CHEM25415 F20 Lab Report Cover Sheet PDF

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FALL2020CHEM25415: INSTRUMENTAL ANALYSIS 1 LAB REPORT COVER SHEET Name: KARTIK ARORA

Lab Day and Time: Thursday / 5:10-7:10 pm

Lab Partner: Parvinder Kaur

Professor: Dr. Steve Clark

Experiment Title: Quantitative Analysis of Iron in Well Water by External Standard Method using a Visible Spectrometer Date Performed: September 7, 2021 Unknown Sample #: 18

Date Submitted: September 7, 2021 Unknown Identity: Caledon

209

Relative Standard Deviation (mg/jug) 10.3

True Value @ 95% Confidence Interval (mg/jug) 221-197

215

11.8

228-202

STATISTICS

Mean Final Result (mg/jug)

Multipoint Method Single Point Method

Report Evaluation Summary A. Lab Report Questions (answers to all questions in Lab Report outline) B. General Format

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C. Spelling/Grammar/Clarity of Comments

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C. Significant Figures and Units

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D. References (ACS format)

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E. Accuracy/Unknown Identity and Precision F. Raw Data (notebook) and Instrumental Output (Grade of zero if missing) G. Late penalty (10% deduction per day, up to a maximum of 5 days) # of days late:______

Deduction: 10%

20%

30%

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Total Lab Report Mark

Improper Formatting: ______________________________ Incorrect Calculations: ___________________________ Improper Referencing: _____________________ Incomplete/Incorrect Discussion: __________________________ ADDITIONAL COMMENTS:__________________________________________________________________________ _________________________________________________________________________________________________

Contents Purpose:.............................................................................................................................3 Procedure:.........................................................................................................................3 Observations......................................................................................................................4 Table 1: Accurate readings.........................................................................................4 Table 2: Volume of Solutions and Time (in seconds) for Part A (Trials 1 – 3)...........4 Table 3: Temperature Data from Part B......................................................................4 Results and Calculations...................................................................................................5 PART A...........................................................................................................................5 TABLE 4: Concentrations of iodate solutions in each sample...................................5 Table 5: Concentrations of sulphite solutions each sample.......................................6 Table 6: Calculating moles of sulphite and iodate......................................................7 Table 7: Time taken, Concentration and Rate Readings............................................9 Table 8: Determining log of iodate concentrations...................................................10 PART B.........................................................................................................................11 Table 9: Average Rates at Different Temperatures..................................................12 Discussions......................................................................................................................13 Conclusion:......................................................................................................................14 Rough Work.....................................................................................................................15 Overall Organization........................................................................................................18

Table of figures: Figure 1 average rate of reaction as a function of iodate concentration.........................11 Figure 2 log(average rate) as a function of log(iodate concentration)............................12

Laboratory 2: Reaction Kinetics (57 Marks) Purpose:

To determine the effect of concentration and temperature on reaction rate. Procedure:

The procedure followed in this Experiment is taken from CHEM25415 Instrumental Analysis 1 Laboratory Manual – Fall 2020 posted on SLATE (1),

OBSERVATIONS: Table 1: Fe2+ external standard solution readings Standard Solution

1 2 3 4 5

Volume of Fe2+ substock solution pipetted (mL) 2.000 4.00 6.00 8.00 10.00

Actual Fe2+ external standard solution concentration (ppm) 6.60 13.2 19.8 26.4 33.0

Table 2: Unknown well water sample readings Standard 1 2 3

Absorbance 0.305 0.284 0.275

Absorbance

0.221 0.486 0.692 0.982 1.211

1.

mass of Fe(NH 4 )2(SO 4 )2 .6 H 2 O(mg) Volume of solution(L) ¿ Actual Fe

2+¿ stock solution concentration=

Where,

Mass of Fe (NH 4)2 (SO 4 )2 .6 H 2 O∈grams measured by technologist =1.6506 g To convert the given mass from grams into milligrams multiply it with 1000

Mass of Fe (NH 4)2 (SO 4 )2 .6 H 2 O∈milligrams=1.6506 g ×

1000 mg =1650.6 mg 1g

Volume of solution=2 L So,

2+¿ stock solution concentration= Actual Fe¿

1650.6 mg =825 ppm 2L

2+¿ stock solution concentration=825 ppm Actual Fe¿ 2.

