GRAVIMETRY- WEIGHT-WEIGHT ANALYSIS:

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.?
ILLUSTRATIVE EXAMPLE (3): 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 ?.
ILLUSTRATIVE EXAMPLE (4): 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.? 
ILLUSTRATIVE EXAMPLE (5): 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)
ILLUSTRATIVE EXAMPLE (6): 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)
ILLUSTRATIVE EXAMPLE (7): 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

DETAIL SOLUTION: COMING SOON....

CONCEPT OF LIMITING REAGENTS:

The reagent which is consumed completely in the reaction and decides the amount of product is known as limiting reagent and left over reagent is known as excess reagent.
HOW TO FIND LIMITING REAGENT:
(1) Divide  the given moles of each reagent by its Stoichiometric coefficient.
(2) The reagent for which the division comes out minimum is called Limiting reagent.
SIGNIFICANT OF LIMITING REAGENT:
(1) The amount of product is decided by Limiting reagent .
(2) Amount of excess reagent left over and participate in the reaction is decided by Limiting reagent.
GENERAL ILLUSTRATION:

ILLUSTRATIVE EXAMPLE (1) : The Chemical reaction 

8 moles of P and 5 moles of Q will produce how many moles of  R ?

SOLUTION:

ILLUSTRATIVE EXAMPLE (2): The Chemical reaction
Carried out by taking 24 gm of Carbon (2 moles ) and 96 gm (3 moles ) of oxygen (O₂) find 

(1) Limiting reagent
(2) How many moles of CO formed
(3) percentage (%) of  reagent left over .

SOLUTION:

ILLUSTRATIVE EXAMPLE (3): 10 gm each of Lithium and Oxygen react to produce Li2O find out?
(1) Find the limiting reagent
(2) Mass of Li2O produced in reaction
(3) % of excess reagent consumed
(4) % of excess reagent undergoes in reaction.

SOLUTION:

ILLUSTRATIVE EXAMPLE (4): Equal mass of Zn (65) and S (32) reacts to form ZnS, Calculate fraction of excess reagent left unreacted.

SOLUTION:

ILLUSTRATIVE EXAMPLE (5):

Above reaction is carried out by taking 6 moles of each X and Y respectively then find % excess reagent react.

SOLUTION: Answer Key 25% unreacted  and 75% reacted 

MOLE-MOLE ANALYSIS:

Mole Concepts:

Mole and Moles Analysis rule:

Ratio of Moles of reactant or product with its coefficient is always constant for a balance chemical equation:

ILLUSTRATIVE EXAMPLE (1):

ILLUSTRATIVE EXAMPLE (2):

ILLUSTRATIVE EXAMPLE (3):

ILLUSTRATIVE EXAMPLE (4):  367.5 gm KClO₃ (122.5) when heated then calculate.

(1) How many gram of O₂ is produced?

(2)How Many litre of O₂ is produced at STP?

SOLUTION:

ILLUSTRATIVE EXAMPLE (5): how many moles O₂ are required to needed produced 5 moles of Fe₂O₃.

SOLUTION:

ILLUSTRATIVE EXAMPLE (6): how many grams of Fe₂O₃ formed by heating of 18 gm FeO with O₂.

SOLUTION:

PERCENTAGE(%) YIELD OF CHEMICAL REACTION:

ILLUSTRATIVE EXAMPLE (1): 200 gm of CaCO₃ on heating produces 11.2 litre of CO₂ (g) at STP calculate % yield of reaction?

ILLUSTRATIVE EXAMPLE (2): 3.9 gm Al(OH)₃  is reacted with excess of HCl , 6.5 gm AlCl₃ is formed determined % yield of reaction ?

ILLUSTRATIVE EXAMPLE (3): Calculate moles of D produce by 4 moles of A.

ILLUSTRATIVE EXAMPLE (4): 9 moles of D and 14 moles of E are allowed to react in closed vessel according to given equation.

Calculate number of B formed in end of reaction, If 4 moles of G are present in reaction vessel. (% yield of each reaction in the reactions)

ILLUSTRATIVE EXAMPLE (5): 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 ?

PERCENTAGE(%) PURITY OF GIVEN SAMPLES:

LLUSTRATIVE EXAMPLE (1): 200 gm of CaCO₃ sample on heating produces 11.2 liters of CO₂ (g) at STP. Calculate % purity of CaCO₃ sample?

LLUSTRATIVE EXAMPLE (2): Calculate the amount of 80 % pure NaOH sample required to react with 21.3 gm Chlorine in hot condition.

LLUSTRATIVE EXAMPLE (3): When 1.25 gm sample of Chalk is strongly heated. 0.44 gm of CO2 is produced. Calculate % purity of Chalk sample?

LLUSTRATIVE EXAMPLE (4): The Mass of 80% pure H₂SO₄ required to completely neutralize 106 gm of Na₂CO₃?

LLUSTRATIVE EXAMPLE (5): When dilute HCl is added to 5.73 gm of contaminated CaCO₃, 2.49 gm of CO₂ is obtained. Find % purity of CaCO3 sample?

LLUSTRATIVE EXAMPLE (6): A sample of impure Iron pyrite (FeS₂) when 13.9 gm heated then it produces iron (iii) oxide (Fe₂O₃) and Sulphur dioxide (SO₂). If 8.02 gm Iron (iii) oxide is obtained, what was the % purity of given sample (original-FeS₂)?