# Acid-Base Titration

Acid- Base titration is used to determine the concentration of an acid or base. It makes the use of neutralization reaction that occurs between the acid and base in-order to find the concentration of acid or base.

Questions:

1. Phenolphthalein shows which of the following colour in acidic medium?

(a)    Pink

(b)   Yellow

(c)    Colourless

(d)   red

2. Phenolphthalein is not a good indicator for titrating:

(a)    ferrous sulphate against $KMnO_4$

(b)   NaOH against oxalic acid

(c)    NaOH against $H_2SO_4$

(d)   NaOH against HCI

3. The pink colour phenolphthalein, in alkaline medium is due to:

(a)    positive ion

(b)   negative ion

(c)    neutral form

(d) $OH^-$ ion

4. The indicator used in the titration of sodium carbonate with sulphuric acid is:

(a)    methyl orange

(b)   fluorescein

(c)    potassium ferrocyanide

(d)   potassium ferricyanid

5. If one drop of methyl orange is added in solution, then solution becomes pink. The solution is:

(a)    basic

(b)   acidic

(c)    netural

(d)   amphoteric

6 A rapid change of pH near stiochiometric point of an acid-base titration is the basis of indicator detection. The pH of solution is related to the ratio of concentration of conjugate acid [Hln] and base forms of the indicator by the expression:

(a) $\log \dfrac{[ln^-]}{[Hln^-]} = p^H- pK_{ln}$

(b) $\log \dfrac{[Hln^-]}{[ln]} = p^H- pK_{ln}$

(c) $\log \dfrac{[Hln^-]}{[ln]} = pK_{ln}- p^H$

(d) $\log \dfrac{[ln^-]}{[Hln]} = pK_{ln}- p^H$