Real World Project:
Hazards: [H]- Hazard [P]- Precautions [R]- Response
Sulfuric Acid:
H1.1- Inhalation
P1.1- Work in hood
R1.1- If inhaled, move person to fresh air
H1.2- Corrosive- burn skin
P1.2- Wear gloves
R1.2- Removed contaminated clothing, washing affected area with water for 15 minutes.
Sodium HydroxideH2.1- Corrosive- burn skin
P2.1- Wear gloves
R2.1- Removed contaminated clothing, wash affected area with water for 15 minutes.
Solid KIH3.1- Inhalation
P3.1- Work in hood
R3.1-If inhaled, move person to fresh air
Purpose:
The purpose of our experiment is to determine the amount of ascorbic acid and citric acid in
multiple powder drink mixes.
Background:
We will be using a redox titration to determine the amount of ascorbic and acid in various
drink mixes. Redox titration involve an oxidation/ reduction reaction between the analyte
and the titrant. Ascorbic acid acts as a mild reducing agent that reacts with triiodide. The
reaction of iodate with iodide will give an excess of triiodide to react with the ascorbic acid.
Ascorbic and Citric acid share the same molecular structure, however one natural while the
other is man-made. Ascorbic acid (vitamin C) is a naturally-occurring compound that is
needed for the metabolism of plants and animals. Humans only produce a small amount of
vitamin C, therefore need to consume a large concentration from their diet. Citric acid is
derived from an acid found in many citrus fruits, it can be used to balance the pH of foods
and preserve foods for long periods of time.
Material List:
Waste:
6M NaOH
Soluble Starch
Na2S2O3 (s)
Na2CO3 (s)
KHP (s)
KI(s)
H2SO4
None
Procedure:
Standardizing NaOH Solution:
1. Dissolve 6M NaOH in 1L of water.
2. Dissolve 0.5106g of KHP in 50 mL of water with a small amount of phenolphthalein
indicator (x3). Standardize the NaOH solution.
Total Acid Analyzation:
1. Pour the contents of ½ packet of drink mix in a 250 mL volumetric flask and fill to the
mark.
2. Titrate with standardized NaOH, three 10 mL samples of from 250 volumetric solution.
Ascorbic Acid Determination:
Standardization of Thiosulfate Solution:
1. Prepare starch indicator solution in the following manner: Make a paste of 5 g soluble
starch in 50 mL water. Pour the paste into 500mL of boiling water, and boil until clear.
2. Prepare 0.07M Na2S2O3 by dissolving an accurately weighed sample of 8.70g of
Na2S2O3* 5 H2O in 500 mL boiled water containing 0.05g of Na2CO3. Put this solution into
an amber bottle.
3. Prepare a 0.01M KIO3 solution by accurately weighing about 1g of solid reagent and
dissolving it in a 500 mL flask.
4. Standardize the thiosulfate solution using the following procedure: Pipet 50 mL of KIO3
solution into an Erlenmeyer flask. Add 1 g of solid KI and 10 mL of 1.0M H2SO4.
5. Immediately titrate with thiosulfate until the solution has lost almost all of its color (pale
yellow). Then add 2 mL of starch indicator and complete titration. Repeat this titration until
you have three good trials.
Analysis of drink mixes:
1. weigh out 2.158g of ascorbic acid for a 10 mL titration and dissolve your sample in 50 mL
1.0M H2SO4 with stirring
2. Add 1g of solid KI and 50 mL of standard KIO3. Titrate with standard thiosulfate as
above, add 2 mL of starch indicator. Repeat until you have 3 good trials.
3. Repeat this procedure using ½ packet of your choice of drink mix; get three good
titrations from each sample.
Analysis of Vitamin C (tablets):
1. Weigh out an appropriate amount of ascorbic acid for a 30 mL titration. Dissolve the
sample in 50 mL 1.0M H2SO4 with stirring.
2. Add 2g of solid KI and 50 mL of standard KIO3. Titrate with standard thiosulfate as
above, adding 2 mL of starch indicator just before the endpoint. Repeat the titration until you
have three good trials.
3. Repeat this procedure using two weighed vitamin C tablets. Tablets will need to be
crushed.
