Q51 of 152 Page 22

A metal X forms a salt XS04. The salt XS04 forms a clear solution in water which reacts with sodium hydroxide solution to form a blue precipitate Y. Metal X is used in making electric wires and alloys like brass.

(a) What do you think metal X could be?


(b) Write the name, formula and colour of salt X S04


(c) What is the blue precipitate Y?


(d) Write a chemical equation of the reaction which takes place when salt XS04 reacts with sodium hydroxide solution. Give the state symbols of all the reactants and products which occur in the above equation.

(a) Metal X is copper, Cu.

(b) Formula for salt XSO4 is CuSO4


And colour is “Blue”.


(c) Blue precipitate is Copper Hydroxide, Cu(OH)2


(d) CuS04 (aq.) +2NaOH (aq.) Cu(OH)2 (s) + Na 2S04 (aq.)


Above is the chemical equation of the reaction.



More from this chapter

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49 A solid substance P which is very hard is used in the construction of many buildings, especially flooring. When substance P is heated strongly, it decomposes to form another solid Q and a gas R is given out. Solid Q reacts with water with the release of a lot of heat to form a substance S. When gas R is passed into a clear solution of substance S, then a white precipitate of substance T is formed. The substance T has the same chemical composition as starting substance P.

(a) What is substance P? Write its common name as well as chemical formula.


(b) What is substance Q?


(c) What is gas R?


(d) What is substances? What is its clear solution known as?


(e) What is substance T? Name any two natural forms in which substance T occurs in nature.

 50 A silvery-white metal X taken in the form of ribbon, when ignited, burns in air with a dazzling white flame to form a white powder Y. When water is added to powder Y, it dissolves partially to form another substances.

(a) What could metal X be?


(b) What is powder Y?


(c) With which substance metal X combines to form powder Y?


(d) What is substance Z? Name one domestic use of substance Z.


(e) Write a balanced chemical equation of the reaction which takes place when metal X burns in air to form powder Y.

 52 The metal M reacts vigorously with water to form a solution S and a gas G. The solution S turns red litmus to blue whereas gas G, which is lighter than air, burns with a pop sound. Metal M has a low melting point and it is used as a coolant in nuclear reactors.

(a) What is metal M?


(b) What is solution S? Is it acidic or alkaline?


(c) What is gas G?


(d) Write a balanced chemical equation for the reaction which takes place when metal M reacts with water.


(e) Is this reaction exothermic or endothermic?

 53 When a mixture of gases X and Y is compressed to 300 atm. pressure and then passed over a catalyst consisting of a mixture of zinc oxide and chromium oxide (heated to a temperature of 300 �C), then an organic compound Z having the molecular formula CH40 is formed. X is a highly poisonous gas which is formed in appreciable amounts when a fuel burns in a limited supply of air; Y is a gas which can be made by the action of a dilute acid on an active metal; and Z is a liquid organic compound which can react with sodium metal to produce hydrogen gas.

(a) What are X, Y and Z?


(b) Write a balanced chemical equation of the reaction which takes place when X and Y combine to form Z. Indicate the conditions under which the reaction occurs.