Chemistry
Define a displacement reaction with a suitable example. State how it is represented. Give a reason why zinc displaces hydrogen from dilute sulphuric acid but copper does not.
Chemical Reaction
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Answer
A chemical reaction which takes place when an element [or radical] has replaced another element in a compound is known as Displacement reaction
It is represented as :
X + YZ ⟶ Y + XZ
e.g.,
Magnesium + Copper [II] sulphate ⟶ Magnesium sulphate + Copper
Mg + CuSO4 ⟶ MgSO4 + Cu
As a more electropositive metal displaces a less electropositive metal from it's aq. soln. therefore, zinc being more electropositive is placed above [H] in activity series and displaces hydrogen from dilute sulphuric acid whereas copper being less electropositive is placed below [H] in electrochemical series and cannot displace hydrogen from sulphuric acid.
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