QUESTION 5 In this experiment you will dilute a known concentration of a coloure

ID: 1029630 • Letter: Q

Question

QUESTION 5 In this experiment you will dilute a known concentration of a coloured sample in order to be able to measure its absorbance A 50 ml coloured solution is made with a concentration of 0.016 mol L:1.3 m of this stock solution is then diluted to 50 mL, what is the millimolar (mmoIL, concentration o: the dilute sample solution? Untounded value Rounded value Concentration of stock coloured solution(mol L-1) 0.016 Concentration of compound in diluted solution (mol L'1) Concentration of compound in diluted solution (mmol L

Explanation / Answer

Unrounded

Rounded

Concentration of stock colored solution (mol/L)

0.016

Concentration of compound in diluted stock solution (mol/L)

Use the dilution equation

C1*V1 = C2*V2

Where C1 = 0.016 mol/L; V1 = 3 mL and V2 = 50 mL.

Plug in values and obtain

(0.016 mol.L-1)*(3 mL) = C2*(50 mL)

====> C2 = (0.016 mol.L-1)*(3 mL)/(50 mL) = 0.00096 mol.L-1

9.6*10-4 mol.L-1

Concentration of compound in diluted stock solution (mmol.L-1)

(concentration of compound in diluted stock solution in mol.L-1)*(1000 mmole/1 mole) = (0.00096 mol.L-1)*(1000 mmole/1 mole) = 0.96 mmol.L-1

0.96 mmol.L-1

The value of the extinction co-efficient is required.