Data:
Molarity of NaOH throughout the experiment
Day 1 :
0.01M
Day 2:
0.0927M
Day 3:
0.103M
Standardizing NaOH
Mass KHP
mL NaOH
Molarity NaOH
1
0.5105
31.00
0.081
2
0.5110
28.60
0.087
3
0.5117
26.70
0.094
AVG
0.5111
28.77
0.087
Standardizing Thiosulfate
KI (g)
Thio (mL)
NaCO3 = 0.0502g
1
1.0002
35.00
Na2S2O3 = 8.7318g
2
1.0037
35.65
KIO3 = 0.9998 g
3
1.0042
34.75
AVG
1.0027
35.13
Molarity Thio = 0.0560 M
Total Acid Analyzation
Propel Zero
Mass =
1.0528 g
mL NaOH
1
3.71
2
3.50
3
3.59
AVG
3.60
Hawaiian Punch
Mass =
1.6020 g
mL NaOH
1
5.45
2
5.44
3
5.43
AVG
5.44
Crystal Light
Mass =
1.3083 g
mL NaOH
1
3.90
2
4.00
3
3.90
AVG
3.93
Wyler’s Light
Mass =
1.9043 g
mL NaOH
1
8.51
2
8.69
3
8.52
AVG
8.57
Ocean Spray
Mass =
1.5056 g
mL NaOH
1
4.90
2
5.20
3
4.90
AVG
5.00
Analysis of Vitamin C
Titrating Ascorbic Acid
KI (g)
A.A (g)
Thio (mL)
1
1.0025
0.0617
26.62
2
1.0054
0.0639
26.70
3
1.0025
0.0624
26.82
AVG
1.0035
0.0627
26.71
Titrating Vitamin C Tablet
0.6360 g
Tablet Mass 1 = 0.6411 g
Tablet Mass 2 = 0.6309g Average Mass =
Tab. Mass
KI (g)
Thio (mL)
1
0.0791
1.0052
26.70
2
0.0780
1.0024
27.28
AVG
0.0786
1.0038
26.99
Determination of Vitamin C
Propel Zero
Mass Powd.
Thio (mL)
KI(g)
1
2.1542
22.46
1.0039
2
2.1573
22.36
1.0031
3
2.1579
23.01
1.0081
AVG
2.1565
22.61
1.0050
Hawaiian Punch
Mass Powd.
Thio (mL)
KI(g)
1
3.2523
24.85
1.0056
2
3.2529
25.52
1.0054
3
3.2540
22.67
1.0082
AVG
3.2531
24.35
1.0064
Mass Powd.
Thio (mL)
KI(g)
1
3.8684
29.51
1.0055
2
3.8618
29.51
0.9994
Wyler’s Light
3
3.8618
29.29
1.0017
AVG
3.8640
29.44
1.0022
Mass Powd.
Thio (mL)
KI(g)
1
5.2897
7.8
1.0073
2
5.2821
3.40
1.0045
3
5.2931
2.40
1.0063
AVG
5.2883
4.53
1.0060
Mass Powd.
Thio (mL)
KI(g)
1
0.6126
30.86
0.9959
2
0.6117
30.73
1.0122
3
0.6115
32.50
1.0329
AVG
0.6119
31.36
1.0137
Crystal Light
Ocean Spray
Calculations for Ascorbic Acid
Propel Zero
Excess
I3-
Moles I3-
Mass
A.A.
Weight % A.A. with
Tablet mass
Weight % A.A. using
Serving Size
1
6.29E-04
7.8112E04
0.137571
43.2612%
13.102%
2
6.26E-04
7.8392E04
0.138064
43.4162%
13.1489%
3
6.44E-04
7.6572E04
0.134858
42.4082%
12.8436%
AVG
6.33E-04
7.7692E04
0.136831
43.0285%
13.0315%
Hawaiian Punch
Excess
I3-
Moles I3-
Mass
A.A.
Weight % A.A. with
Tablet mass
Weight % A.A. using
Serving Size
1
6.96E-04
7.1420E04
0.125785
39.5550%
7.8615%
2
7.15E-04
6.9544E04
0.122481
38.5160%
7.6550%
3
6.35E-04
7.7524E04
0.136535
42.9356%
8.5334%
AVG
6.82E-04
7.2829E04
0.128267
40.3355%
8.0166%
Excess
I3-
Moles I3-
Mass
A.A.
1
8.26E-04
5.8372E04
0.102805
32.3286%
5.4108%
2
8.26E-04
5.8372E04
0.102805
32.3286%
5.4108%
3
8.20E-04
5.8988E04
0.103889
32.6698%
5.4679%
AVG
8.24E-04
5.8577E04
0.103166
32.4423%
5.4298%
Moles I3-
Mass
A.A.
