Question

Write balanced chemical equations for the following reactions. Use ionic equations if appropriate, and consult the activity series of metals where necessary. If there is no reaction, indicate this, and justify.

Aluminum hydroxide is heated.

Aluminum metal heated with manganese dioxide.

A mixture of sodium oxide and aluminum metal is added to water. A flammable gas is released, but there is no precipitate.

Aqueous sodium carbonate is added to a solution of alum, KAl(SO₄)₂.

Ammonia is bubbled into aqueous aluminum nitrate.

Lithium aluminum hydride dissolves in water. A flammable gas is released and a white precipitate forms.

Thallium(III) nitrate is mixed into a solution of potassium iodide. The solution turns brown, and an insoluble precipitate forms.

Representative Syntheses:

Convert AlCl₃ to Al metal

Convert bauxite ore (Al₂O₃) to Al₂S₃

Convert KAl(SO₄)₂ (alum) to Al₂O₃

Answer 1

Answer-

(i)-Aluminum hydroxide is heated.

Solution-

(ii)-Aluminum metal heated with manganese dioxide.

Solution-

(iii)-A mixture of sodium oxide and aluminum metal is added to water. A flammable gas is released, but there is no precipitate.

Solution-First ,

After NaOH is formed then,

  

(iv)Aqueous sodium carbonate is added to a solution of alum, KAl(SO4)2.

Solution-The aluminiumcomponent of potash alum double salt undergoes hydrolysis in water since it is a salt of strong acid and weak base.

Sodium carbonate being a salt of weak acid and strong base produces hydroxide ions by hydrolysis

Then, H+ and HCO3- react to give

OH- and AlOH2+ reacts to give Al(OH)3.

(v)Ammonia is bubbled into aqueous aluminum nitrate.

Answer-

Aluminum nitrate and aqueous ammonia reacts to produce gelatinous white precipitate of aluminium hydroxide, ammonium nitrate remains in solution.

The balanced chemical equation is:

(vi) Lithium aluminum hydride dissolves in water. A flammable gas is released and a white precipitate forms.

Answer- LAH violently reacts with water:

LiAlH₄ + 4 H₂O → LiOH + Al(OH)₃ + 4 H₂

(vii)Thallium(III) nitrate is mixed into a solution of potassium iodide. The solution turns brown, and an insoluble precipitate forms.

Answer- Tl(NO₃)₃ + 2KI → TlNO₃ + I₂ + 2KNO₃

₍viii)Electrolysis of liquid aluminum chloride solution produces aluminum and chlorine.

Answer-2AlCl₃ 2Al + 3Cl₂

(ix)Convert bauxite ore (Al2O3) to Al2S3

Answer-

(x)Convert KAl(SO4)2 (alum) to Al2O3

Answer-Alum on heating gives Al2O3.