Question

Write everything about titration and salt analysis.

Tomorrow is my lab practical!!

Answer 1

there's nothing to worry about because i will help you out.

first of all starting with titration.

what is titration?

the process of titration is carried out to find the volume of one solution required to react completely with a certain volume of solution of some other substance.

now, here is one experiment based on determining the strength of the given sodium hydroxide solution. Provided M/20 oxalic acid solution.

what i just wrote has to be written in the aim.

theory:

the sodium hydroxide solution is taken in the burette and a known volume of oxalic acid solution ( asy 20 ml ) has got to be taken in the titration flask. the titration is carried out by using phenolphthalein as indicator.

chemical equation:

COOH-COOH (aq) + 2NaOH (aq) → COONa-COONa (aq) + 2H2O (l)

indicator: phenolphthalein

end point: colorless to pink

procedure:

• take a burette and wash it with water.
• rinse and then fill the burette with the given sodium hydroxide solution till the meniscus point 0. Clamp it vertically in burette stand.
• rinse the pipette with the given oxalic acid solution.
• pipette out 20 ml of the oxalic acid solution in a clean titration flask.
• add 1-2 drops of phenolphthalein indicator into it and place it just below the nozzle of the burette.
• write the initial reading of burette to be 0.
• now run the NaOH solution dropwise and swirl the titration flask. Keep doing it until pink color is permanently obtained.
• now, record the reading at the point the solution turns pink. It would be 20 ml ( approx ) as well. ( at this point the solution gets neutralized i.e NaOH and oxalic acid neutralize each other. when more drops are added the solution turns pink indicating that the solution has now turned basic in nature. )

• repeat this procedure until three concordant readings are obtained.

observations:

1. molarity of the given oxalic acid solution = M/20
2. volume of oxalic acid taken for each titration = 20 ml

( IRB = s.no. | initial reading of burette )

( FRB = final reading of burette )

( vol. NaOH = volume of the sodium hydroxide solution used )

s.no. | IRB | FRB | vol. NaOH

1. | 0 ml | 9.8 ml | 9.8 ml

2. | 9.8 ml | 19.8 ml | 10 ml

3. | 10 ml | 19.9 ml | 9.9 ml

concordant volume - 10 ml ( mean )

calculations:

one mole of oxalic acid reacts with two moles of sodium hydroxide.

(V oxalic × M oxalic )÷ ( V NaOH × M NaOH ) = stoichiometric coefficient of oxalic acid/ stoichiometric coefficient of NaOH

molarity of given oxalic acid solution = M/20

(20 × 1/20) ÷ ( 10 × M NaOH ) = 1/20

M NaOH = 2/10 mol L^-1

strength of NaOH in g/L = molarity × molar mass

2/10 × 40 = 80/10 g/L

result:

strength of NaOH in g/L = 8 g/L

precautions:

• be careful at the time of taking reading which should not vary much.
• handle carefully all the solutions and take as much as required.
• handle all the apparatus carefully.
• do not blow out drop of solution at the end.

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this was all about titration.

let's start with salt analysis.

→ Carbonate test:

you will be given a salt and your aim would be to find out the acid radical in the given salt.

first you will start by doing the indicatory test.

salt + dil. H2SO4 → you will observe colorless, odourless gas with brisk effervescence. → CO3^2- may be present.

now you will proceed to the confirmatory test.

for this you will have to mix salt and water in a test tube.

you will divide this O.S in two test tubes.

in the 1st test tube:

O.S + dil.HCl → you will observe brisk effervescence → CO3^2- will be confirmed.

in the 2nd test tube:

O.S + MgSO4 (aq) → you will observe white ppt. or precipitate → CO3^2- will be confirmed.

Result:

the given solution contains acidic radical carbonate CO3^2-

now, it is important to write the chemical equations for it.

for example-

1.

CaCO3 + 2HCl → Cacl2 + CO2 + H2O

if you pass this CO2 through Ca(OH)2 it will turn white.

