experiment 3

7/17/2019 Experiment 3

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EXPERIMENT III

SYNTHESIS OF POTASSIUM NITRATE

March 17th 2015

A. Objectives

1. Study the synthesis of potassium nitrate salt from the reaction beteen sodium nitrate and

potassium chloride.

2. Study the separation process this salt from sodium chloride by product based on the

differences in solubility.

!. "heoretical !asic

#otassium $itrate is a compound of potassium nitrate salts ith molecular formula

%$O&. #otassium nitrate salts can be prepared by reactin' potassium chloride (%)l* ere

found in the mineral sylvite+ ith sodium nitrate $a$O&. ,f a saturated solution of each of

these reactions are mi-ed ith each other+ it ill form sodium chloride+ $a)l and %$O & as a

solvent solution of $a)l in auadest is very small+ then the salt ill under'o precipitation+

and throu'h filterin' %$O& solution can be separated from $a)l. !y coolin' the filtrate

sloly+ then %$O& ill under'o crystalli/ation process+ and to meet the needs 'enerated

%$O& crystalli/ation (A/i/+ 2007*.

#otassium itself is a soft silverhite metal. "he metal melts at &.5 ). #otassium

remained unchan'ed in dry air+ but uic3ly o-idi/ed in moist air+ it becomes covered ith a

layer of blue. Metals that decompose auadestt ith poerful+ releasin' hydro'en and burned

ith violet flame.

2% 4(a* 4 22O(l* 6 2% 4(a* 4 2O(a* 4 2(a*

#otassium is usually stored in the solvent naphtha. #otassium salts containin'

monovalent cations % 4. "hese salts are usually soluble and form a colorless solution+ e-cept

hen colored anion.

All nitrate dissolves in auadest. Of mercury and bismuth nitrate yield after

treatment ith al3aline salt auadest+ salt is soluble in dilute nitric acid.

(.Svehla+ 1880*

$itric acid and its salts are o-o compounds of nitro'en. "his acid is mainly made from

chan'e of nitro'en in the atmosphere to ammonia. At room temperature+ nitric acid is in the

form of a liuid phase and boils at 9:.1o). #ure acid can ioni/e ;

2$O&(a* 6 $O24

(a* 4 $O&(a* 4 2O(l*

Acid solution ith a concentration of 0.1 M can be ioni/ed almost perfectly (8&<*.

,oni/ation process is idely used in the nitration reaction in some or'anic compounds. "o

accelerate this process+ the acid mi-ed ith sulfuric acid. $ormal solution nitric acid (70 t

<* as colorless and then 'radually chan'ed to yello due to the photochemical yield of $O 2

;

2$O&(a* 6 2$O2(a* 4 = O2('* 4 2O(l*

"he salts can be prepared by reactin' a solution of saturated %)l solution ith saturated

$a$O& accordin' to the euation;

%)l(a* 4 $a$O&(a* 6 $a)l(a* 4 %$O&(a*



!oth of the above reaction can be separated based on solubility properties that differ

si'nificantly from both the salt at a 'iven temperature conditions. "he solubility of the salt

because of the effect of temperature is presented in fi'ure 1.

>i'ure 1. raph of temperatur and solubility of salt

("eam of lectureship inor'anic chemistry+ 2015*

"he factors factors that affect the solubility as follos;

"emperature

"he effect of temperature depends on the heat dissolution. ,f ne'ative+ the dissolution heat

solubility don to temperatures hen heat is positive+ the dissolution of the solubility rises

ith increasin' temperature.

"ype of solute and solventSubstances substances ith a similar chemical structure can 'enerally mi- ell ith each

other+ hile the unusual hard to mi-.

#ressure

#ressure no lon'er affect the solubility of solids and liuids+ but the effect on the solubility

of the 'as.

>unction rea'ents

%)l and $a$O& function serves as a compound to be reacted to obtain potassium nitrate.

