Question

Chromium, especially Cr(VI), is a toxic heavy metal that finds its way into the environment from a variety of industrial sources. Methods for trace chromium analysis include atomic absorption spectroscopy and anodic stripping voltammetry. To prepare 500 mL of stock standard solution of 1000 mg/L chromium using potassium dichromate one would: Select one:

a. Dissolve 2.9419 g potassium dichromate and make up to a final volume of 0.500 L.

b. Add 1.4145 g potassium dichromate to 1.000 L water.

c. Dissolve 1.4145g potassium dichromate and make up to 0.500 L final volume.

d. Dissolve 0.3535g potassium dichromate and make up to 0.500 L final volume.

e. Add 1.4145 g potassium dichromate to 0.500 L water.

Answer 1

For 1 litre or 1000 ml of solution, salt required is 2.829g

For 1 ml of solution, salt required is 2.829g /1000

For 500 ml of solution, salt required will be 2.829 * 500 / 1000

Option b is the ans

Dissolve 1.1415g potassium dichromate and make up to 500 mL final volume or solution.