EXP 5 Distillation AND Hardness OF Water PDF

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UNIVERSITI TEKNOLOGI MARA

FACULTY OF APPLIED SCIENCES BACHELOR OF SCIENCE (HONS.) APPLIED CHEMISTRY

CHEMICAL LABORATORY

COURSE

: ANALYTICAL CHEMISTRY (CHM421)

EXPERIMENT NUMBER

: EXPERIMENT 5

EXPERIMENT

: DISTILLATION AND HARDNESS OF WATER

NAME

: MIMI ATHIRAH BT R AZIMI

MATRIC NUM

: 2020897434

GROUP

: AS2451M3 LAB421

DATE OF SUMMISION

: 19 NOVEMBER 2020

DATE OF EXPERIMENT

: 12 NOVEMBER 2020

LECTURER’S NAME

: DR NURULFAZLINA EDAYAH RASOL

TITLE Distillation and hardness of water ABSTRACT The main purposed of this experiment are to standardised EDTA solution and to analyse hardness of water samples by titration with EDTA. In part A, a set of apparatus was setup as in the figure. A distillation process is a common method purification for liquids. Experimental boiling range for collected sample is 3C. In part B which is standardisation of EDTA solution is to determine the molarity of EDTA used. One burette was filled with EDTA solution after rinsed by distilled water and EDTA solution. 25ml aliquots of standard Ca2+ solution was pipetted and transfer into a 250ml conical flask. Then, 8ml of Ph 10 ammonia ammonium chloride buffer, 15ml distilled water and 3 drops Eriochrome Black T indicator was added into a conical flask. The solution then was titrated with EDTA solution. The molarity of EDTA is 4.93 x 10-3 M. As in for part C, the hardness of water is determined by the titration of lab tap water, lab distilled water, deionized water, home tap water, distilled home tap water and 0.1 M NaCl. Home tap water will be distillate and will be compared with the hardness of distilled water and other water samples to determine their effectiveness of distillation procedure. For titration, the burette was filled again by EDTA solution. 25 mL of lab tap water was dispense using pipette into the conical flask and added with 8 mL of ammonia-ammonium chloride buffer. Then 3 drops Eriochrome Black T indicator and the titration process begin. The hardness result for lap tap Lab distilled water, Home tap water, Distilled home tap water, deionize water and 0.1 M NaOH water is 37.44ppm, 37.44ppm, 32.57ppm, 3.95ppm, 114.1ppm and 16.82ppm respectively. Complexation titration method was used in this experiment.

OBJECTIVE 1. To Purify water sample by distillation 2. To standardise EDTA solution 3. To analyse hardness of water samples by titration with EDTA

INTRODUCTION Distillation process will be carried out in this experiment. The hardness of a tap water will be determined and compared with other 4 samples of water. This is to determine the effectiveness of the distillation procedure. Complexation titration method is used for determination of hardness of water sample.

Water hardness can be defined as the amount of a dissolved calcium and magnesium in the water. The difference between hard water and soft water is hard water are rich in mineral while soft water contains very few elements. To be more clear, hard water is the water that contains an appreciable quantity of dissolved minerals (like calcium and magnesium) while soft water is treated water in which the only ion is sodium (salty). For example, calcium ion and magnesium ions react with soap to form a precipitate when sticks to fabrics. They can form large amounts of insoluble calcium carbonate, magnesium carbonate, and iron (III) carbonate. In this experiment, the method of titration will be used to determine the total hardness (amount of calcium and magnesium ions) in some water samples.

Distillation is the process of separating components of a mixture based on different boiling points and most commonly used technique for the purification of liquids. Simple distillation at atmospheric pressure will be used in this experiment as it is effectively to separate liquids that have difference in their boiling points. Low boiling impurities will vaporise and condensed first to be collected and put aside. High boiling impurities will be remained in the distilling flask. The vapor pressure of the liquid will increase as the temperature of the liquid increases, and when the vapor pressure equals the atmospheric pressure, the liquid will boil.

METHOD A. Distillation of the home tap water

A typical distillation apparatus is illustrated and was referred to the figured as a guide to assemble the distillation apparatus. 150ml round bottom flask and 250ml of conical

flask has been used as a distilling flask and for the receiver to collect the distillate respectively. The apparatus was clamped adequately and at strategic places to avoid breakages.

The distilling flask was filled to about two thirds with home tap water and a couple of chips was added too into the flask to prevent bumping. Next, the tap is turned on and the water flows was checked in the condenser. The mercury bulb of the thermometer also has been checked it is lower than the junction of the condenser with the distillation column. When boiling occurs, condensation is followed and was started to collect water in the receiving flask. While waiting for the distillation process, the titration for standardizing the EDTA has been set up.

