Experiment No : 1
AIM: To prepare 250 ml of M/20 standard solution of ferrous ammonium sulphate (Mohr’s salt).
With the help of this solution find out the molarity and strength of the given KMnO4 solution.
Apparatus: Chemical balance, weight box, watch glass, 250 ml of measuring flask, funnel, burette,
pipette, conical flask, tile, burette stand two beakers etc.
Chemical Required: Ferrous ammonium sulphate Crystals (Mohr's Salt), Dilute H2SO4,, Distilled H2O,
KMnO4 solution.
Theory: Ferrous ammonium sulphate is a double salt and act as a reducing agent against KMnO4,
whereas KMnO4 act as oxidizing agent and it oxidizes iron present in Mohr’s salt. Hence the reaction
between the two is redox reaction.
To prepare M/20 solution of Mohr’s salt, the weight of the Mohr’s salt required can be calculated
by using the formula
W ×1000
b Molarity × M ×volume in ml
b
𝑀𝑜𝑙𝑎𝑟𝑖𝑡𝑦 = 𝑊𝑏 =
Mb ×volume in ml 1000
Wb = Weight of Mohr’s salt, Mb = Molecular mass of Mohr’s salt = 392 g/mol
392 ×250
𝑊𝑏 = 20 ×1000 = 4.9 g
Molecular mass of KMnO4 = 158
Reaction Involved:
2KMnO4 + 8H2SO4 + 10FeSO4.(NH4)2SO4.6H2O K2SO4 + 2MnSO4 + 5Fe2(SO4)3 + 10
(NH4)2SO4 + 68 H2O
Ionic equation:
MnO4─ + 8H+ + 5Fe+2 5Fe+3 + Mn+2 + 4H2O
Indicator: KMnO4 solution acts as a self indicator.
End point: Colourless to permanent pink.
Observation-
(i) Mass of watch glass (a) = 36.49 gm
(ii) Mass of Mohr’s salt (b) = 4.9 g
(iii) Mass of watch glass (a) + Mass of Mohr’s salt (b) = 41.39 g
(iv) Volume of Mohr's salt solution prepared = 250 ml
(v) Molarity of Mohr's salt solution = M/20
Observation table:
S.No. Volume of Mohr’ Initial reading of Final reading of Volume of KMnO4
salt soln(ml) Burette(ml) Burette(ml) soln used(ml)
1 10 o.o 10.8 10.8
2 10 11 21.8 10.8
3 10 22 32.8 10.8
Concordant Volume = 10.8 ml
,Calcculation:
Molarity of KMnO4 solution (M2) = ? Molarity of Mohr’s salt M1 = M/20
M1V1 = 5M2V2 Volume of Mohr’s salt V1 = 10 ml
M2 = M1VV2 Molarity of KMnO4 M2 = ?
M ×10
M2 = Volume of KMnO4 V2 = 10.8 ml
20 ×5 ×10.8
M2 = ·0092 M
(Due to 2 moles of KMnO4 reacts with 10 moles of Mohr’s salt in overall balance equation)
Strength of KMnO4 solution in gm/lit = ?
= Molarity (M2) × Molecular mass of KMnO4
= ·0092 × 158
= 1·453 gm/lit
RESULT: Molarity o the given KMnO4 Solution = ·0092M
Strength of the given KMnO4 Solution = 1·453 gm/lit
Precaution:
(i) All the volumetric apparatus should be washed well before used.
(ii) Rinse burette with the solution of KMnO4 and pipette with the solution of Mohr’s
salt. Wash the titration flask with Distilled water after every titration.
(iii) Always read the upper meniscus in case of coloured solution.
(iv) Excess of Dil H2SO4 should be add in Mohr’s salt solution.
, Experiment No : 2
AIM: To prepare 250 ml of M/50 standard solution of Oxalic acid. With the help of this solution find
out the molarity and strength of the given KMnO4 solution.
Apparatus: Chemical balance, weight box, watch glass, 250 ml of measuring flask, funnel, burette,
pipette, conical flask, tile, burette stand two beakers etc.
Chemical Required: Oxalic acid, Dilute H2SO4,, Distilled H2O, KMnO4 solution.
