Question 10
Representation of the results of a chemical change – is a chemical equation.
For the equation: FeCl3 + 3NH4OH ⟶ 3NH4Cl + Fe(OH)3 ↓
Answer the following:
(a) Write the word equation for the above molecular equation.
(b) Is the equation given above a balanced equation. Give reasons.
(c) Name the reactants and the products in the above equation.
(d) What is the indications of the arrow between the reactants and the products and of the arrow pointing downwards at the end.
(a) Iron (III) chloride + ammonium hydroxide ⟶ Ammonium chloride + Iron (III) hydroxide
(b) In the given equation:
| Reactants | Products |
|---|---|
| 1 atom of iron [Fe] | 1 atom of iron [Fe] |
| 3 atoms of chlorine [Cl] | 3 atoms of chlorine [Cl] |
| 3 atoms of nitrogen [N] | 3 atoms of nitrogen [N] |
| 15 atoms of hydrogen [H] | 15 atoms of hydrogen [H] |
| 3 atoms of oxygen [O] | 3 atoms of oxygen [O] |
As, the number of atoms of each element of reactants = the number of atoms of each element of products. Hence, the equation is balanced.
(c) Reactants – Iron (III) Chloride [FeCl3 ] and Ammonium hydroxide [3NH4OH],
Products – Ammonium Chloride [3NH4Cl] and Iron (III) Hydroxide [Fe(OH)3].
(d) The arrow between reactants and products indicates the chemical reaction taking place in the forward direction i.e., reaction is taking place between reactants and as a result products are formed. The arrow pointing downwards indicates formation of precipitate.
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)
Bright Tutorials | ICSE Class VII Chemistry | Chapter 4: Language of Chemistry | Contact: 9403781999