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Chemistry SL
Chemistry SL
Sample Internal Assessment
Sample Internal Assessment

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Table of content
Genesis
Research question
Background information
Hypotheses
Variables
Materials required
Apparatus required
Risk assesment
Procedure
Conclusion
Evaluation
Biblography

Effect of cooking temperature on acetic acid content of vinegar

Effect of cooking temperature on acetic acid content of vinegar Reading Time
11 mins Read
Effect of cooking temperature on acetic acid content of vinegar Word Count
2,095 Words
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Table of content

Genesis

Kitchen chemistry and cooking science is one of the most wide and major application of Chemistry. All the food products that we use starting from different spices to food additives are organic compounds and thus cooking is basically an organic reaction they go through. For example, change of color of green vegetables while cooking, souring of milk, caramelization of sugar are all examples of organic reactions. Thus, changes in chemical composition of substances during cooking has always been a major topic of interest in Chemistry. Due to the global pandemic, when access to school laboratory was not there, selecting and identifying a appropriate topic for the Chemistry Internal Assessment became an issue especially when I was determined to opt for an IA that uses experimental data. So, I chose to base my investigation on chemicals that are used in our daily life. Focusing on the fact that compounds change their molecular structure as well as composition during cooking, I decided to understand how it happens and what factors may impact it. I chose to deal with vinegar as that is one of the most widely used ingredients for cooking. Heating is an essential condition of cooking. Almost all foods that we prepare involves thermal exposure of chemicals in some or the other way. So, I decided to explore how exposure to temperature would alter the chemical composition of vinegar and to what extent.

Research question

How does the molar concentration of ethanoic acid (CH3COOH) in mol dm-3 within vinegar depends on the temperature to which it is heated temperature, determined using acid base titration with a primary standard NaOH solution?

Background information

Vinegar

Vinegar is a commercially used aqueous solution of ethanoic acid. As per FDA (Food and Drug Adminstration), vinegar must contain ethanoic acid within the range of 4.00% to 8.00% (volume by volume). It means that 100 cm3 of vinegar should contain 4.00 cm3 to 8.00 cm3 of ethanoic acid. The most widely used vinegar is Apple Cider Vinegar which is named based on the fact that it is made from apple. Vinegar is used as a souring agent and is used in marination of meats as it aids in the breaking down of polypeptide chains into smaller uses and thus makes it easier for the meat to become tender. Researches reports that vinegar has various medical benefits as well. Journals of medical researches reveals that direct consumption of vinegar may be beneficial to treat health conditions like hyperacidity, Type-II Diabetes and so on.

Synthesis of vinegar

Vinegar is prepared in a biological process. The biochemical pathway consists of preparing vinegar involves two enzymatic pathways:

  • Alcoholic fermentation of glucose:

C6H12O6 (glucose) ----→ 2 C2H5OH (aq) +2 CO2 (g)

 

Glucose undergoes fermentation to form ethanol and release carbon dioxide. This step is a breakdown process where a large organic molecule of glucose decarboxylates (loses CO2) to produce ethanol.

  • Oxidation of ethanol formed from fermentation:

2 C2H5OH (aq) + O2 (g) ---→ 2 CH3COOH

 

Here ethanol when exposed to oxygen in air oxidizes to ethanoic acid. The oxidation number of C increases from -2 in ethanol to 0.

 

The first step is anaerobic as it happens in absence of oxygen while the second step needs presence of oxygen. Both the steps involve the use of enzymes secreted from the microbes present within the fruit which undergoes fermentation. As both of them are enzyme catalyzed reactions, they occur at an optimum temperature and also requires a definite pH level. The ethanoic acid made is diluted and a dilute solution of vinegar containing ethanoic acid at 4% to 8% by volume is then used as vinegar.

Reaction of ethanoic acid with NaOH

Ethanoic acid is a weak organic acid and reacts with the strong base NaOH to produce the salt- Sodium ethanoate and water. This is a neutralization reaction and can thus be used as a basis of the analytical process to deduce the concentration of ethanoic acid from an acid base titration.

