Students can compare the amounts of vitamin C in a variety of apple juice samples. Teachers should prepare five beakers, each containing 100ml of a different brand of apple juice, per group. A coded system is important so the teacher will know whether students complete the experiment correctly, and to determine whether the amount of vitamin C in the sample reflects the package information. Add 1g of oxalic acid to each beaker to stabilize the juice. Divide students into groups and distribute juice samples along with a 50ml buret, a funnel, iodine, thyodene indicator and an Erlenmeyer flask. Fill the buret with iodine, using a funnel, and record the initial amount. Pipet 25ml juice into the flask and add a small amount of thyodene indicator. Add iodine, swirling the flask constantly, until you see a color change. Record the final level of iodine solution and determine the content of vitamin C based on the fact that 1ml iodine is equivalent to 0.3mg of vitamin C.
Measuring the acidity of vinegar requires a few complex elements, but most science teachers should find them readily available in their campus lab supply room. Instruct students to place 1.5ml vinegar in an Erlenmeyer flask and dilute with 50ml distilled water. Add three drops of 0.5 percent phenolphthalein solution. Fill a buret with 0.1 mol solution of sodium hydroxide and record the fluid level. Drip the sodium hydroxide solution into the vinegar and swirl the flask until the color changes to a consistent pink, close the buret and record the level of sodium hydroxide remaining. Subtract this from the starting measurement to determine the number of moles of the solution required for titration, and set up a proportional equation between the sodium hydroxide solution and initial amount of vinegar and water to calculate the amount of acetic acid in the sample of vinegar. Repeat this with additional types of vinegar to compare acid concentration.
Glucose concentration levels are extremely important for students to understand if they're considering a future in the medical field, and a simple titration experiment can provide a basic introduction to this topic. Teachers should divide students into groups of four and provide students with a potato and triiodide. Add triiodide to the potato one drop at a time from a pipet until the potato turns blue. The ratio of glucose and triiodide is 1:1, so the amount of triiodide added to the potato represents the equivalent amount of glucose contained in the starch.
Teachers must prepare 0.25mol sodium hydroxide solution and 0.2mol potassium acid phthalate solution before this experiment. Distribute pH meters, pre-made solutions, phenolphthalein, pH and reference electrodes with holders, magnetic stirrers, stir bars, pipettes, beakers, deionized water and an unidentified acid to lab groups. Fill a 50ml buret with sodium hydroxide solution. Pipet 25ml of the second solution into an Erlenmeyer flask. Add 3 drops phenolphthalein to the flask and stir until you get a pink color. Record the mass of the unidentified acid and add 100ml deionized water. Stir until the acid is dissolved. Pipet 50ml into a beaker and stir. Insert the pH electrode in the beaker and add the titrant mix 1ml at a time, pausing after each for the pH electrode reading to update. Determine the amount of moles added and identify the unknown acid by referring to an acid chart, which can be found in chemistry textbooks or at http://www.chem.uky.edu/courses/che226/Labs/070-Acid-Base_Titration.pdf