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Question
What do you mean by a precipitation reaction? Explain giving an example.
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Solution 1
When two solutions containing soluble salts are combined, a double-displacement reaction occurs in which ions are exchanged between the compounds. When one such compound is in solid form (that is, insoluble in water), it settles to the bottom of the container. This solid is known as the precipitate, and the respective reaction is termed the precipitation reaction. A few examples of precipitation reactions are:
- \[\ce{CdSO4_{(aq)} + K2S_{(aq)} -> CdS_{(s)} + K2SO4_{(aq)}}\]
- \[\ce{2NaOH_{(aq)} + MgCl2_{(aq)} -> 2NaCl_{(aq)} + Mg(OH)2_{(s)}}\]
Solution 2
Any reaction in which an insoluble solid (called a precipitate) is formed that separates from the solution is called a precipitation reaction.
If barium chloride solution is added to copper sulphate solution, then a white precipitate of barium sulphate is produced along with copper chloride solution:
\[\ce{\underset{Barium chloride}{BaCl2_{(aq)}} + \underset{Copper sulphate}{CuSO4_{(aq)}} -> \underset{(White ppt{.})}{\underset{Barium sulphate}{BaSO4_{(s)}}} + \underset{Copper chloride}{CuCl2_{(aq)}}}\]
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RELATED QUESTIONS
Give an example of a double displacement reaction other than the one given in the following Activity.
•Take about 3 mL of sodium sulphate
solution in a test tube.
• In another test tube, take about 3 mL of
barium chloride solution.
• Mix the two solutions given in the following fig.
• What do you observe?
What type of chemical reaction is represented by the following equation?
\[\ce{PQ + RS -> PS + RQ}\]
What type of reaction is represented by the following equation?
\[\ce{CuSO4 + 2NaOH -> Cu(OH)2 + Na2SO4}\]
What is meant by a double displacement reaction? Explain with the help of one example.
Consider the reaction:
\[\ce{KBr_{(aq)} + AgNO3_{(aq)} -> KNO3_{(aq)} + AgBr_{(s)}}\]
This is an example of:
A red-brown metal X forms a salt XSO4. When hydrogen sulphide gas is passed through an aqueous solution of XSO4, then a black precipitate of XS is formed alongwith sulphuric acid solution.
(a) What could the salt XSO4 be?
(b) What is the colour of salt XSO4?
(c) Name the black precipitate XS.
(d) By using the formula of the salt obtained in (a) above, write an equation of the reaction which takes place when hydrogen sulphide gas is passed through its aqueous solution.
(e) What type of chemical reaction takes place in this case?
The aqueous solutions of copper sulphate and zinc sulphate appear
(A) blue and green respectively
(B) green and colourless respectively
(C) blue and brown respectively
(D) blue and colourless respectively.
Solutions of copper sulphate, iron sulphate and zinc sulphate are prepared and marked I, II and III respectively. Few pieces of aluminium are added to each solutions. After some time a change will be observe in
(A) I and II
(B) II and III
(C) III and I
(D) All the three
Give scientific reason.
It takes time for pieces of Shahabad tile to disappear in HCl, but its powder disappears rapidly.
When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of copper sulphide is obtained and the sulphuric acid so formed remains in the solution. The reaction is an example of a:
Which option denotes a double displacement reaction?
Which among the following is (are) double displacement reaction(s)?
(i) \[\ce{Pb + CuCl -> PbCl2 + Cu}\]
(ii) \[\ce{Na2SO4 + BaCl2 -> BaSO4 + 2NaCl}\]
(iii) \[\ce{C + O2 -> CO2}\]
(iv) \[\ce{CH4 + 2O2 -> CO2 + 2H2O}\]
Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride. Which of the following correctly represents the type of reaction involved?
(i) Displacement reaction
(ii) Precipitation reaction
(iii) Combination reaction
(iv) Double displacement reaction
Balance the following chemical equation and identify the type of chemical reaction.
`"TiCl"_4("l") + "Mg"("s") -> "Ti"("s") + "MgCl"_2("s")`
Add potassium chromate (K2CrO4) into the solution of barium sulphate (BaSO4).
- What was the colour of the precipitate formed? Also, write the name of the precipitate.
- Write down the balanced equation for this reaction.
- Will you call this reaction a displacement reaction or a double displacement reaction? Why?
Identify the product which represents the solid state in the above reaction.
Give scientific reason.
While preparing dilute sulphuric acid from concentrated sulphuric acid in the laboratory, the concentrated sulphuric acid is added slowly to water with constant stirring.
