J.R. S. answered • 09/03/17
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Convert 200 ppm to ppb so you can work in the same units.
200 ppm x 1000 ppb/1 ppm = 200,000 ppb
Use C1V1 = C2V2 to calculate volume of 200,000 ppb to be used.
(200,000 ppb)(x ml) = (500 ppb)(50 ml)
x = 0.125 mls = volume of 200 ppm solution to be transferred to 50 ml flask
Convert 500 ppb to mg/liter.
1 ppb = 0.001 mg/L
500 ppb x 0.001 mg/L /ppb = 0.5 mg/L
Convert 0.5 mg/L to moles/L
molar mass quinine = 324.4 g/mole
0.5 mg/L x 1 mmole/324.4 mg = 0.00154 mmole/L = 1.54x10-3 mM = 1.54x10-6 M
J.R. S.
tutor
You are welcome. Hope you understood the steps.
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09/03/17
Sonia B.
Hello, could u help me with this one :)
Calculate the volume of solution 2 that you will need to add to a 50 mL volumetric flask so that when diluted to 50 mL in solution 1 it will yield the desired concentration.
100 ppm quinine (as quinine sulfate) in 0.05 M H2SO4 (aq) (Stock solution 2).
0.05 M H2SO4 (aq) (Stock solution 1)
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09/03/17
J.R. S.
tutor
I could help you with this, but it doesn't state what the "desired" concentration is. Apparently you have a solution (2) that is 100 ppm quinine, and you want to dilute it to 50 mls, but what is the desired concentration of this diluted solution?
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09/03/17
Sonia B.
Here is the instructions
Calibration
To calibrate the instrument you will need to accurately prepare a series of samples containing
known concentrations of quinine and over a wide concentration range. These will be required to be prepared accurately.
Prepare the following solutions (make sure you carefully label each flask):
50 mL of 1000 ppb quinine sulfate in 0.05 M H2 SO4 (aq)
To calibrate the instrument you will need to accurately prepare a series of samples containing
known concentrations of quinine and over a wide concentration range. These will be required to be prepared accurately.
Prepare the following solutions (make sure you carefully label each flask):
50 mL of 1000 ppb quinine sulfate in 0.05 M H2 SO4 (aq)
50 mL of 750 ppb quinine sulfate in 0.05 M H2SO4 (aq)
50 mL of 500 ppb quinine sulfate in 0.05 M H2SO4 (aq)
50 mL of 250 ppb quinine sulfate in 0.05 M H2SO4(aq)
1.
Calculate the volume of solution 2 that you will need to add to a 50 mL volumetric flask so that when diluted to 50 mL in solution 1 it will yield the desired concentration.
2. Carefully pipette the amount of solution 2 that you calculated above (using an adjustable pipette) to give the desired concentration. Then carefully the flask to the mark with solution 1, stopper and shake until mixed. Repeat to prepare
the other solutions.
50 mL of 500 ppb quinine sulfate in 0.05 M H2SO4 (aq)
50 mL of 250 ppb quinine sulfate in 0.05 M H2SO4(aq)
1.
Calculate the volume of solution 2 that you will need to add to a 50 mL volumetric flask so that when diluted to 50 mL in solution 1 it will yield the desired concentration.
2. Carefully pipette the amount of solution 2 that you calculated above (using an adjustable pipette) to give the desired concentration. Then carefully the flask to the mark with solution 1, stopper and shake until mixed. Repeat to prepare
the other solutions.
Report
09/03/17
J.R. S.
tutor
If, as you stated in the previous comment, solution #2 is 100 ppm, then here is how you go about this.
100 ppm = 100,000 ppb and this is the concentration of solution 2. Now to make 50 mls of the other concentrations:
1000 ppb: (x ml)(100,000 ppb) = (50 ml)(1000 ppb) and x = 0.5 mls of solution 2
750 ppb: (x ml)(100,000 ppb) = (50 ml)(750 ppb) and x = 0.375 mls of solution 2
500 ppb: (x ml)(100,000 ppb) = (50 ml)500 ppb) and x = 0.25 mls of solution 2
250 ppb: (x ml)(100,000 ppb) = (50 ml)250 ppb) and x = 0.125 mls of solution 2
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09/03/17
Sonia B.
Thank you so much :) :)
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09/03/17
Sonia B.
09/03/17