experiment of distillation and hardness of water

ABSTRACT

The distillation is the process of common purification for liquids. Home tap water will be distillated and will compare with the hardness of the non-distille d tap water to determine the effectiveness of the distillation procedure. When doing the distillation, the boiling range for collected sample of temperature was taken, this is around 68!. The standardi"ation of the #$T% solution is added of #riochrome &lack T indicator. The #$T% solution must be the fresh solution one, to ensure that the e'periment was successful. When doing the titration part, make sure that dropwise of the titrant is added to the solution before the endpoint. (t is to make sure that to prevent the overshoot of the endpoint. The average concentration of the #$T% solution is ).*8+8. The hardness of water is determined b the titration of lab tap water, lab distilled water, deioni"ed water and ).  /a!l. The water sample can be classified b the hardness 0soft1 and also hardness 0medium1. The hardness 0soft1 is from lab tap water, lab distilled water, home tap water and deioni"ed water. eanwhile, for the hardness 0medium1 is onl ).  /a!l.

OBJECTIVE

. To purif water sample b distillation. +. To standardi"e #$T% solution. 2. To analses hardness of water samples b titration with #$T%.

INTRODUCTION

(n this e'periment, we will carr out about distillation process. The home tap water has been distilled and then the hardness of the non-distilled tap water are compared to that of the distilled tap water to determine the effectiveness of the distillation process, which is been used the titration to determine the hardness of water sample. Water containing high concentration of !a +3, g+3, 4e+3, or 4e 23 ion is called hard water. !a+3 and g +3 are the most common sources of hardness in water. !alcium ion and magnesium ions react with soap to form a precipitate when sticks to stinks, bathtubs, and fabrics. The can form large amounts of insoluble calcium carbonate, magnesium carbonate, and iron 0(((1 carbonate when heated and form scale inside pipes, tea kettles and water heaters. 5cale build up can impede water

flow. Water softening using ion e'changers can remove the hard water ions to produce soft water. 5oft water produced b ion e'changers contains sodium ion 0/a31 instead. %bout distillation process, it is the most used technique for the purification of liquids. The liquid is placed in a distilling flask and is heated to its boiling point. The vapour those, leaving behind higher boiling impurities still in the flask are passed along a condenser which condenses the vapour back to liquid form and is collected in a different flask. 7ow boiling impurities can also be separated similarl. &oiling will happen when the vapour pressure of a substance equals the confining pressure. /ormal boiling point occurs when the confining pressure equals the atmospheric pressure. Hard water can be softened b other methods such as b ion e'change. When hard water is passed through a home water softener, the calcium and magnesium ions in the water are replaced b sodium ions. (n other cation e'change resins, the cations in the sample are replaced b the hdrogen ions while the anion e'change resins, replace the anions in the sample with hdro'ide or chloride ions. (f both hdrogen and hdro'ide resins are used, the ielded hdrogen and hdro'ide ions reacts with each other to produce water i.e. deioni"ed water. $eioni"ed water is more superior to distilled water. (n this e'periment, the total amount of calcium and magnesium in water is determined b titrating with a standard solution of ethlenediamine-tetraacetic acid 0#$T%1. Hardness is more commonl e'pressed in units of ppm rather than molarit because of the low concentration value of these ions.

PROCEDURE A. Distillation of the Home Tap Wate . % tpical distillation apparatus is illu strated and was refe rred to the figur e as a guide

to assemble the distillation apparatu s. The +*) m7 round bottom flask is used for the distilling flask and a +*) m7 conical flask for the receiver to collect the distillate. The apparatus was clamped adequatel and at strategic places to avoid breakages. +. The distilling flask was fill ed abou t two thirds with home tap wate r. % couple of boiling chips is added to the flask to prevent bumping and the tap is turned on. The water flows uphill was checked in the condenser and the mercur bulb of the thermometer also has been checked it is lower than the unction of the condenser with