 

CH3COOH (aq) + NaOH (aq) -------→ CH3COONa (aq) + H2O ...........(equation - 1)

 

The salt formed is a basic salt as ethanoic acid is a weak acid and NaOH is a strong base. Thus, the pH at equivalence point will lie above 7.00 and thus phenolphthalein can be used as a suitable indicator for this titration. Here, the analyte is ethanoic acid and the titrant is NaOH. Thus, the color changes from colorless (in acidic medium) to pink (in basic medium).

Experimental methodology

The vinegar solutions will be heated to various temperatures using a water bath. After being heated, the solutions were titrated with a solution of NaOH of known concentration. The burette reading will be used to calculate the number of moles of NaOH consumed and thus the moles of ethanoic acid present. This will then be used to determine the concentration of ethanoic acid. Following this, a scatter plot will be used to elucidate the correlation of temperature and concentration of ethanoic acid in vinegar.

Alternate methodology

The main purpose of the investigation is to determine the molar concentration of ethanoic acid in vinegar. It can be done using a pH curve instead of an acid base titration. That would give us more accurate result. Moreover, concentration of ethanoic acid can also be determined spectrophotometrically by measuring the absorbance of the molecule at a wavelength at which it displays maximum absorbance. Since ethanoic acid is a colorless liquid, it would show absorbance in the ultra violet region and thus a UV-Visible spectrophotometer is required for this. However, the first method was discarded as a pH probe was not accessible and the lack of a UV-Visible spectrophotometer did not allow to use the second method.

Literature survey

In a medical study on the anti-bacterial and anti-glycemic effect of Vinegar, it was found that the increase of temperature reduces the concentration of ethanoic acid in vinegar. The study is titled as – “Vinegar: Medicinal Uses and Antiglycemic Effect” by Carol S. Johnston and Cindy A.Gaas published in the journal – “Medscape General Medicine”.

Hypotheses

Null hypotheses

The temperature at which vinegar is heated has no correlation with the molar concentration of ethanoic acid in the vinegar.

Alternate hypotheses

As temperature increases, the molar concentration of ethanoic acid increases. With heating, the volume of water evaporates and thus the solution becomes more concentrated. Thus, molar concentration of ethanoic acid in vinegar would increase.

Variables

Indepenendent variable

Temperature of Vinegar: A water bath was set to the required temperature and then the samples were incubated inside it. A thermometer was used for each sample to ensure the required temperature is reached. The cooking temperature usually differs from a range of 40°C to 100°C. So, the temperature measured were 20°C, 40°C, 60°C, 80°C and 100°C.

Dependent variable

Concentration of Ethanoic Acid (CH3COOH) in Vinegar: The vinegar samples were titrated against NaOH solution of known concentration. The change in the burette readings were recorded. Using the volume of NaOH required as obtained from the burette reading, the moles and the stoichiometric ratio in which ethanoic acid reacts with NaOH, the molar concentration of ethanoic acid was deduced. The molar concentration was measured in the unit – moldm-3.

Variable
Effect on the experiment
How it was controlled
Apparatus used
The molarity of NaOH solution (1M)
The concentration affects the amount of affect the amount of NaOH required for titration. As higher concentration of NaOH will result in lesser solution of NaOH required to finish titration.

150 cm3 aqueous solution of NaOH with the same concentration was prepared and stored. The solution was stirred regularly and whenever needed.

Digital mass balance
Heating device
Change in the method used for heating would actually differ the accuracy of the temperature to which the solutions are heated.
Water bath was used for heating in all cases.
Water bath
The type of Vinegar
The type of vinegar used could impact of the experiment as different types of vinegar contain different amount of acetic acid. Difference in the amount of acetic acid could lead to difference readings between each trial as more amount of acetic acid would take more solution NaOH to finish titration.
The same bottle of Apple Cider vinegar was used throughout the experiment. It was stirred properly before considering it for a trial.
---
The amount of Phenolphthalein indicator
The amount of Phenolphthalein indicator could impact the solution as the indicator would affect the final pH, therefore lowering the accuracy of the experiment.
2 drops of Phenolphthalein indicator was used for each trial.
Dropper
Figure 1 - Table On Controlled Variable With Their Effects In The Experiment, How They Were Controlled And The Apparatus Used For Them

