Maharashtra State Board · Class 10 · Chemistry · Chapter 5

Acids, Bases and Salts — Formula Sheet

Board Formulas

12 formulas

1.Ionisation of an Acid
$H C l \to H^{+} + C l^{-}$
Acid releases H+ ions in aqueous solution (Arrhenius). Strong acid ionises completely.
2.Ionisation of a Base
$N a O H \to N a^{+} + O H^{-}$
Base releases OH- ions in aqueous solution.
3.Neutralisation Reaction★
$Acid + Base \to Salt + Water$
H+ from acid combines with OH- from base to give water; remaining ions form the salt. Exothermic.
4.Definition of pH★
$p H = - lo g_{10} [H^{+}]$
$[H^{+}]$ : Molar concentration of H+ ions (mol/L)
Negative logarithm of H+ concentration in mol/L. Range 0-14.
5.pOH and its Relation
$pO H = - lo g_{10} [O H^{-}], p H + pO H = 14$
At 25 °C the sum is always 14 for aqueous solutions.
6.Ionic Product of Water
$K_{w} = [H^{+}] [O H^{-}] = 1 0^{- 14} at 25 ° C$
In pure water [H+] = [OH-] = 10^-7 mol/L, giving pH = 7.
7.Acid + Metal
$Z n + 2 H C l \to Z n C l_{2} + H_{2} ↑$
Metals above H in activity series displace H_2. Test: burning splinter gives 'pop'.
8.Acid + Metal Carbonate
$2 H C l + N a_{2} C O_{3} \to 2 N a C l + H_{2} O + C O_{2} ↑$
CO_2 evolved turns lime water milky — a standard SSC identification.
9.Chlor-alkali Process★
$2 N a C l (a q) + 2 H_{2} O electrolysis 2 N a O H + C l_{2} ↑ + H_{2} ↑$
Three products: NaOH (solution), Cl_2 (anode), H_2 (cathode). Basis of soaps, PVC, bleaches.
10.Formation of Baking Soda (Solvay first step)
$N a C l + H_{2} O + C O_{2} + N H_{3} \to N H_{4} C l + N a H C O_{3}$
NaHCO_3 = baking soda (Marathi: खाण्याचा सोडा).
11.Formation of Washing Soda
$2 N a H C O_{3} Δ N a_{2} C O_{3} + H_{2} O + C O_{2}$
Heating baking soda and then recrystallising with 10 waters gives washing soda Na_2CO_3·10H_2O.
12.Bleaching Powder
$C a (O H)_{2} + C l_{2} \to C a O C l_{2} + H_{2} O$
Dry slaked lime + chlorine → bleaching powder. Used as disinfectant and bleach.