Exp 2 Chemistry

UNIVERSITI PENDIDIKAN SULTAN IDRIS FUNDAMENTAL CHEMISTRY (TKU 1033) EXPERIMENT 2: DILUTION

NAME: NURHASNI BINTI MA’RUF MATRIC NUMBER: D20081032343 LECTURER’S NAME: PUAN FARIDAH BINTI YUSOF SESSION: 3.00 PM – 6.00 PM (FRIDAY) GROUP : 2

EXPERIMENT 2: DILUTION TITLE: Dilution. OBJECTIVE: To determine the concentration of coloured solution such that as FeCl3 by using dilution and colour differentiating (colorimetric) techniques. CONCEPTS: 1. To determine molarity, normality and mole concept. 2. To learn dilution technique. 3. To learn the way to use M1V1=M2V2 equation in the dilute liquid calculation. INTRODUCTION: Concentration can be expressed in many different ways such as percentage volume and percentage weight etc. in laboratory, normally concentration 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) =

Mole

.

Volume (1 liter/1 dm³ ) 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

MATERIALS: a) 0.10 M FeCl3 solution b) 0.10 M KCNS solution c) FeCl3 solution (B) PROCEDURES: 1. The following solution were calculated and prepared from standard solution of 0.10 M FeCl3 based on a given equation. a) 50/100 mL FeCl3 solution (5.0x 10 ‾² M) b) 50/100 mL FeCl3 solution (1.0x 10 ‾² M) c) 50/100 mL FeCl3 solution (5.0x 10 ‾³ M) d) 50/100 mL FeCl3 solution (1.0x 10 ‾³ M) e) 50/100 mL FeCl3 solution (5.0x 10 ‾4 M) The volume of solution used was recorded. 2. Each 5 mL of prepared solution was transferred into test tube and 1 drop of KCNS (potassium thiocyanante) was added to each test tube. It was shook until homogen and for any colour changes was waiting. 3. 5 mL of B solution was transferred into another test tube and 2 drops of KCNS solution was added. It was shook and colour of solution was compared with the series of solution that have prepared previously (2). The concentration of B solution was suggested.

RESULTS:

solution a) b) c) d) e)

50ml FeCl3 solution (5.0x10-2M) 50ml FeCl3 solution (1.0x10-2M) 50ml FeCl3 solution (5.0x10-3M) 50ml FeCl3 solution (1.0x10-3M) 50ml FeCl3 solution (5.0x10-4M)

Volume of FeCl3 (mL) 25.0 5.00 2.50 0.50 0.25

CALCULATION: We calculate the following solution by using formula M1V1 = M2V2. (a) 50 mL FeCl3 solution (5.0x10-2M) M1V1 = M2V2 (0.10 M) V1 = (5.0 × 10‾² M) (50.0 ml) V1 = 25.0 ml (b) 50 mL FeCl3 solution (1.0x 10 ‾² M) M1V1 = M2V2 (0.10 M) V1 = (1.0 × 10‾² M) (50.0 ml) V1 = 5.0 ml (c) 50 mL FeCl3 solution (5.0x 10 ‾³ M) M1V1 = M2V2 (0.10 M) V1 = (5.0 × 10‾³ M) (50.0 ml) V1 = 2.5 ml (d) 50 mL FeCl3 solution (1.0x 10 ‾³ M) M1V1 = M2V2 (0.10M) V1 = (1.0 × 10‾³ M) (50.0 ml) V1 = 0.05 ml (e) 50 mL FeCl3 solution (5.0x 10 ‾4 M) M1V1 = M2V2

Color after add KCNS Magenta Dark brown Brown Light brown Light peach

(0.10 M) V1 = (5.0 × 10‾4 M) (50.0 ml) V1 = 0.25 mL DISCUSSION: In chemistry, molar concentration also called molarity. Molarity is a measure of the concentration of a solute in a solution. The equation of the molarity is Molarity (M) =

Mole

.

Volume (1 liter/1 dm³ ) M=n/V Normality is measure of concentrations. It is equal to number of gram equivalents of a solute per liter of solution. Equation of normality is: Normality =

Weight of solute in grams

x Volume in liter

Gram equivalent weight In chemistry, concentration is the measure of how much of a given substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of solute in the solvent. While dilution in chemistry is process reducing the concentration of a solute in solution, usually simply by mixing with more solvent. The colorimetric techniques to identify coloured solutions and measure their concentration. Colorimetry relies on coloured solutions absorbing light of a particular wavelength. However the technique can also be used to if

analyse they

colourless substances

react

with a dye.

a

b

c

d

e

In this experiment, before during the dilution process, the volume of the FeCl3 is calculated using the formula M1V1=M2V2. For M1 is concentration of concentrated solution and V1 is the volume of the solution.M2 is the concentration of dilute solution and V2 is volume of dilute solution.

a

b

c

d

e

B )

Before drop KCNS

a

b

c

d

e

B )

After drop KCNS After the volume of the dilute solution already calculate, the dilution process. In this experiment five dilute solution is prepared. We can determine the concentration of the solution according to the colour concentration of the solution after added the KCNS solution

as the indicator. After the KCNs id droped into the all dilute solution the colour of dilute solution is change.

From the observation, the dilution solution (a) change to magenta colour. Dilute solution of (b) Change to dark brown, the dilution solution (c) change to brown, while dilute solution of (d) change to light brown and the dilution solution of (e) change to light peach. The darkest colour of solution it determine as higher concentration. This experiment, we compared the B solution that have been prepared with the five solution, We compared based on the colour of the solution B that have been prepared with the all five solution. From the observation, we can see that the colour solution of B same the colour solution of dilute solution that we have prepared. So, we decided that the concentration of B solution is same. So based on the result we know that, the concentration of B solution is 5.0x10-3M. The precaution during doing this experiment is we must clean the all apparatus by distilled water before use Beside that, we must measure the volume the solution with properly and use the right apparatus. CONCLUSION From this experiment we can know about the molarity, normality and mole concept. We also learn dilution process and use the equation. REFERENCES: Brown, Lemay, Bursten, Murphy,Chemistry the central science, eleven edition. Kotz, Treichel, townsend, Chemistry and Chemical reactivity seventh edition.