Analytical Chem Lab 4 - Grade: 88% PDF

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Analytical Laboratory Report...

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ANALYTICAL CHEMISTRY LABORATORY REPORT SHEET 78.82 4.970 Laboratory Title: Stomach Acid Neutralized by Tums or Rolaids 6.306 Partner A or B : B Name

Thinh Vo

Lab Partner

Ning Zhu

Date Performed Oct 16 2019 Date Due

November 20, 2019

Date Submitted

November 20, 2019

Sample Number: Rolaid

Laboratory 4: Stomach Acid Neutralized by Tums or Rolaids

Purpose This experiment allows students to neutralize the hydrochloric content of the Rolaids with the standardized sodium hydroxide 0.1M to simulate how Rolaids or Tum tablets are neutralized by the stomach acid.

Observation Numerical Table 1: Record for Titration Data

Volume of HCl used (ml) Initial volume of NaOH used (ml) Final Volume of NaOH used (ml0 Net volume of NaOH used (ml)

25.00

25.00

25.00

0.00

0.30

0.00

21.70

22.00

21.30

21.70

21.70

21.30

Sample 1 75.00

Sample 2 75.00

Sample 3 75.00

0.19

0.30

0.21

28.40

30.80

32.10

28.21

30.50

31.89

0.5020

0.5105

0.5676

Table 2: Record for Rolaid Sample Titration

Mass of Rolaids (g) Volume of used HCl (mL) Initial volume of used NaOH (ml) Final Volume of used NaOH (ml) Net Volume of NaOH used (ml) Weight of Samples (g)

Calculations 1. Ratio Titration 2. Ratio between HCL and NaOH (1st) RA1 =

volume of HCl titrated (ml) 25.00 ml =1.152 = volume of NaOH used (ml) 21.70 ml

Ratio of HCl to NaOH (2nd) RA2 =

volume of HCl titrated (ml) 25.00 ml =1.152 = volume of NaOH used (ml) 21.70 ml

Ratio of HCl to NaOH (3rd) RA3 =

volume of HCl titrated (ml) 25.00 ml =1.174 = volume of NaOH used (ml) 21.30 ml

3. The mean of RA RA ¿

1.152 x 2+1.174 =1.159 3

4. Standard deviation SD =

√

(1.152−1.159 )2 x 2+(1.174 −1.159)2 3−1

= 0.01271

5. % Relative standard deviation %RSD =

0.01271 ×100 %=1.097 % 1.159

6. Expected value of RA Expected RA =

0.09112 M =0.8662 0.1052 M

2. Neutralization Titration 1. Weight of stomach acid  Sample 1 Volume of stomach acid neutralized = V- (V1 x RA) = 75.00- (28.21 x 1.159 ) = 42.30 mL Weight of stomach acid: d= Final ratio =

g m → m=1.000 x 42.30 mL=42.30 g v ml

42.30 g =84.26 0.5020 g



Sample 2

Volume of stomach acid neutralized = V- (V2 x RA) = 75.00- (30.50 x 1.159 ) = 39.65 mL Weight of stomach acid: d= Final ratio = 

m g → m=1.000 x 39.65 mL=39.65 g ml v

39.65 g =77.67 0.5105 g

Sample 3

Volume of stomach acid neutralized = 75.00 ml – (31.89 ml ×1.159) = 38.04 ml Weight of stomach acid: d= Final ratio =

g m → m=1.000 x 38.04 mL=38.04 g v ml

38.04 g =74.52 0.5105 g

2. The mean of Ratio Mean =

84.26 + 77.67 + 74.52 =78.82 3

3. Standard deviation SD =

√

(84.26−78.82)2 +( 77.67−78.82 )2 +( 74.52−78.82 )2 =4.970 3−1

4. % Relative standard deviation %RSD =

4.970 × 100 %=6.306 % 78.82

Results Table 3: Ratio Titration Data

Volume of HCl used (ml)

25.00

25.00

25.00

Initial Volume of NaOH used (ml)

0.00

0.30

0.00

Final Volume of NaOH used (ml)

21.70

22.00

21.30

Net Volume of NaOH used (ml)

21.70

21.70

21.30

Calculated Ratio (RA)

1.152

1.152

1.174

Average RA

1.159

Standard Deviation

0.01271

%RSD

1.097

Concentration of NaOH used (M)

0.1052

Concentration of HCl used (M)

0.09112

Expected value of RA

0.8662

Table 4: Neutralization Titration Using Tums or Rolaids

Weight of Rolaids (g)

Sample 1

Sample 2

Sample 3

0.5020

0.5105

0.5676

Volume of HCl used (ml) - V

75.00

75.00

75.00

Initial Volume of NaOH used (ml) Final Volume of NaOH used (ml)

0.19 28.40

0.30 30.80

0.21 32.10

Net Volume of NaOH used (ml)-V1

28.21

30.50

31.89

Weight of Stomach Acid Neutralized (g)

42.30

39.65

38.04

Final Ratio of Acid Neutralized by Rolaids

84.26

77.67

74.52

Average Final Ratio of Acid Neutralized by Rolaids

78.82

Standard Deviation

4.970

%RSD

6.306

Conclusion The average final ratio of acid neutralized by Rolaids was 78.82 with a relative standard deviation of 6.306%

Possible and actual sources of error 1. It is essential to rinse the burette carefully to remove the contaminants before use and condition correctly by placing the burette at the eye level, filling up the standardized base and recording the figure. 2. When doing the ratio titration, it is extremely important to notice the colour change of the phenolphthalein indicator that turns from colourless to light pink whose color kept for 30 seconds. Then, we have to stop titrating immediately unless the indicator turns to dark pink which causes the determinate error and the result is no longer accurate. 3. After boiling those samples to obtain the HCl absorbed by the Rolaid tablet, we have to cool it down to room temperature because at the high temperature, the reaction of the acid and base may occur sooner as expected. So, the figure may not be accurate.

Raw Data...