the distillation column. The &unsen flame is carefull turned on and it was started heating the distillation flask. When boiling occurs, condensatio n is followed and was started to collect water in the receiving flask. While waiting for the distillation process, the titration for standardi"ing the #$T% has been set up. 2. The first +) drops or so of the dis tilled water collected was disc arded as the might contain volatile impurities and the impurities form the distillation glassware. The temperature on the thermometer was read as soon as it was started to collect  m7 of the distillate. The distillation process is continued and was kept a watch on the distilling the flask so as not to let it dr. The flame is turned off when have collected enough of the distillate or before the sample flask is dried. The temperature is recorded when stop the distillation. B. Stan!a!isation of the ED TA sol"tion . % *) m7 burette is cleaned and the insides were rinsed with distilled water. The stopcock

was opened and drained completel into a 9waste: beaker. The burette was ensured clean and there are no ;reagent spot< in the interior. 4inall the burette was rinsed with the #$T% solution and it was discarded. +. The #$T% solution was pou red into the burette be ond the "ero mar k, and it was made sure to close the burette valve earlier. The burette was attached to a burette stand and was checked to make sure that there is no air bubble trapped in the tip of the burette. When there is presence of air bubble, the bubble was removed b full turning the stopcock 26)=. The force of the solution coming out from the burette is now strong enough to

push

the bubble out. %fter the bubble was removed, the initial reading is adusted. (nitial reading does not have to be at ) and does not waste time tring to bring the level e'actl to the ) m7 mark. The outside of the burette tip was wiped to remove b adhering liquid there. 2. +*.) m7 aliquots of the pre pared standard !a

+3

solution has been pipette and transferred

to a +*) m7 conical flask. The concentration of the !a!> 2 prepared is recorded in the lab notebook. ?. 8 m7 of pH ) ammonia-ammonium chloride buffer, * m7 of distilled water and 2 drops of #riochrome &lack T indicat or were added into the flask. The solution should be of red wine colour initiall and does not added too man drops of the indicator since this can create problems with seeing the end point. The sample is immediatel titrating with the #$T% solution against a white background until the red solutions turns to sk blue. The volume of the burette at the end point was recorded and the process was repeated with at least two more samples.

The above reaction mi'ture will evaporate /H

2

to some e'tent. This changes the pH of

the solution. (t is therefore advisable to carr out the titrations quickl but carefull. The faster the titrations are done, the better the results will be. However, be careful not to overshoot the endpoint due to e'cessive haste. (n an titration it is a good practice to sacrifice one sample solution to perform a rough titration. This is to determine the appro'imate endpoint and to observe the colour change. (n the ne't subsequent titrations, dropwise or @ drop is added at a time of the titrant to the solution in the conical flask about 2 or ? m7 before the endpoint. C. Ha!ness of Wate Water hardness is determined b titration on lab tap water, lab distilled water, deioni"ed

water, home tap water, distilled home tap water and a ).  /a!l. . The burette was filled up with more #$T% solution. +. % +* m7 pipette with tap water an d pipette +*.) m7 o f lab tap wate r were rin sed into a +*) m7 conical flask. The content of the pipette has been empt into the flask, and the last drop off is touched b touching the tip of the pipette onto the interior wall of the flask. The remaining liquid in the pipette does not blow into the flask as this are deliver more than +*.) m7. 2. 8 m7 of the ammo nia-ammonium chloride buffer and 2 drops of #riochrome &lack T were added into the water sample in the flask. The initial burett e reading was recorded to the nearest ).) m7. The stopcock of the burette is turned to release the standard #$T% solution into the water sample in the flask. The rate of releasing the #$T% solution has been slowed down into the flask when the blue coloured solution is formed. (f the calcium and magnesium in the sample has e'hausted, the solution is turned into blue colour. The titration is stopped and the final reading has been taken. The titration is repeated with another two more lab tap water samples. ?. The inside of a +*.) m7 pipe tte is rinse d with disti lled water. % little bit of lab distilled water was obtained using rubber filler. The filler is removed, tilted and rotated the pipette to rinse the inside of the pipette with the distilled water. The tainted distilled water is discarding. +*.) m7 of fresh distilled water is pipette into a clean dr conical flask 0rinsing with distilled water is adequate1. &uffer and indicator were added as above and titrate with the standardi"ed #$T% solution to the endpoint and the process was repeated. *. The pipette was rins ed wit h home tap wat er or an unkn own available. +*. ) m7 of the unknown is pipette into a clean flask. &uffer and indicator were added and it was titrate with the standardi"ed #$T% solution.

