Question

I NEED HELP WITH THIS LAB

color marks the endpoint of the titration. We can then relate the volume of EDTA solution required to reach the endpoint to the mass of zinc present in each lozenge. Procedure: 1. Fill the buret with 0.0100 M EDTA solution. Clean any spills immediately. Run some EDTA solution out of the buret to get rid of the air bubble in the buret tip. Adjust the amount of EDTA to the 0.0 mL mark. Record this as the "initial reading of buret". 2 Obtain one Cold-Eeze" and crush it to powder using a mortar and pestle. Dissolve the crushed lozenge in 50 mL of buffer solution (pH 5.5) using a 250-ml beaker. It must be completely dissolved before titrating. 3. 4. Add about 4 or 5 drops of xylenol orange indicator solution to your lozenge solution. It should have a peach color at this stage. Titrate your solution by adding EDTA from the buret 1 mL at a time while swirling the flask. When a yellow color is obtained, stop adding EDTA and record the reading on the buret to the nearest 0.1 mL (read at the bottom of the meniscus). This reading is the "final reading of buret". The volume used is calculated as: final reading - initial reading = volume of EDTA used. Rinse the contents of the flask down the sink. Repeat steps 2-5 for two additional titrations-- except add the EDTA dropwise as you approach the endpoint. Try to determine the absolute minimum volume of EDTA necessary to reach the endpoint. Refill the buret as needed. Average the values obtained for "volume of EDTA used" in these two trials (trials 2-3). 6. Convert the “average volume of EDTA used” to “average moles of EDTA used” using the given molarity (0.0100 M) of the EDTA solution. 7. The number of moles of EDTA used will equal the number of moles of zinc in the lozenge. Use this to calculate the number of grams of zinc per lozenge. Convert this number to milligrams of zinc. 8. Drain any remaining EDTA from the buret and rinse it with distilled water.