Theory: Oxalic acid is a dicarboxylic acid. Oxalic acid act as a reducing agent against KMnO4,
whereas KMnO4 act as oxidizing agent and it oxidizes oxalic acid into carbon dioxide and water.
Hence the reaction between the two is redox reaction. The reaction between KMnO4 and oxalic
acid at room temperature is slow due to which oxalic acid after acidification in the conical flas is
heated to about (50-60)°C.
To prepare M/50 solution of oxalic acid, the weight of the oxalic acid required can be calculated by
using the formula
W b ×1000 Molarity × M b ×volume in ml
𝑀𝑜𝑙𝑎𝑟𝑖𝑡𝑦 = 𝑊𝑏 =
Mb ×volume in ml 1000
Wb = Weight of oxalic acid, Mb = Molecular mass of oxalic acid = 126 g/mol
126 ×250
𝑊𝑏 = 50 ×1000 = 0·63 g
Molecular mass of KMnO4 = 158
Reaction Involved:
2KMnO4 + 3H2SO4 + (COOH)2 K2SO4 + 2MnSO4 + 8 H2O + 10CO2
Ionic equation:
2MnO4─ + 16H+ + 5(COO)2─ 2Mn+2 + 8H2O +5CO2
Indicator: KMnO4 solution acts as a self indicator.
End point: Colourless to permanent pink.
Observation-
(i) Mass of watch glass (a) = 36.33 gm
(ii) Mass of oxalic acid (b) = 0·63 g
(iii) Mass of watch glass (a) + Mass of oxalic acid (b) = 36·96 g
(iv) Volume of oxalic acid solution prepared = 250 ml
(v) Molarity of oxalic acid solution = M/50
Observation table:
S.No. Volume of oxalic Initial reading of Final reading of Volume of KMnO4
acid soln(ml) Burette(ml) Burette(ml) soln used(ml)
1 10 0·0 4·6 4·6
2 10 5·0 9·5 4·5
3 10 10·0 14·5 4·5
Concordant Volume = 4·5ml
AIM: To prepare 250 ml of M/20 standard solution of ferrous ammonium sulphate (Mohr’s salt).
With the help of this solution find out the molarity and strength of the given KMnO4 solution.
Apparatus: Chemical balance, weight box, watch glass, 250 ml of measuring flask, funnel, burette,
pipette, conical flask, tile, burette stand two beakers etc.
Chemical Required: Ferrous ammonium sulphate Crystals (Mohr's Salt), Dilute H2SO4,, Distilled H2O,
KMnO4 solution.
Theory: Ferrous ammonium sulphate is a double salt and act as a reducing agent against KMnO4,
whereas KMnO4 act as oxidizing agent and it oxidizes iron present in Mohr’s salt. Hence the reaction
between the two is redox reaction.
To prepare M/20 solution of Mohr’s salt, the weight of the Mohr’s salt required can be calculated
by using the formula
W ×1000
b Molarity × M ×volume in ml
b
𝑀𝑜𝑙𝑎𝑟𝑖𝑡𝑦 = 𝑊𝑏 =
Mb ×volume in ml 1000
Wb = Weight of Mohr’s salt, Mb = Molecular mass of Mohr’s salt = 392 g/mol
392 ×250
𝑊𝑏 = 20 ×1000 = 4.9 g
Molecular mass of KMnO4 = 158
Reaction Involved:
2KMnO4 + 8H2SO4 + 10FeSO4.(NH4)2SO4.6H2O K2SO4 + 2MnSO4 + 5Fe2(SO4)3 + 10
(NH4)2SO4 + 68 H2O
Ionic equation:
MnO4─ + 8H+ + 5Fe+2 5Fe+3 + Mn+2 + 4H2O
Indicator: KMnO4 solution acts as a self indicator.
End point: Colourless to permanent pink.
