Road an appropriate reference, such as TECH 349, Standardizing a Hydrochloric Ad

Question

Road an appropriate reference, such as TECH 349, Standardizing a Hydrochloric Add Solution, for a discussion of titration techniques, and an appropriate reference, such as TECH 329, Laboratory Techniques: Mass Measurements, for a discussion of mass measurement techniques. Briefly explain why ns advisable to cover the beaker containing NH_3 - NH_4CI buffer solution when you are not using it. A student analyzed powdered cultured buttermilk using the procedure n this experiment. A 2.270-g sample of the powdered buttermilk required 37.18 mL Of 1.183 times 110^-2 M EDTA solution for titration of the Ca^2+ ion. How many motes of Ca^2+ ion wore present in the sample? How many grams of Ca^2+ ion did the titrated sample contain? What is the mass percent Ca^2+ ion in the milk powder? If the powdered buttermilk costs $2.49 for a 12-oz container, what is the cost of 1.00 oz of Ca^2+ ion supplied by the powdered buttermilk? Suppose that students m a class are asked to provide their own milk powder samples for analysis. Would the student who brings chocolate milk powder have difficulty completing the Ca^2+ ton analysis using the procedure in this experiment? Briefly explain.

Explanation / Answer

2. It is important to cover the beaker with buffer when not using otherwise, the NH3 from solution can go out and change concentration of buffer solution.

3. Titration

(1) moles Ca2+ = 1.183 x 10^-2 M x 37.18 ml = 0.44 mmol

(2) mass Ca2+ present = 0.44 mmol x 40.08 g/mol/1000 = 0.0176 g

(3) mass% Ca2+ in buttermilk = 0.0176 x 100/2.270 = 0.777%

(4) cost buttermilk = $2.49 per 12 Oz

1 Oz = 28.35 g

0.0176 g Ca2+ in 2.27 g buttermilk

So, 28.35 g Ca2+ present in = 3656.506 g

So cost of 1 Oz Ca2+ = 3656.506/1 = $3656.506

4. chocolate milk has other ingredients that may interfere with the analysis of Ca2+ in the milk powder and thus would be difficult to analyze.

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