Question

3. (20) You are required to prepare standards for a calibration curve. All the glassware and pipettes your method requires have a tolerance (RSD) of 0.1%. You start with a working solution of 0.1 M analyte. Remove 10 mL of that solution with a pipette, add it to a 100 mL volumetric flask and dilute it to the mark. Remove 10 mL of the newly prepared (diluted) standard, add to a 50 mL volumetric flask, and dilute it to the mark. Report the concentration of analyte in the 50 mL flask with uncertainty.

Answer 1

Using

$M_{1}V_{1}=M_{2}V_{2}$

and

$RSD=\frac{\sigma }{\mu }$

$0.1\times10=M_{2}\times100$

$M_{2}=0.01\: M$

$\sigma _{2}=0.01\times0.001=10^{-5}M$

$M_{2}V_{2}=M_{3}V_{3}$

$0.01\times10=M_{3}\times50$

$M_{3}=0.002\: M$

$\sigma _{3}=0.002\times0.001=2\times10^{-6}M$