A supersaturated solution is a solution menstabil system can be converted into a

saturated solution by addin' a crystal ?seeds? are small (usually crystalline solute* althou'h aforei'n substance can also be successful. "he crystal is a nucleus around hich the e-cess

dissolved solutes can be crystalli/ed

)olorless compounds and al3ali ions rather not reactive. Simple salts such as @i)l+

%$O&+ )a2SO: and b2)O& usually very soluble in ater. Solution of these compounds is a

typical electrolytic (%eenan+ 189:*.

"o understand the ionic bond+ presupposed a $a)l molecules in the vapor phase. At

very lar'e distances beteen the ions formed in ener'etics are $a and )l atoms. ,f the

particles approachin' the chan'es into $a 4 and )l ith the release and bindin' ener'y as

shon in the euation above. ,n addition there is a lar'e electrostatic forces that cause the toions closer to the euilibrium state is reached+ ie the minimum point. ,n the distance beteen

the nuclei very near that role is repulsion beteen similar ions. ,onic crystals formed then



consists of a re'ular arran'ement of positive ions and ne'ative in the crystal lattice (Surdia+

188&*.

). Buipment and Material

Buipment ;

1. !ea3er 100 m@ (2*

2. Bvaporatin' dish (1*

&. lass funnel (1*

:. !ea3er 250 m@ (1*

5. Measurin' 'lass 25 m@ (1*

. Crops pippet

7. !urner methylated

9. Spatula

8. "hermometer

10. Analytical balance11. >ilter papper

12. Stirrer

Material ;

1. #otassium chloride (poder*

2. Sodium nitrate (poder*

&. Auadest

:. >ilter paper

5. ,cecube



C. Dor3 ,nstruction

1* Synthesis of potassium nitrate salt

2* #urification of potassium nitrate crystal

B. esult of observation

1. )olor and structure (solid+ liuid+ 'as* %)l ; hite (solid*+ colorless (aueous*

2. )olor and structure (solid+ liuid+ 'as* $a$O& ; hite (solid*+ colorless (aueous*

&. )olor and structure (solid+ liuid+ 'as* %$O& ; hite (solid*+ colorless (aueous*

:. "he reactions that occur in the e-periment ;

a. %)l(s* 4 2O(l* ∆→ %)l (a*

b. $a$O&(s* 4 2O(l*

∆

→ $a$O&(a*

Auadest 25 m@ heated

$a$O& :+25 'r in 7.5 m@ hot

auadest dissolved

%)l &+75 'r in 7.5 m@ hot

auadest dissolved

Mi-ed (to solution above*+ evaporated in auadest

heater until the volume 10 m@%$O& from $a)l separated by referrin' to fi'ure 1.

"he crystal filtered

A little crystal dissolved ith little of auadest by

heated (2+5 m@*

"he solution cooled+ then the crystal filtered

Dei'h the crystal and counted the percenta'e of product

resulted



c. %)l(a* 4 $a$O&(a*

∆→ %$O&(a* 4 $a)l(s*

d. %$O&(a* Low temperature

→ %$O&(s*

5. Dei'ht of %$O& crystals produced ; 2.198 'r

. )rystal color and structure of %$O& ; hite and rombic crystal

7. "he percenta'e of %$O& yield

Mol of %)l¿3,75

74,5

¿0,05mol

Mol of $a$O& ¿ 4,25

85

¿0,05mol

%)l(a* 4 $a$O&(a* %$O&(a* 4 $a)l(s*

m 0+05 mol 0+05mol 0 0

r 0+05 mol 0+05 mol 0+05 mol 0+05 mol

s 0 0 0+05 mol 0+05 mol

"he mass of %$O& theoretical ¿0,05mol x Mr KNO3

¿0,0501 x 101

¿5,0500 gram

endement ¿ themass of KNO3by experiment

the mass of KNO3by theoretical - 100<

¿2,189

5,05 - 100<

¿43,35

>. Ciscussion

B-periment of synthesis %$O& to 3no the procedure of ma3in' %$O& salt based on

solubility. #rinciple of this e-periment based on diverification of solubility. ,n this e-perimentused crystalli/ation and recrystalli/ation methode. )rystali/ation is separate by crystals

formation. ecrystalli/ation is purification of precipitate.