Volume of Fe2+ ¿substock solution used (mL) Fe 2+¿ stock solution pipetted (mL) Volume of ¿ 2+¿ stock solution concentration( ppm)× ¿ 2+¿ substock solutionconcentration= Actual Fe ¿ Actual Fe ¿ Where,

2+¿ stock solution concentration=825 ppm Actual Fe¿ 2+¿ stock solution pipetted =10.00 mL Volume of Fe ¿ 2+¿ substock solutionused=100.00 mL Volume of Fe ¿ So,

2+¿ substock solutionconcentration=825 ppm× Actual Fe¿ 2+¿ substock solutionconcentration=82.5 ppm Actual Fe¿

10.00 mL 100.00 mL

3. For 1st Standard solution:

Volume of Fe2 +¿external standard solutionused (mL) Fe2+¿ substock solution pipetted (mL) Volume of ¿ 2+¿ substock solution concentration(ppm )× ¿ 2+¿ external standard solution concentration=Actual Fe¿ Actual Fe¿ Where,

2+¿ substock solutionconcentration ( ppm) =82.5 ppm Actual Fe ¿ 2+¿ substock solution pipetted ( mL) =2.000 mL Volume of Fe ¿ 2+¿ external standard solutionused ( mL ) =25.00 mL Volume of Fe ¿ So,

2+¿ external standard solution concentration=82.5 ppm × Actual Fe¿

2.000 mL 25.00 mL

2+¿ external standard solution concentration=6.60 ppm Actual Fe¿ Table 1: Fe2+ external standard solution concentration and absorbance Standard Solution

1 2 3 4 5

Volume of Fe2+ substock solution pipetted (mL) 2.000 4.00 6.00 8.00 10.00

Actual Fe2+ external standard solution concentration (ppm) 6.60 13.2 19.8 26.4 33.0

5. Table 2: Replicate unknown well water sample absorbance Standard 1 2 3

Absorbance 0.305 0.284 0.275

Absorbance

0.221 0.486 0.692 0.982 1.211

Table 3: Actual concentration and absorbance measurements Actual Fe2+ concentration (ppm) (on x- axis) 6.60 13.2 19.8 26.4 33.0

Absorbance (on y- axis) 0.221 0.486 0.692 0.982 1.211

Figure 1 Actual Fe2+ concentration (ppm) (on x- axis) Vs Absorbance (on y- axis)

Absorbance Vs Actual Fe2+concentration (ppm) 1.4

1.21

1.2

f(x) = 0.15 x − 0.02 R² = 1

Absorbance

1

0.98

0.8

0.69

0.6 0.4

0.49 0.22

0.2 0

1

2

3

4

5

6

7

8

9

Actual Fe2+ concentration (ppm)

Correlation Coefficient:

R2=0.9981 Linear Regression Equation:

y =0.0375 x −0.0244 Where, for 1st replicate sample:

y= Absorbanceof 1 st replicate sample So, y= 0.305

2+¿ concentration∈the diluted unknown replicate well water sample( ppm) x=Fe¿ So,

y =0.0375 x −0.0244 0.305=0.0375 x− 0.0244

x=

0.305+0.0244 0.0375

x=8.78

mg =8.78 ppm L

2+¿ concentration∈the 1st replicate sample=8.78 ppm Fe¿

Table 2: Replicate unknown well water sample absorbance Standard

Absorbance

Fe2+concentration in the diluted unknown replicate well water sample (ppm)

Fe2+ concentration in original well water sample (ppm)

1 2 3

0.305 0.284 0.275

8.78 8.22 7.98

110 103 99.8

Fe2+ concentration in original well water sample (mg/jug) 220 206 200

9. For 1st replicate sample:

2+¿ concentration∈the diluted unknown replicate well water sample ( ppm) × Dilution Factor 2+¿ concentration ∈original well water sample= Fe ¿ Fe¿ Where,

2+¿ concentration∈the diluted unknown replicate well water sample=25.0 ppm Fe¿ Dilution Factor=

Volume of the solution Volume of the original sample taken

Volume of solution (mL ) =25.00 mL

Volume of original sample taken ( mL )=2.000 mL So,

Dilution Factor=

25.00 mL =12.50 2.000 mL

Also,

2+¿ concentration ∈original well water sample=8.78 ppm × 12.50 Fe¿ 2+¿ concentration∈original well water sample=110 ppm Fe ¿ 10. For 1st replicate sample:

2+ ¿ concentration∈original well water sample × 2 L mg =Fe ¿ 2+¿ concentration∈original well water sample ∈ jug(2 L) Fe¿ Where,

2+¿ concentration∈original well water sample=110 ppm Fe ¿ So,

2+¿ concentration∈original well water sample ∈ Fe¿

mg =110 ppm × 2 L jug(2 L)

2+¿ concentration∈original well water sample=220 Fe¿

mg jug

11.

