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प्रश्न
When water is added gradually to a white solid X, a hissing sound is heard and a lot of heat is produced forming a product Y. A suspension of Y in water is applied to the walls of a house during white washing. A clear solution of Y is also used for testing carbon dioxide gas in the laboratory.
(a) What could be solid X? Write its chemical formula.
(b) What could be product Y? Write its chemical formula.
(c) What is the common name of the solution of Y which is used for testing carbon dioxide gas?
(d) Write chemical equation of the reaction which takes place on adding water to slid X.
(e) Which characteristic of chemical reactions is illustrated by this example?
उत्तर
(a) Solid X is calcium oxide, commonly known as quicklime. Its chemical formula is CaO.
(b) Product Y is calcium hydroxide, commonly known as slaked lime. Its chemical formula is Ca(OH)2.
(c) Common name of the solution of Y is "lime water", which is used to test carbon dioxide gas.
(d) CaO (s) + H2O (l)→ Ca(OH)2 (aq) + HEAT
(e) This chemical reaction is characterised by change in temperature because a huge amount of heat is evolved in this reaction, causing rise in temperature of the mixture.
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संबंधित प्रश्न
What do you understand by endothermic reactions?
Write word equation for the following skeletal equation:
\[\ce{NaOH + H2SO4 -> Na2SO4 + H2O}\]
Write symbolic representation for the following word equation and balance them :
Calcium carbonate → Calcium oxide + Carbon dioxide.
What is the limitation of the reaction given in question 2?
Write the balanced chemical equation of the following reaction.
silver nitrate → silver + nitrogen dioxide + oxygen
Write the balanced chemical equation of the following reaction.
aluminium carbide + water → aluminium hydroxide + methane
\[\ce{MnO2 + 4HCl -> MnCl2 + 2H2O + Cl2}\]
0.02 moles of pure MnO2 is heated strongly with conc. HCl. Calculate mass of MnO2 used.
A chemical reaction is generally accompanied by certain external indications or characteristics. These include – change of – (a) colour (b) state (c) smell (d) evolution of gas (e) formation of precipitate (f) evolution or absorption of heat. With reference to change of colour – state the change in colour seen when the following are heated – lead [IV] oxide.
In certain reaction a change of state is observed i.e. solid to liquid, liquid to gas etc. – State the change of state of the products – to give the respective reactant.
\[\ce{2H2O ->[electric][current] 2H2 + O2}\]
In certain reaction an insoluble solid called precipitate is formed. State the colour and name of the precipitate formed in the following reaction involving addition of:
Dilute hydrochloric acid to silver nitrate.