RESU#TS A. $. %. &.

Distillation of Home Tap Wate Temperature at the start of collecting the distillate A 2? =! Temperature at the end of collecting the distillate A )+ =! #'perimental boiling range for collected sample A 68 =!

+3 sol"tion B. a!isation of the ED TA . Stan! !oncentration of standard !a solution A ).  +3 +. Bolume of the standard !a solution A +*) m7

Cough 4inalreadingof#$T%solution0m71 (nitialreadingof#$T%solution0m71 Bolumeof#$T%solution0m71

D. *).) ?+.E

 D. *).) ?+.E

+

2

-

-

-

-

C. Ha!ness of Wate $. !oncentration of #$T% A ). 

Watersample

7abtapwater

7ab distilled

4inal reading of standard #$T% (nitial reading of standard #$T% Bolofstandard#$T%used0m71 Bolofwatersample0m71 F!a+3 3 g+30mol71 G Hardness0ppm1

?E.D m7 *).) m7 ).2)m7 +*m7 DI) -? D)).8

$eioni"ed

). 

water

/a!l

water ?*.* m7 2*.6 m7 28.) m7 ?E.D m7 ?*.* m7 ?*.* m7 ?.+m7 E.Em7 D.*m7 +*.)m7 ).)m7 +*.)m7 ).)E8 ).+2)8 .D*I)-6 E8)8 *DD*) D?E6

CA#CU#ATIONS 'OR STANDARDISATION O' THE EDTA SO#UTION !oncentration of standard !a+3 solution A ).  Bolume of the standard !a+3 solution A +*) m7 To calculate the number of moles of !a+3 A olarit of !a +3 I Bolume of !a+3 A ).  I +*I) -2 7 A +*I) -2 moles

When,  mol of !a+3 A  mol of #$T% Therefore +*I) -2 moles of !a+3 A +*I)-2 moles of #$T% 4or the roughl calculation, the volume of #$T% used is ?+.E m7

olarit of #$T%

A

Number of moles of EDTA Volume of EDTA −3

25 × 10

A

moles −3 L

42.9 × 10

A ).*8+8  Therefore, the average of concentration of #$T% is ).*8+8 . 'OR HARDNESS O' WATER i.

#a( Tap Wate /o of mole of #$T%

A olarit of #$T% I Bolume of #$T% A ).*8+8  I 2I) -? 7 A .D*I)-? moles  mol of #$T% A  mol of !a+3 and g+3 .D*I) -? moles of #$T% A .D*I)-? moles of !a+3 and g+3

5o, the calculation for F!a+3 3 g+3G

A

Number of Moles Volume −4

1.75 × 10

A

moles L

−3

25 × 10

A DI) -?  eanwhile, the calculation for the hardness 0ppm1 ass of !a!>2 A /umber of mole of !a!> 2 I olar ass

Jpm 0wv1 A

A .D*I)-? moles I )).)E gmol A ).)D*+ g Weight of the solute 6 × 10 Volume of the solution 0.01752 g

A

25 mL

6

× 10

A D)).8 ppm Therefore, it is hardness 0soft1 ii.

