Real World Project: Determination of Vitamin C in Fruit Juices

Real World Project: Determination of Vitamin C in Fruit Juices

Brian GilleaseAnd

Lauren Burns

Objective

• Calculate vitamin C in a Vitamin C tablet• Titrate fruit juices• Calculate amount of vitamin C in each juice• Compare juices to tablet

Importance

• Vitamin C –– antioxidant; binds with carbon, hydrogen, oxygen;

oxidizes easily– Safe and efficient nutrient, helps protect body

against cardiovascular disease, eye disease, and other diseases

Procedures - Errors

• Juicer – too much pulp

• Filtration – pulp too thick

• Strawberry Juice – red color of juice

Picture Perfect!

Clementine Juice

30 mL filtered, digested soln. + 50 mL KIO3 soln. + KI + 10 mL H2SO4 + starch indicator

TrialMass KI

(g)

Initial Vol. Na2S2O3

(mL)

Final Vol. Na2S2O3

(mL)

Vol. Na2S2O3

AddedConsumed Moles I3-

Moles I3- Present

Grams Ascorbic

Acid % Difference

1 2.0013 0 26 260.0011110

920.0002935

740.0517059

62 70.62161244

2 2.0009 0 28.1 28.10.0012008

340.0002038

320.0359000

91 79.60222108

3 2.0022 0 29.5 29.50.0012606

620.0001440

040.0253628

43 85.5892935

Moles I3- Formed

0.001404666 Average

0.037656299 78.60437568

Manufacturer's Claim 0.176

grams per fruit

Data

Clementine Juice Spike

30 mL filtered, digested soln. + 50 mL KIO3 soln. + KI + 10 mL H2SO4 +

starch indicator

TrialMass KI (g)

Mass AA (g)

Total Mass AA (g)


(mL)

Final Vol.

Na2S2O3 (mL)

Vol. Na2S2O3

Added

Consumed Moles

I3-

Moles I3-

Present

Grams Ascorbic

Acid%

Difference

1 2.00560.003

10.020

7 0 22 220.001574

384

-0.00016

9717

-0.0298915

87244.403800

1

2 2.0150.003

4 0.021 0 18.5 18.50.001323

9148.07527

E-050.0142226

1832.2732466

8

3 2.00150.004

20.021

8 0 20.25 20.250.001449

149

-4.44824

E-05

-0.0078344

84135.938000

9

Moles I3- Formed

0.001404666 Average

-0.0078344

84137.538349

2


Papaya Juice


TrialMass KI

(g)


(mL)

Final Vol. Na2S2O3

(mL)

Vol. Na2S2O3


Moles I3- Present

Grams Ascorbic

Acid%

Difference

1 2.0009 0 22.2 22.20.00094870

20.00045596

50.08030706

2100.097215

1

2 2.0022 0 21.4 21.40.00091451

40.00049015

20.08632834

7 93.7988006

3 2.0014 0 23.2 23.20.00099143

6 0.000413230.07278045

7107.970233

2

Moles I3- Formed

0.001404666 Average

0.079805289

16.52166457


grams per fruit

Papaya Juice Spike

30 mL filtered, digested soln. + 50 mL KIO3 soln. + KI + 10 mL H2SO4 + starch

indicator

TrialMass KI (g)

Mass AA (g)

Total Mass AA (g)

Initial Vol.

Na2S2O3

(mL)

Final Vol. Na2S2O3

(mL)

Vol. Na2S2O3 Added

Consumed Moles I3-

Moles I3- Present

Grams Ascorbic

Acid

% Differenc

e

1 2.0021 0.0029 0.0985 0 20 200.0014312

58

-2.65916E

-05

-0.004683

47104.7547

914

2 2.009 0.0032 0.0988 0 18.2 18.20.0013024

450.000102

2220.018003

83681.77749

418

3 2.0029 0.0036 0.0992 0 19.3 19.30.0013811

642.35024E

-050.004139

37195.82724

659

Moles I3- Formed

0.001404666 Average

0.005819913

94.11984407


Orange Juice


Trial Mass KI (g)


(mL)

Final Vol. Na2S2O3

(mL)

Vol. Na2S2O3


Moles I3- Present

Grams Ascorbic

Acid%

Difference

1 2.005 0 31.1 31.10.00132903

77.56294E-

050.01332027

573.9329258

3

2 2.0067 0 30.3 30.30.00129484

90.00010981

70.01934155

962.1495906

7

3 2.0039 0 30 300.00128202

90.00012263

70.02159954

157.7308399

9

Moles I3- Formed

0.001404666 Average

0.018087125

64.60445217


grams per fruit

Orange Juice Spike


indicator

TrialMass KI (g)

Mass AA (g)

Total Mass AA (g)

Initial Vol.

