(a) Common salt contains impurities like magnesium chloride, are deliquescent substances. So on exposure to air especially during the rainy season, table salt turns moist though sodium chloride is not deliquescent. (b) This impurity can be removed by passing a current of dry hydrogen chloride gas through a saturated solution of the affected salt. Pure sodium chloride is produced as a precipitate, which can be recovered by filtering and washing first with water and then with alcohol. (c) Conc. H2SO4 can change the blue colour of copper sulphate to white. (d) Two crystalline substance which do not contain water of crystallization are: Common salt, Nitre, Sugar. Misc. Exercise. (a) A is sodium salt: It is prepared by neutralization of a base with acids. (b) B is an insoluble salt: An insoluble salt is obtained from another insoluble salt by double decomposition. The insoluble salt is first converted into a soluble salt which is then used to prepare the desired salt. (c) C is soluble salt of copper: The soluble salt of copper can be prepared by the decomposition of carbonates by acids. (d) D is soluble salt of Zinc: The soluble salt of Zinc can be prepared by decomposition of chlorides by conc. H2SO4. (2004) i) Copper (II) chloride - (B) Action of an acid on an oxide or carbonate (ii) Iron (II) chloride - (A) Action of acid on metal (iii) Iron (III) chloride - (C) Direct combination (iv) Lead (II) chloride - (E) Precipitation (double decomposition) (v) Sodium chloride - (D) Neutralization of an alkali by an acid
(a) Common salt contains impurities like magnesium chloride, are deliquescent substances. So on exposure to air especially during the rainy season, table salt turns moist though sodium chloride is not deliquescent. (b) This impurity can be removed by passing a current of dry hydrogen chloride gas through a saturated solution of the affected salt. Pure sodium chloride is produced as a precipitate, which can be recovered by filtering and washing first with water and then with alcohol. (c) Conc. H2SO4 can change the blue colour of copper sulphate to white. (d) Two crystalline substance which do not contain water of crystallization are: Common salt, Nitre, Sugar. Misc. Exercise. (a) A is sodium salt: It is prepared by neutralization of a base with acids. (b) B is an insoluble salt: An insoluble salt is obtained from another insoluble salt by double decomposition. The insoluble salt is first converted into a soluble salt which is then used to prepare the desired salt. (c) C is soluble salt of copper: The soluble salt of copper can be prepared by the decomposition of carbonates by acids. (d) D is soluble salt of Zinc: The soluble salt of Zinc can be prepared by decomposition of chlorides by conc. H2SO4. (2004) i) Copper (II) chloride - (B) Action of an acid on an oxide or carbonate (ii) Iron (II) chloride - (A) Action of acid on metal (iii) Iron (III) chloride - (C) Direct combination (iv) Lead (II) chloride - (E) Precipitation (double decomposition) (v) Sodium chloride - (D) Neutralization of an alkali by an acid
CH-3-Acids-Bases-and-Salts..docx