Materials required

Sl. No.
Material
Quantity
Source
1
Solution of NaOH

150.00 cm3

School Laboratory
2
Vinegar

150.00 cm3

Local supermarket
3
Distilled Water

1000.00 cm3

School Laboratory
4
Phenolphthalein Indicator

15.00 cm3

School Laboratory
Figure 2 - Table On The Materials Required With Their Quantities And Their Sources

Apparatus required

Apparatus
Quantity
Least Count
Uncertainty
Funnel
1
N.A.
N.A.
White Tile
1
N.A.
N.A.

Burette (50cm3)

1

0.10 cm3

± 0.05 cm3

Graduated pipette – 10.00 cm3

1

0.10 cm3

± 0.05 cm3

Graduated Cylinder (50 cm3)

1

2.00 cm3

± 1.00 cm3

Graduated Cylinder (10 cm3)

1

0.20 cm3

± 0.10 cm3

Clamp Stand
1
N.A.
N.A.
Dropper
1
N.A.
N.A.

Test tube (100 cm3)

5
N.A.
N.A.
Test tube Rack
1
N.A.
N.A.
Reagent Bottle
1
N.A.
N.A.
Water Bath
1
N.A.
N.A.
Spatula
1
N.A.
N.A.

Conical Flask (100 cm3)

5

10 cm3

± 5 cm3

Thermometer
1
0.1°C
± 0.05°C
Digital mass balance
1
0.01g
± 0.01g

Glass Beaker (250 cm3)

1

25 cm3

± 12.5 cm3

Figure 3 - Table On The Required Apparatus With Their Quantities And Uncertainty (If Applicable)

Risk assesment

Safety Precautions

  • Protective Lab equipment were worn such as gloves, lab coat, safety goggles and mask.
  • Chemicals were handles with care to avoid spillage
  • Foods and drinks were kept outside the lab
  • Skin and eye contact with chemicals were avoided throughout.
  • The boiling tube was held with the support of a test tube holder while taking it outside the water bath to avoid possible skin burns.

Ethical Issues:

  • There were no significant ethical issues but the wastage of chemicals was kept to the minimum.

Environmental issues

  • There were no significant environmental issues.

Procedure

Preparation of 100 cm3 of 1.00 mol dm-3 NaOH solution

Number of Moles = concentration × Volume = 1.00 × \(\frac{100}{1000}\) = 1.00 × 0.10 = 0.10 moles Mass of solid NaOH required = moles mass  = 0.10 × (23.00 + 16.00 + 1.01 + 1.01) = 4.00g

  • A watch glass was put on the digital mass balance. The scale was now set to zero grams.
  • A spatula was taken and solid NaOH of 4.00 ± 0.01 g was put on the watch glass and weighed.
  • A beaker (250 cm3 ) was cleaned and then distilled water was put till 100 cm3 using a graduated measuring cylinder.
  • The weighed solid NaOH of 4.00 ± 0.01 g was put inside the beaker.
  • The solid particles were mixed thoroughly with the distilled water using a glass rod.
  • Now, this solution was stored in a clean glass reagent bottle and labelled.

