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Chemistry HL
Chemistry HL
Sample Internal Assessment
Sample Internal Assessment

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Table of content
Rationale
Research question
Background information
Hypothesis
Variables
Procedure
Raw data
Data processing
Conclusion
Evaluation
References

Effect of pH on rate of ketal formation between propanone and ethanol

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Table of content

Rationale

Understanding how scientific principles governs us and regulates us has always been an interesting task for me. Being a skilled IB learner, I have always been intrigued to understand the way various chemical reaction occurs and the mechanism they follow. I have developed a special interest for this especially during my classes for Topic-10 (Organic Chemistry) in my second year of Diploma program. I always wanted to know more examples of organic reactions especially when I understood the concept of synthetic routes. This interest became stronger when I came across a research paper (Wright et al.) that spoke about the use of ‘ketals’ and ‘acetals’ as a precursor to synthesize resins. Exploring some organic chemistry websites and text books, I got to know more about them and could identify a similarity between this reaction and esterification which I studied in my class. The fact that intrigued me the most is that what factors could influence the way this reaction occurs. I realized the importance of this fact more when I understood the importance of knowing the mechanism of an organic reaction. I decided to study how certain conditions at which the reaction takes place would impact the reaction. To narrow down my thoughts into a precise platform, I faced two major challenges – Which parameter should I study to delineate the effect of some conditions on an organic reaction? The simplest choice I could get was rate of reaction. The next challenge was to design a process that allows me to collect the adequate data for this investigation. Going back to the concepts, I studied in Topic-6 (Kinetics), I could recollect about using colorimetry or spectroscopy as an analytical method to study rates of reaction. This led me to the research question given below:

Research question

How does the average rate of the reaction (measured in abs s-1 ) of the intermolecular condensation between propanone and ethanol to produce 2,2-diethoxy propane in presence of HCl as catalyst depends on the pH of the medium, determined using UV-Vis spectrophotometer?

Background information

Ketal formation

Propanone is an organic liquid having the functional group ketone. It has the displayed formula – CH3COCH3. Ethanol is an organic liquid belonging to the functional group of alcohol. This has a displayed formula of CH3CH2OH. In presence of dilute HCl as a catalyst, they undergo inter molecular condensation to produce a ketal – 2,2-diethoxy propane. Condensation products of ketones and alcohols are termed as ketals while condensation products of aldehyde and alcohols are known as acetals.

Figure 1 - Reaction Between Propanone And Ethanol
Figure 1 - Reaction Between Propanone And Ethanol

This reaction exemplifies condensation as it joins the two molecules – propanone and ethanol by elimination of a simple molecule-water.

Mechanism

The mechanism of the reaction (MacKENZIE and Stocker) is demonstrated below using skeletal structures of the reactants, intermediates and the products and curly arrows to indicate the movement of the pairs of electron.

 

Step - 1: The O atom of the propanone donates a lone pair to the Hydrogen (H+) ion furnished from dilute HCl and gets protonated. As a result, it gets a positive charge. Here, O atom behaves as a nucleophile and the H+ ion behaves as an electrophile.

Figure 2
Figure 2

Step - 2: The O atom of the ethanol molecule attacks the carbonyl C atom of the propanone group by using it’s lone pair. Here, the O atom of the ethanol is a nucleophile and the C atom of the carbonyl group is an electrophile. As a result, the pi bond of C=0 is broken and the electrons are given to the O atom which eventually neutralizes the positive charge acquired by the O atom is Step-1. This is also termed as ‘nucleophilic addition to C = O’ (Dong et al.).

Figure 3
Figure 3

Step - 3: The intermediate thus formed undergoes an intra molecular proton transfer. A H atom from the O atom of the OH group in ethanol moiety is transferred to the O atom of the OH group of the propanone moiety. This is an example of 1-3 proton shift causing the molecule to rearrange itself. The shift is 1-3 as if the O atom the H is shifting from is considered as 1 while the O atom, the H is shifting to is 3.

