Complete all of the calculations for creating a calibration curve that you will

Question

Complete all of the calculations for creating a calibration curve that you will use to determine the concentration of an unknown sample in lab this week. The s is 300 ppm quinine. First determine the dilution to create a25-mL solution of 1 ppm quinine solution. Then use that 1 ppm stock solution to prepare five standard solutions of quinine, 25 mL each. You can choose your concentration range but keep the max below 0.2 ppm. Show all work and clearly label each dilution concentration. (15 pts) 1. tock solution

Explanation / Answer

To prepare a set of quinine standard solutions from stock solution

Concentration of stock = 300 ppm

(a) prepare 25 ml of 1 ppm solution

using,

V1 = C2V2/C1

with,

V1 = volume of stock needed

V1 = final volume of solution

C1 and C2 are the concentrations of stock and final solutions respectively

Thus,

V1 = 1 ppm x 25 ml/300 ppm = 0.083 ml

So take 0.08 ml of quinine stock solution and dilute it with 24.92 ml water to prepare 1 ppm solution

Now preparing the five standard solutions below 0.2 ppm

(a) prepare 25 ml of 0.1 ppm solution from 1 ppm standard

V1 = 0.1 ppm x 25 ml/1 ppm = 2.5 ml

So take 2.5 ml of 1 ppm quinine solution and dilute it with 22.5 ml water to prepare 0.1 ppm solution

(b) prepare 25 ml of 0.08 ppm solution from 1 ppm standard

V1 = 0.08 ppm x 25 ml/1 ppm = 2 ml

So take 2 ml of 1 ppm quinine solution and dilute it with 23 ml water to prepare 0.08 ppm solution

(c) prepare 25 ml of 0.06 ppm solution from 1 ppm standard

V1 = 0.06 ppm x 25 ml/1 ppm = 1.5 ml

So take 1.5 ml of 1 ppm quinine solution and dilute it with 23.5 ml water to prepare 0.6 ppm solution

(d) prepare 25 ml of 0.04 ppm solution from 1 ppm standard

V1 = 0.04 ppm x 25 ml/1 ppm = 1.0 ml

So take 1.0 ml of 1 ppm quinine solution and dilute it with 24 ml water to prepare 0.04 ppm solution

(e) prepare 25 ml of 0.02 ppm solution from 1 ppm standard

V1 = 0.2 ppm x 25 ml/1 ppm = 0.5 ml

So take 0.5 ml of 1 ppm quinine solution and dilute it with 24.5 ml water to prepare 0.02 ppm solution

Note the final volume in each case equals to 25 ml

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