Chemistry Quiz

Molarity of Ca²⁺ solution = ________________ M

• 0.1000 M

• 0.01000 M

• 1.000 M

• 1.0100 M

Average (mean) calculated molarity EDTA ______________

Standard deviation ______________

• is a measure of the amount of variation or dispersion in a set of values

• is the average of the data set

• is the sum of all data points

• is the difference between the highest and lowest values

Unknown number/letter ______________

• Q

• R

• S

• T

Average ppm CaCO₃ ______________

Classification of your water sample according to Table 1 ____________________

• Option A: Soft

• Option B: Moderately Hard

• Option C: Hard

• Option D: Very Hard

A titration was performed to standardize an EDTA solution. Use the following data to calculate the molarity of the EDTA solution: 20.00 mL of a standard solution containing 0.01000 M Ca²⁺ required 24.33 mL of EDTA to reach a distinct blue endpoint. What is the molarity of the EDTA solution? Type in your numerical answer with the correct number of significant figures

Suppose the student performing the standardization in question 7 above, rinsed a buret with deionized water, but neglected to rinse the buret with EDTA before filling it. How will this oversight impact the calculated molarity of the EDTA? Select one of the following:

• artificially low.

• artificially high.

• unaffected by the oversight.

A student used 6.05 mL of 0.0100 M EDTA solution to titrate 25 mL of the sample water. Report the hardness in milligrams of CaCO3 per liter of the sample. What is the classification of the water sample?

• Soft

• Moderately hard

• Hard

• Very Hard

EDTA or other chelating agents can be found in many products such as shampoos, soaps, cleaning products, plant foods, salad dressings, canned foods, etc. Choose such a product and suggest the function of EDTA.

• To enhance flavor

• To act as a preservative

• To bind metal ions

• To provide fragrance