A. During Part I of the water Analysis series, you prepared a Stock solution of

Question

A. During Part I of the water Analysis series, you prepared a Stock solution of Phosphate ion containing 50.0 mg P/L. In the second part of this experiment, you will use this Stock solution to prepare Standard solutions to be used to make a calibration plot. As described in the background information for this experiment, the concentration of Phosphorus in these standards should be between 0 mg /L (Solution A)and 0.6 mg/L (Solution C). A. Describe HOW you are going to prepare Solution C, which must contain 0.3 mg P/L. Assume you are going to use a 250-mL volumetric flask for this preparation. Be sure to include necessary CALCULATIONS !

B.  Another standard (Solution B) should have the concentration between 0 and 0.6 mg P/L. Choose a value for this concentration and show calculations to be used for preparation of 250 mL of Solution B.

Explanation / Answer

A) mass of phosphorus in C =0.3*0.25

=0.075 mgrams

so, amount of solution A required=0.075/50

=0.0015 L

=1.5 mL

so amount of water to be added = 250-1.5

=248.5 mL

so 248.5 mL of water has to be added to A to make C.

B) let the concentration of B be 0.3 mg P/L

mass of phosphorus in B =0.3*0.25

=0.075 mgrams

so, amount of solution A required=0.075/50

=0.0015 L

=1.5 mL

so amount of water to be added = 250-1.5

=248.5 mL

so 248.5 mL of water has to be added to A to make B

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