09-Titration of Commercial Antacids Experiment Nine - Titrations of Commercial A

Question

09-Titration of Commercial Antacids Experiment Nine - Titrations of Commercial Antacids OBJECTIVES Acids can back up in the stomach and flow up into the esophagus, causing heartburn. This may be caused by spicy or fatty foods, eating before bed, over drinking, stress and smoking. Commercial antacids (i.c. TUMS) serve to rapidly neutralize these acids. Here, we will apply the technique of an acid/base titration to determine the number of moles of active antacid ingredient present in a single tablet. BACKGROUND Antacids are basic chemicals in a form that is as pleasant to the eye and palate as possible. The basic chemical reacts with the excess hydrochlorie acid (HCI) found in the stomach after over stimulation from stress or overindulgence. The active basic chemical ingredient in TUMS is calcium carbonate (CaCO,). Stomach acid is neutralized by CaCO, as illustrated below: CaCO(HCI (aq) - CaCl; (aq)+H:CO, (aq) (double replacement rxn!!) H,CO, (aq) ? ? CO2 (g) + H2O (l) (H,COs breaks down to a gas and water) To determine the moles of active ingredient (CaCO,) in TUMS, we will first dissolve the tablet in an excess amount of HCI acid (stomach acid) of known concentration. (note: If you look up CO, on a solubility ta we would find that CaCO, salt is not soluble in water.) Importantly, some of this HCI will be neutralized the CaCO, in the tablet, but there will be some HCl acid remaining. We will then perform a titration with a base (NaOH) to determine the amount of excess HCl acid present in the sample. Since we know how much HCI was added initially to dissolve the tablet, and the titration data will tell us how much HCI remains (that didn't react with the tablet's CaCO,), we can do some calculations to determine the moles of active ingredient in the TUMS tablet. Note: The H,CO, reactions above is reversible, which means that CO, dissolved in water will produce some carbonic acid. This acid will react with the NaOH we are titrating and give us inaccurate results. Therefore in the procedure it is important to boil the solution when the carbonate reacts with acid, to remove CO2 as a gas. Analysis and Calculations: To determine the amount of active ingredient in TUMS we will perform an acid-base titration. A titration is conducted by quantitatively delivering a reagent (typically from a buret), to a sample until an "endpoint" is reached. In this analysis, the acid originates solely with the HCl; the base originates with the NaOH and the antacid. Therefore at the endpoint moles of acid from HCl - moles of base from NaOH + moles base from antacid (I) Mole can be writing in terms of Molarity for HCl and NaOH, ??? x Vict : M,uce. x VNOH + nmoles base antacid Rearranging this equation and solving for Mole of antacid, moles base antacid-Mc? x v,'a-N1N0H X VNIH

Explanation / Answer

Initial volume of NaOH should be zero if the entire burette is filled.
Final volume of NaOH = 0.0168 L
Volume of NaOH used = 0.0168 - 0
Volume of NaOH used = 0.0168 L

MHCl = 0.3316
MNaOH = 0.9255

Trial 1:
vHCl = 0.05 L
vNaOH = 0.0168 L

moles base antacid = MHClvHCl - MNaOHvNaOH
moles base antacid = 0.0010316 moles

Trial 2:
vHCl = 0.05 L
vNaOH = 0.0166 L
moles base antacid = MHClvHCl - MNaOHvNaOH
moles base antacid = 0.0012167 moles

Average moles of base in antacid = 0.00112415 moles

Related Questions

Navigate

• Browse (All)
• Browse
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.