Question

Construct a standard curve (absorbance vs. concentration) using the following results.

A 5mL, 10mL, 15mL,20mL aliquot of 0.010M sodium salicylate solution was diluted to 100 mL in four different volumetric flasks with the Iron (III) chloride solution. The % Transmittance for the iron complex formed in each of these given solutios was 60.3%, 39.8%, 26.3%, and 15.1% respectively

Answer 1

A) apply dilution formula, M1V1 =M2V2

M1=molarity of stock solution,0.01

V1= volume of Stock solution,xml

M2 = Molarity of diluted solution,?

V2= volume of dilute soolution,100ml

on rearranging, M2=M1V1/V2

if x=5ml = M2 =0.0005M

x=10ml = M2=0.001M

   x= 15ml =M2= 0.0015M

   x= 20ml = M2= 0.002M

B) Absorbance = 2-log10 ( % of transmittance)

   apply the equation to all values of of % of transimttance

Transmittance   Absorbance

60.3%, 0.2197

39.8%, 0.4001

26.3%, 0.580

15.1% 0.821

then construct plot abs vs. concentration

Abosrbance (Y) Concentration (X)

0.2197 0.0005

0.4001 0.0010

0.58 0.0015

0.821 0.002