The concentration of bivalent lead ions in a sample of polluted of polluted water that aslo contains nitrate ions is determined by adding solid sodium sulphate (M=142) to exactly 500mL water. Calculate the molarity of lead ions if 0.355g is sodium sulphate was nedded for complete precipitation of lead ions as sulphate.

If 0.561g of KOH is dissolved in water to give 200mL of solution at 298K . Calculate the concentrations of potassium, hydrogen and hydroxyl ions. What is its pH ?

Soap is the sodium salt of a long chain fatty acid, Sodium salt stearic acis is soluble in water, whereas calcium and magnesium salts are insoluble, so when soap is added to soft water, it dissolves and forms lather readily. Temporary hardness in water can be easily removed by boiling. Permanent hardness can be removed by the addition of washing soda, Calgon process, ion exchange process. The degree of hardness of a sample of water containing 6 mg of magnesium sulphate (other salts are absent) per kilogram of water is

All titration which involves the direct titration of Iodine with a reducing agent are grouped under lodimetry. Iodimetry is employed to determine the strength of reducing agent such as sodium thio sulphate I_(2) + 2Na_(2)S_(2)O_(3) rarr 2I^(-)+S_(4)O_(6)^(-) If iodine is liberated as a result of chemical reaction involving oxidation of an idodide ion by a strong oxidizing agent in neutral or acidic medium the liberated iodine is then titrated with reducing agent. This titration is called lodometry. Todometry is used to estimate the strength of oxidizing agent. For example the estimation of Cu^(++) with thiosulphate. Cu^(+ +) +I^(-) Cu_(2)I_(2)+I_(2) , I_(2) +S_(2)O_(3)^(-) rarrS_(4)O_(6)^(-) +I^(-) Starch used as indicator near the end point which form blue colour complex with I_(3)^(-) . The blue colour disappears when When 159.50g of CuSO_4 in a solution is reacted with KI, then the liberated iodine required 100 ml 1 M Na_(2)S_(2)O_3 for complete reaction, then what is the percentage purity of sample used in making the solution.

All titration which involves the direct titration of Iodine with a reducing agent are grouped under lodimetry. Iodimetry is employed to determine the strength of reducing agent such as sodium thio sulphate I_(2) + 2Na_(2)S_(2)O_(3) rarr 2I^(-)+S_(4)O_(6)^(-) If iodine is liberated as a result of chemical reaction involving oxidation of an idodide ion by a strong oxidizing agent in neutral or acidic medium the liberated iodine is then titrated with reducing agent. This titration is called lodometry. Todometry is used to estimate the strength of oxidizing agent. For example the estimation of Cu^(++) with thiosulphate. Cu^(+ +) +I^(-) Cu_(2)I_(2)+I_(2) , I_(2) +S_(2)O_(3)^(-) rarrS_(4)O_(6)^(-) +I^(-) Starch used as indicator near the end point which form blue colour complex with I_(3)^(-) . The blue colour disappears when 10 mL of H_2O_2 solution on treatment with KI and titration of liberated I_2 required 10 mL of 1 N hypo . Thus H_2O_2 is :

A sample of hard water contains 0.005 moles of calcium chloride per litre.What is the minimum concentration of sodium sulphate which must be added for removing the Ca^(2+) ions from this water sample ? K_(sp) " of " CaSO_4= 2.4 xx 10^(-5)

A solution which remains in equilibrium with undissolved solute is said to be saturated. The concentration of a saturated solution at a given temperature is called solubility. The product of concentration of ions in a saturated solution of an electrolyte at a given temperature, is called solubility product (K_(sp)) . For the electrolyte, A_(x),B_(y),:A_(x),B_(y(s)) rarr xA^(y+)+ y^(Bx-) , with solubility S, the solubility product (K_(sp)) =x^(x)xxy^(y) xx s^(x+y) . While calculating the solubility of a sparingly soluble salt in the presence of some strong electrolyte containing a common ion, the common ion concentration is practically equal to that of strong electrolyte. If in a solution, the ionic product of an clectrolyte exceeds its K_(sp) , value at a particular temperature, then precipitation occurs. The solubility of PbSO_(4) , in water is 0.303 g/l at 25^(@) C, its solubility product at that temperature is