anyaforgerLv1

3 Jul 2022

EXPERIMENTAL PROCEDURE

Some accurately weighed 0.1250 g of was transferred into a 100-mL beaker. 10.0 mL of distilled water was added to the beaker followed by a slow addition of about 10 drops of 12 M HCl (to convert to thereby freeing the calcium ions into the solution). The beaker was then covered with a watch glass and the reaction was allowed to proceed until all of the solid calcium carbonate had dissolved. This solution was the heated to an initial boil, then carefully transferred, using a clean funnel, to the 100mL volumetric flask. The beaker was rinsed several times with small portions of distilled water, transferring each portion to the volumetric flask through the funnel. The funnel was rinsed several times also. This rinses were done to ensure that all of the originally in the beaker ended up in the volumetric flask.

 

This 100-mL volumetric flask was then filled with distilled water to the mark, stoppered and the solution was mixed thoroughly by inverting the flask at least a dozen times and shaking at intervals over a period of five minutes. Total solution in the volumetric flask at this point was therefore 100.0 mL

Using a pipet 25 mL portions of the  solution was transferred from the volumetric flask into two clean 250 mL Erlenmeyer flasks. To each flask 5 mL of the pH 10 buffer and 3 drops of indicator were added. The initial color was red.

 

The buret was then filled with EDTA and the initial buret reading recorded to 0.01 mL. The EDTA. solution was titrated against the solutions to the blue endpoint.

 

Data obtained is in Table 1 below. Use the provided data and the concepts of stoichiometry, molarity and dilutions to determine the average molarity of EDTA solution used in this experiment.

 

Next, using a pipet, = 50.0 mL of some water sample was transferred into a clean 250 mL Erlenmeyer flask with the goal of determining the hardness of the water sample in terms of milligrams of calcium carbonate per liter of the water sample. 2 drops of indicator and 5 mL of pH 10 buffer were added here too before ETDA solution (whose average molarity was determined in the first part of the experiment) was added from the buret to a blue endpoint.

 

Use the data provided in Table 2, EDTA average molarity determined in the first part of the experiment, and the concepts of stoichiometry and molarity to determine the amount of in the water sample in mg / L of the water sample.

Remember EDTA:  mole ratio is 1:1 and so is s : .

 

Mass of                          0.1250 g

Moles of ______________________ 

Molarity of the 100.0 mL of standard solution ______________________ 

 

STANDARDIZATION OF EDTA

TABLE 1

Trial 1            Trial 2

Volume of Titrated                                    25.00 mL       25.00 mL 

Moles of Titrated                                        ______          ______

Moles of EDTA                                                     ______          ______

Initial buret reading                                            0.05 mL         0.10 mL 

Final buret reading                                             31.68 mL       31.77 mL

Volume of EDTA                                                  ______          ______

Molarity of EDTA                                                 ______          ______

Average Molarity of EDTA                                     ______          ______

 

WATER SAMPLE ANALYSIS

TABLE 2

Volume of water sample used                             50.00 mL

Initial buret reading                                            0.15 mL

Final buret reading                                            34.98 mL

Volume of EDTA Used                                        ________

Moles of EDTA                                                  ________

Moles of in sample                                   ________

Moles of per liter                                      ________

Grams of per liter                                 ________