Figure 4
Figure 4

Step - 4: Another nucleophilic addition is done by the second ethanol molecule in a way similar to that in Step - 2. The product formed finally deprotonates itself to yield the main organic product – 2,2-diethoxy propane and water as a by-product.

Figure 5
Figure 5

Beer-lambert law

A = ∈ cl

 

If molar absorptivity (∈) and path length are constant, then absorbance and concentration is directly related. Thus, these two terms become interchangeable

 

As the sample remains same and the path length remains unaltered (because the same spectrophotometer has been used), ∈ and path length (l) are assumed to be constant.

 

Therefore, rate of reaction = \(\frac{change\ of\ concentration}{time\ taken}\) = \(\frac{change\ of\ absorbance}{time\ taken}\)

 

Here, propanone is a reactant and thus,

 

Rate of disappearance of propanone = \(\frac{change\ is\ concentration\ of\ propanone}{time\ taken\ for\ the\ change}\) = \(\frac{change\ is\ concentration\ of\ propanone}{time\ taken\ for\ the\ change}\)

 

\(\frac{Absorabnce\ of\ propanone\ at\ start-Absorabnce\ of\ propanone\ at\ end}{Time\ for\ which\ the\ reaction\ was\ carried\ out}\) = \(\frac{ΔA}{time\ taken}\) abs s-1

Hypothesis

Null hypothesis

There is no correlation between the rate of the reaction and the pH of the medium.

Alternate hypothesis

There is no correlation between the rate of the reaction and the pH of the medium. This can be justified based on the fact that H+ is acting as a catalyst in this reaction and change in concentration of catalyst has an effect on rate of reaction.

Variables

Independent variable

The independent variable is the pH of the medium. The pH will be varied from 1.00 to 7.00. For the values of pH from 1.00 to 6.00, dilute HCl of appropriate concentrations, 1.0 × 10-1 mol dm-3, 1.0 × 10-2 mol dm-3, 1.0 × 10-3 mol dm-3, 1.0 × 10-4 mol dm-3, 1.0 × 10-5 mol dm-3, 1.0 × 10-6: mol dm-3 will be used. The pH will be calculated using the formula:

 

pH of the medium = - log (molar concentration of HCl used)

 

It has been assumed that HCl dissociates completely in aqueous solution.

Dependent variable

The dependent variable is the rate of the reaction in abs s-1.

 

The rate of the reaction will be calculated as the rate of disappearance of propanone. To do this, the absorbance of the propanone will be recorded at the start of the reaction and at the end of the reaction, change of absorbance will be calculated and the rate will be calculated using the formula:

 

Rate of the reaction = \(\frac{difference\ in\ absorbance}{time\ taken}=\frac{ΔA}{600.00}\) abs s-1

 

A UV-Visible spectrophotometer was used to record the absorbance of the sample at a wavelength at which propanone shows maximum absorbance.

Controlled variables

Variable
Why should it be controlled?
How will it be controlled?
Time for which the reaction continues
Longer the time, the reaction is carried out for, more the amount of propanone consumed and thus lower the absorbance of the propanone at the end of the reaction. Thus, differing the time gap would make the comparison unfair.
All reactions were carried out for 10 mins (600.00s). A stop-watch was used to monitor this.
Temperature
More the temperature, more the average kinetic energy of the propanone and ethanol molecules that collide with each other and thus higher the frequency of the effective collisions between the propanone and ethanol. This will increase the rate at which the 2,2-diethoxy propane is produced.
All reactions were carried out at the room temperature.
Initial concentration of propanone and ethanol
The rate of a reaction increases as the initial concentration of the reactant is more. This is due to increase in frequency of successful collisions.
In all cases, the initial moles of propanone and ethanol added were kept same at 0.10 . The total volume was also kept same at 100 cc. As both ethanol and propanone are liquids at room temperature, a graduated pipette was used to control the amount added for them. A 100 cc glass beaker was used to control the volume.
Surface area of the reaction
As the size of the beaker or reaction vessel changes, the exposure of the reactant molecules towards each other increases. This allows them to have more number of effective collisions in the same time period which in turn increases the rate of the reaction.
All reactions were carried out in a 100 cc glass beaker.
Figure 6 - Table On Controlled Variables

