Assignment directions for a project measuring the amount of citric acid fruit juices

Manager of Chem Projects

CheMystery Labs

380 South Buzz Blvd

Bee Hive, UT 84302

Dear Manager:

The Citrus Growers of the county would like to know which of the fruits they grow has the most citric acid content. 

They would like to exact the citric acid to sell to candy makers who produce sour type candies.  The Citrus Growers have a budget of $100,000 to answer their question.

 Before you begin your work, I will need the following information from you so that I can approve your work.  The planning space for these items is found in your project packet.

Ø       a detailed summary of your hypothesis, experimental

      design table, a plan for the procedures along with all

       necessary data tables

Ø       a description of necessary calculations

Ø       an itemized list of equipment with costs and chemical with

      their costs, include labor costs of $80 / hour and cost for

      laboratory space $10,000/day, and a standard disposal

      fee of $2000 / gram of material. 

After you complete the analysis, prepare a report for the Citrus Growers.  Remember that this report will be seen by a variety of people, so be certain it projects the image we want to present.  The items that should be included in the report are found in your project packet.

Good luck with the project.  Please keep in close contact me as you proceed with the project.  You will need a data verification signature, by having me observe one of the trials in the experiment.

Sincerely

Your teacher

President and CEO

CheMystery Labs Inc.

Background

                    Fruits such as lemons, limes, oranges, and grapes fruits are acidic.  Their acidity is due to the presence of
              citric acid.  These fruits are referred to as citrus fruits because of their high concentration of citric acid.  By
              neutralizing the citric acid, the amount of citric acid can be determined.  The set up would look like:

 

        TITRATION PROCEDURES
 

START ALL TITRATIONS WITH THE BURET FILLED
TO THE ZERO MARK !!!!

            1. Prepare a standard citric acid solution(10 mg/ mL of solution).
            2. Fill a buret with household ammonia.
            3. Measure 15 mL of the standard citric acid solution and pour into a flask.
            4. Put 10 drops (or until the liquid turns yellow) of bromothymol blue indicator into the flask
                containing the citric acid solution.

(solution should be bright yellow at this point- an Acid solution)

            5. Slowly add ammonia into the flask, while stirring, until the liqiud turns blue-green.
            6. Record the amount of ammonia added to the flask in a data table.
            7. Do 3 trials, using steps 1-6.
 

            Measuring the Citric Acid in Fruit Juice

            1. Fill a buret with household ammonia.
            2. Measure 15 mL of the fruit juice solution and pour into a flask.
            3. Put 10 drops (or until the liquid turns yellow) of bromothymol blue indicator into the flask
                containing the citric acid solution.

(solution should be bright yellow at this point- an Acid solution)

            4. Slowly add ammonia into the flask, while stirring, until the liqiud turns blue-green.
            5. Record the amount of ammonia added to the flask in a data table.
            6. Do 3 trials of each juice, using steps 1-5.
 
            Calculations

            7. After conducting the experiment, use this equation to find out the amount of citric
                acid (mg/mL of solution) in the fruit juice.
 

                  ___mL of NH₃ added  |           15 mL of citric acid standard     |          10 mg citric acid   
                     15 mL of juice          |  __  mL of NH₃ to neutralize standard  |  mL of citric acid standard
 
 



 

Other Ideas for Citric Acid Research Projects
 

 
 All the solutions and apparatus required for Citric Acid studies and analysis will be provided, except that you must provide the juices or other materials to be tested.  Here are some general suggestions for the types of projects that you might consider.

                        What type of sour candy has the most citric acid (mL of base consumed/gram of candy)?