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Sunday, March 10, 2019


Analysis of mass of reactants and products of given chemical reaction is known as Gravimetric analysis.
Two important method deal with the trapping and weighing of product in solid and gaseous state
(1) PRECIPITATATION METHOD: This method uses for metallic elements in their ionic form react with negative counter ions to produced stable (Insoluble) precipitate.
(I) Silver ppt with halides ions
(II) Calcium ppt with Oxalates
(III) Barium ppt with Sulphates
(2) VOATILIZATION METHOD: This method generally uses for analysis of Bicarbonate from the mixture of Carbonate and Bicarbonate.

ILLUSTRATIVE EXAMPLE (1): A mixture of FeO and Fe2O4 when heated in air to constant weight gain 5% in its weight, The % of FeO in sample is?
ILLUSTRATIVE EXAMPLE (2): A mixture of FeO and Fe2O3 is produced by 1 mole of Fe reacts Completely with 0.65 moles of O2. Find out the mole’s ratio of ferrous oxide to ferric oxide.?
8 gm mixture of sodium carbonate and sodium bicarbonate are heated until a constant mass equal to 6 gm is obtained calculate % of sodium bicarbonate in the original mixture ?.
1 litre of a mixture of CO and CO2 is passed through a tube containing red hot charcoal. The total volume of the mixture become 1.5 litre. Calculate Volume % of CO in the original mixture.? 
1-gram mixture of cuprous and cupric oxide was reduced to 0.839 gm metallic cupper. What is the weight of cuprous oxide in given sample.?  (Cu= 63.5, O= 16)
A mixture of pure AgCl and AgBr contains 60.94 % silver by mass, what is percentage of AgCl in sample.? (Ag= 108, Br= 80 Cl = 35.5)
1.48 gm mixture of CaCO3 and MgCO3 was heated to a constant weight till 0.96 gm residue formed, % of MgCO3 in the sample was?
ILLUSTRATIVE EXAMPLE (8): When 40 gm of 200% solution by weight was cooled, 50 gm of solute precipitated. The percentage of concentration of remaining solution is.
ILLUSTRATIVE EXAMPLE (9): 18.4 gm mixture of CaCO3 and MgCO3 was heated to produce a constant volume of carbon dioxide is 4.48 litre the calculate amount of MgCO3 and CaCO3 in mixture?
ILLUSTRATIVE EXAMPLE (10): 31.3 gm NaCl mixture of NaBr and NaCl treated with H2SO4, 4.48 gm of Na2SO4 is produced. Then Calculate the amount of NaCl and NaBr in mixture.

Answers: (1) 20.25 % (2) 4/3 (3) .......  (4) 50 %  (5) 0.45 grams (6) 19.64 % (7) 45.66 % (8) 8.57 % (9) CaCo3 = 10 gram, (10) NaCl=13.1grams and NaBr= 18.28 grams

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