List of apparatus required

Apparatus
Quantity
Least count
Uncertainty
UV-Visible spectrophotometer
1
0.001 abs
± 0.001 abs
Stop-watch
1
0.01 s
± 0.01 s
Glass Beaker-100 cc
5
---
---
Glass rod
1
---
---
Cuvette
2
---
---
Graduated pipette -10 cc
1
0.10 cc
± 0.05 cc
Graduated pipette -20 cc
1
0.10 cc
± 0.05 cc
Cuvette
1
---
---
Soft tissue
1
----
----
Graduated measuring cylinder – 100 cc
1
1.00 cc
± 0.50 cc
Figure 7 - Table On List of apparatus required

Materials needed

  • Propanone – 10 cc
  • Ethanol – 10 cc
  • Concentrated HCl (11.00 moldm-3) – 10 cc

Safety considerations

  • Both propanone and ethanol are volatile organic liquids. If inhaled, they can cause respiratory disorders and even senseless ness. A safety mask was used to ensure that these chemicals are not inhaled.
  • Concentrated HCl is a corrosive liquid. If exposed to skin, it may cause severe burns. Inhaling vapors may lead to dizziness and headache. A safety masks, hand gloves and a laboratory coat was used to ensure that this does not happen.

Environmental considerations

All unused chemicals were first diluted and disposed of into a waste bin for further disposal as per the standard laboratory protocols for safe disposal of chemicals.

Ethical considerations

The investigation has been performed with minimum possible amount of raw materials.

Procedure

Part-a

Determining the wavelength of maximum absorbance for propanone

  • A cuvette was taken and filled with 2.00 ± 0.05 cc of propanone.
  • Another cuvette was taken and filled with distilled water.
  • Both the cuvettes were wiped off with soft tissues and inserted into the spectrophotometer. The cuvette with propanone was in the sample chamber and the cuvette with distilled water was in the blank chamber.
  • The wavelength of the spectrophotometer was set at 200 nm.
  • The absorbance of the sample was recorded.
  • The wavelength was increased by 5 nm and the absorbance was recorded again till 400 nm.

Part-b

Preparation of HCl solutions:

 

Concentration of HCl supplied (C1) = 11.00 moldm-3

 

Concentration of HCl to be made (C2) = 0.10 moldm-3

 

Volume of HCl to be made (V2) = 100 cm3 = 0.10 dm3

 

Volume of supplied HCl to be taken (V1) = \(\frac{C_2V_2}{C_1}=\frac{0.10×0.10}{11}\) = 0.00090 dm3 = 0.90 cm3

  • A volumetric flask containing 20.00 ± 0.05 cc of distilled water added using a 20 cc pipette was taken.
  • A 1.00 cm3 pipette was used to transfer 0.90 ± 0.05 cc supplied HCl to it.
  • Distilled water was added till the mark of 100 cc.

The other HCl solutions 1.0 × 10-2 mol dm-3, 1.0 × 10-3 mol dm-3, 1.0 × 10-4 mol dm-3, 1.0 × 10-5 mol dm-3, 1.0 × 10-6 mol dm-3 of HCl solutions were prepared through serial dilution. For example, 1.0 × 10-2 mol dm-3 was diluted 10 times to prepare 1.0 × 10-3 mol dm-3. To do this, 10.00 ± 0.05 cc of 1.0 × 10-3 mol dm-3 was pipetted out and transferred to a 100 cc volumetric flask. Distilled water was added till the mark following this.

