Penn State CHEM 111
Section F: Acid Concentration in Fruits
Please change the hypothesis in your Chemtrek to: There is a hypothesis that the pucker-promoting
potential of fruits and fruit juices is directly proportional to the concentration of organic acids present in
the fruit. Knowing that the order of sour taste, or pucker power, is Lemon > lime > grapefruit > orange for
fruit juices, please use the information in the video to tell us whether you accept or reject the hypothesis.
Pre-lab data collection and observations. Complete before lab.
Read through this section in your Chemtrek and watch the video associated with this section. In the space
below, summarize how the experiment was performed. Include any data and observations from the video
in a table.
Hypothesis: the pucker-power of fruit juice is directly related to the concentration of organic acid present
in the fruit
Juices least -> most
orange juice, grapefruit juice, lime juice, lemon juice
Large well titration on two drops of each juice all with BTB indication
Titrate with .1 M NaOH
Each of the juices when leveled out with the NaOH turned blue
The more sour the more drops it took
There was a significant leap of the number of drops between grapefruit and Lime
They didn’t mix after each drop
They introduced the NaOH a lot faster
Amount of drops
Report the concentration of acid in each of the fruit juices.