determination of the percentage of ligands in coordination compound

1.0 DATA

a) Data table for the standardisation of KMnO 4 solution using Na 2C2O4 as sample. Mass of sample (g)

0.2109

0.2018

I

II

Final burette reading (ml)

11.60

22.20

Initial burette reading (ml)

0.00

11.60

Volume of KMnO 4 (ml)

11.60

10.60

Burette reading

b) Data table for the standardisation of KMnO 4 solution using K 3[Fe(C2O4)3].3H2O as sample. Mass of sample (g)

0.2010

0.2011

I

II

Final burette reading (ml)

10.00

20.00

Initial burette reading (ml)

0.00

10.00

Volume of KMnO 4 (ml)

10.00

10.00

Burette reading

c) Data table for the standardisation of KMnO 4 solution using K 2[Cu(C2O4)2(H2O)2] as sample. Mass of sample (g)

0.2017

0.2020

I

II

Final burette reading (ml)

8.40

16.90

Initial burette reading (ml)

0.00

8.40

Volume of KMnO 4 (ml)

8.40

8.50

Burette reading

d) Data table for the standardisation of KMnO 4 solution using K 3[Cr(C2O4)3].3H2O as sample. Mass of sample (g)

0.2016

0.2006

I

II

Final burette reading (ml)

5.40

10.90

Initial burette reading (ml)

0.00

5.40

Volume of KMnO 4 (ml)

5.40

5.50

Burette reading

2.0 CALCULATION

(A) Standardization of KMnO4 with Na2C2O4 Redox equation : MnO4- + 8H+  + 5e- → K2SO4  + 2MnSO4  + 5Na2SO4  + 10CO2 + 8H2O 2KMnO4 + 5Na2C2O4 + 8H2SO4 → K2SO4 + 2MnSO 4 + 5Na2SO4 + 10CO2 + 8H2O Molar mass Na2SO4 = 2(22.99) + 2(12.01) + 4(15.99) = 133.96 g/mol First burette reading : Mol Na2SO4 =

0.2019 g 133.96 g/mol

= 0.0015 mol

5 mol of Na2C2O4 : 2 mol of KMnO 4 mol of KMnO4 =

2

 X 0.0015 mol

5

= 0.0016 mol Molarity KMnO 4 =

0.0016 mol 0.0116 L

Second burette reading : Mol Na2SO4 =

= 0.0552 M

0.2018 g 133.96 g/mol

= 0.0015 mol

5 mol of Na2C2O4 : 2 mol of KMnO4 mol of KMnO4 =

2 5

X 0.0015 mol

= 0.0006 mol Molarity KMnO 4 =

0.0006 mol 0.0106 L

Average molarity KMnO4 0.0552 M + 0.0556 M = 2

= 0.0566 M

= 0.0559 M

(B-1) Standardization of KMnO 4 with K3[Fe(C2O4)3].3H2O Average volume of KMnO4 used

=

10.00 ml + 10.00 ml 2

=

10.00 ml

No of mol KMnO4

=

0.0559 M X 0.0100L

=

5.59 X 10-4 mol KMnO4

2 mol of MnO 4-

=

5 mol C2O42-

mol C2O42-

= =

Mass oxalate in K3[Fe(C2O4)3].3H2O

=

Average mass of sample

=

Percentage by weight of oxalate

=

1.3975 X 10-3 mol

x

0.2010 g + 0.2011 g 2 0.1230 g 0.20105 g

Molar mass oxalate in K3[Fe(C2O4)3].3H2O

=

Molar mass K3[Fe(C2O4)3].3H2O

=

491.21 g/mol

Theoretical % of oxalate

=

Theoretical mass oxalate

=

× 100%

3 × 88.0 g/mol

264 g/mol 491.21  g/mol 53.74 100

× 100%

× 0.20105 g

 

X 5.59 X 10-4 mol

1.3975 X 10-3 mol

88.0 g/mol

= 0.1230 g

=

0.20105 g

=

61.18 %

=

264 g/mol

=

53.74 %

=

0.1080 g

Purity of the complex : 10K3[Fe(C2O4)3].3H2O + 24KMnO4 + 96H2SO4 -> 15Fe(SO4)3 + 24MnSO4 + 27K2SO4 + 180CO2 + 106H2O 24 mol KMnO4 mol K3[Fe(C2O4)3].3H2O