Part-c

Density of propanone3 = 0.791 g /cc

 

Molar mass = 58

 

Number of moles = 0.10

 

Mass = moles × molar mass = 0.10 × 58 = 5.80 g

 

Volume \(\frac{Mass}{Density}\) = \(\frac{5.80}{0.791}\) = 7.33cc ≅ 7.30 cc

 

Density of ethanol = 0.789 g /cc

 

Molar mass = 46

 

Number of moles = 0.10

 

Mass = moles × molar mass = 0.01 × 46 = 0.46 g

 

Volume = \(\frac{Mass}{Density}=\frac{0.46}{0.789}\) = 5.83 ≅ 5.80 cc

 

Volume for 0.20 moles = 5.80 cc × 2 = 11.60 cc

 

In both the cases, the value of volume in the second decimal place has been rounded off to zero as the least count of the apparatus used for measuring the volume (a 10 cc graduated pipette) is 0.10 and thus it is not possible to measure the second decimal place in it. For example, 5.80 cc can be measured using it but not 5.83 cc.

  • A 100.00 cc glass beaker was taken and washed with distilled water.
  • A 20.00 cc graduated pipette was used to transfer 7.30 ± 0.05 cc (0.10 moles) of propanone.
  • A 20.00 cc graduated pipette was used to transfer 11.60 ± 0.05 cc (0.10 moles) of ethanol.
  • A graduated measuring cylinder was used to add 1.0 × 10-1 mol dm-3 of dilute HCl till the mark of 100.00 cc.
  • The stop-watch was started.
  • A 1.00 cc graded pipette was taken to transfer 1.00 ± 0.05 cc of the reaction mixture to the cuvette.
  • The absorbance of the reaction mixture was measured at 275 nm
  • As soon as the stop-watch reads 600.00 s, Step-7 was repeated.
  • Steps 1-7 were repeated for two more times to collect data in triplicates.
  • Steps 1-9 were repeated for other concentrations 1.0 × 10-2 mol dm-3, 1.0 × 10-3 mol dm-3, 1.0 × 10-4 mol dm-3, 1.0 × 10-5 mol dm-3, 1.0 × 10-6 mol dm-3 of diluted HCl.
  • Steps 1-8 were repeated using distilled water instead of dilute HCl

Quantitative data

  • Propanone is a colorless liquid with a distinct odor.
  • Ethanol is a colorless liquid with a distinct odor.
  • Fumes were observed on opening the bottle of concentrated HCl.
  • Any visible observation like color change, formation of bubbles was not observed when the reaction was in progress.

Raw data

Wavelength in nm
Absorbance in ± 0.001 abs
Wavelength in nm
Absorbance in ±0.001 abs
200
0.523
305
0.538
205
0.524
310
0.537
210
0.524
315
0.537
215
0.536
320
0.536
220
0.537
325
0.536
225
0.537
330
0.536
230
0.538
335
0.535
235
0.538
340
0.535
240
0.539
345
0.535
245
0.539
350
0.535
250
0.539
355
0.534
255
0.54
360
0.534
260
0.541
365
0.534
265
0.541
370
0.532
270
0.541
375
0.532
275
0.673
380
0.531
280
0.539
385
0.531
285
0.539
390
0.531
290
0.539
395
0.531
295
0.538
400
0.531
300
0.538
305
0.538
200
0.523
310
0.537
205
0.524
315
0.537
Figure 7 - Table On Absorbance Versus Wavelength For Propanone
Figure 8 - Absorbance Versus Wavelength For Propanone
Figure 8 - Absorbance Versus Wavelength For Propanone

Figure - 8 shows that propanone shows maximum absorbance at a wavelength of 275 nm. Thus, this wavelength will be used further in this investigation.

