Antacid titrations
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University of Massachusetts, Lowell**We aren't endorsed by this school
Course
CHEMISTRY 1230L
Subject
Chemistry
Date
Dec 18, 2024
Pages
16
Uploaded by CaptainFalconMaster1163
ANTACID TITRATIONS
QUALITATIVE VS QUANTITATIVEExperimental tests in chemistry labs can give many types of informationThe type of information these experiments give, can be grouped into Qualitative or QuantitativeQualitative tests typically answer the question “What?”What is the product of the reaction?What ions are found in the solution?What will the compound react with?Quantitative tests typically answer the question “How much?How much of the product is produced?How much of each ion is present in the solution?How much of the compound will react?Qualitative tests see if a substance is present, where Quantitative tests measure the amount of substance presentA standard Qualitative technique to measure the quantity of a substance, is a titration
PERFORMING TITRATIONS•Titrations are the careful addition of one reactant to another by adding small amounts at a time•By doing so, the exact moment where the reaction is complete can be determined•Titrations are typically done to determine an unknown concentration of something by adding a precisely known concentration of the other reactant•A number of different types of chemistry can be studied looking at titrations, most frequently seen in acid/base chemistry Under-TitratedOverTitratedExactTitrations are very exact measurements using burets and very precise concentrationsTitrations a complete when a single drop from the burette will cause a color changeBurettesThe value listed on the burette is recordedThe volume delivered is the Final reading minus the Initial reading
BURETTESBurettes are a type of volume measuring device to measure how much liquid is added to something elseWhen a burette is filled, the volume reading is 0.00mLThe number markings on the burette increase as the volume inside is decreasingThe markings indicate how much has left the burette, and been added to another containerIn this example, the reading is 19.70mL, meaning was added to the flask belowWhen recording volume readings from a burette, you should record the numbers themselvesThe difference between the final reading and the initial reading, is the volume that was dispensed
INDICATORSMost acids are clear and colorless, as are most bases. When they react they form a clear and colorless productAn indicator is a chemical that is added to a solution that undergoes a visual change at a specific point to know when a reaction is completedThese typically do not interact with the overall reaction, but as more products are formed, they will be in equilibrium with them and change their appearanceMany indicators display specific colors based on the concentration of H+ (pH) of a solutionPhenolphthaleinColorless at low pHPink at high pH
ACID BASE STOICHOMETRYAcid & Base reactions are covered extensively in the second semesterThe fundamental reaction for all Acid/Base reactions is the equation:The reaction has a 1:1 stoichiometric ratioFor every one mole of Acid (H+), it reacts with one mole of Base (OH-) to produce one mole of WaterIf one component of the reaction is known, the stoichiometric ratio can be used to determine how much of the other component it reacts with𝐻+¿+𝑂𝐻−→𝐻2𝑂¿𝑀𝑜𝑙𝑠 𝐻+¿×1𝑚𝑜𝑙𝑒𝑂𝐻−1𝑚𝑜𝑙𝑒 𝐻+¿=𝑀𝑜𝑙𝑠𝑂𝐻−¿¿𝑀𝑜𝑙𝑠𝑂𝐻−×1𝑚𝑜𝑙𝑒𝐻+¿1𝑚𝑜𝑙𝑒𝑂𝐻−=𝑀𝑜𝑙𝑠 𝐻+¿ ¿¿
ANTACID TITRATION EXPERIMENT
BACK TITRATIONMany times in chemistry and in labs, a direct measurement is difficultIt is much easier to measure something else, and relate that to the initial componentThe exact amount of HCl that reacts is not measured directlyAn excess of HCl is measured out and reactsThe Antacid is the Limiting ReagentThe leftover HCl is measured through titration
