In this experiment, we will determine the mass percent of ascorbic acid in a vitamin C tablet by titration with a sodium hydroxide solution of known concentration.
Hello chemistry students today we’re going to be performing our determining ascorbic acid and vitamin c tablet experiment so the purpose of this experiment is to determine the mass percent of ascorbic acid in a vitamin c tablet by titration with a sodium hydroxide solution of known concentration let’s get started we first need to prepare our vitamin c samples
We’re going to be using these nature made vitamin c tablets and we’re going to remove one of the tablets and crush it using a mortar and pestle after completely crushing our vitamin c tablet we need to divide the tablet in half and record the mass of each half the mass of the first half of the tablet that we will be using for trial number one is 0.3108 grams
The mass of the second half of the tablet which will be using for trial number two is 0.3349 grams we’re next going to analytically transfer each half of our vitamin c tablet into a corresponding 250 milliliter erlenmeyer flask and then we’re also going to add up to 75 milliliters of deionized water to each flask in order for the vitamin c to dissolve now don’t
Be concerned if all the powder does not dissolve tablets contain various binders and fillers which may not dissolve in the water well we allow the vitamin c to dissolve in the deionized water we’ll set our buret up for titration i prepared our buret by washing our buret with deionized water and a small amount of soap and then rinsing our buret several times with
Deionized water i then rinsed our buret with five milliliters of our previously standardized sodium hydroxide solution which is 0.09794 molar sodium hydroxide i dumped that wash into the waste beaker and then i filled our buret with our standardized sodium hydroxide solution and opened the stopcock to allow some of that standardized sodium hydroxide solution to
Flow through the tip of the buret and remove any bubbles that may have been in the tip of our buret our buret is now prepared for titration if you would like to view how to properly prepare the buret please refer to one of the previous titration experiment videos we are next going to add three drops of our one percent phenolphthalein indicator to our flask with
The first half of our vitamin c tablet we’ll then swirl our flask and we’re now ready to begin titration number one we will have reached the end point of our titration when a pink color persists for 30 seconds while swirling this is the initial buret reading for the titration of the first half of our vitamin c tablet or titration number one we will now begin
Titration of the first half of our vitamin c tablet or titration number one we now have a pink color that has persisted with swirling for at least 30 seconds so we have reached the endpoint of titration number one for the first half of our vitamin c tablet this is our final buret reading for the titration of the first half of our vitamin c tablet or titration
Number one we will now add three drops of our one percent phenolphthalein indicator to our second flask which contains the second half of our vitamin c tablet and we’ll swirl to mix and we’re now ready to begin titration for the second half of our vitamin c tablet for titration number two this is the initial buret reading for the titration of the second half
Of our vitamin c tablet or titration number two we now have a pink color that is persisting after 30 seconds of swirling so we have reached the end point of titration number two this is the final buret reading upon the completion of the titration of the second half of our vitamin c tablet or titration number two okay students you should now be able to calculate
The mass percent of ascorbic acid in the sample this concludes our determining ascorbic acid and vitamin c tablet experiment thank you for joining me for this laboratory you
Transcribed from video
Determining Ascorbic Acid in Vitamin C Tablets By Tyler Johns