lab report #7.docx - CH 204 Introduction to Chemical...

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CH 204 – Introduction to Chemical Practice Experiment #7 – Strong Acid Strong Base Titration Amna Ali Anusia Mansukhani TA: Joseph Guerrera November 2, 2017 INTRODUCTION Neutralization reactions are Acid-Base reactions. In this type of reaction, an acid and base react and form the products that are salt and water. This happens through the H + (aq) of the acid and the OH - (aq) of the base. They combine to form H 2 O (l). The salt is produced due to the reaction of the anion of the acid and the cation of the base. Different salts have different solubility. Strong acids and strong bases are those that dissociate completely in solution, weak acids and weak bases only dissociate partially. Although there are eight strong bases, there are only seven strong acids. The strong bases are NaOH, RbOH, KOH, LiOH, CsOH, Ca(OH) 2, Sr(OH) 2 , Ba(OH) 2 . The strong acids are HCl, HBr, HI, HNO 3 , H 2 SO 4 , HClO 3 , HClO 4 . A titration is a method of quantitative analysis. It was developed due to its rapidness as well as its accuracy and inexpensiveness. The previous methods of quantitative analysis were inaccurate, hazardous, and expensive, requiring the use of Bunsen burners and other materials. A titration uses a species of known concentration to react with the species of unknown concentration in order to determine that concentration. Titrations may be used for determining the amount of any type of species, not just acids/bases. A titration curve plots pH vs. Volume, which in this case was the volume of the base. It also demonstrates the equivalence point and the endpoint of the titration. The endpoint is where the titration has stopped (the indicator changes color). The equivalence point, on the other hand is when OH - has neutralized any and all excess H + ions. In this lab, KHP (a weak acid) will be reacted with NaOH (a strong acid) with the goal of determining the quantity of NaOH solution. This will be done to standardize the NaOH solution, which will then be used for the HCl (known volume, unknown concentration) solution. The results from this titration will provide the information necessary to calculate the concentration of HCl in the original solution. The equation that will be used to do this is: molesof solute Lof solvent = Molarity. In order to motor the pH throughout the experiment, a pH probe and the pH indicator phenolphthalein will be used along with the LabQuest. The pH scale is described from 0-14 where a neutral solution has a pH equal to 7, a basic solution has a pH above 7 and an acidic solution has a pH below 7. The pH is what determines the quantity of hydronium ions. The data from the titrations will be graphed using Logger Pro 3.11. EXPERIMENTAL Part A was the standardization of NaOH. The theoretical 0.5 M NaOH volume that would be required to neutralize 2 grams of KHP had been calculated in the prelab. Because NaOH is hyrgroscopic and therefore absorbs moisture rapidly it was ensured that the NaOH bottle was recapped right away after opened. In a 400 mL beaker, 50 mL of deionized water was added out of a beaker of 200 mL of deionized water. Using the beaker filled with 50 mL, 4 grams of solid NaOH was

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