First 20 drops or so of the distilled water collected was discarded as they might contained volatile impurities from the distillation glassware. The temperature of distilling flask was read and has been recorded as soon as it was started to collect 1 mL of the distillate. The collection of distillates is continued until 5ml of the liquid left in the distillation flask. The temperature is recorded when stop the distillation and the burner is turned off.

B. Standardisation of the EDTA solution

50 ml of burette was rinsed with a distilled water and drained completely into a waste beaker. The burette was ensured clean and there are no ‘reagent spot’ in the interior. Then the burette was rinsed again with the EDTA solution and it was discarded. The EDTA solution was poured into the burette beyond the zero mark, and it was made sure to close the burette valve earlier. The burette then was attached to the burette stand. The air bubble trapped in the tip of the burette was checked removed. The adjustment of initial reading also was done. 25.0 mL aliquots of the prepared standard Ca2+ solution has been pipetted and transferred into a 250 mL conical flask. The concentration of the CaCO3 prepared was recorded.

8ml of PH 10 ammonia ammonium chloride buffer, 15 ml of distilled water and 3 drops of Eriochrome Black T indicator was added into the flask. The sample was titrated

immediately with the EDTA solution against a white background until the pale pink solutions turns to light sky blue. The volume of the burette at the end point was recorded and the process was repeated with at least two more samples. Then, the reaction mixture will evaporate NH3 to some degree so the pH of the solution changes.

The first sample performed was a rough titration. This is to determine the approximate endpoint and to observe the colour change. In the next subsequent titrations, dropwise or ½ drop is added at a time of the titrant to the solution in the conical flask about 2 or 3 mL before the endpoint. The burette tip and the side of the flask was washed to ensure all the titrant has gotten into the solution in the flask.

C. Water hardness

The burette was filled up again by using EDTA solution. Then, a 25 mL pipette was rinsed with tap water and pipette 25.0 mL of lab tap water were rinsed into a 250 mL conical flask. 8 ml of ammonia ammonium chloride buffer, 3 drops of Eriochrome black T indicator was added into water sample flask. The reading of the initial burette was recorded to the nearest 0.01 ml. The stopcock of the burette is turned on to release the standard EDTA solution drop by drop into the water sample in the flask. The same titration was then repeat with another 2 more lab tap water samples.

A little bit of lab distilled water was obtained with the help of rubber filler. Then, the filler was removed, tilted and rotated the pipette to rinsed the interior of pipette with the distilled water. The tainted distilled water was discarded and 25.0 mL of fresh distilled water was pipette again into a cleaned flask. The same buffer and indicator were added and the titration of standardised EDTA solution to the endpoint began. Next, the pipette was rinsed with home tap water or an unknown supplied and 25.0 mL of the unknown was pipetted into a cleaned flask. Buffer and indicator were added and the titration of standardised EDTA solution to the endpoint began. The same process and method were repeated with other samples. All the data was recorded and every glassware were washed and return back to their original places.

DATA AND RESULT A. Distillation of Home Tap Water

1. Temperature at the start of collecting the distillate

= 96.0C

2. Temperature at the end of collecting the distillate

= 99.0C

3. Experimental boiling range for collected sample

= 3.0C

B. Standardisation of EDTA solution Concentration of standard Ca2+ solution

= 0.007M

Volume of the standard Ca2+ solution

= 25.0 ml

1

2

4

Final reading of EDTA solution (ml)

35.70 35.75 35.55

Initial reading of EDTA solution (ml)

0.10

Volume of EDTA solution (ml)

35.60 35.60 35.35

0.15

0.20

C. Hardness of water

Concentration of EDTA

Water sample

Lab tap water

= 4.93 x 10-3 M

Lab distilled water 4.00

Home tap water

Distilled home tap water 0.30

Deionize water

0.1 M NaOH

Final reading of 2.00 1.85 9.90 10.85 standard EDTA Initial reading of 0.10 2.10 0.20 0.10 4.10 10.00 standard EDTA Volume of 1.90 1.90 1.65 0.20 5.80 0.85 standard EDTA used (ml) Volume of water 25.0 25.0 25.0 25.0 25.0 25.0 sample (ml) [Ca2+ + Mg2+] 3.74 𝑥 10−4 3.74 𝑥 10−4 3.2538 𝑥 10−4 3.944 𝑥 10−5 1.14 𝑥 10−3 1.68 𝑥 10−4 (mol/L) Hardness (ppm) 37.44 37.44 32.57 3.95 114.1 16.82

