Nephlo Flame

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Expt.No:

Date:

NEPHELOMETRY

Aim: To determine the turbidity of given solution using Nephelometer.

Theory: Turbidity is an expression of the optical property of a sample

which causes the light to be scattered and absorbed rather than

transmitted in straight line through the sample. Scattering is elastic so

that both incident and scattered light have same wave length. Turbidity is

caused by the presence of suspended matter as a dispersant in the liquid.

The intensity of the perpendicularly polarized

component of scattered light and parallel polarized component of

scattered light are functions of the relative refractive index, the size

parameter, the angle of observation as well as the concentration of

dispersant. Light scattering theory is based on tyndall effect also known

as Rayleigh’s scattering.

Principle: At low concentration of a suspension, there is uniform

scattering. Hence the intensity of scattered light is proportional to the

concentration.

Is α [C]

Apparatus Required: Nephelometer

Instrumentation: The main components of nephelometer are

1. Source of light

2. Filters and monochromators

3. Sample cells

4. Detectors

Nephelometer, consists of tungsten lamp as a source of light

and the sample cell is placed on top of light source passing through the



filter falls on suspended particles. These particles scattered the light. The

light by the particles are collected by the curve mirrors and reflected to

the photo voltaic cell kept at the bottom of the instrument.

Applications Of Nephelometry: Nephelometer is used

1. Control of potable water

2. Monitoring the quality of raw water & products in food industry

3. Assessing suitability of boiler feed & industrial process water

4. Water pollution analysis

5. Measurement of concentration of sediments in waste water

6. Estimation of transparency of beer, alcoholic beverages, fruit juices

and various products of pharmaceutical and chemical industries.

7. Estimation of concentration of insoluble substance in liquid.

Expt.No:



Date:

ESTIMATION OF SULPHATE

Aim: To estimate the amount of sulphate present in the given sample by

Nephelometry.

Phenomenon In The Dispersant: The turbidity of a dilute BaSo4

suspension is difficult to produce. So, the velocity of precipitation as well

as the concentration of reactants must be controlled by adding pure

BaCl2. The rate of solution of BaCl2 controls the chloric acid solution in

order to inhibit the growth of micro crystals of BaSo4 .Optimum pH

minimizes the effect of variable amounts of other electrolytes present in

the sample. A glycerol alcohol solution stabilizes the turbidity. The

mixture should be shaken gently in order to obtain the uniform particle

size.

Requirements: Nephelometer, test tubes

Reagents:1. STANDARD SULPHATE SOLUTION: Dissolve 1.814g of dry

potassium sulphate in distilled water dilute to 1 litre in a graduated

volumetric flask. This solution contains 1.000 mg of sulphate ion per ml

that gives 1000 ppm.

2. SODIUM CHLORIDE – HYDROCHLORIC ACID REAGENT:

Dissolve 60 g of sodium chloride in 200 ml of distilled water, add 5 ml of

pure concentrated hydrochloric acid and dilute to 250 ml.

3. SOLID BARIUM CHLORIDE: 0.3g (for each tube)

4. GLYCEROL – ETHANOL SOLUTION: Dissolve 1 volume of pure

glycerol in two volumes of absolute ethanol.

Procedure:



1. Pipette out 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 ml of standard potassium

sulphate solution into a series of separate 100ml volumetric flask.

2. Test solution was taken into a separate 100 ml volumetric flask.

3. To each flask 10 ml of sodium chloride – hydrochloric acid reagent and

20 ml of the glycerol – ethanol solution were added and diluted to 100ml

with turbidity free distilled water.

4. 0.3 gm of barium chloride was added to each flask and mixed

thoroughly.

5. Allowed each flask to stand for 2 or 3 min and transfer. The contents of

each numbered test tubes.

6. In a separated flask, blank was prepared by adding 3ml of turbidity free

distilled water and performed the steps 2, 3 and 4. Blank was transferred

into a separate marked test tube.

7. The blank filled test tube was kept on the sample compartment and

calibrated to

zero.8. The blank was replaced with the 0.5ml reference standard solution.

9. The same was repeated for 1.0, 1.5, 2.0, 2.5, 3.0ml and unknown test

tubes and readings were noted.