Wyler’s Light
Weight % A.A. with
Tablet mass
Weight % A.A. using
Serving Size
Crystal Light
Excess
I3-
Weight % A.A. with
Tablet mass
Weight % A.A. using
Serving Size
1
2.18E04
0.0011916
0.209865
65.9952%
16.1434%
2
9.52E05
0.0013148
0.231563
72.8184%
17.8125%
3
6.72E05
0.0013428
0.236493
74.3688%
18.1918%
AVG
1.27E04
0.0012831
0.225974
71.0608%
17.3826%
Ocean Spray
Excess I3-
Moles I3-
Mass A.A.
Weight % A.A. with Tablet mass
1
8.64E-04
5.4592E-04
0.0961474
30.2350%
2
8.60E-04
5.4956E-04
0.0967885
30.4366%
3
9.10E-04
5.0000E-04
0.0880600
27.6918%
AVG
8.78E-04
5.3183E-04
0.0936653
29.4545%
Calculations for Citric Acid Content
Propel Zero
mol
NaOH
mol
C.A.
mass
C.A.
Molarity
C.A. Soln.
mol C.A. in
250 mL
Volum.
mass C.A. in
250 mL
Volum.
Percentage of
C.A. per serving
1
3.71E04
1.24E04
0.02376
0.012
3.09E03
0.594
56.42%
2
3.50E04
1.17E04
0.02241
0.012
2.92E03
0.560
53.19%
3
3.59E04
1.20E04
0.02299
0.012
2.99E03
0.575
54.61%
AVG
3.60E04
1.20E04
0.02305
0.012
3.00E03
0.576
54.74%
Hawaiian Punch
mol
NaOH
mol
C.A.
mass
C.A.
Molarity
C.A.
Solution
mol C.A. in
250 mL
Volumetric
mass C.A. in
250 mL
Volumetric
Percentage of
C.A. per
serving
1
5.45E04
1.82E04
0.03490
0.018
4.54E03
0.873
54.49%
2
5.44E04
1.81E04
0.03484
0.018
4.53E03
0.870
54.30%
3
5.43E04
1.81E04
0.03477
0.018
4.53E03
0.869
54.24%
AVG
5.44E04
1.81E04
0.03484
0.018
4.53E03
0.871
54.34%
Wyler’s Light
1
mol
NaOH
mol
C.A.
mass
C.A.
Molarity
C.A.
Solution
8.51E04
2.84E04
0.05450
0.028
mol C.A. in 250
mL Volumetric
mass C.A. in
250 mL
Volumetric
7.09E03
Percentage of
C.A. per serving
1.36
71.47%
2
8.69E04
2.90E04
0.05565
0.029
7.24E03
1.39
72.99%
3
8.52E04
2.84E04
0.05456
0.028
7.10E03
1.36
71.47%
AVG
8.57E04
2.86E04
0.05490
0.028
7.14E03
1.37
71.98%
Crystal Light
mol
NaOH
mol
C.A.
mass
C.A.
Molarity
C.A.
Solution
mol C.A. in
250 mL
Volumetric
mass C.A. in
250 mL
Volumetric
Percentage of
C.A. per
serving
1
3.90E04
1.30E04
0.02497
0.013 M
3.25E03
0.624
47.69%
2
4.00E04
1.33E04
0.02561
0.013 M
3.33E03
0.641
48.99%
3
3.90E04
1.30E04
0.02497
0.013 M
3.25E03
0.624
47.69%
AVG
3.93E04
1.31E04
0.02518
0.013 M
3.28E03
0.630
48.12%
Ocean Spray
mol
NaOH
mol
C.A.
mass
C.A.
Molarity C.A.
Solution
mol C.A. in 250 mL
Volumetric
mass C.A. in 250 mL
Volumetric
1
4.90E04
1.63E04
0.03138
0.016
4.08E03
0.784
2
5.20E04
1.73E04
0.03330
0.017
4.33E03
0.832
3
4.90E04
1.63E04
0.03138
0.016
4.08E03
0.784
AVG
5.00E04
1.66E04
0.03202
0.016
4.16E03
0.800
Calculations for Vitamin C
Ascorbic Acid: Average
AVG
Excess I3-
Moles I3-
Mass A.A.
7.48E-04
6.62E-04
0.1166
Weight % A.A. with Tablet mass
36.66%
Vitamin C Tablet: Average
AVG
Excess I3-
Moles I3-
Mass A.A.