Titration of vinegar with NaOH

  • A clean and dry burette was taken and rinsed with NaOH solution.
  • The burette was filled with the 1.00 moldm-3 NaOH solution using a funnel and to ensure that there are no bubbles, it was done slowly. The burette was filled till the mark of 0.00 cm3.
  • A 100 cm3 conical flask was taken and 5.00 ± 0.05 cm3 of the vinegar solution was added to it using a graduated pipette.
  • The flask was kept on a water bath and the temperature was set at 40.0°C. A laboratory thermometer was inserted inside the conical flask to monitor the temperature. The heating was continued till the temperature reached a mark of 40.0°C.
  • After heating, the conical flask was kept on a mat on the table top to allow it to come down to room temperature.
  • 2 drops of phenolphthalein was added to the same conical flask using a dropper.
  • The vinegar in the flask was titrated against the NaOH solution running down the burette.
  • The end point was detected by the appearance of a permanent pink color and the burette reading was noted.
  • Steps 2-9 were repeated for four more times to obtain concordant readings.
  • The same process was followed for other values of temperature- 60.00 ± 0.50°C, 80.00 ± 0.50°C and 100.00 ± 0.50°C. To get the reading at 20.00°C, the water bath was not used as the room temperature was 20.00° C.

Qualitative observations

  • The vinegar solution was soluble in distilled water and colorless solution was formed even adding phenolphthalein.
  • The test tubes started getting hotter as the temperature increased and more evaporation started to occur.
  • A light pink color was formed which would disappear as the solution was shaken.
  • The color of the solution after titration changed to permanent pink from colorless.

Quantitative data

Figure 4 - Table On Raw Data Table Difference In Burette Readings For The Titration Of Vinegar With NaOH
Figure 4 - Table On Raw Data Table Difference In Burette Readings For The Titration Of Vinegar With NaOH

Sample calculation for table 4

For Temperature: 20.00°C:

 

For Trial - 1, Difference in burette reading

 

= Final burette reading – Initial burette reading

 

= 4.20 ± 0.05 cm3 – 0.00 ± 0.05 cm3 = 4.20 ± (0.05 + 0.05) cm3 = 4.20 ± 0.10 cm3

 

Mean burette reading = \(\frac{Trial-1+Trial-2+Trial-3+Trial-4+Trial-5}{5}\) 

 

 = \(\frac{4.20(±0.05)+4.00(±0.05)+4.60(±0.05)+4.70(±0.05)+4.20(±0.05)}{5}\) = 4.34 ± 0.05 cm3

 

As no concordant reading has been obtained, the arithmetic mean has been considered instead of the precise reading.

Temperature(±0.50°C)

Mean difference in Burette Reading (± 0.10cm3)

Moles of NaOH used
Moles of Acetic Acid

Molar concentration of Acetic Acid ( × 10-2 mol dm-3)

20.00
4.34
0.0043
0.0043
86.80
40.00
3.98
0.0040
0.0040
79.60
60.00
3.50
0.0035
0.0035
70.00
80.00
3.18
0.0032
0.0032
63.60
100.00
2.80
0.0028
0.0028
56.00
Figure 5 - Table On Processed Data Table For The Determination Of Concentration Of Ethanoic Acid

Sample calculations

For temperature 20.00 ± 0.50°C

 

Mean burette reading = 4.34 ± 0.10 cm3

 

Volume of NaOH consumed = mean burette reading = 4.34 ± 0.10 cm3

 

Moles of NaOH used = \(\frac{molar\ concentration\ of\ NaOH\ solution\ used\ in\ mol\ dm^{-3}×Volume\ of\ NaOH\ concumed\ in\ cm^3}{1000}\)

 

\(=\frac{1.00×4.34}{1000}\) = 0.0043 moles

 

Moles of ethanoic acid = moles of NaOH consumed (as they react in the mole ratio 1:1) = 0.0043 moles

 

Molar concentration of ethanoic acid = \(\frac{moles\ of\ ethanoic\ acid}{total\ volume\ of\ the\ solution\ in\ dm^3}\)

 

\(=\frac{0.0043}{\frac{5}{1000}}\) = 0.8680 = 86.80 × 10-2 mol dm-3

Error propagation

Mass of NaOH taken = 4.00 ± 0.01 g

 

Fractional error in concentration \((\frac{Δc}{c})=\frac{Δn}{n}+\frac{ΔV}{V}=\frac{±0.01}{4.00}+\frac{±0.10}{100.00}\) = ± 0.0035

 

Fractional error in moles of ethanoic acid

 

\(\frac{Δc_{ethanoic\ acid}}{c_{ethanoic\ acid}}=\frac{Δn}{n}+\frac{Δvolume\ of\ vineger}{Volume\ of\ vinegar}\) = ± 0.0265 + \(\frac{±0.05}{5.00}\) = ± 0.0365

 

Percentage error in concentration of ethanoic acid = ± 0.0365 × 100 = ± 3.65

Comparison with literature value

The bottle of Apple Cider Vinegar used claims to have 5.00 % ethanoic acid as mentioned in the label. This means that 100.00 cm3 of this vinegar has 5.00 cm3 of ethanoic acid.