Figure 9 - Table On Absorbance Of Propanone At The Start Of The Reaction (t=0.00 s)
Figure 10 - Table On Absorbance Of Propanone At The End Of The Reaction (After 600.00 s)

Data processing

Molar concentration of dilute HCl used (in moldm-3)

pH of the medium

Mean absorbance of propanone at 275 nm at the start A initial (t=0.00 ± 0.01 s) (±0.001 abs)

Mean absorbance of propanone at 275 nm at the end A final (t=600.00 ±0.01 s) (±0.001 abs)

Difference in absorbance (∆A in ± 0.002 abs)

Rate of the reaction In 10-4abs s-1

1.0 × 10-1

1.00
0.785
0.681
0.104
1.733

1.0 × 10-2

2.00
0.785
0.694
0.091
1.517

1.0 × 10-3

3.00
0.786
0.702
0.084
1.400

1.0 × 10-4

4.00
0.786
0.710
0.076
1.267

1.0 × 10-5

5.00
0.786
0.722
0.064
1.067

1.0 × 10-6

6.00
0.785
0.734
0.051
0.850

0.0 × 10-0 (pure water)

7.00
0.785
0.746
0.039
0.650
Figure 11 - Table On Calculation Of Rate Against pH Of The Medium

Sample calculation

pH of the medium = - log (molar concentration of HCl used)

 

For pure water, the pH is considered as 7.00

 

Difference in absorbance (A)

 

= Mean absorbance at the start (t=0.00 s) – Mean absorbance at the end (t=600.00 s)

 

Rate of the reaction = \(\frac{difference\ in\ absorbance}{time\ taken}=\frac{∆A}{600.00}\) abs s-1

pH of the medium

Rate of the reaction in 10-4abs s-1

Percentage error
1.00
1.733
1.92
2.00
1.517
2.20
3.00
1.400
2.38
4.00
1.267
2.63
5.00
1.067
3.13
6.00
0.850
3.92
7.00
0.650
5.13
Figure 12 - Table On Error Propagation

Sample calculation

For the pH of the medium = 1.00

 

Rate of the reaction (r) = \(\frac{difference\ in\ absorbance}{time\ taken}\)

 

\(\frac{∆r}{r}=\frac{∆(∆A)}{∆A}+\frac{∆t}{t}=\frac{±0.002}{0.104}+\frac{±0.01}{600.00}\) = 0.01924

 

Percentage error = \(\frac{∆r}{r}\) × 100 = 0.01924 × 100 = 1.92474359 ≅ 1.92

 

Total Percentage error = \(\frac{∆r}{r}\) \(\frac{1.92+2.20+2.38+2.63+3.13+3.92+5.13}{7}\) = 3.05

 

The total percentage error is 3.05 and the magnitude is really small. This shows that there is not enough systematic error in the investigation. Thus, the data collected is coherent and the result concluded may be claimed to be reliable and accurate.

<p>Figure 13 - Rate Of The Reaction In Abs s<sup>-1</sup>&nbsp;Against pH Of The Medium</p>

Figure 13 - Rate Of The Reaction In Abs s-1 Against pH Of The Medium

Figure 13 indicates that rate of the reaction against the pH of the medium. As the pH of the medium decreases from 1.00 to 7.00, the rate of the reaction decreases from 1.73 × 10-4 abs s-1 to 6.50 × 10-5 abs s-1. This shows that as pH decreases, the rate at which the propanone reacts with ethanol also reduces. As pH decreases, the medium becomes less acidic and thus the molar concentration of Hydrogen ion (H+) in the medium decreases and the rate at which the propanone reacts with ethanol decreases.

 

The graph also displays an equation of trend line. The trend line indicates that the rate of the reaction between propanone and ethanol follows a linear relationship that follows the equation: y=-0.175 x + 1.9143; where y indicates the rate of the reaction between propanone and ethanol in acidic medium and x represents the pH of the medium.