2+¿ concentration

220+206 + 200 mg = ( mg ( jug ) =209 mg 3 jug ) jug Meanof Fe¿

|220 −209|+|206 −209|+¿ 200−209∨ ¿ =7.67 3 Absolute standard deviation=¿

mg jug

√

(220−209 )2+( 206 −209)2 +(200−209 )2 mg Relative standard deviation= =10.3 jug 2 True value at 95 % confidence : ¿ mean+¿−

relative standard deviation× z value ( at 95 % ) mg 10.3× 1.960 =209 +¿− jug √3 √3

¿ 209

mg j

+¿−11.7=221

mg mg ∨197 jug j

So, the true value might exist between 221 to 197 mg/jug. Table 4: Multi Point Statistical Results Statistical results Mean of Fe2+ concentration (mg/jug) Absolute standard deviation (mg/jug) Relative standard deviation (mg/jug) True value range at 95% confidence (mg/jug)

Readings 209 7.67 10.3 221-197

12. As after comparing the external standard absorbance values to those of replicate unknown samples it is noticed that the 1st external standard solution having the absorbance of 0.221 is closest to all the unknown replicate samples. For 1st replicate sample:

2 +¿ concentration∈1 st external standard solution ( ppm) Absorbance of dilutedunknown well water sample × Fe¿ 2+¿ concentration∈diluted unknown well water sample= Absorbance of 1st external standard solution ¿ Fe Where,

2+¿ concentration∈1 st external standard solution=6.60 ppm Fe¿ Absorbance of 1st external standard solution=0.221

Absorbance of diluted unknownwell water sample=0.305 So,

2+¿ concentration∈diluted unknown well water sample=

0.305 ×6.60 ppm 0.221

Fe¿ 2+¿ concentration∈diluted unknown well water sample=9.11 ppm Fe¿ Table 4: Single Point Method Results Standard

Absorbance

Fe2+ concentration in diluted unknown well water sample (ppm)

1 2 3

0.305 0.284 0.275

9.11 8.48 8.21

Fe2+ concentration in original well water sample (mg/jug) 228 212 205

For 1st replicate sample:

2+¿ concentration∈the diluted unknown replicate well water sample ( ppm) × Dilution Factor 2+¿ concentration ∈original well water sample= Fe ¿ Fe¿ Where,

2+¿ concentration∈the diluted unknown replicate well water sample=9.11 ppm Fe¿ Dilution Factor=

Volume of the solution Volume of the original sample taken

Volume of solution (mL )=25.00 mL

Volume of original sample taken ( mL )=2.000 mL So,

Dilution Factor=

25.00 mL =12.50 2.000 mL

Also,

2+¿ concentration∈original well water sample=9.11 ppm× 12.50 Fe ¿ 2+¿ concentration∈original well water sample=114 ppm Fe ¿ 10. For 1st replicate sample:

2+ ¿ concentration∈original well water sample × 2 L mg ¿ 2+¿ concentration∈original well water sample ∈ =Fe jug(2 L) Fe¿ Where,

2+¿ concentration∈original well water sample=114 ppm Fe ¿ So,

2+¿ concentration∈original well water sample ∈ Fe¿

mg =114 ppm× 2 L jug(2 L)

2+¿ concentration∈original well water sample=228 Fe¿

mg jug

11.

2+¿ concentration

228+212 + 205 mg = ( mg ) ( jug ) =215 mg 3 jug jug Meanof Fe ¿

|228 −215|+|212 −215|+¿ 205−215∨ ¿ =8.67 mg 3 Absolute standard deviation=¿

Relative standard deviation=

√

jug

(228−215 )2+(212−215)2 +( 205−215 )2 mg =11.8 jug 2

True value at 95 % confidence :

¿ mean+ ¿− ¿ 215

relative standard deviation× z value ( at 95 % ) mg 11.8 ×1.960 =215 + ¿− jug √3 √3

mg mg mg +¿−13.4 =228 ∨202 jug jug jug

So, the true value might exist between 228 to 202 mg/jug. Table 4: Single Point Statistical Results Statistical results Mean of Fe2+ concentration (mg/jug) Absolute standard deviation (mg/jug) Relative standard deviation (mg/jug) True value range at 95% confidence (mg/jug)

Readings 215 8.67 11.8 228-202

Table 4: Summary resuts table Statistical results Mean of Fe2+ concentration (mg/jug) Absolute standard deviation (mg/jug) Relative standard deviation (mg/jug) True value range at 95% confidence (mg/jug)