 

Mass of ethanoic acid = Volume × Density = 5.00 cm3 × 0.997 g cm-3  = 4.985 g

 

Molar concentration = \(\frac{\frac{mass}{molar\ mass}}{\frac{volume}{1000}}\) = \(\frac{\frac{4.985}{48.00}}{\frac{100}{1000}}\) × 100 = \(\frac{1.04-0.8680}{1.04}\) × 100 = 16.53

 

There is a percentage error 16.53 % which also indicates that there is a systematic error in this investigation.

Figure 6 - Concentration Of Acetic Acid Compared To The Temperature Of The Vinegar
Figure 6 - Concentration Of Acetic Acid Compared To The Temperature Of The Vinegar
  • The graph above, shows the trend between the change in temperature compared to the change in the concentration of ethanoic acid in vinegar. Along the x-axis, the temperature of the vinegar is considered as it is the independent variable while along the y-axis, the concentration of ethanoic acid in vinegar is considered as it the dependent variable and depicts the change as the change in temperature is made. The graph presents a downwards sloping straight line. As the temperature increases from 20.00 ± 0.50°C to 100.00 ± 0.50°C, the molar concentration of ethanoic acid 86.80 × 10-2 mol dm-3 to 56.00 × 10-2 mol dm-3
  • The graph depicts a negative relationship between the temperature of the vinegar and concentration of acetic acid because as the temperature increases, the concentration of acetic acid in vinegar decreases. This concludes, as the temperature will increase the concentration of acetic acid will decrease with temperature. The value of R2 which tells the data is very close to the line of best fit.
  • The graph presents a trendline equation of (y = -0.0043x + 0.9596) where y represents the concentration of acetic acid in vinegar and x represents the temperature of the vinegar.
  • At y = 0, that is (0 = -0.0043x + 0.9596), the x value derived is 223.16°C. This gives a conclusion that when the temperature of the vinegar sample reaches 223.16°C, the concentration of acetic acid in vinegar will become 0.00 mol/ dm3 . Therefore, the vinegar sample will not contain any acetic acid.
Temperature (±0.50°C)

Decrease in Concentration of Acetic Acid (mol.dm-3 )

20.00 to 40.00
0.0720
40.00 to 60.00
0.0960
60.00 to 80.00
0.0640
60.00 to 80.00
0.0760
Figure 7 - Table On Processed Data For The Average Decrease In Concentration Of Ethanoic Acid

Sample Calculations

For increase of temperature 20.00 ± 0.50o C to 40.00 ± 0.50o C,

Decrease in Concentration of ethanoic acid (mol.dm-3 )

= concentration of ethanoic acid at 20.00 ± 0.50°C – concentration of ethanoic acid at 40.00°C

= 0.8680 – 0.7960 = 0.0720 mol dm-3

Figure - 8 Bar Graph Representing The Decrease In Concentration Of Acetic Acid
Figure - 8 Bar Graph Representing The Decrease In Concentration Of Acetic Acid

The graph above, shows the decrease in concentration of Acetic acid in vinegar as concentration is increases. Temperature is taken along the x axis as it is the independent variable and the decrease in concentration of Acetic Acid is taken in the y axis as it the dependent variable. The values of decrease in increase temperature are very inconsistent. Although, an average decrease in concentration was found to be 0.0770 moles. This average predicts that as a temperature of 20°C is increased, the concentration of Acetic Acid in vinegar will decrease by 0.0770 moles.

