Question

The bitter taste often associated with leafy green vegetables such as spinach, parsley, and cilantro is often due to oxalic acid, which has a molecular weight of 90.04g. The percentage of the acid present can be determined through an acid-base titration with NaOH once the sample has been prepared and the oxalic acid is extracted into an aqueous solution. A 100.0-g sample was treated so that all of the oxalic acid dissolved. Because the solution was intensely green due to chlorophyll, an indicator could not be used, and the titration was monitored using pH meter. The following data were obtained. Concentration of NaOH -0.693 M volume 0.00 pH 1.63 2.02 14.00 1.01 12.00 2.49 2.46 10.00 4.56 2.80 8.00 6.01 2.98 pH 7.69 3.16 6.00 8.33 3.23 4.00 3.51 10.72 13.35 2.00 3.91 14.14 4.09 0.00 0 5 10 1516 20 15.41 4.67 15.67 4.97 Volume of NaOH 15.85 5.49 5.79 15.89 (a) How many moles of oxalic acid were present in the 100- g sample? 15.91 6.09 15.95 12.14 16.01 12.74 16.52 13.61 17.06 13.65 (b) Calculate the percentage of oxalic acid in the spinach.

Answer 1

1. Moles of oxalic acid in 100 g sample = 0.0055moles

2. Percentage oxalic acid in 100g sample = 0.5%

Step-by-step explanation:

Check attachment below for explanation and correct chart arrangement