10. A graph was plotted by taking concentration of standards on x-axis

and turbidity (NTU) on y-axis.

Precautions:1. Solutions should have uniform turbidity size of the particles should be

equal to or greater than the wavelength of the incident light.

2. Wavelength of the incident light should not absorb the light but only

scatter the incident light.

3. Refractive index of the particles and the medium should be

different.K 2So4



Observations:

S.

No

.

Standar

d K 2So4

solution

(ml)

NaCl-HCl

reagent(ml

)

Glycerol

-ethanol

solution

(ml)

Barium

chloride(g

)

Total

volum

e (ml)

Turbidit

y

1 Blank 10 20 0.3 100

2 0.5 10 20 0.3 1003 1.0 10 20 0.3 100

4 1.5 10 20 0.3 100

5 2.0 10 20 0.3 100

6 2.5 10 20 0.3 100

7 3.0 10 20 0.3 100

8 Test 10 20 0.3 100

Calculation:

Unknown concentration = Unknown samples NTU

Standard NTU (mg/ml) x Standard

concentration

Result: The amount of sulphate present in the given sample was

estimated as………NTU



Expt.No:

Date:

FLAME PHOTOMETRY

Introduction: Flame photometric analysis method is more or less

similar to that of spectrophotometry, with the exception that a flame is

used instead of sample cell. By this technique, the absorption or emission

of specific wavelengths by excited atoms can be measured.

Flame photometry is of 2 types

1. Emission flame photometry

2. Absorption photometry

Principle: Volatilization of molecules in a flame produces free atoms

and then excites them to higher energy levels. The characteristic emission

spectrum of the element is produced when excited atoms return to their

ground state. This is a principle behind the emission flame photometry.

Since the transitions available to the electrons in any given atom are

specified by the available energy levels. The atomic spectra are specific

for the element involved. Moreover, the energy absorbed or emitted is

proportional to the number of atoms in the given path. Thus, flame

photometry provides us identify and quantify of elements present. The

amount of energy depends on temperature and composition of flame. It is

therefore very necessary that the two flame variables must be kept

constant.

Instrumentation: The basic components are of flame photometry are

1. Nebulizers or atomizers

2. Flame

3. Monochronators



4. Photo cells

Applications:



1. Food and agriculture: To determine Ca and K content in soils, plant

material, food and beverages.

2. Medicine: Na, K, Li electrolytes in serum.

3. Mining and metallurgy: Alkali and alkaline earth metals.

Expt.No:

Date:



ESTIMATION OF SODIUM BY FLAME

PHOTOMETER

Aim: To determine the concentration of sodium by using flame

photometry.

Requirements: 1. Flame photometer

2. Sodium filter

Reagents:

1. Stock Standard Solution: The stock standard solution is weighing

accurately 2.542g of quality sodium chloride and transfers it into a 1 liter

volumetric flask. Add double distilled water to the flask, dissolve the

crystals and make up the solution to the mark with double distilled water.

This stock standard contains 1000 ppm of sodium.

2. Working Standard Solution:

The stock standard solution is successively diluted further with

double distilled water to have working standard solution of lower

concentrations of 20, 40, 60, 80 and 100 ppm of sodium.

Principle:

When sodium solution enters the flame chamber, the solution evaporates

and leaves the residue. The Na ions were excited by the thermal energy of

the flame of higher energy levels. These excited Na ions radiate energy,

which were passed through the specific filter designed for Na. These

radiations were detected by the detector to give the digital display of

concentration.

Procedure:

1. Samples of 0, 20, 40, 60, 80 and 100 ppm and an unknown

concentration were taken in test tubes numbered from 1-6. All the test

tubes were made to equal volumes by adding distilled water.



2. Various samples including the unknown were fed at the capillary tube

of the flame photometer. The solution was sucked into the chamber.

3. The solvent was evaporated and Na ions were excited to higher energy

state and the radiation was detected by the photocell of the detector.

4. The concentration was displayed on the display.

5. A graph was plotted by taking concentration of samples (in ppm) on x-

axis vs. emitted radiation on y- axis and obtained a straight line.

Result:

Precautions:

Nephlo Flame

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