Analytical Chemistry

Sodium hydroxide solution is added first in a small amount, then in excess to the aqueous salt solutions of:

State in each case :

(i) the colour of the precipitate when NaOH is added in a small quantity;

(ii) the nature of the precipitate [i.e. soluble or insoluble] when NaOH is added in excess.

Write balanced equations for — (a) Aluminium (b) Zinc — is warmed with NaOH [caustic soda] soln.

The questions below refers to the following salt solutions listed A to F:

A: Copper nitrate

B: Iron [II] sulphate

C: Iron [III] chloride

D: Lead nitrate

E: Magnesium sulphate

F: Zinc chloride

(i) Which soln. becomes a deep/inky blue colour when excess of ammonium hydroxide is added to it.

(ii) Which solution gives a white precipitate with excess ammonium hydroxide solution.

From the list of substances given — Ammonium sulphate, Lead carbonate, Chlorine, Copper nitrate, Ferrous sulphate — State a solution of the compound which gives a dirty green precipitate with sodium hydroxide.

Write a balanced equation for the reaction between aluminium oxide and sodium hydroxide solution.

Give one test to distinguish between the following:

Iron [III] chloride soln. and Copper chloride soln.

The salt which in soln. gives a pale green precipitate with NaOH solution and a white ppt. with BaCl₂ soln. is :

Find the odd one with reasons [valency is not a criterion] :

Identity the substance P based on the information given :

The deliquescent salt P, turns yellow on dissolving in water, and gives a reddish brown precipitate with sodium hydroxide solution.

Give an equation for —

Select the correct answer from A, B, C —

A: Sodium hydroxide soln.
B: A weak acid
C: Dilute sulphuric acid.

The solution which with zinc sulphate solution will give a white precipitate.

Choose the correct answer :

Hydroxide of this metal is soluble in NaOH solution.

Sodium hydroxide solution is added to the solutions containing the ions mentioned in List 1.

List 1 —

The precipitates obtained are in list 2 —

A: Reddish brown
B: White insoluble in excess
C: Dirty green
D: White soluble in excess
E: White soluble in excess
F: Blue.

Match list 1 with list 2

Give balanced equations for —

(i) Zinc oxide dissolves in NaOH

(ii) Zinc is heated with NaOH solution

Name: The gas evolved on reaction of aluminium with boiling concentrated caustic alkali solution.

State one observation for:

State two relevant observations for the reaction:

Ammonium hydroxide solution is added to copper (II) nitrate solution in small quantities and then in excess.

State your observation: When excess sodium hydroxide is added to calcium nitrate solution.

To a salt solution 'Y' a small quantity of NH₄OH solution is added slowly and then in excess. A pale blue precipitate is formed which dissolves in ex­cess to form a clear inky blue solution. Identify the posi­tive ion in the salt 'Y'

State your observations when ammonium hydroxide solution is added drop by drop and then in excess to each of the following:

(i) copper sulphate solution

(ii) zinc sulphate solution.

State one relevant observation – Action of sodium hydroxide solution on iron [II] sulphate solution.

How will you distinguish between — Ammonium Hydroxide & Sodium Hydroxide using CuSO₄

Choose the correct answer from the options given :

The salt solution which does not react with ammonium hydroxide is :

Write a balanced chemical equation for :

(i) Reaction of sodium hydroxide solution with iron [III] chloride solution.

(ii) Reaction of zinc with potassium hydroxide solution.

State one relevant observation : Lead nitrate solution is treated with sodium hydroxide soln. drop wise, till it is in excess.

Write balanced chemical equation for —

Ammonium hydroxide is added to ferrous sulphate solution.

Copper [II] sulphate solution reacts with NaOH solution to form a precipitate of Cu(OH)₂. State it's colour.

State one relevant observation for the reaction : Addition of excess ammonium hydroxide into copper sulphate solution.

Salts of ............... [normal/transitional] elements are generally coloured. From the ions K¹⁺, Cr³⁺, Fe²⁺, Ca²⁺, SO₃^2-, MnO₄^1-, NO₃^1- the ions generally coloured are ...............

The hydroxide which is soluble in excess of NaOH is ............... [Zn(OH)₂/Fe(OH)₃/Fe(OH)₂]

The salt which will not react with NH₄OH solution is ............... [ZnCl₂/CuCl₂/NH₄Cl/FeCl₂]

The substance/s which react with hot conc. NaOH soln. and undergoes a neutralization reaction ............... [Al₂O₃/Al/Al(OH)₃]

To distinguish soluble salts of zinc and lead, ............... [NaOH/NH₄OH] can be used.

Oxides and hydroxides of certain metals i.e ............... [iron/ zinc/copper/aluminium/magnesium/lead] are amphoteric and react with ............... [acids/alkalis/acids and alkalis] to give salt and water.