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Title: AB: Antacid Test Name: Zam Onwusah Student Number: 101181282 CHEM1101B-L4 Submission Date: 04.12.2020

Purpose The purpose of this experiment is to quantitatively determine the amount of stomach acid that could be neutralised by magnesium hydroxide, milk of magnesia.

Theory An acid is any substance that contains hydrogen that can donate a hydrogen ion to another substance. It is a proton donor. A base is the chemical opposite of an acid. It is a substance that accept hydrogen ions or donate a pair of valence electrons to form a bond. pH is the potential of hydrogen. It is a scale used to specify how acidic or basic a solution is. A strong acid contains easily ionisable hydrogen atoms because they are loosely bonded. Strong acids also completely ionise in water while weak acids only partially ionise. He molecules of a weak acid also maintain its covalent bond in the solution. A strong base tends to make strong bonds with the protons in the solution and they completely dissociate in water. Weak bases are not likely to bond with the protons in solution and they do not completely dissociate in water but partially react with the water molecule. Phillips’ Milk of Magnesia contains dextrates, magnesium stearate, peppermint oil, silicon oxide, starch, sucrose and maltodextrin. The active ingredient in milk of magnesia is magnesium hydroxide. Magnesium hydroxide has a chemical formula of Mg(OH)2 and its molar mass is 58.32 g/mol. It has a Ksp of 5.61 x 10-12. The compound is ionic and exists mainly as Mg2+ and OH-. Mg(OH)2 → Mg2+ + 2OHEach chewable tablet contains 311 mg of magnesium hydroxide while the suspension contains 80 mg/mL of magnesium hydroxide. The tablets are relatively small, white and spherical with the word “Phillips” engrained into the pill. The human stomach produces gastric acid to aid digestion of food and to kill germs. Gastric acid consists mainly hydrochloric acid which is very corrosive. The stomach produces a mucus barrier which protects the stomach lining from being eroded by the acid. Milk of magnesia works by using its basic properties to neutralise the gastric acid in the stomach. The side effects of this antacid are diarrhoea, excessive thirst, gas, headaches, nausea, stomach cramps and vomiting. Titration is addition of titrant of known concentration to a known volume of another solution of unknown concentration until the reaction is completely neutralised. The equivalence point is the point in a titration where the amount of titrant added is enough to completely neutralise the solution. An indicator is a substance that will usually change colour due to a change in pH. An acid-base indicator exhibits a colour change as the pH concentration of hydrogen or hydroxide ions changes in an aqueous solution.

Materials and Procedure The materials for this experiment are: o o o o o o o o

Phillips’ milk of magnesia A mortar and pestle Ring stand and ring clamp Two Erlenmeyer flaks Two 100 mL beakers Bunsen burner Two burettes HCl and NaOH solution

With the mortar and pestle, crush one tablet of the Phillips’ milk of magnesia. Place about 0.5g of the crushed antacid into the pre-weighed 250 mL Erlenmeyer flask and record the mass of this sample. Fill one of the burettes with 0.1M NaOH solution and the other with 0.1M HCl solution. Record the initial readings of these solutions. Add about 20 mL of HCl to some of the crushed antacid sample. Boil the mixture to completely dissolve the antacid in the HCl. Add six drops of bromophenol blue to the solution. If there are excess hydrogen ions in the solution. If the solution is not this colour, there is an excess of hydroxide ions and that means more HCl should be added. Add about 10 mL of HCl to the solution and record it. Titrate 10 mL of NaOH with the left over HCl. The endpoint is when the solution turns blue. Record this.

Results and Discussion The pH at the equivalence point would be approximately 5.5. The endpoint of the experiment would be yellow. Number of moles of NaOH = Number of moles of HCl = 0.001 moles Some limitations of performing this experiment at home is not having the proper apparatus or lab equipment. The NaOH may cause skin and eye irritation and the HCl could cause eye irritation.

Quality Discussion The pH is chosen at the neutralisation point because in the case of a strong acid vs a weak base, the solution is acidic at the equivalence point. My solution should be yellow because that means the solution is acidic and there is an excess of hydrogen ions. 1 dose = 1 tablet

0.5g of 311g was analysed 30 mL of 0.1M HCl was dissolved into the sample Moles of NaOH = molarity x volume = 0.001 moles 0.001 mole of acid as neutralised by 0.5g of the antacid Therefore, the antacid tablet neutralises 0.622 moles of acid.

Bibliography Knott, L. (Last Edited April 2020). Antacids. Retrieved from https://patient.info/digestivehealth/indigestion-medication/antacids Edermaniger, L. (March 2020). Too Much Acid In The Stomach: What Causes Reflux and Acid Reflux Disease? Retrieved from https://atlasbiomed.com/blog/too-much-acid-in-the-stomach-what-causesreflux-and-acid-refluxdisease/#:~:text=Your%20stomach%20has%20a%20nifty,cells)%20and%20your%20gastric%20glands. Canoe.com. (N.D.). Phillips’ Milk of Magnesia – Uses, Side Effects< interactions. Retrieved from https://chealth.canoe.com/drug/getdrug/phillips-milk-ofmagnesia#:~:text=Each%20chewable%20tablet%20contains%20311,starch%2C%20sucrose%2C%20and %20maltodextrin.&text=Each%20mL%20of%20suspension%20contains%2080%20mg%20of%20magnesi um%20hydroxide. Soft Schools. (N.D.). Magnesium Hydroxide Formula – Magnesium hydroxide Uses, Properties, Structure and Formula. Retrieved from https://www.softschools.com/formulas/chemistry/magnesium_hydroxide_uses_properties_structure_f ormula/249/#:~:text=Formula%20and%20structure%3A%20The%20chemical,mass%20is%2058.32%20g %2Fmol.&text=Physical%20properties%3A%20Magnesium%20hydroxide%20is,an%20aqueous%20suspe nsion%20in%20water. Helnemstine, A. M. (February, 2020). Definition and Examples of Acid-Base Indicator. Retrieved from https://www.thoughtco.com/definition-of-acid-base-indicator-604738 WebMD. (N.D.). Phillips’ Milk of Magnesia Side Effects by Likelihood and Severity. Retrieved from https://www.webmd.com/drugs/2/drug-9415/phillips-milk-of-magnesia-oral/details/list-sideeffects Libre Texts. (June, 2020). Evaluating the Cost-Effectiveness of Antacids (Experiment). Retrieved from https://chem.libretexts.org/Bookshelves/Ancillary_Materials/Laboratory_Experiments/Wet_Lab_Experi ments/General_Chemistry_Labs/Online_Chemistry_Lab_Manual/Chem_11_Experiments/09%3A_Evalua ting_the_Cost-Effectiveness_of_Antacids_(Experiment)...