 

The gradient of the trend line is -0.175 and it is a negative value. This again confirms the fact that as pH decreases, the medium becomes less acidic and thus the molar concentration of Hydrogen ion (H+) in the medium decreases and the rate at which the propanone reacts with ethanol decreases. Thus, a negative correlation is predicted between the pH of the medium and the rate of the reaction between propanone and ethanol carried out in presence of dilute HCl. This in turn implies a positive correlation between the concentration of Hydrogen ions and the rate of the reaction.

 

The value of the correlation of regression (R2 ) is 0.9913; this confirms that there is a strong correlation between the values of rate of the reaction between propanone and ethanol and the pH of the medium.

Scientific justification

The discussion above clearly indicates that as the pH decreases, there are less Hydrogen ions (H+) in the medium and thus the rate of the reaction between propanone and ethanol decreases. A scientific justification for this trend can be provided if the mechanism of this reaction is referred to.

 

As indicated in the mechanism, (refer to Page - ), more the number of H+ ions, more the number of propanone molecule that gets protonated in Step-1. Consequently, the subsequent steps are also favored. This in turn increases the frequency of successful collision and thus increases the rate of the reaction. In other words, the pH increases, the amount of Hydrogen ions (H+) decreases, the rate of the reaction decreases. As a result, less amount of propanone is consumed. Thus, the amount of propanone left in the reaction medium increases. Hence, the absorbance of the reaction mixture after the end of the reaction increases. At all values of pH, the initial concentration of propanone remains the same. With increase in pH, concentration of hydrogen ion (H+) decreases, rate of reaction decreases, less propanone is consumed, final concentration of propanone increases, absorbance of reaction mixture after the end of the reaction increases and thus the values of change in absorbance decreases. This is also evident from Figure 10; as the pH increases from 1.00 to 7.00, the value for change in absorbance decreases from 0.104 ± 0.001 abs to 0.039 ± 0.001 abs.

Conclusion

How does the average rate of the reaction (measured in abs s-1 ) of the intermolecular condensation between propanone and ethanol to produce 2,2-diethoxy propane in presence of HCl as catalyst depends on the pH of the medium, determined using UV-Vis spectrophotometer?

  • As the pH of the medium decreases from 1.00 to 7.00, the rate of the reaction decreases from • 1.73 × 10-4 abs s-1 to 6.50 × 10-5 abs s-1. This shows that as pH decreases, the rate at which the propanone reacts with ethanol also reduces.
  • As pH decreases, the medium becomes less acidic and thus the molar concentration of Hydrogen ion (H+) in the medium decreases and the rate at which the propanone reacts with ethanol decreases.
  • The rate of the reaction between propanone and ethanol follows a linear relationship that follows the equation: y=-0.175 x + 1.9143; where y indicates the rate of the reaction between propanone and ethanol in acidic medium and x represents the pH of the medium.
  • With increase in pH, concentration of hydrogen ion (H+) decreases, rate of reaction decreases, less propanone is consumed, final concentration of propanone increases, absorbance of reaction mixture after the end of the reaction increases and thus the values of change in absorbance decreases.
  • The null hypothesis has been rejected and the alternate hypothesis has been accepted.

Evaluation

Strengths

  • The wavelength of maximum absorbance has been detected experimentally instead of using a literature value. Moreover, the value obtained experimentally is in agreement with the literature value. This indicates that the data collected is reliable and accurate.
  • The total percentage error is 3.05 and the magnitude is really small. This shows that there is not enough systematic error in the investigation. Thus, the data collected is coherent and the result concluded may be claimed to be reliable and accurate.
  • The magnitude of standard deviation has been shown in Figure-7 and Figure-9. The values are quite less in magnitude in comparison to the data values. For example, in Figure-9, the data values for absorbance are – 0.681,0.681 and 0.680 (at pH =1.00) while the standard deviation is 0.001. Thus, it can be claimed that the raw data collected is precise.

