The pH range of a basic indicator is 4 to 6.5 Calculate the dissociation constant of indicator?.

SOLUTION:  pK_In must be midpoint of pH range for acidic indicators and pOH range for basic indicators

The pH range = 4 to 6.5 so pOH range is 10 to 7.5

Hence Pk_In =   (10+7.5) /2 = 8.75 

What are DOUBLE SALTS ?

DOUBLE SALTS:

(1)The addition compounds formed by the combination of two simple salts are termed as double salts.

(2) Double salts are stable in solid state only.

(3) When dissolved in water, it furnishes all the ions present in the simple salt form which it has been constituted.

(4)The solution of double salt shows the properties of the samples salts from which it has been constituted

For examples

Mohar’s salt-FeSO₄ (NH₄)₂SO₄ .6H₂O (Ferrous ammonium sulphate)

Alum’s- K₂SO₄Al₂ (SO4)₃. 24H₂O (Potassium ammonium sulphate)

Karnalite- KCl.MgCl_2.6 (H₂O)

Dolomite- CaCO₃.MgCO₃ or CaMg (CO₃)₂

What is the pH of 0.10 M CH3COONa solution. Hydrolysis constant of sodium acetate is 5.6 × 10-10 ?

SOLUTION: Hydrolysis of the salt may be represented as

A 0.0258 M solution of the sodium salt, NaH of the weak monoprotic acid, HA has a pH of 9.65. Calculate Ka of the acid AH.

For the reaction Initially 2.5 moles of Fe(NO3)3 and 3.6 moles of Na2CO3 are taken. If 6.3 moles of Na2CO3 is obtained the % yield of given reaction is ?