Laboratory report

Acid-base titration


Chemical analysis by Acid-base titration

Some of data below is not inside tables. I copy & paste it from Word. If you need a full raport in Microsoft Word file let me know! Paste tables from Word into WordPress is a time consuming activity I try to avoid. I scored 75% on this raport.

Marcin Krynski

Aim
Identify, factor ANC, Acid Neutralization Capacity in two antacid tablets. Rennie® & Bisodol®. Answer how many tablets are required to neutralize HCl in the human stomach based on in vitro laboratory studies. Provide stoichiometry calculation, explain equations. Identify possible uncertainty and propose solutions to further experiment improvement.

Description
According to Lab Manual, it has been given straight instructions how to process experiments. The experiments have aim to practically use back titration to assess acid neutralization capacity. The ph indicator, methyl orange, is used to find reaction ending point of titrated substances. Change of acidity or alkali is indicated by methyl orange dye. Therefore, the valve of burette will be closed and information about add volume is recorded.

Introduction
Tablets, Rennie® (Delpharm Gaillard, July 2020) & Bisodol® (Brunel Healthcare Manufacturing Ltd., march, 2020) Add volumes, masses were recorded. Tablets shredded by mortar, weighted, and move to test flask. Hydrochloric acid of 0.500 M add. Then 0,2 ml of methyl orange dye added. The solution changed color into dark red. NaOH of concentration 0.500 M was titrated to the canonical flask. Swirling was conducted until the color changed from red to yellow. The valve was closed when the reaction was observed. The amount of add substrate was recorded. Those steps were conducted separately with two antacid tablets.

Equations

Molarity(M) =
ACN % error + x 100%

Experiment no. 1 Renii®
Theoretical calculations, without back titration based on information provided in the leaflet.
To conduct theoretical calculations, data provided by the manufacturer was used. There is no back titration involve in the first stage of calculation, however, back-titration will be used to assess the validity of these theoretical stoichiometry calculations.

Table 1. reagent Rennie® Volume Molar mass Mass in moles
Volume of HCl 0.500 M/dm3 42,1 ml =0,0421 dm3 36.4610 g/mol 0,0210 mol
Volume of NaOH 0.500 mol/dm3 11.8 ml = 0,0118 dm3 39.997g/mol 0,0059 mol
Volume of Methyl Orange [4 drops] 0.2 ml N/A N/A
Mass of tablet weighted before grind. 1,27 g
Mass of powder weighted after grind. 1.19 g
Table 2. reagent Rennie® Structural Quantity
In mg Mass
in grams Molar
mass Quantity in moles
Calcium Carbonate CaCO3 625 mg 0.625 g 100.0869 g/mol 0.006244 mol
Magnesium Carbonate MgCO3 73.5 mg 0.0735 g 84.3139 g/mol 0.000872 mol

Chemical reactions balanced on recipe factor.
Recipe factor = 0,006244 mol
1CaCO3 (s) + 2HCl (aq)  → 1CaCl2 + 1CO2 ↑(g) 1H2O (l)
limiting reagent excess reagent
0,006244 mol + 0,012488 mol → 0,006244 mol +0,006244 mol +0,006244 mol
Amount of fully reacted neutralized HCl = 0.012488 mol

Recipe factor = 0,000872 mol
1MgCO3 (s) + 2 HCl (aq) → 1MgCl2 (aq) + 1H2O (l) + 1CO2 ↑ (g)
limiting reagent excess acid
0.000872 mol +0,001744 mol → 0,000872 mol +0,000872 mol +0,000872 +mol
Amount of fully reacted neutralized HCl = 0,001744 mol

ANC of HCL = (MgCO3 0,001744 mol) + (CaCO3 0,012488 mol) = 0,014232mol

Mass of two compounds CaCl2 + MgCO3 reacted with HCl
0,006244 mol + 0,000872 mol = 0,007116 mol.

Quantity of 0.014232 mol of HCl is neutralized by 0,007116 mol of mixture (CaCl2 + MgCl2) in Renii®
Renii® Theoretical ANC is 0,014232 mol of HCl.