Limitations

Source of error
How does it affect?
How can it be improved?
The rate of the reaction has been determined by monitoring the absorbance of propanone at the wavelength where it shows maximum absorbance. In the reaction medium, unreacted ethanol and the product – 2,2- diethoxy ethane is also there along with propanone. Thus, at the wavelength used (275 nm). Both ethanol and 2,2-diethoxy propane can show some absorbance at this wavelength.
This means that the absorbance recorded both at the start of the reaction and at the end of it are not exclusively for propanone. Thus, the values of absorbance are higher than the actual value. This error is a unidirectional error and, in all case, will make the data collected to have a value more than actual.
Once the reaction mixture is extracted to measure the absorbance, a mixture of ethanol and the product 2,2-diethoxy propane must be used as a blank to nullify the absorbances they show at 275 nm.
There will be a time gap between the instant the experimenter records 600.00 s in the stop-watch and the absorbance of propanone is recorded.
This leads to inaccuracy of result. Because, the time is taken as 600.00 s while calculating the rate of the reaction whereas the actual time should be 600.00s added to the time gap between the instant the stop watch records 600.00 s and the absorbance is recorded.
The reaction must be monitored in a cuvette which is inserted in a UV-Visible spectrophotometer.
Figure 14 - Table On Systematic Error

Random error

Source of error
How does it affect?
How can it be improved?
Various measuring devices like digital mass balance, colorimeter, stop-watch, pipette has been used to collect the raw data. All of this apparatus has their own uncertainty.
The data collected is not accurate and has some uncertainty associated with it. For example, the absorbance for Trial-1 in pH=1.00 is not exactly 0.681 abs; it is 0.681 ± 0.001 abs.
The data was collected in triplicates. For example, the data for absorbance was collected in three different trails and an arithmetic mean was used.
Figure 15 - Table On Random Error

Further scope of investigation

There are many organic reactions that happens in acidic medium. For example, aldol condensation (Zalkow et al.) – reaction between aldehydes to produce a compound that has both aldehyde and alcohol group. This is one of the oldest reactions in organic reaction that made a way to join molecules by making C-C bond. Structural features of a molecule always impact the rate of reaction. Thus, I would like to see if the chain length of the aldehyde is increased from 2 in ethanal to 6 in hexanal, how would the rate of the reaction change. To do this, an absorbance versus wavelength plot can be made for the aldehyde and the wavelength of maximum absorbance can be determined from that. Following this, the absorbance of that aldehyde can be recorded after the reaction is over and the change of absorbance can be calculated. This would allow us to determine the rate of the reaction as done here. Finally, a scatter graph can be plotted for the rate of the reaction versus the chain length of the aldehyde used which can indicate that how does the rate of the reaction depends on the chain length of the aldehyde.

References

Dong, Jian-Lian, et al. “A Simple and Versatile Method for the Formation of Acetals/Ketals Using Trace Conventional Acids.” ACS Omega, vol. 3, no. 5, May 2018, pp. 4974–85. DOI.org (Crossref), doi:10.1021/acsomega.8b00159.

 

MacKENZIE, C. A., and J. H. Stocker. “PREPARATION OF KETALS. A REACTION MECHANISM.” The Journal of Organic Chemistry, vol. 20, no. 12, Dec. 1955, pp. 1695–701. DOI.org (Crossref), doi:10.1021/jo01364a015.

 

Wright, Austin C., et al. “Small-Scale Procedure for Acid-Catalyzed Ketal Formation.” The Journal of Organic Chemistry, vol. 84, no. 17, Sept. 2019, pp. 11258–60. DOI.org (Crossref), doi:10.1021/acs.joc.9b01541.

 

Zalkow, L. H., et al. “A new circular dichroism study of ketal formation of some steroidal ketones.” Tetrahedron, vol. 26, no. 21, Jan. 1970, pp. 4947–52. ScienceDirect, doi:10.1016/S0040- 4020(01)93146-1.