#a( ! istille! ) ate /o of mole of #$T%

A olarit of #$T% I Bolume of #$T% A ).*8+8  I ?.+I) -2 7 A +.?*I)-2 moles

When +3  mol of-2#$T% A  mol of !a+3 and g +.?*I) moles of #$T% A +.?*I)-2 moles of !a+3 and g+3

5o, the calculation for F!a+3 3 g+3G

A

Number of Moles Volume −3

2.45 × 10

A

25 × 10

moles L

−3

A ).)E8  eanwhile, the calculation for the hardness 0ppm1 ass of !a!>2 A /umber of mole of !a!> 2 I olar ass A +.?*I)-2 moles I )).)E gmol A ).+?*+ g

Jpm 0wv1 A

Weight of the solute 6 × 10 Volume of the solution 0.2452 g

A

6

× 10

25 mL

A E8)8 ppm Therefore, it is hardness 0soft1. iii.

Deioni*e! )ate /o of mole of #$T%

A olarit of #$T% I Bolume of #$T% A ).*8+8  I E.EI) -2 7 A *.DDI)-2 moles

When  mol of #$T% A  mol of !a+3 and g+3 *.DDI) -2 moles of #$T% A *.DDI)-2 moles of !a+3 and g+3

5o, the calculation for F!a+3 3 g+3G

A

Number of Moles Volume −3

A

5.77 × 10 moles −3 25 × 10 L

A ).+2)8  eanwhile, the calculation for the hardness 0ppm1 ass of !a!>2 A /umber of mole of !a!> 2 I olar ass A *.DDI)-2 moles I )).)E gmol A ).*DD* g

Jpm 0wv1 A

Weight of the solute 6 × 10 Volume of the solution 0.5775 g

A

10 mL

× 10

6

A *DD*) ppm Therefore, it is hardness 0soft1 i+.

,.$ - of NaCl /o of mole of #$T%

A olarit of #$T% I Bolume of #$T% A ).*8+8  I D.*I) -2 7 A ?.2DI)-2 moles

When  mol of #$T% A  mol of !a+3 and g+3

?.2DI) -2 moles of #$T% A ?.2DI)-2 moles of !a+3 and g+3

5o, the calculation for F!a+3 3 g+3G

A

Number of Moles Volume 4.37 × 10

A

−3

moles L

−3

25 × 10

A .D?8I) -6  eanwhile, the calculation for the hardness 0ppm1 ass of !a!>2 A /umber of mole of !a!> 2 I olar ass A ?.2DI)-2 moles I )).)E gmol A ).?2D? g

Jpm 0wv1 A

Weight of the solute 6 × 10 Volume of the solution 0.4374 g

A

25 mL

6

× 10

A D?E6 ppm Therefore, it is hardness 0medium1 DISCUSSION 4rom the first purpose of this e'periment is the purification of the water sample b

distillation, which is to separate the substances and as such can be used for water purification. The e'perimental boilin g range for collected sample is about 68! and the water sample was kept for the other procedure. 4or the second obectives is to standardi"e #$T% solution. We are using ).  of concentration of standard !a +3 solution and the volume of it is +*) m7. When we are alread finished the pipetting, we get the results of the volume of #$T% solution that we are used which is ?+.E m7. eanwhile, the average concentration of #$T% solution as we have been calculated is ).*8+8. To analse the hardness of water samples b titration with #$T% is the last purpose of this e'periment. %s ou can see at the table data, about four water sample than si' we are doing when conduct the e'periment which is lab tap water, lab distilled water, deioni "ed water and lastl ).  of /a!l. We do not have the water sample of home tap water and also distilled home tap water because we are conducting the e'periment in the laborator room. The total amount of !alcium ion and agnesium ion that react with the #$T% solution in lab tap water is DI) -? mol7 and their hardness is D)).8 ppm. The water hardness is ver hard because the theoretical value for ver hard water is more than or equal to ?*) ppm. /e't, for the lab

distilled water, the amount of concentration of !alcium ion and agnesium ion is about ).)E8 mol7. The hardness of water is also ver hard, which is E8)8 ppm. %bout ).+2)E mol7 of concentration of !a