Na2S2O3 (mL)

Final Vol. Na2S2O3 (mL)

Vol. Na2S2O3 Added

Consumed

Moles I3-

Moles I3-

Present

Grams Ascorbic

Acid

% Differenc

e

1 2.0105 0.004 0.0551 0 21 210.00150

2821

-9.81545

E-05

-0.01728

7528131.374

8241

2 2.0008 0.0039 0.055 0 19.35 19.350.00138

47421.99242

E-050.00350

916893.6196

9371

3 2.0065 0.0037 0.0548 0 18.55 18.550.00132

74927.71746

E-050.01359

241575.1963

225

Moles I3- Formed

0.001404666 Average

-6.19815

E-05100.063

6134


Grapefruit Juice


TrialMass KI

(g)

Initial Vol.

Na2S2O3 (mL)

Final Vol. Na2S2O3

(mL)

Vol. Na2S2O3


Moles I3- Present

Grams Ascorbic

Acid%

Difference

1 2.0022 0 30.1 30.10.00128630

30.00011836

4 0.0208468845.7112494

2 1.995 0 33.8 33.8 0.00144442-3.97532E-

05-

0.00700156118.233227

9

3 2.0039 0 30.5 30.50.00130339

6 0.000101270.01783623

853.5514632

8

Moles I3- Formed

0.001404666 Average 0.01056052

72.49864685


grams per fruit

Grapefruit Juice Spike


TrialMass KI

(g)Mass AA

(g)

Total Mass AA

(g)


(mL)

Final Vol. Na2S2O3

(mL)

Vol. Na2S2O3


Moles I3- Present

Grams Ascorbic

Acid%

Difference

1 2.0056 0.0037 0.0421 0 19 190.0013596

954.49713E-

050.0079205

8981.186249

55

2 2.015 0.0033 0.0417 0 18.5 18.50.0013239

148.07527E-

050.0142226

1865.893001

92

3 2.0015 0.0037 0.0421 0 19.5 19.50.0013954

779.1898E-

060.0016185

696.155440

19

Moles I3- Formed

0.001404666 Average

0.007920589

81.07823055


Strawberry Juice


TrialMass KI

(g)

Initial Vol.

Na2S2O3 (mL)

Final Vol. Na2S2O3

(mL)

Vol. Na2S2O3


Moles I3- Present

Grams Ascorbic

Acid%

Difference

1 2.0012 0 37 370.0015811

69

-0.0001765

03

-0.0310866

97537.84079

67

2 1.9992 0 28.7 28.70.0012264

750.0001781

920.0313841

28342.02996

76

3 2.0003 0 25.5 25.50.0010897

250.0003149

420.0554692

65681.25725

02

Moles I3- Formed

0.001404666 Average

0.018588899

161.8154737


grams per fruit

Strawberry Juice Spike


indicator

TrialMass KI (g)

Mass AA (g)

Total Mass AA

(g)

Initial Vol.

Na2S2O3

(mL)

Final Vol. Na2S2O3

(mL)

Vol. Na2S2O3

Added

Consumed Moles

I3-Moles I3- Present

Grams Ascorbic

Acid

% Differenc

e

1 2.0034 0.0031 0.0102 0 18.4 18.40.001316

7578.7909E-

050.015483

02451.79435

343

2 2.0021 0.0038 0.0109 0 19.1 19.10.001366

8513.7815E-

050.006660

18338.89740

287

3 2.0018 0.0035 0.0106 0 20.2 20.20.001445

571

-4.09042E

-05

-0.007204

281167.9649

177

Moles I3- Formed

0.001404666 Average

0.004979642

86.21889134


Error Source

• Over titrated thiosulfate• Not enough KI– Wasn’t an excess of KI to react with

• Refrigerate– Juices were not refrigerated

• Solutions degrade– KIO3 degraded; did not work

Real World Project: Determination of Vitamin C in Fruit Juices

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