Scientific justification

The trend shows that the molar concentration of ethanoic acid decreases with the increase in the heating temperature. Applying the understanding that with rise of temperature, the water would start evaporating at a faster rate and thus volume of water would decrease eventually increasing the concentration of ethanoic acid, this trend cannot be justified. Hence, it is clear that the reason behind the decrease is not an outcome of a physical process but is related to some chemical reaction that ethanoic acid may have undergone. Carboxylic acids on heating undergoes thermal decarboxylation to produce a hydrocarbon and carbon dioxide. Ethanoic acid is also a weak carboxylic acid and may undergo the same process.

 

CH3COOH ----→ CH4 + CO2 (g)

 

With the increase in temperature, the rate of decomposition increases and thus the amount of ethanoic acid in the mixture decreases. Thus, there is lesser number of moles of ethanoic acid in the vinegar solution titrated. This also explains why the volume of NaOH required for the neutralization of ethanoic acid in the mixture decreases as temperature is increased. Table-5 (raw data table) clearly shows a decrease in the value of mean burette reading and that clearly supports this fact.

Conclusion

How does the molar concentration of ethanoic acid (CH3COOH) in mol dm-3 within vinegar depends on the temperature to which it is heated temperature, determined using acid base titration with a primary standard NaOH solution?

 

The molar concentration of ethanoic acid (CH3COOH) in mol.dm-3 in vinegar is inversely proportional to the temperature. Furthermore, it is concluded that the rate of change of concentration is not uniform throughout the change in temperature. The maximum rate of change of concentration is obtained between 40°C to 60°C and the minimum rate of change of concentration is obtained between 60°C and 80°C.

  • There is a decrease in molar concentration of acetic acid in vinegar from 86.80 mol.dm-3 to 56.00 mol.dm-3 when the temperature decreases from 20.00°C to 100.00°C.
  • The equation of trend for the relationship between molar concentration of acetic acid and temperature:y = −0.0043 + 0.9596, where y represents the concentration of acetic acid in vinegar and x represents the temperature of the vinegar.
  • When the temperature of the vinegar sample reaches 223.16°C, the concentration of acetic acid in vinegar will become 0.00 mol/ dm3. Therefore, the vinegar sample will not contain any acetic acid.
  • The values of decrease in increase temperature are very inconsistent. Although, an average decrease in concentration was found to be 0.0770 moles. This average predicts that as a temperature of 20°C is increased, the concentration of Acetic Acid in vinegar will decrease by 0.0770 moles.
  • Carboxylic acids on heating undergoes thermal decarboxylation to produce a hydrocarbon and carbon
    dioxide. Ethanoic acid is also a weak carboxylic acid and may undergo the same process. With the
    increase in temperature, the rate of decomposition increases and thus the amount of ethanoic acid in
    the mixture decreases.
  • The obtained relationship between the molar concentration of acetic acid in vinegar and temperature is inverse which is why a negative slope of -0.38 has been obtained. Hence, Null hypothesis has been rejected. Furthermore, as an alternate hypothesis, it was assumed that a positive relationship would be obtained. However, that has also obtained to be false. Hence, alternate hypothesis is also rejected.
  • There is a percentage error of ±3.65% obtained in the experimental data.
  • When the experimental data has been compared with the literature data, the percentage error obtained was ±16.53 % which also indicates that there is a systematic error in this investigation.

Evaluation

Strengths

  • The independent variable chosen has a wide range with values at uniform intervals. The values chosen are justified as those are usually the temperature that is created during cooking.
  • The trend obtained is in agreement with the literature survey done and is thus supported by a secondary data from a different source. As mentioned in the literature survey, decrease of molar concentration of ethanoic acid with temperature was observed and the result in this investigation is also the same.
  • The methodology is simple and the experiment can be easily performed as it does not require any complex chemicals or apparatus that is difficult to procure.
  • The values of standard deviation are quite low (as indicated in Table-5) and thus indicates a significant level of precision in the raw data collected.
  • The percentage uncertainty calculated and the percentage error determined is also quite low indicating a high level of accuracy in this investigation.