!ased on manual or3 of inor'anic chemistry practicum+ practicant must do some

treatment. @i3e as heatin'+ evaporatin'+ stirrin'+ coolin'+ and dryin'. B-planation for those

treatment are ;

eatin' up to 10 ml done in order to obtain the volume of $a$O& plus %)l.

Bvaporatin' function that can purify the substance.

Stirrin' function that can be dissolved by the solvent rea'ent homo'eneously.

)oolin' can be crystalli/ed %$O&.

Cryin' are to dry %$O& crystals+ in order to free from solvent.

1) Synthesis of potassium nitate sa!t



At the e-periment e use to salts there are potassium chloride and sodium nitrate to

'et potassium nitrate. %)l and $a$O& mi-ed ith same amount of molles. So e must

prepare %)l &.75 'r and $a$O& :.25 'r. ,n order to %)l and $a$O& used up at balance

condition. !ased on theory+ e 3no %$O& 0.05 mol produced at the reaction. So after

calculated the mass of %$O& are 5.05 'r based on theory.

,f %)l solution react ith $a$O& solution+ so it can product %$O& and $a)l. %)l and

$a$O& in first time are poder (solid*. !ecause of in poder form+ the surface area more and

more bi' area. !i' area can accelerate reaction. De also dillute both of salts ith hot

auadest+ in order to %)l and $a$O& can dillute perfectly. ot auadest 'ood for dillute that

salts than auadest ithout heated. "his be related to temperature.

Dhen practicant dillute $a$O& ith auadest 90o)+ it can dillute. !ut not for %)l+ it

very dificult to dillute %)l. So practicant heat a'ain the %)l. Suitable ith characteristics of

chemistry+ auadest become vapour. ,tEs ma3e %)l become solid more. Add auadest is

solution to handle the problem. So e repeat a'ain to heated until all %)l poder can dillute.

!y loo3 in fi'ure 1 (loo3 theoritical basis* %)l has smaller solubility than $a$O&. So e

need more hi'h temperature to dillute %)l. "he color of both solution is colorless.

"he reaction potassium chloride ith hot auadest and reaction sodium nitrate ith hot

auadest can rite li3e this ;

!ased on that reaction e 3no reaction produce ions. "he poder of %)l become %)l

solution+ and the poder of $a$O& become $a$O& solution.

After become solution+ both salts are mi-ed and heated a'ain. eatin' is to accelerate

reaction. ,ons ill be move very fast+ so the collision produced ma-imally. Bvaporated until

volume become 10 m@. Bvaporatin' are to clean solution from other substance and lostin'

auadest. Auadest ill be lost by fission become O 2('* and 2('*. ,f evaporated until volume

10 m@+ in order to potassium nitrate crystals easily formed.

Separation %$O& and $a)l based on solubility. !y loo3 in fi'ure 1 (loo3 theoritical

basis* %$O& has hi'her solubility than $a)l at temperature F &0o ) . ,f temperature than &0o)

all poder of %$O& ill dillute easily than the poder of $a)l. De 'et precipitate and

filtrate. "he precipitate is $a)l+ and the filtrate is %$O&. @oo3 at this reaction ;

%$O& dillute because of it has more solubility than the solubilty of $a)l. So e can 3no the

phase of them. #otassium nitrate is solution+ but sodium chloride is solid (crystals*. Solution

of %$O& is colorless.

%)l and $a$O& has different shape crystals ith the shape crystals of $a)l and %$O&.

