CBSE · Class 10 · Chemistry · Chapter 2

Acids, Bases and Salts — Formula Sheet

Board Formulas

9 formulas

1.Acid Ionisation in Water★
$H C l (a q) + H_{2} O (l) ⟶ H_{3} O^{+} (a q) + C l^{-} (a q)$
Acids produce H⁺ (or hydronium H₃O⁺) in water. The H⁺ ion is responsible for acidic behaviour.
2.Base Ionisation in Water
$N a O H (a q) ⟶ N a^{+} (a q) + O H^{-} (a q)$
Bases produce OH⁻ ions in water. Only water-soluble bases are called alkalis.
3.Neutralisation★
$A c i d + B a se ⟶ S a l t + W a t er$
H⁺ from acid combines with OH⁻ from base. Highly exothermic.
4.Acid + Metal
$A c i d + M e t a l ⟶ S a l t + H_{2} (g)$
Common active metals (Zn, Fe, Mg) liberate H₂ gas with dilute acids. Test: hydrogen 'pops' with a burning splinter.
5.Acid + Metal Carbonate
$2 H C l + N a_{2} C O_{3} ⟶ 2 N a C l + H_{2} O + C O_{2} (g)$
Bubbles of CO₂ turn lime water milky (Ca(OH)₂ + CO₂ → CaCO₃↓). Same result with metal hydrogencarbonates.
6.pH Scale★
$p H = - lo g_{10} [H^{+}]$
$[H^{+}]$ : Molar concentration of H⁺ ions (mol/L)
Range 0-14. pH < 7 acidic, pH = 7 neutral, pH > 7 basic. Each unit change ⇒ 10× change in [H⁺].
7.Chlor-Alkali Process
$2 N a C l (a q) + 2 H_{2} O (l) electrolysis 2 N a O H (a q) + C l_{2} (g) + H_{2} (g)$
Industrial electrolysis of brine. Products: NaOH at cathode, Cl₂ at anode, H₂ as by-product.
8.Water of Crystallisation
$C u S O_{4} \cdot 5 H_{2} O Δ C u S O_{4} + 5 H_{2} O$
Fixed number of water molecules in the crystal lattice. Blue (hydrated) → white (anhydrous). Adding water reverses it.
9.Setting of Plaster of Paris
$C a S O_{4} \cdot \frac{1}{2} H_{2} O + \frac{3}{2} H_{2} O ⟶ C a S O_{4} \cdot 2 H_{2} O$
PoP + water → gypsum. Slight expansion on setting makes it ideal for casts/moulds.