A hyperactive stomach contains the mass of HCl = 0,0075 mol. One Renii® tablet has the capacity to neutralize 0,014232 mol of HCl. Mass of HCl in stomach 0,0075 mol / 0,014232 mol Renii® = 0,53. The answer is that we need to take 0,53 of Renii® tablet is need to neutralize all acid in the hyperactive stomach.

Back-Titration of Rennie®
Recipe factor HCl = 0,02105 mol
HCl (aq)  + NaOH (aq)  → NaCl (aq)  + H2O(l) 
0,0210 mol – 0,0059 mol → Mass of substance fully reacted with HCl
0,0210 mol – 0,0059 mol = 0,0151 mol

(moles of acid neutralized) = (moles of HCl added) – (moles of NaOH necessary to back-titration)
Excess mass HCl added before titration equal = 0,0210 mol
Laboratory back-titration result of Rennie® tablet is to neutralize 0,0151 mol of HCl

Table 3.
Experiment types & results. Rennie® Back-Titration, laboratory practical experiment. Rennie® theoretical calculations without back titration.
Capacity of HCl neutralization 0,0151 mol 0,014232 mol
Quantity of tablets need to
Neutralize 0,0075 mol of HCl 0,50 tablet 0,53 tablet
Deviation between practical/theoretical experiment. 5.82 %

Errors
Mass balance 0.01g
volumetric flask 0.00015 dm3
burette (start & read) 0.00015 dm3

ACN % error + x 100%

ACN % error HCL = + x 100 ≈20%
ACN % error NaCl = + x 100 ≈ 20%
MASS % error after griding Rennie® tablet = x 100 ≈ 6,29%
% error of uncertainty 46,29%

Experiment no. 2 Bisodol®
Theoretical calculations, without back titration
based on information provided in leaflet.

Table 4.
Bisodol® tablet active ingredients: Structural
Volume Mass In mg Mass
in grams Molar mass Mass in moles
Calcium Carbonate CaCO3 522 mg 0,522 g 100.0869 g/mol 0.005215 mol
Light Magnesium Carbonate MgCO3 68 mg 0,068 g 84.3139 g/mol 0.000806 mol
Sodium Bicarbonate NaHCO3 64 mg 0,064 g 84,007 g/mol 0.000761 mol

Mass of tablet number 2, [Bisodol®]: 1.21g
Mass of tablet powder [Bisodol®]. 1.18g
Volume of HCl 0.500 M/dm3 40.4 ml = 0,0404 dm3 36.4610 g/mol 0,0202 mol
Volume of NaOH 0.500 mol/dm3 20.1 ml = 0,0201 dm3 39.997g/mol 0,01005 mol
Volume of Methyl Orange [4 drops] 0.2 ml

Chemical reactions between HCl and two active ingredients CaCO3 + MgCO3
To conduct calculations, data about masses were withdrawal from leaflet provided by manufacturer. There is no back titration involve in the process. Back-titration will be used to assess the validation of calculations.

Recipe factor CaCO3 = 0.005215 mol
1CaCO3(s) +2HCl (aq) →1CaCl2 + 1CO2 ↑(g)+ 1H2O(l)
0,005215 mol + 0,01043 mol → 0,005215 mol +0,005215 mol+0,005215 mol
Mass of neutralized HCl by CaCO3= 0,01043 mol

Recipe factor MgCO3= 0,000806 mol
1MgCO3 (s) + 2 HCl (aq) → 1MgCl2 (aq) + 1H2O (l) + 1CO2 ↑ (g)
0.000806 mol + 0,001612 mol → 0.000806 mol +0.000806 mol +0.000806 mol
Mass of neutralized HCl by MgCO3 = 0,0026075 mol

Recipe factor NaHCO3 = 0.000761 mol
1NaHCO3 (aq) +  1HCl (aq) → 1NaCl (aq) + 1CO2↑ + 1H2O (l)
0.000761 mol + 0.000761 mol
Mass of HCl neutralized by NaHCO33 = 0.000761 mol

Table 5.
Mass of HCl neutralized by CaCO3 0,01043 mol
Mass of HCl neutralized by MgCO3 0,0026075 mol
Mass of HCl neutralized by NaHCO3 0,000761 mol
ACN of HCl acid in one tablet of Bisodol® 0,01380 mol
Back-Titration of Bisodol® Back-titration method.

