Acid-Base Titration BQ: 1) what is the strength of the antacid? 2) How accurate/precise is this strength? Safety consideration: Goggles and gloves must be worn at all time during experiment to prevent any contact with eyes and skin. If spilled any chemical in gloves throw it away and wear a new one immediately. Handle all chemical carefully. Handle all carefully to prevent from breaking. Procedure and Tests: Week 1 1) 600ml of a 0. 5M NaOH solution will be needed, 3MNaOH is provided. Determine how much of the 3M NaOH will be needed. 2) Determine how many mls of a 0. 5M NaOH solution will be required to titrate 1. g of potassium hydrogen phthalate to the nolphthalein endpoint. 3) Use bromothymol blue or phenolphthalein. Week 2 1) Determine the molarity of the NaOH prepared from precedent week. 2) Estimate how many mls of NaOH solution will be required to reach the bromothymol blue endpoint. 3) Identify the antacid preparation that will be used. Procedures 1) Preparation and standardization of NaOH 1. Prepare NaOH solution by using stock 3M NaOH. Prepare 600ml of a 0. 5 M NaOH. 2. Weigh a sample of potassium hydrogen (KHP) between 1. 1 to 1. 3 gram. 3. Dissolve the KHP by adding 50 ml of water. Swirl to complete solution. 4.
Titrate be as accurate as possible, repeat titration several times. 2) Preparation and standardization of HCl. 1. Prepare hydrochloric acid stock solution. 2. Measure out a sample of HCl. Use a 10 ml volumetric pipet to transfer solution to flask and add indicator. 3. Perform titration. 3) Antacid Titration 1. Measure out the amount of sample decided 2. Add an excess of acid. Add 10. 00 mL of standard HCl solution to sample. Swirl to mix. 3. Back titration. Data, Observations and Calculations: M1V1=M2V2 600mL*0. 5M NaOH=M2* 3M NaOH M2= 300mL NaOH/3 M NaOH M2= 100mL Data 1, standardization of NaOH trials| KHP(g)| Moles of KHP| Moles of NaOH| . M NaOH(mL)| Molarity(M)| 1| 1. 212| . 006| . 006| 11. 6| . 52| 2| 1. 211| . 006| . 006| 11. 9| . 5| 3| 1. 211| . 006| . 006| 12| . 5| 4| 1. 212| . 006| . 006| 11. 6| . 52| | | | | | Average = 0. 51| | | | | | Deviation= 0. 011547005| Data 2, standardization of HCl Trials | Volume of NaOH(mL)| Moles of NaOH| Moles of HCl| 1| 22. 2 | . 011| . 011| 2| 21. 8| . 011| . 011| 3| 22. 0| . 011| . 011| 4| 22. 2| . 011| . 011| | | | Average = 0. 011| | | | Derivation = 0| Data 3, Antacid Titration. Trials| Mass of tablets (g)| Volume of NaOH(mL)| Moles of NaOH| Moles of HCl| Moles of OH-| 1| 1. 194| 15. 8| 0. 008| 0. 011| 0. 03| 2| 1. 199| 19. 0| 0. 009| 0. 011| 0. 002| 3| 1. 215| 13. 5| 0. 007| 0. 011| 0. 004| | | | | | Average = 0. 003| | | | | | Derivation = 0. 001| Calculations: Mole of KHP= mole of NaOH (use for column 3 on table 1) Moles of NaOH= moles of HCl(use for column 3 on table 2) Moles of OH-= moles of HCl-moles of NaOH(use for column 4 on table 3) Price per mole Price of one pack=$33. 03 500 tablets in one pack. $33. 03/500tblt = $. 0606 per tablet $ 20. 2 per mole of OH-| $. 0606/. 003M= Claims: both beginning questions are asking about the strength of the antacid, based on table 3, it can be concluded that the strength is 0. 03 moles. On this experiment accuracy is based on how accurate the mole of NaOH and HCl are, and the volume of NaOH that were used in each trial. Evidence and Analysis: 1) What is the strength of the antacid? The strength of the antacid is . 003 moles 2) How accurate/precise is this strength? The accuracy of this strength is based on the standardization of NaOH and also that of HCl, as well as the back titration since they are linked to each other in some point. It is very likely for this strength not to be accurate because, it is likely to have errors on the previous calculations and data.
Reading, Reflection: The main possible source of errors on this experiment is based on the measurement of mass and volume for the experiment, which could affect moles of NaOH and HCl, could as well affect the antacid titration. One question I have after this experiment is that, how the increasing of mole of the tablet would affect the titration? This experimental work can be related to lecture on how acid and acid bases interact to each other, and also this experiment give a better understanding on term pH. A real life application for acid base titration is that is use in medicine and most food ingredients.