EXPERIMENT SETUPObtain 1 Antacid TabletCrush in a Mortar & PestleMeasure 50.0mL of 0.500M HCl using your 50mL Graduated CylinderPour the crushed tablet into an Erlenmeyer FlaskRinse the mortar with some of your HCl from the graduated cylinder and pour it into the flaskAdd the remaining HCl to the flask and allow the tablet powder to dissolveAdd Phenolphthalein IndicatorFill Burette with 0.500M NaOHSlowly add NaOH until the reaction is complete
TOTAL MOLES OF ACIDIn the reaction setup, the total moles of HCl is knownSome of the HCl will react with the Antacid TabletAll remaining HCl will react with NaOHThe molarity of the HCl is found in lab on the bottleThe volume of HCl used in the reaction is 50.0mLIf you use more than 50.0mL, this must be accounted for𝑴=𝒎𝒐𝒍𝒔𝑳Total Moles HClReacts with AntacidReacts with NaOHKnown𝑴𝒐𝒍𝒂𝒓𝒊𝒕𝒚𝑯𝑪𝒍=𝒎𝒐𝒍𝒔𝑯𝑪𝒍𝑳𝒊𝒕𝒆𝒓𝒔𝑯𝑪𝒍𝑴𝒐𝒍𝒔𝑯𝑪𝒍=𝑴𝒐𝒍𝒂𝒓𝒊𝒕𝒚𝑯𝑪𝒍×𝑳𝒊𝒕𝒆𝒓𝒔𝑯𝑪𝒍
MOLES OF BASE USEDThe mols of NaOH used comes from the measurement of the BuretteThe NaOH will react with HCl to form Water and NaClThe reaction is 1:1, for every one mole of NaOH that reacts, it reacts with one mole of HClThe molarity of the NaOH is provided in lab on the bottleThe volume of NaOH is measured from the burette in the titration𝑴=𝒎𝒐𝒍𝒔𝑳Total Moles HClReacts with AntacidReacts with NaOH𝑴𝒐𝒍𝒂𝒓𝒊𝒕𝒚𝑵𝒂𝑶𝑯=𝒎𝒐𝒍𝒔𝑵𝒂𝑶𝑯𝑳𝒊𝒕𝒆𝒓𝒔𝑵𝒂𝑶𝑯𝑴𝒐𝒍𝒔𝑵𝒂𝑶𝑯=𝑴𝒐𝒍𝒂𝒓𝒊𝒕𝒚𝑵𝒂𝑶𝑯×𝑳𝒊𝒕𝒆𝒓𝒔𝑵𝒂𝑶𝑯Measured𝑴𝒐𝒍𝒔𝑵𝒂𝑶𝑯=𝑴𝒐𝒍𝒔𝑯𝑪𝒍 𝒓𝒆𝒂𝒄𝒕𝒆𝒅
MOLES OF ACID NEUTRALIZEDThe mols of Acid which reacted with the Antacid is the difference between the total amount, and what reacts with NaOHTotal Moles HClReacts with AntacidReacts with NaOHSolve𝑻𝒐𝒕𝒂𝒍𝒎𝒐𝒍𝒆𝒔 𝑯𝑪𝒍−𝑴𝒐𝒍𝒆𝒔 𝑯𝑪𝒍𝒓𝒆𝒂𝒄𝒕𝒊𝒏𝒈𝒘𝒊𝒕𝒉 𝑵𝒂𝑶𝑯=𝑴𝒐𝒍𝒔 𝑯𝑪𝒍𝒓𝒆𝒂𝒄𝒕𝒊𝒏𝒈 𝒘𝒊𝒕𝒉𝑻𝒂𝒃𝒍𝒆𝒕Mass of Acid Neutralized1𝐻@1.008𝑔𝑚𝑜𝑙1𝐶𝑙@35.452𝑔𝑚𝑜𝑙𝐻𝐶𝑙=36.46𝑔𝑚𝑜𝑙𝑴𝒐𝒍𝒔 𝑯𝑪𝒍×𝟑𝟔.𝟒𝟔𝒈𝟏𝒎𝒐𝒍=𝑴𝒂𝒔𝒔 𝑯𝑪𝒍To determine the mass of HCl, the moles are multiplied by the molecular weight of Hydrochloric Acid
COLLECTIVE RESULTSOnly perform the titration on one tablet of one brand of AntacidDetermine the Mass of HCl that reacts with the tablet before you leave the labShare your result with others in the lab who did not choose your brandObtain the results for the three other brands, from other students in the labYou must record the mass of HCl reacted for all four brands of tablet, before you leave the lab
BEST ANTACIDAntacids are meant to react with and neutralize stomach acidLook at the results for each of the different antacid brands availableThe best brand would be the one that neutralizes the most acidBrandActive IngredientRolaids550mg CaCO3 & 110mg Mg(OH)2Tums500mg CaCO3Physician’s Care420mg CaCO3Store brand500mg CaCO3
COST ANALYSISBrandActive Ingredient# Tablets per BottleCost per BottleRolaids550mg CaCO3 & 110mg Mg(OH)2150$10.00Tums500mg CaCO3150$6.00Physician’s Care420mg CaCO3250$5.00Store brand500mg CaCO3150$4.00𝑯𝑪𝒍𝒑𝒆𝒓 𝑻𝒂𝒃𝒍𝒆𝒕×𝑻𝒂𝒃𝒍𝒆𝒕𝒔𝒑𝒆𝒓 𝑩𝒐𝒕𝒕𝒍𝒆𝑪𝒐𝒔𝒕=𝒎𝒈 𝑯𝑪𝒍 𝒑𝒆𝒓 𝒅𝒐𝒍𝒍𝒂𝒓Each antacid brand can neutralize an amount of HClThe best brand is the one which can react with the most HClThe most cost effective however, is the one which reacts with the most HCl per dollar of antacid
SUMMARYChoose an Antacid TabletCrush in a Mortar & PestleDissolve the powder in 50.0mL of HCL solutionDetermine how many moles of HCl are usedAdd 5-10 drops of Phenolphthalein indicatorFill your burette with SetupTitrationAnalysisRecord the Initial Burette readingSlowly add the NaOH solution to the Erlenmeyer FlaskSwirl the flask repeatedly to mix the contentsContinue adding NaOH solution until the solution in the flask changes to a faint pink colorThe color must remain and not disappearRecord the Final Burette ReadingDetermine how many moles of NaOH are used in the titrationWith the total mols of HCl and the mols of NaOH that reacts, determine how much HCl reacted with the tabletCompare your answer to other students who choose different brands of antacidDetermine which antacid tablet is the best (neutralizes the most acid)Determine which antacid brand is the most cost effective (neutralizes the most acid per dollar)