2.

this second confirmatory test is done with soluble carbonates only.

we know that Na2CO3 is soluble so,

Na2CO3 + MgSO4 → MgCO3 ↓ + Na2SO4

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god bless..

half answer in next answer

word limit exceeded.

Answer 2

→ Sulfide ( S^2- test )

you will be given a sulfide salt and your aim would be to identify the acid radical in the given salt.

you will have to do the indicatory test first.

salt + dil H2SO4 → you will observe rotten egg like smell → which indicates that S^2- gas may be present.

now, you will have to do the confirmatory test.

for this you will have to mix the given sulfide salt with water. Then it must be divided into two test tubes.

1st test tube: ( lead acetate test )

O.S + acetic acid + lead acetate sol. → a black ppt. would be observed by you → confirming presence of S^2-

2nd test tube: ( sodium nitroprusside test )

O.S + sodium nitroprusside → you will observe purple coloration → confirming presence of S^2-

result:

the given salt contains acid radical S^2-

as i wrote before it is important to write chemical equations so i will write them again for this test.

1st test: ( lead acetate test ) ( confirmatory )

Na2S + (CH3COO)2Pb → PbS + 2CH3COONa

2nd test: ( sodium nitroprusside test )

Na2S + Na2[Fe(CN)5NO] → Na4[Fe ( CN )5 NOS]

→ Sulfide ( S^2- test )

you will be given a sulfide salt and your aim would be to identify the acid radical in the given salt.

you will have to do the indicatory test first.

salt + dil H2SO4 → you will observe rotten egg like smell → which indicates that S^2- gas may be present.

now, you will have to do the confirmatory test.

for this you will have to mix the given sulfide salt with water. Then it must be divided into two test tubes.

1st test tube: ( lead acetate test )

O.S + acetic acid + lead acetate sol. → a black ppt. would be observed by you → confirming presence of S^2-

2nd test tube: ( sodium nitroprusside test )

O.S + sodium nitroprusside → you will observe purple coloration → confirming presence of S^2-

result:

the given salt contains acid radical S^2-

as i wrote before it is important to write chemical equations so i will write them again for this test.

1st test: ( lead acetate test ) ( confirmatory )

Na2S + (CH3COO)2Pb → PbS + 2CH3COONa

2nd test: ( sodium nitroprusside test )

Na2S + Na2[Fe(CN)5NO] → Na4[Fe ( CN )5 NOS]

→ sulfite (SO3^2-) test:

you'll be given sulfite salt and your aim would be to find out the acid radical of the given salt.

for this you will have to first do the indicatory test:

salt + dil. H2SO4 → you will observe a pungent smell. → SO3^2- may be present.

confirmatory test:

for this test you will have to mix water with the given salt. Then it has got to be divided into two test tubes.

1st test tube : ( BaCl2 test )

O.S + BaCl2 (aq) → you will observe a white ppt. → SO3^2- will be confirmed.

2nd test tube: ( potassium dichromate test )

O.S + K2Cr2O7 + dil.H2SO4 → you will observe green coloration → SO3^2- will be confirmed.

result:

the given salt contains acid radical SO3^2- or sulphite

Na2SO3 + H2SO4 → Na2SO4 + H2O + SO2 ( indicatory test )

( confirmatory tests )

Na2SO3 + BaCl2 → BaSO3 + 2NaCl

BaSO3 + 2HCl → BaCl2 + H2O + SO2

Na2SO3 + K2Cr2O7 + 4H2SO4 → K2SO4 + Cr2(SO4)3 + 3Na2SO4 + 4H2O

→ Nitrite ( NO2- ) test

we will first start up with the indicatory test.

salt + dil.H2SO4 → brown fume is observed → NO2- may be present.

we will now do the confirmatory test.

for this we will mix the given salt with water and divide it into two test tubes.

test tube 1: ( ferrous sulphate test )

O.S + acetic acid + FeSO4 → dark brown color → NO2- confirmed

test tube 2: ( potassium iodide test )

O.S + Dil.H2SO4 + KI sol. + starch sol. → blue coloration → NO2- confirmed

result:

the given sol. contains acid radical NO2-

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good life...!!