CALCULATION

Standardisation of the EDTA solution

Concentration standard Ca2+ solution = 0.007M Volume Ca2+ solution = 25.0 ml Volume EDTA average = 35.52 ml

𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝑣𝑜𝑙𝑢𝑚𝑒 𝐸𝐷𝑇𝐴 =

35.60 + 35.60 + 35.35 = 35.52 𝑚𝑙 3

𝑀1 𝑉1 (𝐸𝐷𝑇𝐴) = 𝑀2 𝑉2 (𝐶𝑎 2+𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛) 𝑀1 (35.52) = (0.007)(25) 𝑀1 =

(0.007)( 25) = 4.93 𝑥 10−3 𝑀 𝑜𝑓 𝐸𝐷𝑇𝐴 35.52

Hardness of Water

Molar mass CaCO3 = (40.1)+(12.0)+(16 x 3) = 100.1 g/mol

i.

Lab tap water

𝑀1 𝑉1 (𝑙𝑎𝑏 𝑡𝑎𝑝 𝑤𝑎𝑡𝑒𝑟) = 𝑀2 𝑉2 (𝐸𝐷𝑇𝐴) 𝑀1 =

(4.93 𝑥 10−3 )( 1.90) 𝑚𝑜𝑙 = 3.74 𝑥 10−4 𝑜𝑓 𝑙𝑎𝑏 𝑡𝑎𝑝 𝑤𝑎𝑡𝑒𝑟 25 𝐿

𝑚𝑎𝑠𝑠 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝐶𝑎𝐶𝑂3 = 3.74 𝑥 10−4 𝑝𝑝𝑚 (𝑤 ⁄𝑣 ) 𝐶𝑎𝐶𝑂3 =

𝑚𝑔 𝑔 = 𝑥 1000 𝐿 𝐿

𝑝𝑝𝑚 (𝑤 ⁄𝑣 ) 𝐶𝑎𝐶𝑂3 = 0.03744 𝑥 1000 = 37.44 𝑝𝑝𝑚 𝐶𝑎𝐶𝑂3

𝑚𝑜𝑙 𝑔 𝑥 100.1 = 0.03744 𝑔⁄ 𝐿 𝐿 𝑚𝑜𝑙

ii.

Lab distilled water

𝑀1 𝑉1 (𝑙𝑎𝑏 𝑑𝑖𝑠𝑡𝑖𝑙𝑙𝑒𝑑 𝑤𝑎𝑡𝑒𝑟) = 𝑀2 𝑉2 (𝐸𝐷𝑇𝐴) 𝑀1 =

(4.93 𝑥 10−3 )( 1.90) = 3.74 𝑥 10−4 𝑚𝑜𝑙⁄ 𝐿 𝑜𝑓 𝑙𝑎𝑏 𝑑𝑖𝑠𝑡𝑖𝑙𝑙𝑒𝑑 𝑤𝑎𝑡𝑒𝑟 25

𝑚𝑎𝑠𝑠 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝐶𝑎𝐶𝑂3 = 3.74 𝑥 10−4 𝑝𝑝𝑚 (𝑤 ⁄𝑣 ) 𝐶𝑎𝐶𝑂3 =

𝑚𝑜𝑙 𝑔 = 0.03744 𝑔⁄ 𝐿 𝑥 100.1 𝑚𝑜𝑙 𝐿

𝑚𝑔 𝑔 = 𝑥 1000 𝐿 𝐿

𝑝𝑝𝑚 (𝑤 ⁄𝑣 ) 𝐶𝑎𝐶𝑂3 = 0.03744 𝑥 1000 = 37.44 𝑝𝑝𝑚 𝐶𝑎𝐶𝑂3

iii.

Home tap water

𝑀1 𝑉1 (ℎ𝑜𝑚𝑒 𝑡𝑎𝑝 𝑤𝑎𝑡𝑒𝑟) = 𝑀2 𝑉2 (𝐸𝐷𝑇𝐴) 𝑀1 =

(4.93 𝑥 10−3 )( 1.65) = 3.2538 𝑥 10−4 𝑚𝑜𝑙⁄ 𝐿 𝑜𝑓 ℎ𝑜𝑚𝑒 𝑡𝑎𝑝 𝑤𝑎𝑡𝑒𝑟 25

𝑚𝑎𝑠𝑠 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝐶𝑎𝐶𝑂3 = 3.2538 𝑥 10−4 𝑝𝑝𝑚 (𝑤 ⁄𝑣 ) 𝐶𝑎𝐶𝑂3 =

𝑚𝑜𝑙 𝑔 𝑥 100.1 = 0.03257 𝑔⁄ 𝐿 𝐿 𝑚𝑜𝑙

𝑚𝑔 𝑔 = 𝑥 1000 𝐿 𝐿

𝑝𝑝𝑚 (𝑤 ⁄𝑣 ) 𝐶𝑎𝐶𝑂3 = 0.03257 𝑥 1000 = 32.57 𝑝𝑝𝑚 𝐶𝑎𝐶𝑂3

iv.