Table 6. Bisodol® tablet active ingredients: Structural Mass In mg Mass
in grams Molar mass Mass in moles
Calcium Carbonate CaCO3 522 mg 0,522 g 100.0869 g/mol 0.005215 mol
Light Magnesium Carbonate MgCO3 68 mg 0,068 g 84.3139 g/mol 0.000806 mol
Sodium Bicarbonate NaHCO3 64 mg 0,064 g 84,007 g/mol 0.000761 mol

Mass of tablet number 2, [Bisodol®]: 1.21g
Mass of tablet powder [Bisodol®]. 1.18g
Volume of HCl 0.500 M/dm3 40.4 ml = 0,0404 dm3 36.4610 g/mol 0,0202 mol
Volume of NaOH 0.500 mol/dm3 20.1 ml = 0,0201 dm3 39.997g/mol 0,01005 mol
Volume of Methyl Orange [4 drops] 0.2 ml
Recipe factor HCl = 0,0202 mol
1HCl(aq)  + 1NaOH (aq) + → 1NaCl (aq) + 1H2O(aq) 
↓ ↓
0,0404 dm3 x 0,500M/dm3
↓ ↓
0,0202 mol – 0,0087 mol → Mass of substances fully reacted with bond HCl.
(moles of acid neutralized) = (moles of HCl added) – (moles of NaOH necessary to back-titration)
Excess mass HCl added before titration = 0,0202 mol
Laboratory back-titration result of Bisodol® tablet is ANC of 0,0117 mol HCL

Table 7. Methods & Results Bisodol® theoretical calculations
without back titration method Bisodol® Back-Titration laboratory practical experiment
Capacity of HCl neutralization 0,01380 mol of HCl 0,0117 mol of HCl
Quantity of tablets need to
Neutralize 0,0075 mol of HCl 0,54 tablet 0,64 tablet
ACN % error HCL = + x 100 = 20%
ACN % error NaCl = + x 100 = 20%
MASS % error after griding Bisodol® tablet = x 100 ≈ 2,5%
% error uncertainty 42,5%

Conclusion
Half of Bisodol® tablet is enough to neutralize all HCl acid in the stomach. The deviation between a practical and theoretical experiment is noticeable. However, from the customer’s point of interest deviation is not significant. Theoretical HCl neutralization capacity of Bisodol®, based on the leaflet is lower than observed in the laboratory. Consumers who complain about incorrect information should be rejected. Based on conducted experiments, it is obvious, that the manufacturer states true information on the package. The statement that one antacid tablet can reduce the acidity of one stomach is true. However, based on practical research Bisodol® indicate a lower rate of acidity inhibition. If the customer chooses Bisodol® then one tablet is not enough to reduce HCl in two hyperactive stomachs. Therefore, the potential patient claim may be justifiable. Rennie® tablet is recommendable.
Theoretical and practical experiments reveal that antacid tablets have beneficial qualities. One antacid tablet can neutralize two hyperactive stomachs. Mass of Hydrochloric acid in stomach 0,0075 mol To neutralize all acid it is enough to take 0.50 tablet of Rennie®. Therefore, to get the same, neutralizing effect we need to take 0.64 tablets of Bisodol® respectively.
The term, ‘real neutralizing power’ may be appropriate to describe that antacid tablets have real bonding capacity. The level of uncertainty must be considered. Laboratory measurement equipment offered precision to two decimal places. The concentration of HCl & NaOH equal 0.500 M. Used measurement equipment should have better precision. I highly recommend the scales with at least four decimal places. According to Table 1. after grinding 0.08g of Rennie® tablet was lost. Mean indicates that ≈6,29% mass does not participate in the reaction. An issue with weighting powder also occurred with Bisodol®. It was found that 0,03g of substance disappear in a period of conducted research it is ≈2,5% of tablet mass. Those quantities were significant to assess ACN. Calculations of errors and uncertainty were done. For Bisodol®, error uncertainty is ≈42,5% for Rennie® tablet it reached ≈46,29%. Under all of the circumstances, and pieces of evidence. The ratio uncertainty vs. ACN seems to be significant. My recommendation for the patient who decided to buy an antacid product is Rennie®. Enormous theoretical pieces of evidence were presented in this document and confirmed by practical examinations at the laboratory. Theoretical and practical evidences support my justification.

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