Precipitation

Question 1

Precipitation Method is also called ?

Answer 1

Argentometric Titration

Question 2

Volumetric methods based on reactions that yield ionic COMPOUNDS OF LIMITED SOLUBILITY.

Answer 2

Precipitation Method

Question 3

Analyte is titrated with a _____________________________ in the presence of a suitable indicator.

Answer 3

standard solution of a precipitating agent

Question 4

Precipitation Method applies the _______________ principle.

Answer 4

solubility product

Question 5

States that in a saturated solution of an ionic compound, the product of the molar activities (Ksp), has a constant value at any particular temperature and pressure.

Answer 5

Solubility Product Principle

Question 6

Ksp meaning

Answer 6

Solubility Product Constant

Question 7

Determined by

❖ Cessation of precipitation or appearance of turbidity
❖ Instrumental methods (potentiometry)
❖ Use of internal indicators

Answer 7

Endpoint

Question 8

Potentiometry has?

Answer 8

Electrodes

Question 9

Indicators

Answer 9

Colored lon - Volhard Method (Jacob Volhard)

Colored precipitate - Mohr Method (Karl Friedrich Mohr)

Colored Adsorption product - Fajan Method (Kazimiers Fajan)

Question 10

Colored Ion

Answer 10

Volhard Method (Jacob Volhard)

Question 11

Colored Precipitate

Answer 11

Mohr Method (Karl Friedrich Mohr)

Question 12

Colored Adsorption Product

Answer 12

Fajan Method (Kazimiers Fajan)

Question 13

Indicator used in Volhard’s Method

Answer 13

Ferric alum TS

(ferric ammonium sulfate, FeNH4(SO4)2)

Question 14

Arrow up

Answer 14

Evolution of gas

Question 15

Arrow down

Answer 15

Precipitation

Question 16

In colored ion,

Slight excess thiocyanate ion reacts with ferric ion from the indicator producing a ________________ coloration.

Answer 16

faint reddish brown

Question 17

Used in thiocyanate titrations.

Answer 17

Colored Ion

Question 18

Indicator used in Colored Secondary Precipitate

Answer 18

Potassium chromate solution (Kr2CO4)

Question 19

In colored secondary precipitate,

Chromate reacts with excess silver ions forming a secondary precipitate of _______ silver chromate.

Answer 19

reddish

Question 20

Used in the titration of halides with standard silver nitrate solution.

Answer 20

Colored Secondary Precipitate

Question 21

Indicator used in Fajan Method

Answer 21

• Dichlorofluorescein
• Eosin Y (Tetrabromofluorescein)
• TEE - fluorescence (Tetrabromophenolphthalein ethyl ester)

Question 22

Eosin Y chemical name

Answer 22

Tetrabromofluorescein

Question 23

TEE - fluorescence other name

Answer 23

Tetrabromophenolphthalein ethyl ester

Question 24

Used as indicator in the titration of potassium chloride with standard silver nitrate solution.

Answer 24

Colored Adsorption Product

Question 25

In colored adsorption product,

Silver chloride (ppt) formed is negatively charged due to adsorbed chloride ion and the indicator exists in the solution with a ______________.

Answer 25

greenish yellow

Question 26

Direct titration with silver nitrate.

Answer 26

Colored Adsorption Product

Question 27

In colored adsorption product,

slight excess of silver ion is adsorbed by the silver chloride precipitate colloid particles became positively charged which adsorb the fluoresceinate ions forming a __________ adsorption product.

Answer 27

reddish pink

Question 28

The _______________ of a substance in the precipitation method is obtained by dividing the molecular weight by the total valence of the precipitating or precipitated ion

Answer 28

gram-equivalent weight

Question 29

Method of titration if FAS is used as an indicator.

Answer 29

Volhard’s Method

Question 30

What is the endpoint in Mohr’s Method?

Answer 30

Reddish silver chromate

Question 31

Substances assayed:

❖ mainly used for determination of halides (Cl-, Br- & I-), SCN-,CN- and some compounds that form insoluble products (ppt) with AgNO3

Question 32

Volhard Method is (direct/residual)?

Answer 32

Residual

Question 33

Mohr’s Method is (direct/residual)?

Answer 33

Direct