=

=  

10 mol K3[Fe(C2O4)3].3H2O

X 5.59 X 10-4 mol

= 2.3292 X 10-4 mol Mass K3[Fe(C2O4)3].3H2O

% purify of the complex =

= 2.3292 X 10-4 mol × 491.21 g/mol 0.1144 g 0.20105 g

× 100 %

= 0.1144 g

= 56.90 %

(B-2) Standardization of KMnO 4 with K2[Cu(C2O4)2(H2O)2 Average volume of KMnO4 used

=

8.40 ml + 8.50 ml 2

=

8.45 ml

No of mol KMnO4

=

0.0559 M X 0.00845L

=

4.7236 X 10-4 mol KMnO4

2 mol of MnO 4-

=

5 mol C2O42-

mol C2O42-

= =

Mass oxalate in K2[Cu(C2O4)2.(H2O)2

=

Average mass of sample

=

Percentage by weight of oxalate

=

Molar mass oxalate in K2[Cu(C2O4)2.(H2O)2

1.1809 X 10-3 mol

0.1039 g 0.20185 g

=

Theoretical % of oxalate

=

Theoretical mass oxalate

=



X 4.7236 X 10-4 mol

1.1809 X 10-3 mol

88.0 g/mol

0.2017 g + 0.2020 g 2 × 100%

2 × 88.0 g/mol

=

Molar mass K2[Cu(C2O4)2.(H2O)2]

x



=

0.20185 g

=

51.47 %

=

176 g/mol

=

49.89 %

=

0.1007 g

= 0.1039 g

352.79 g/mol 176 g/mol 352.79 g/mol 49.89 100

× 100%

× 0.20185 g

Purity of the complex : 2K2[Cu(C2O4)2.(H2O)2] + 3KMnO4 + 12H2SO4 -> 8CO2 + 16H2O + 7KSO4 + 3MnSO4 + 2CuSO4 3 mol KMnO4 mol K3[Fe(C2O4)3].3H2O

=

=  

2 mol K2[Cu(C2O4)2.(H2O)2]

X 4.7236 X 10-4 mol

= 3.1491 X 10-4 mol Mass K3[Fe(C2O4)3].3H2O

= 3.1491 X 10-4 mol × 491.21 g/mol

% purify of the complex =

0.1547 g 0.20185 g

× 100 %

= 0.1547 g

= 76.64 %

(B-3) Standardization of KMnO 4 with K3[Cr(C2O4)3].3H2O Average volume of KMnO4 used

=

5.40 ml + 5.50 ml 2

=

5.45 ml

No of mol KMnO4

=

0.0559 M X 0.00545L

=

3.0466 X 10-4 mol KMnO4

2 mol of MnO 4-

=

5 mol C2O42-

mol C2O42-

= =

Mass oxalate in (K3[Cr(C2O4)3].H2O)

=

Average mass of sample

=

Percentage by weight of oxalate

=

Molar mass oxalate in (K3[Cr(C2O4)3].H2O)

7.6164 X 10-4 mol

0.2016 g + 0.2006 g 2

0.0679 g 0.2011 g

=

Theoretical % of oxalate

=

Theoretical mass oxalate

=

× 100%

3 × 88.0 g/mol

=

Molar mass (K3[Cr(C2O4)3].H2O)

x

 

X 3.0466 X 10-4 mol mol

7.6164 X 10-4 mol

88.0 g/mol

=

0.2011 g

=

33.76 %

=

264 g/mol

=

54.17 %

=

0.1089 g

= 0.0670 g

487.36 g/mol 264 g/mol 487.36 g/mol 54.17 100

× 100%

× 0.2011 g

Purity of the complex : 24KMnO4 + 10K3[Cr(C2O4)3].3H2O + H2SO4  24 mol KMnO4 mol K3[Fe(C2O4)3].3H2O

=

=  

15Cr2(SO4)3 + 24MnSO4 + 27K2SO4 + 180CO2 + 106H2O 10 mol K2[Cu(C2O4)2.(H2O)2]

X 3.0466 X 10-4 mol

= 1.2694 X 10-4 mol Mass K3[Fe(C2O4)3].3H2O

= 1.2694 X 10-4 mol × 487.36 g/mol

% purify of the complex =

0.0619 g 0.2011 g

× 100 %

= 0.0619 g

= 30.78 %