Observation-
(i) Mass of watch glass (a) = 36.49 gm
(ii) Mass of Mohr’s salt (b) = 4.9 g
(iii) Mass of watch glass (a) + Mass of Mohr’s salt (b) = 41.39 g
(iv) Volume of Mohr's salt solution prepared = 250 ml
(v) Molarity of Mohr's salt solution = M/20
Observation table:
S.No. Volume of Mohr’ Initial reading of Final reading of Volume of KMnO4
salt soln(ml) Burette(ml) Burette(ml) soln used(ml)
1 10 o.o 10.8 10.8
2 10 11 21.8 10.8
3 10 22 32.8 10.8
Concordant Volume = 10.8 ml
,Calcculation:
Molarity of KMnO4 solution (M2) = ? Molarity of Mohr’s salt M1 = M/20
M1V1 = 5M2V2 Volume of Mohr’s salt V1 = 10 ml
M2 = M1VV2 Molarity of KMnO4 M2 = ?
M ×10
M2 = Volume of KMnO4 V2 = 10.8 ml
20 ×5 ×10.8
M2 = ·0092 M
(Due to 2 moles of KMnO4 reacts with 10 moles of Mohr’s salt in overall balance equation)
Strength of KMnO4 solution in gm/lit = ?
= Molarity (M2) × Molecular mass of KMnO4
= ·0092 × 158
= 1·453 gm/lit
RESULT: Molarity o the given KMnO4 Solution = ·0092M
Strength of the given KMnO4 Solution = 1·453 gm/lit
Precaution:
(i) All the volumetric apparatus should be washed well before used.
(ii) Rinse burette with the solution of KMnO4 and pipette with the solution of Mohr’s
salt. Wash the titration flask with Distilled water after every titration.
(iii) Always read the upper meniscus in case of coloured solution.
(iv) Excess of Dil H2SO4 should be add in Mohr’s salt solution.
, Experiment No : 2
AIM: To prepare 250 ml of M/50 standard solution of Oxalic acid. With the help of this solution find
out the molarity and strength of the given KMnO4 solution.
Apparatus: Chemical balance, weight box, watch glass, 250 ml of measuring flask, funnel, burette,
pipette, conical flask, tile, burette stand two beakers etc.
Chemical Required: Oxalic acid, Dilute H2SO4,, Distilled H2O, KMnO4 solution.
Theory: Oxalic acid is a dicarboxylic acid. Oxalic acid act as a reducing agent against KMnO4,
whereas KMnO4 act as oxidizing agent and it oxidizes oxalic acid into carbon dioxide and water.
Hence the reaction between the two is redox reaction. The reaction between KMnO4 and oxalic
acid at room temperature is slow due to which oxalic acid after acidification in the conical flas is
heated to about (50-60)°C.
To prepare M/50 solution of oxalic acid, the weight of the oxalic acid required can be calculated by
using the formula
W b ×1000 Molarity × M b ×volume in ml
𝑀𝑜𝑙𝑎𝑟𝑖𝑡𝑦 = 𝑊𝑏 =
Mb ×volume in ml 1000
Wb = Weight of oxalic acid, Mb = Molecular mass of oxalic acid = 126 g/mol
126 ×250
𝑊𝑏 = 50 ×1000 = 0·63 g
Molecular mass of KMnO4 = 158
Reaction Involved:
2KMnO4 + 3H2SO4 + (COOH)2 K2SO4 + 2MnSO4 + 8 H2O + 10CO2
Ionic equation:
2MnO4─ + 16H+ + 5(COO)2─ 2Mn+2 + 8H2O +5CO2
Indicator: KMnO4 solution acts as a self indicator.
End point: Colourless to permanent pink.
Observation-
(i) Mass of watch glass (a) = 36.33 gm
(ii) Mass of oxalic acid (b) = 0·63 g
(iii) Mass of watch glass (a) + Mass of oxalic acid (b) = 36·96 g
(iv) Volume of oxalic acid solution prepared = 250 ml
(v) Molarity of oxalic acid solution = M/50
Observation table:
S.No. Volume of oxalic Initial reading of Final reading of Volume of KMnO4
acid soln(ml) Burette(ml) Burette(ml) soln used(ml)
1 10 0·0 4·6 4·6
2 10 5·0 9·5 4·5
3 10 10·0 14·5 4·5
Concordant Volume = 4·5ml
