H2​OConc. H2​SO4​​CuSO4​ [White Anhydrous]+5H2​O

Question 15

Question 5Give balanced equation(s) for :(a) Reaction of dilute sulphuric acid when poured over sodium sulphite(b) Manufacture of sulphuric acid by the Contact process.(c) Heating sulphur with conc. sulphuric acid(d) Dehydration of sugar crystals by conc. sulphuric acid(e) Action of concentrated sulphuric acid on carbon.

Accepted Answer

(a) Na2SO3 + H2SO4 (dil.) ⟶ Na2SO4 + H2O + SO2(b) Contact process:Sulphur or Pyrite Burner:S + O2 ⟶ SO24FeS2 + 11O2 ⟶ 2Fe2O3 + 8SO2Contact Tower :2SO2+O2⇌450−500°C /1−2 atmosV2O52SO3+45 K cals2 ext{SO}_2 + ext{O}_2 \xrightleftharpoons[450-500 ext{\degree C }/1 - 2 ext{ atmos}]{ ext{V}_2 ext{O}_5} 2 ext{SO}_3 + 45 ext{ K cals}2SO2+O2V2O5450−500°C /1−2 atmos2SO3+45 K calsAbsorption Tower :SO3 + H2SO4 ⟶ H2S2O7Dilution Tank:H2S2O7 + H2O ⟶ 2H2SO4(c) S + 2H2SO4 [conc.] ⟶ 3SO2 + 2H2O(d) C12H22O11Cane Sugar (s)→Conc. H2SO412C (s)Sugar Charcoal+11H2O\underset{ ext{Cane Sugar}}{ ext{C}{12} ext{H}{22} ext{O}_{11}} ext{ (s)} \xrightarrow{ ext{Conc. H}_2 ext{SO}_4} \underset{ ext{Sugar Charcoal}}{12 ext{C (s)}} + 11 ext{H}_2 ext{O}Cane SugarC12H22O11 (s)Conc. H2SO4Sugar Charcoal12C (s)+11H2O(e) C + 2H2SO4 [conc.] ⟶ CO2 + 2H2O + 2SO2

Question 16

Question 8Give two balanced reactions of each type to show the following properties of sulphuric acid:(a) Acidic nature(b) Oxidising agent(c) Dehydrating Nature(d) Non-volatile nature

Accepted Answer

(a) Acidic natureMg + H2SO4 (dil.) ⟶ MgSO4 + H2 ↑Zn + H2SO4 (dil.) ⟶ ZnSO4 + H2 ↑(b) Oxidising agentC + 2H2SO4 ⟶ CO2 + 2H2O + 2SO2 ↑Zn + 2H2SO4 ⟶ ZnSO4 + 2H2O + SO2 ↑(c) Dehydrating NatureHCOOH→Conc. H2SO4CO+H2O	ext{HCOOH} \xrightarrow{	ext{Conc. H}_2	ext{SO}_4} 	ext{CO} + 	ext{H}_2	ext{O}HCOOHConc. H2​SO4​​CO+H2​OC2H5OH ethyl alcohol→170°CConc. H2SO4[excess]C2H4ethene↑+H2O\underset{	ext{ ethyl alcohol}}{	ext{C}_2	ext{H}_5	ext{OH}} \xrightarrow[170\degree	ext{C}]{	ext{Conc. H}_2	ext{SO}_4	ext{[excess]}} \underset{ 	ext{ethene}}{	ext{C}_2	ext{H}_4} ↑ + 	ext{H}_2	ext{O} ethyl alcoholC2​H5​OH​Conc. H2​SO4​[excess]170°C​etheneC2​H4​​↑+H2​O(d) Non-volatile NatureNaCl + H2SO4 ⟶ NaHSO4 + HClKCl + H2SO4 ⟶ KHSO4 + HCl

Question 17

Question 11Making use only of substances given: dil. sulphuric acid, Sodium carbonate, Zinc, Sodium Sulphite, Lead, Calcium carbonate:Give equations for the reactions by which you could obtain:(a) hydrogen(b) sulphur dioxide(c) carbon dioxide(d) zinc carbonate (2 steps)

Accepted Answer

(a) Zn + H2SO4 [dil.] ⟶ ZnSO4 + H2(b) Na2SO3 + H2SO4 [dil.] ⟶ Na2SO4 + H2O + SO2(c) Na2CO3 + H2SO4 [dil.] ⟶ Na2SO4 + H2O + CO2(d) Zn + H2SO4 [dil.] ⟶ ZnSO4 + H2ZnSO4 + Na2CO3 [dil.] ⟶ ZnCO3 + Na2SO4

Question 18

Question 3(2008)Copy and complete the following table relating to an important industrial process and it's final output.Name of processInputsCatalystEquation for catalyzed reactionOutputContact ProcessSulphur dioxide + oxygen

Accepted Answer

Name of processInputsCatalystEquation for catalyzed reactionOutputContact ProcessSulphur dioxide + oxygenVanadium pentoxide [V2O5] or platinum [Pt.]2SO2+O2⇌450−500°C /1−2 atmosV2O52SO3+45 K cals2	ext{SO}_2 + 	ext{O}_2 \xrightleftharpoons [450-500	ext{\degree C }/1 - 2 	ext{ atmos}]{	ext{V}_2	ext{O}_5} 2	ext{SO}_3 + 	ext{45 K cals}2SO2​+O2​V2​O5​450−500°C /1−2 atmos​2SO3​+45 K calsSulphuric acid

Question 19

Question 5(2008)What property of conc. H2SO4 is used in the action when sugar turns black in it's presence.

Accepted Answer

Dehydrating agent.C12H22O11+ nH2SO4 ⟶ 12C + 11H2O

Question 20

Question 6(2008)Write the equations for:(1) dil. H2SO4 and barium chloride.(2) dil. H2SO4 and sodium sulphide.

Accepted Answer

(i) BaCl2 + H2SO4 (dil) ⟶ 2HCl + BaSO4 ↓ [white ppt. formed](ii) Na2S + H2SO4 ⟶ Na2SO4 + H2S

Study of Compounds — Sulphuric Acid

Additional Questions

Equation Worksheet

Exercise 11 Long Answer Type

Exercise 11 Multiple Choice Type

Exercise 11 Short Answer Type

Questions

Unit Test Paper 7D — Sulphuric Acid