+3

and g +3 and the amount of their hardness is *DD*) ppm for

water samples of deioni"ed water. 7as tl, ).  of /a!l was done b calculate its concentration of !a

+3

and g +3, .D*I) -6 mol7, hence their hardness of water is ver

hardness which is about D?E6 ppm. The hardness is divided b two parts, which is soft and also medium. 4or hardness 0soft1, it is include lab tap water, lab distilled water, home tap water and deioni"ed water. Hence, ).  /a!l is for hardness 0medium1. %s a student, ( have found that some errors while doing the e'periment b us which is when reading the scale of the liquid inside the pipette. %fter that, mabe we are put an e'tra drops of titrant to the solution which is to prevent the overshoot of the endpoint, frequentl wash the sides of the flask and the burette tip to ensure all the titrant has gotten into the solution in the flask. /ot even that, the #$T% solution that we are used must be not e'posed to the air and it was made sure that the solution is alwas closed. The #$T% solution also must be in a fresh solution, not the old solution one. CONC#USION %s a conclusion, the purification water sample b distillation was achieved. /e't, the average

value of standardi"e the #$T% solution is ).*8+8 . 7astl, the analse hardness of water samples b titration with #$T% is hardness 0soft1 include lab tap water, lab distilled water, deioni"ed water and the hardness 0medium 1 is include ). /a!l, which is their hardness is around D)).8 ppm, E8)8 ppm, *DD*) ppm and D?E6 ppm. RE'ERENCES . %nonmous, 0n.d.1. $etermination of Hardn ess of Water. Cetrieved on %pril +*,+)6

from

website

httpKchemistr.bd.psu.eduircitanoWater)*.pdfhttpKchemistr.bd.psu.eduircitanoWat er)*.pdf +. Laithersburg, $., 0n.d.1. $istilled Bs. Jurified Water. Cetrieved on %pril +6,+)6 from website httpKwww.drinkmorewater.comdistilled-or-purified-water 2. %naltical !hemistr slides notes. ?. %naltical !hemistr 7aborator manual. *. %ristotle. 9eteorolog M &ook ((: 0J$ 41, The Nni versit of %de laide. Cetrieved on %pril +D, +)6.

UESTIONS . Wh should the water in the condenser flow uphill during distillationO The flowing of water should be flow uphill during distillation to prevent the condenser •

from becoming too hot on its inner surface. When the condenser become too hot, the distillate will escape as a vapour from the sstem. +. !ompare the har dness between 0i1 lab tap wate r and lab disti lled water and 0ii 1 home tap

•

water and home distilled tap water. $id the distillation have a significant effect on the water hardnessO #'plain our answer. 7ab tap water is more hardness than lab distilled water. eanwhile, for home tap water it is more hardness than home distilled tap water. $istillations have significant effect on the water hardness. $istillation process will remove the impurities in the water, so distilled water and home distilled tap water is clean because it does not contain impurities.

2. Water with hardness in th e range ) M 6) ppm is te rmed soft, 6) M +) ppm med ium hard, +) M 8) ppm hard and above 8) ppm ver hard. !lassif the water samples that ou • •

analsed in this e'periment. Hardness 0soft1K 7ab tap water, 7ab distilled water, Home tap water, $eioni"ed water. Hardness 0medium1K ).  /a!l

?. $o ou think the re should be a correlation between conductance and hardn ess resultsO •

#'plain our answer. !onductivit will have a large concentration to the water hardness because concentrat ion of calcium is easier to measure than the calcium ion concentration. The conductivit combustion due to the sodium can be subtracted from the total observed electrolte conductivit.

*. 5uggest an was ou can think of to improve an part0s1 of this e'periment. 4or the part !, the hardness of water, at least + or 2 readings should have been taken to • obtain a more precise reading for the hardness of water samples.