Distilled home tap water

𝑀1 𝑉1 (𝑑𝑖𝑠𝑡𝑖𝑙𝑙𝑒𝑑 ℎ𝑜𝑚𝑒 𝑡𝑎𝑝 𝑤𝑎𝑡𝑒𝑟) = 𝑀2 𝑉2 (𝐸𝐷𝑇𝐴) 𝑀1 =

(4.93 𝑥 10−3 )( 0.20) 25

= 3.944 𝑥 10−5 𝑚𝑜𝑙⁄ 𝐿 𝑜𝑓 𝑑𝑖𝑠𝑡𝑖𝑙𝑙𝑒𝑑 ℎ𝑜𝑚𝑒 𝑡𝑎𝑝 𝑤𝑎𝑡𝑒𝑟

𝑚𝑎𝑠𝑠 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝐶𝑎𝐶𝑂3 = 3.944 𝑥 10−5 𝑝𝑝𝑚 (𝑤 ⁄𝑣 ) 𝐶𝑎𝐶𝑂3 =

𝑚𝑔 𝑔 = 𝑥 1000 𝐿 𝐿

𝑝𝑝𝑚 (𝑤 ⁄𝑣 ) 𝐶𝑎𝐶𝑂3 = (3.9479 𝑥 10−3 ) 𝑥 1000 = 3.95 𝑝𝑝𝑚 𝐶𝑎𝐶𝑂3

𝑚𝑜𝑙 𝑔 = 3.9479 𝑥 10−3 𝑔⁄ 𝐿 𝑥 100.1 𝑚𝑜𝑙 𝐿

v.

Deionize water

𝑀1 𝑉1 (𝑑𝑒𝑖𝑜𝑛𝑖𝑧𝑒𝑑 𝑤𝑎𝑡𝑒𝑟) = 𝑀2 𝑉2 (𝐸𝐷𝑇𝐴) 𝑀1 =

(4.93 𝑥 10−3 )(5.80) = 1.14 𝑥 10−3 𝑚𝑜𝑙⁄ 𝐿 𝑜𝑓 𝑑𝑒𝑖𝑜𝑛𝑖𝑧𝑒𝑑 𝑤𝑎𝑡𝑒𝑟 25

𝑚𝑎𝑠𝑠 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝐶𝑎𝐶𝑂3 = 1.14 𝑥 10−3 𝑝𝑝𝑚 (𝑤 ⁄𝑣 ) 𝐶𝑎𝐶𝑂3 =

𝑚𝑜𝑙 𝑔 = 0.1141 𝑔⁄ 𝐿 𝑥 100.1 𝑚𝑜𝑙 𝐿

𝑚𝑔 𝑔 = 𝑥 1000 𝐿 𝐿

𝑝𝑝𝑚 (𝑤 ⁄𝑣 ) 𝐶𝑎𝐶𝑂3 = 0.1141 𝑥 1000 = 114.1 𝑝𝑝𝑚 𝐶𝑎𝐶𝑂3

vi.

0.1 M NaOH

𝑀1 𝑉1 (0.1 𝑀 𝑁𝑎𝑂𝐻) = 𝑀2 𝑉2 (𝐸𝐷𝑇𝐴) (4.93 𝑥 10−3 )(0.85) = 1.68 𝑥 10−4 𝑚𝑜𝑙⁄ 𝐿 𝑜𝑓 0.1 𝑀 𝑁𝑎𝑂𝐻 𝑀1 = 25 𝑚𝑎𝑠𝑠 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝐶𝑎𝐶𝑂3 = 1.68 𝑥 10−4 𝑝𝑝𝑚 (𝑤 ⁄𝑣 ) 𝐶𝑎𝐶𝑂3 =

