Incorrect statement for the use of indicators in acid-base titration is :
Phenolphthalein may be used for a strong acid vs strong base titration.
Indicator | pH range |
Methyl orange | 3.2 - 4.5 |
Phenolpthalein | 8.3 - 10.5 |
Methyl orange may be used for a strong acid vs strong base and strong acid vs weak base titration. Phenolpthalein may be used for a strong acid vs strong base and weak acid vs strong base titration
So , the correct option is (A) : Methyl orange may be used for a weak acid vs weak base titration.
The suitable indicators for different types of acid-base titrations are:
Thus, the incorrect statement is option (1).
A bob of mass \(m\) is suspended at a point \(O\) by a light string of length \(l\) and left to perform vertical motion (circular) as shown in the figure. Initially, by applying horizontal velocity \(v_0\) at the point ‘A’, the string becomes slack when the bob reaches at the point ‘D’. The ratio of the kinetic energy of the bob at the points B and C is:
Acid is any hydrogen-containing substance that is capable of donating a proton (hydrogen ion) to another substance. Base is an ion or molecule capable of accepting a hydrogen ion from acid.
Physical Properties | ACIDS | BASES |
Taste | Sour | Bitter |
Colour on Litmus paper | Turns blue litmus red | Turns red litmus blue |
Ions produced on dissociation | H+ | OH- |
pH | <7 (less than 7) | >7 (more than 7) |
Strong acids | HCl, HNO3, H2SO4 | NaOH, KOH |
Weak Acids | CH3COOH, H3PO4, H2CO3 | NH4OH |
Type of Reaction | Acid | Bases |
Reaction with Metals | Acid + Metal → Salt + Hydrogen gas (H2) E.g., Zn(s)+ dil. H2SO4 → ZnSO4 (Zinc Sulphate) + H2 | Base + Metal → Salt + Hydrogen gas (H2) E.g., 2NaOH +Zn → Na2ZnO2 (Sodium zincate) + H2 |
Reaction with hydrogen carbonates (bicarbonate) and carbonates | Metal carbonate/Metal hydrogen carbonate + Acid → Salt + Carbon dioxide + Water E.g., HCl+NaOH → NaCl+ H2O 2. Na2CO3+ 2 HCl(aq) →2NaCl(aq)+ H2O(l) + CO2(g) 3. Na2CO3+ 2H2SO4(aq) →2Na2SO4(aq)+ H2O(l) + CO2(g) 4. NaHCO3+ HCl → NaCl+ H2O+ CO2 | Base+ Carbonate/ bicarbonate → No reaction |
Neutralisation Reaction | Base + Acid → Salt + Water E.g., NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l) | Base + Acid → Salt + Water E.g., CaO+ HCl (l) → CaCl2 (aq)+ H2O (l) |
Reaction with Oxides | Metal oxide + Acid → Salt + Water E.g., CaO+ HCl (l) → CaCl2 (aq)+ H2O (l) | Non- Metallic oxide + Base → Salt + Water E.g., Ca(OH)2+ CO2 → CaCO3+ H2O |
Dissolution in Water | Acid gives H+ ions in water. E.g., HCl → H+ + Cl- HCl + H2O → H3O+ + Cl– | Base gives OH- ions in water. |
Read more on Acids, Bases and Salts