Question

1. How would you prepare 100 mL of F^- solutions with the following concentrations: (A) 10.0 ppm, (B) 5.00 ppm, (C) 0.500 ppm and (D) 0.100 ppm. What is this experimental protocol called? (10 pts)

Answer 1

We express ppm concentration in a variety of units depending on what we need to use. But they are all interrelated.
ppm =   1 g        =      1 g      =       1 mg       =    1 mg     =   1 microgram
            10⁶ mL        1000 L             1 L                   1 kg                    1 g                 

A) We have to prepare 100 ml of 10 ppm F- solution.

We have to calculate how much amount of F- is required to prepare the above solution.

10 ppm means 10g of solute in 10^6 ml.

then in 100ml, the amount of solute = 100ml *10g / 10^6 ml.

                                                         = 0.001g of F- is present in 100ml of solution.

B) We have to prepare 100 ml of 5.0 ppm F- solution.

We have to calculate how much amount of F- is required to prepare the above solution.

5 ppm means 5g of solute in 10^6 ml.

then in 100ml, the amount of solute = 100ml *5g / 10^6 ml.

                                                         = 0.0005g of F- is present in 100ml of solution.

C) We have to prepare 100 ml of 0.5 ppm F- solution.

We have to calculate how much amount of F- is required to prepare the above solution.

0.5 ppm means 0.5g of solute in 10^6 ml.

then in 100ml, the amount of solute = 100ml *0.5g / 10^6 ml.

                                                         = 0.00005g of F- is present in 100ml of solution.

D) We have to prepare 100 ml of 0.1 ppm F- solution.

We have to calculate how much amount of F- is required to prepare the above solution.

0.1 ppm means 0.1g of solute in 10^6 ml.

then in 100ml, the amount of solute = 100ml *0.1g / 10^6 ml.

                                                         = 0.00001g of F- is present in 100ml of solution.

A protocol is simply a written design, for performing the experiment.