Chemistry
(a) Define efflorescence. Give examples.
(b) Define deliquescence. Give examples.
Acids Bases Salts
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Answer
(a) Efflorescence is the property of some salts to loose wholly or partly their water of crystallisation when their crytals are exposed to dry air even for a short time.
Examples: MgSO4.7H2O (Epsom salt) , Na2SO4.10H2O (Glauber's salt).
(b) Certain water-soluble substances, when exposed to the atmosphere at ordinary temperature, absorb moisture from the atmospheric air to become moist and ultimately dissolve in the absorbed water, forming a saturated solution. The phenomenon is called deliquescence and the salts are called deliquescent.
Examples: Caustic soda (NaoH), Caustic potash (KOH)
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Related Questions
Which of the following methods A, B, C, D or E is generally used for preparing the chlorides listed below from (i) to (v). Answer by writing down the chloride and the letter pertaining to the corresponding method. Each letter is to be used only once.
A Action of an acid on a metal B Action of an acid on an oxide or carbonate C Direct combination D Neutralization of an alkali by an acid E Precipitation (double decomposition) (i) Copper (II) chloride (ii) Iron (II) chloride (iii) Iron (III) chloride (iv) Lead (II) chloride (v) Sodium chloride What do you understand by the water of crystallisation?
Give four substances which contain water of crystallisation and write their common names.
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(a) What name is given to the water in the compound copper sulphate-5-water?
(b) If copper sulphate-5-water is heated, anhydrous copper sulphate is formed. What is it's colour?
(c) By what means, other than heating, could you dehydrate copper sulphate-5-water and obtain anhydrous copper sulphate?
(d) Name a deliquescent salt.
(e) Why does hydrated copper sulphate turn white on heating?
State your observation when the following are exposed to the atmosphere:
(a) Washing soda crystals
(b) Iron (III) chloride salts.