Sources of error and improvement

Type of error
Source of error
How does it affect?
How can it be reduced?
Random error
The measuring devices used like burette has an absolute uncertainty.
The burette readings are not accurate.
accurate. The titration must be repeated and data can be collected in multiple trials. Arithmetic mean or the most precise reading can be considered as the mean burette reading.
Systematic error
The end point of the titration and the equivalence point of the titration is not identical. In an acid base titration, we detect the end point of the titration from the color change and not the equivalence point.
The volume of NaOH required (mean burette reading) taken is actually one drop more than what is actually required in the equivalence point. Thus, the values of molar concentration of ethanoic acid calculated is higher than ideal values. This is a source of positive systematic error as it always leads to values more than actual.
Use a pH curve to determine the equivalence point from the inflexion point of the graph instead of using an acid base titration.
The thermometer is a measuring device and will have an uncertainty associated with it.
Values of temperature recorded will not be accurate.
A temperature probe and Vernier Logger Pro can be calibrated using boiling water and used instead of using a laboratory thermometer.
The digital mass balance is an electrical device. Fluctuations in power supply will cause it to have an instrumental error.
The values of mass recorded will be inaccurate.
The balance must be calibrated using standard mass.
Methodological
The NaOH solution used for titration is a primary standard solution. It may change its concentration with time if not used on the same day.
The result of any calculation done using the value of concentration of NaOH would be inaccurate.
The NaOH solution must be prepared on the day it is used.
Figure 9 - Table On Sources Of Error And Improvement

Further scope of investigation

To investigate further, I would like to study how temperature affects other bio chemical reactions. Souring of milk is a chemical reaction which leads to formation of lactic acid from the hydrolysis of lactose present within it. I would like to heat the milk to different temperatures and then add a definite volume of souring agent (lime water) to it. This will result in the production of lactic acid within it. The volume of lactic acid produced can be deduced using an acid base titration with NaOH solution of known concentration. Thus, we can determine the mass of lactic acid produced on addition of a souring agent as a function of temperature.

Biblography

  • Akanksha, Singh & Mishra, Sunita. (2017). STUDY ABOUT THE NUTRITIONAL AND MEDICINAL PROPERTIES OF APPLE CIDER VINEGAR ARTICLE INFO ABSTRACT. 8.
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  • Biological Synthesis of Vinegar. http://ndpublisher.in/admin/issues/IJFFV3N2d.pdf.
  • Brainard, Daniel C., et al. ‘Temperature and Relative Humidity Affect Weed Response to Vinegar and Clove Oil’. Weed Technology, vol. 27, no. 1, Mar. 2013, pp. 156–64. bioone.org, doi:10.1614/WT-D- 12-00073.1.
  • Foundation, In association with Nuffield. ‘The Acidic Reactions of Ethanoic Acid’. RSC Education, https://edu.rsc.org/experiments/the-acidic-reactions-of-ethanoic-acid/462.article. Accessed 20 May 2021. 
  • Kiefer, Donald. ‘Chemical Synthesis of Vinegar - Food Fermentation’. Buffalo Brewing Blog, 9 May 2020, https://www.buffalobrewingstl.com/food-fermentation/chemical-synthesis-of-vinegar.html.
  • Lu, Xincheng, et al. ‘Effect of Pyrolysis Temperature on the Characteristics of Wood Vinegar Derived from Chinese Fir Waste: A Comprehensive Study on Its Growth Regulation Performance and Mechanism’. ACS Omega, vol. 4, no. 21, Nov. 2019, pp. 19054–62. ACS Publications, doi:10.1021/acsomega.9b02240.
  • Odahara, M. (Kewpie Jyozo Co Ltd, et al. ‘The effect of sushi vinegar on texture of sushi rice before and after storage under low temperature’. Journal of the Japanese Society for Food Science and Technology (Japan), 2004. agris.fao.org, https://agris.fao.org/.
  • Untitled. http://www.chem.latech.edu/~deddy/chem122m/L04U00Vinegar122.htm. Accessed 20 May 2021.