𝑚𝑜𝑙 𝑔 𝑥 100.1 = 0.017 𝑔⁄ 𝐿 𝐿 𝑚𝑜𝑙

𝑚𝑔 𝑔 = 𝑥 1000 𝐿 𝐿

𝑝𝑝𝑚 (𝑤 ⁄𝑣 ) 𝐶𝑎𝐶𝑂3 = 0.017 𝑥 1000 = 16.82 𝑝𝑝𝑚 𝐶𝑎𝐶𝑂3

DISCUSSION

From part A, purification of the water sample by distillation is to separate the substances and to be used as a water purification. The experimental boiling range for collected sample is 3.0C. Standardisation of EDTA solution was done in part B. The concentration used for standard Ca2+ solution is 0.007 M and the volume of it is 250 mL. The average volume of EDTA used is 35.52 ml and the concentration of EDTA used that has been calculated is 4.93 x 10-3 M. The same concentration of EDTA was used in Part C to analyse the hardness of water samples

by titration with EDTA solution. In this part six water sample is used which is lab tap water, lab distilled water, home tap water, distilled home tap water, deionized water and 0.1 M NaOH. The hardness of water can be determined by using this formula, 𝐻𝑎𝑟𝑑𝑛𝑒𝑠𝑠 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟 (𝐶𝑎𝐶𝑂3) =

𝑀𝑎𝑠𝑠 𝑜𝑓 𝐶𝑎𝐶𝑂3 (𝑚𝑔) 𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒 (𝐿)

The hardness of water can be divided by three parts, which is hard, soft and also medium. From the calculation for part C, we can see that the highest in number of water hardness is deionized water with 114.1ppm (moderately hard) while the least in number of water hardness is distilled home tap water with 3.96 ppm (soft). Followed by lab tap water (37.44ppm), lab distilled water (37.44ppm), home tap water (32.57ppm) and 0.1of NaOH (16.82ppm). Theoretical value of hardness of water is from (120-180) ppm hard, (60-120) ppm moderate hard, (17.1-60) ppm slightly hard and below from that value is soft. Some error might occur while doing the experiment, one of it is parallax error while reading the scale of the standard solution from the pipette. Next, extra dropped of titrant into the solution also possible to overshoot the endpoint and cause error. Plus, EDTA solution that was used must be not exposed to the air and it was made sure that the solution is always closed.

CONCLUSION To conclude, all three objectives for this experiment was achieved. The average value of concentration of EDTA solution is 4.93 𝑥 10−3 . The hardness of water samples obtained by titration with EDTA is hardness (slightly hard) include lab tap water, lab distilled water, home tap water , the hardness (soft) is distilled home tap water and 0.1 of NaOH, the hardness (moderately hard) is deionized water and ( which is their hardness is 37.44ppm, 37.44ppm, 32.57ppm, 3.95ppm, 16.82ppm and 114.1ppm respectively.

REFERENCE Burnham, D. (2020, January 16). How Hard Water Affects the Laundry Process. Retrieved from https://laundryledger.com/how-hard-water-affects-the-laundry-process/ Claude Yoder, C. (2020). Wired Chemist. Retrieved from http://www.wiredchemist.com/chemistry/instructional/laboratory-tutorials/distillation Admin. (2020, August 12). Difference Between Hard Water and Soft Water with Detailed Comparison - BYJU'S. Retrieved from https://byjus.com/chemistry/difference-between-hardwater-and-soft-water/ Haerany, N. (2019, July 14). Sources of errors in titration. Retrieved November 30, 2020, from http://syatillakmk.blogspot.com/2019/07/sources-of-errors-in-titration.html

QUESTION 1. Why should the water in the condense flow uphill during distillation? To completely fill the condenser. 2. Compare the hardness between lab tap water, lab distilled water, home tap water and home distilled tap water. Did the distillation have a significant effect on the water hardness. The hardness of lab tap water and lab distilled water is higher than the hardness of home tap water and home distilled tap water because it is naturally occur and other things dissolved in it. Lab tap water and lab distilled water is sensible as it contain no dissolved minerals, impurities and other chemicals. Water hardness caused by calcium ions and magnesium ions. 3. Water in the hardness in the range (0-60) ppm is term soft, 60-120 ppm medium hard, 120-180ppm hard and above 180ppm is very hard. Classify the water samples that you analysed in this experiment. Lab tap water, lab distilled water, home tap water , distilled home tap water, 0.1 of NaOH is hardness (soft) with 37.44ppm, 37.44ppm, 32.57ppm, 3.95ppm and 16.85ppm respectively. While deionize water is medium hard with 114.1 ppm. 4. Do you think there should be a correlation between conductance and hardness result ? explain your answer.

Conductivity is a measure of a solution’s ability to conduct electricity, and therefore a measure of the water’s ionic activity and content as hardness is the concentration of multivalent cations. 5. Suggest any ways you can think to improve any part(s) of this experiment

Add the boiling water sample to determine the hardness as the boiling process will evaporate pure water, thus increasing the concentration of minerals including calcium, thereby increasing hardness. Boiling also will remove CO2, making apparently CaCO3 precipitate, thereby reducing hardness....