Chemistry
Explain with the help of balanced equations, how precipitation reactions are used for identifying the positive radicals in three different salts, each having a different cation [positive ion].
Answer
Precipitation reactions finds it's use in analytical chemistry for identifying the positive radical in a salt by analyzing the colour of the precipitate.
(i) FeSO4 + 2NaOH ⟶ Na2SO4 + Fe(OH)2 ↓
Identified ion: Fe2+ ; Dirty green ppt. of Iron [II] hydroxide is obtained. Hence, it can be identified.
(ii) CuSO4 + 2NaOH ⟶ Na2SO4 + Cu(OH)2 ↓
Identified ion: Cu2+ ; Pale blue ppt. of Copper [II] hydroxide is obtained. Hence, it can be identified.
(iii) Pb(NO3)2 + 2NaOH ⟶ 2NaNO3 + Pb(OH)2 ↓
Identified ion: Pb2+ ; Chalky white ppt. of Lead [II] hydroxide is obtained. Hence, it can be identified.
Related Questions
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.
Explain the term double decomposition precipitation reaction. Give a balanced equation for the preparation of two different insoluble lead salts from their salt solutions by double decomposition precipitation.
Define the term – double decomposition – neutralization reaction with a suitable representation.
Convert :
(a) an insoluble base (b) a soluble base
to their respective soluble salts by neutralization reaction.
Explain the term energy changes in a chemical change or reaction. Give an example with a balanced equation, for each of the following reactions:
(a) exothermic reaction
(b) endothermic reaction
(c) photochemical reaction
(d) electrochemical reaction.