lab report

TITLE OF EXPERIMENT 2 : DILUTION

2.1: OBJECTIVES

Upon completion of this experiment, students should be able to:
1. determine the concentration of coloured solution such as FeCl3 by using dilution and colour differentiating (colorimetric) techniques.

2.2: INTRODUCTION

Concentration can be expressed in many different ways such as percentage volume and percentage weight etc. In laboratory, normally concentrations were expressed as molarity and normality.

Molarity is the mole of material in 1000 mL (1 liter or 1 dm3) of solution, as shown as followed equation:

Molarity (M) =

M = n / V

Stock solution is the solution with known concentration. When the solution was diluted, only the concentrations will change while the mole number is remain the same. Based on this principle, the concentration of dilute solution can be determined by using followed equation:

M1V1 = M2V2

Where M1 = concentration of concentrated solution (mol dm3) V1 = volume of concentrated solution (dm3) M2 = concentration of dilute solution V2 = volume of dilute solution

Chemicals
0.100 M FeCl3 solution
0.100 M KCNS solution
0.005 M FeCl3 solution (B)

Apparatus

Burette 1 x 50 mL
Pipette 1 x 5 mL
Test tube 10

2.3: ACTIVITIES

Method:

1. Based on given equation, calculate and prepare the following solution from standard solution of 0.100 M FeCl3 by using pipette.

a. 25mL FeCl3 solution (5.0 x 10-2 M)
b. 25mL FeCl3 solution (1.0 x 10-2 M)
c. 25mL FeCl3 solution (5.0 x 10-3 M)
d. 25mL FeCl3 solution (1.0 x 10-3 M)
e. 25mL FeCl3 solution (5.0 x 10-4 M)

Records the volume of solution used.

2. Transfer each 5 mL of prepared solution into test tube and add 2 drops of KCNS (potassium thiocyanate) to each test tube. Shake it until homogen and wait for any colour changes.

2. Transfer 5 mL of B solution into another test tube and add 2 drops of KCNS solution. Shake it and compare colour