7.56E-04
6.54E-04
0.1152
Weight % A.A. with Tablet mass
36.22%
Sample Calculations
Molarity NaOH: g KHP*mol KHPm.w. KHP*1L NaOH
0.5105g KHP*1 mol KHP204.22g KHP*10.031L
NaOH=0.806M NaOH
Molarity Thiosulfate: g KIO3*mol KIO3g KIO3*mol I3-mo KIO3*mol S2O32-moI3-*1L
0.9998g KIO3*1mol KIO3214.00277g KIO3*3mol I3-1mo KIO3*2mol S2O32-1moI3-*10.50L=0.0560 M
S2O32-
Mass of Sample Needed for Titratrion:
20% DVA.A. for womenServing Size=g A.A.g Sample
x=2.158g Propel Zero
0.015g1.05g=0.0305g A.A.Xg Sample
Excess I3-: M Na2S2O3*L Na2S2O3*mol S2O32- mol Na2S2O3*mol I3-mol S2O320.0560M Na2S2O3*0.02246L Na2S2O3*1mol S2O32- 1mol Na2S2O3*1mol I3-2mol S2O32-=6.2888*104
Moles I3-: M KIO3*L KIO3*molI3-mol KIO30.0094M KIO3*0.05L KIO3*3molI3-1mol KIO3-=0.00141 moles I3-
True Moles I3-: Moles I3-- Excess I30.00141 moles I3-- 6.2888*10-4mol Excess I3-=7.8112*10-4true moles I3-
Mass Ascorbic Acid: mol I3-*mol A.A.mol I3-*g A.A.mol A.A.
7.8112*10-4mol I3-*1mol A.A.1mol I3-*176.12g A.A.1mol A.A.=0.137571 g A.A.
Weight Percent of Ascorbic Acid: gA.A.g tablet*100%*2
0.137571g A.A.0.636g tablet*100%=21.6306*2=43.2612%
Weight Percent of Ascorbic Acid per Serving Size: g A.Ag Serving Size*100%
0.137571g A.A1.05g Serving Size*100%=13.102%
Moles NaOH: mL NaOH *1 L1000mL*0.1 mol NaOH1 L
3.71mL NaOH *1 L1000mL*0.1 mol NaOH1 L=3.71*10-4mol NaOH
Moles Citric Acid: mol NaOH*1 mol C.A.3 mol NaOH
3.71*10-4mol NaOH*1 mol C.A.3 mol NaOH=1.2367*10-4mol C.A.
Grams of Citric Acid: mol C.A.*192.124g C.A.1 mol C.A.
1.2367*10-4mol C.A.*192.124g C.A.1 mol C.A.=0.02376 g C.A.
Molarity of Citric Acid Solution: mol C.A.l aliquot
C.A.
1.2367*10-4mol C.A.0.010L aliquot=0.012367M
Moles of Citric Acid Present in 250 mL Volumetric Flask: M C.A.*L solution
0.012367M C.A.*0.250L solution=3.0918*10-3mol C.A. in 250 mL volumetric flask
Grams of Citric Acid Present in 250 mL Volumetric Flask: mol C.A. in 250 mL volumetric flask*192.124g
C.A.1 mol C.A.
3.0918*10-3mol C.A. in 250 mL volumetric flask*192.124g C.A.1 mol C.A.=0.594 g C.A. in 250 mL
volumetric flask
Weight Percent of Citric Acid per Serving Size: g C.A. in 250 mL volumetricg Serving Size*100%
0.594g C.A. in 250 mL volumetric1.05g Serving Size*100%=56.57% C.A.
Reactions needed for calculations:
H3C6H5O7(aq)+ 3NaOH(aq) Na3C6H5O7(aq)+ 3H2O(l)
citric acid
sodium citrate
IO3-+ 8I-+ 6H+3I3-+ 3H2O
Conclusion:
According to our data, we found that Wyler’s Light Pink Lemonade had the highest citric acid content
overall. Propel Zero was found to have the lowest citric acid mass per serving but Crystal Light had the
lowest citric acid percentage per serving; Wyler’s Light Pink Lemonade had the lowest ascorbic acid
percentage per serving. Crystal Light had the highest ascorbic acid mass per serving.For Crystal Light,
this data does not coincide with known data that green teas generally are low in ascorbic acid. There
could be several explanations to why our data for Crystal Light was inconsistent to the known data. Such
as we could have used a different kind of indicator; and possibly use a different type of titrant. It may have
also had something to do with the flavor of the drink mix or just that it was a green tea mix; a different
procedure may have been needed for a green tea mix. Our lab was based off of an ACS published lab
that used different flavors of Koolaid packets to determine the citric and ascorbic acid content and our
data appears similar to their published data. Based off of our data, we can conclude that our lab was
successful in determining the amount of citric and ascorbic acid content per serving of different drink mix
packets.