lab report

Author 's Name 1

Experiment 5 : Introduction to Volumetric Method

Introduction : This experiment was conducted as an introduction to volumetric analysis using the titration method . Volumetric analysis is defined as a chemical procedure used for determining the concentration of a solution . Using titration for this analysis , we can determine the concentration of an unknown reagent using a standard concentration of another reagent that chemically reacts with the unknown . This standard solution is referred to as the "titrant . We have to have some way to determine when the reaction is complete that

we are using . This is referred to as the "end point " or more technically the equivalence point . The amount of titrant added to reach this equivalence point will be used in the stoichiometric calculations for the concentration of the unknown solution . For the purposes of this experiment , phenolphthalein is used as the color indicator while potassium hydrogen phthalate (KHP was used to standardize a 0 .1 M NaOH solution . This NaOH solution will be titrated to determine the unknown concentrations of hydrochloric acid , acetic acid and sulfuric acid

Experimental : Before proceeding with the experiment , standard laboratory procedures should be observed . In handling acids , especially strong ones , and NaOH solutions , gloves must be used to avoid wounds and skin burns . And in to prevent intoxication , avoid the inhalation of acid fumes as much as possible

To produce 0 .1 M NaOH , carbon dioxide was removed form 1000mL distilled water by boiling it for ten minutes in to prevent the bicarbonate formation upon titration with acids . 8mL NaOH was taken from a 500g /L sample and was placed in a polyethylene bottle . The distilled water with carbon dioxide already removed , was gently cooled aside until its temperature is appropriate for handling . This was added into the polyethylene bottle and then was mixed by inverting the bottle several times without vigorous shaking . The bottle was

Author 's Name 2

placed in an ice bath to further decrease its temperature . Using KHP as the primary standard , 2 .076g was measured and was further divided into three samples weighing 0 .399g , 0 .391g , and 0 .369g each . They were transferred to three separate labeled Erlenmeyer flasks , where 30 to 40 mL of carbon dioxide free water was added in to dissolve these solid substances . Three drops of phenolphthalein was added to dissolved KHP to serve as the color indicator . In to ensure that the buret is free of impurities that would potentially alter results , it was cleaned using distilled water that was later water flushed out . In to determine if the buret was completely cleaned , the newly produced NaOH was added and flushed out of the buret . When droplets do not adhere to the sides of the buret , this indicates that the latter is cleaned When this is done , NaOH solution was placed into the buret . This was titrated against sample 1 of KHP with 1 mL increments until a stable pink color is achieved upon swirling . Since 17...