Chemistry
You are given three solutions A, B and C. A is a strong acid, B is a weak acid and C is a strong alkali.
(a) Which solution contains solute molecules in addition to water molecules ?
(b) Which solution gives gelatinous white precipitate with zinc sulphate which disappears in excess solution ?
Answer
(a) Solution B — weak acid
Reason — Weak Acid is an acid which dissociates only partially in aqueous solution thereby producing a low concentration of hydrogen [H+] ions [or H3O+ ions]. For example — CH3COOH ⇌ CH3COO- + H+ [contains molecules and ions]
(b) Solution C — strong alkali
Reason — Alkalis react with certain salt solutions to precipitate insoluble hydroxide. Hence,
ZnSO4 + 2NaOH ⟶ Na2SO4 + Zn(OH)2 [gelatinous white precipitate]
Related Questions
From the substances given in the list below, write the equations for the reactions by which you could obtain the compounds given ahead :
Dilute sulphuric acid sodium carbonate Zinc sodium sulphite Lead calcium carbonate - hydrogen,
- sulphur dioxide,
- carbon dioxide,
- zinc carbonate (two steps required).
Choosing the substances from the list given:
dil. Sulphuric acid, Copper, Iron, Sodium, Copper (II) carbonate, Sodium carbonate, Sodium chloride, Zinc nitrate
Write balanced equations for the reactions which would be used in the laboratory to obtain the following salts:
- Sodium sulphate
- Zinc carbonate
- Copper (II) sulphate
- Iron (II) sulphate.
Write balanced chemical equations for the following:
(a) Reaction of silver nitrate solution and sodium chloride solution.
(b) Lead nitrate solution is added to sodium chloride solution.
(c) State what happens to the crystals of washing soda when they are exposed to air. Name the phenomenon exhibited.
Give a balanced equation for the preparation of the following salts:
(a) Copper [II] sulphate from copper [II] oxide.
(b) Iron [III] chloride from the metal iron.
(c) Lead sulphate from lead carbonate.
(d) Potassium sulphate from KOH solution.
(e) Lead [II] chloride from lead carbonate [give two equations].
(f) Sodium sulphate — using dilute sulphuric acid.
(g) Copper chloride — using copper carbonate.