"he shape of $a)l crystals is face center cube (fcc*+ it has hite color. After loo3 thats

different+ practicant can separate them. "hen used only the filtrate of potassium nitrate for

purification.

") Puifi#ation of potassium nitate #ysta!>iltrate of %$O& are heated. >unction heatin' is lostin' other substance hich e-ist in

%$O& crystals. So practicant can 'et result of crystals more purify.

$%!&s) ' H"O&!) ∆→ $%!&a()

$%! a ' NaNO a ∆→ $NO a ' Na%! s



Some nitrate salts are hi'roscropis and easy dissolve in auadestt at hi'h temperature+

included too %$O&. !ut %$O& difficult to dissolved at lo temperature (cold*+ then it can

form crystals. So to 'et crystals of %$O & practicant must put %$O& solution at cold place. De

prepare a ashbasin and put bea3er 'lass hich contain %$O& solution in ashbasin. "hen

pour ice cube in ashbin cover the bea3er 'lass.

De 3no the filtrate of %$O& can formin' crystals by coolin'. !ecause lo

temperature can ma3e %$O& solution become small for solubility+ so it ill be precipitate.

Some minutes the filtrate ill become crystals. "he shape of crystal is rombiue crystals and

the color is hite. )rystals of %$O& 3eep on purified by coolin' continuous. "his do for 'et

crystals many more. @oo3 at this reaction ;

After that crystals must dried+ so e can save the crystals ithout contain auadest.

Sunli'ht or oven can dried crystals.!ased on theory e 3no that the moles of %$O & is 0.05 moles. So the mass of %$O&

is 5.05 'r. !ut practicant only 'et 2.198 'r of %$O & crystals. >rom data e can 3no ho

much rendemen 'et+ there ere :&.&5<. "hat mista3en can occur because ;

a. esidue of %$O& crystals left behind in filter paper.

b. Cisplacement %$O& crystals e-ceedin'ly used many filter paper+ so it can decrease the

mass of crystals.

c. Bvaporatin' or coolin' are not ma-imal.

. )onclusion

1. Synthesis of potassium nitrate salt can occur from the reaction beteen sodium nitrateand potassium chloride. "he reaction are ;

a* %)l(s* 4 2O(l* ∆→ %)l(a*

b* $a$O&(s* 4 2O(l* ∆→ $a$O&(a*

c* %)l(a* 4 $a$O&(a* ∆→ %$O&(a* 4 $a)l(s*

d* %$O&(a* Low temperature

→ %$O&(s*

2. Separation process this salt (%$O&* from sodium chloride by product based on the

differences in solubility. %$O& has bi' solubility at temperature F&0o) than solubilty

of $a)l. So e can separate both hen %$O & at aueous phase and $a)l at solid

phase.

&. "his e-periment use crystalli/ation and recrystalli/ation methode.

:. "he crystals of %$O& is rombiue.

5. endement of %$O& crystals is :&.&5<.

. Su''estion

1. ConEt over and over hile displacement %$O& crystals.

2. "he temperatur of auadest for dillute %)l ≥ 100o)+ so %)l can dillute perfectly.

Low temperature



,. efference

A/i/+ ". 2007. #enuntun #ra3ti3um %imia Anor'ani3 Gurusan %imia. %endari; Hniversitas

aluoleo.

,nor'anic )hemistry @ecturer "eam. 2015. Manual Dor3 of ,nor'anic )hemistry #racticum.

Semaran' ; H$$BS.

%eenan. 189:. %imia Hntu3 Hniversitas. Brlan''a ; Ga3arta.

Surdia + Mansdsjoertah. 188& . ,3atan dan Stru3tur mole3ul . !andun' ; ,"! #ress.

Svehla+ . 1880. Io'el !u3u "e3s Analisis Anor'ani3 %ualitatif Ma3ro dan Semimi3ro.

!a'ian 1 dan 2 Bdisi 3elima. Ga3arta; #". %alman Media #usta3a.

experiment 3

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