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ICSE Class 7 Chemistry Question 6 of 11

Language of Chemistry — Question 4

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Question 4

Give a balanced equation for addition of iron to copper [II] sulphate solution. State the change in color seen.

Answer

CuSO4Blue+Fe⟶FeSO4Light green+CuBrownish red\underset{\text{Blue}}{\text{CuSO}_4} + \text{Fe} \longrightarrow \underset{\text{Light green}}{\text{FeSO}_4} + \underset{\text{Brownish red}}{\text{Cu}}

Colour changes from blue to light green.

ICSE Class VII Chemistry Chapter 4 12 Marks

Language of Chemistry — Quick Study Guide

Chemical symbols, formulae, and equations are the language chemists use to describe substances and reactions.

Key Concepts

  • Chemical symbol: Shorthand for an element (first letter capital, second lowercase)
  • Chemical formula: Shows types and numbers of atoms in a molecule
  • Cross-multiplication: Write symbols → valencies → cross → simplify
  • Balanced equation: Same number of each atom on both sides
  • Combination reaction: A + B → AB
  • Decomposition reaction: AB → A + B

Latin-Origin Symbols to Memorise

Na (Sodium), Fe (Iron), Au (Gold), Ag (Silver), K (Potassium), Cu (Copper), Hg (Mercury), Pb (Lead), Sn (Tin)

Exam Tips

  • Never change subscripts when balancing — only change coefficients
  • Use brackets for polyatomic ions when subscript > 1
  • Practice writing formulae using cross-multiplication daily
  • CO ≠ Co (carbon monoxide vs cobalt)

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