Multi Point Results 209

Single Point Results 215

7.67

8.67

10.3

11.8

221-197

228-202

Yes, mostly both of the multipoint and single point results agree at an average level to each other. As the absolute standard deviation of multipoint method and single method that is 7.67 and 8.67 are almost similar with very little difference in their values. Also, the relative standard deviation values of multipoint method and single method

that are 10.3 and 11.8 makes no difference and are quite like each other. So, the standard and relative standard deviation of both methods is merely same and so the results of both agree to each other in this case. But in case of mean concentration of iron cation, both the methods silmpy disagree as the mean values of single point method is 215 mg/jug which differs significantly by a factor of 6 mg/jug from multipoint method with mean value of 209 mg/jug. So, in case of mean, the results of singlepoint method disagree completely with the multipoint results due to the major difference between their mean results. The true value range of both the methods gets common at a point between 221 to 202 as in case of multipoint method the true value range is between 221 to 197 and between 228 to 202 in case of single point method. So, the original sample identified with the help of either method will lead to similar results and as both the methods agree together in this case of true values with seemingly very small difference. Allover multipoint method results agree significantly with the single point results.

18. Genesys 20 spectrophotometer is compact and cheaper as it is a lower cost visible spectrophotometer used for various applications. This spectrophotometer requires proper calibration against blank solution. The blank solution is a solution containing everything that is in the similar cuvette except the one material whose absorbance is going to be measured. The blank solution is mostly used to calibrate the readings of spectrophotometr and to set the spectrophotometr to zero before measuring unknown solution. The blank solution is also used so that absorbance from it can be added to any light that is absorbed or reflected from the sample. As the blank solution containing cuvette is used as a treference to set the spectrophotometr with zero absorbance (that it with 100%T ). So because of this reason blank solution is always analysed prior to using spectrophotometr to make any absorbance relaterd measurements.

21. Iron is a troublesome chemical in water supplies with fluctuating concentrations at different different wavelengths. The iron makes up at least 5% of the earth’s crust and is the most plentiful resource out of the majority of chemicals. Rainwater as it infiltrates the soil and underlying geological formation which dissolves iron causing water to seep into the aquifers that serves as a source of groundwater for wells. Iron is mainly present in two forms that are Fe 2+ and Fe3+ in well water. Water containing Fe2+ that is ferrous iron is clear and completely dissolved. The median iron concentration is mostly 0.7 mg/L in river, 0.3 mg/L in normal drinking water and between 0.05 to 10 mg/L in groundwater. It is noticed that Fe2+ concentration is more in the unknown well water samples than in the external standard solutions. Also, the higher the absorbance of light by a solution, the lower the percent transmittance is. The wavelength at which absorbance is highest is the wavelength to which solution is more sensitive to changes in concentration. So, at the lower wavelength of 420nm the concentration of Fe2+ is quite lesser but at the higher wavelength of 508nm in the unknown well water samples, the mean Fe2+ concentration is more and so with the increase in the wavelength of the unknown well water sample, resulting in the rise of the mean Fe2+ concentration. Table 4: Well Water Samples

mg Fe2+ per 2L jug

Wiarton

35.9

Experimental Mean Fe2+ Concentration (mg / 2L jug) 209

Lion’s Head Caledon

61.8 105

As the value of Experimental Mean Fe2+ Concentration (mg / 2L jug) is 209 which seems to be closest to true value of Caledon well water sample that 105 mg Fe2+ per 2L jug as compared to the others. So, the unknown well water sample is Caledon. For multipoint method:

Relativeerror =

actual value−measured value actual value

Actual value = 105 mg Fe2+ per 2L jug Measured value= 209 mg Fe2+ per 2L jug So,

Relativeerror =

105 −209 =−0.990 105

Percent error=−0.990 ×100 =−99.0 % Table 4: Error Readings table Statistical results Relative error Percent error (%)

Multi Point Results -0.990 -99.0

Single Point Results -1.05 -105

// The calibration plot obtained by both manuals is a straight linear line. The only difference between the appearance of two is that Winter 2018 calibration plot would have the shorteer variation of x axis that is it has the shorter range of concentration due to to the smaller final volume values used in to calculate the concentration of standard solutions as both concentration and final volumes are directly proportional so smaller final volumes are used in Winter 2018 so the range values of standard solution concentrations would also be shorter in the calibration plot. While in Fall 2020 calibration plot, larger final volumes are used so the standard solution ...