This document provides details about an experiment conducted using a colorimeter to measure the color of various solutions. It includes 7 chapters that discuss the theory of colorimetry, objectives of the experiment, equipment used, procedures, results, errors and recommendations. The results show that absorbance increases with concentration, pH level, and temperature based on Beer-Lambert's law. Different color scales like APHA and Gardner were used to measure lighter and darker solutions. The document concludes that understanding color properties aids in determining a solution's composition and behavior in industries like petroleum.

1. College of Engineering
Faculty of petroleum Engineering
Petroleum Fluid Properties Laboratory
PENG212L
Colorimeter
Name: Ruba Alsoheil - ID: 201801530
Submitted to: Dr. Jamil Mahfoud
Date: 1-Jan-2021

2. Table of Content:
List of Figures……………………………………………………………………………………...i
List of Tables……………………………………………………………………………………....ii
Chapter 1: Introduction……………………………………………………………………………1
1.1 Theory and Definitions………………………………………………………………………...1
1.2 Objectives……………………………………………………………………………………...2
Chapter 2: Apparatus………………………………………………………………….…………...4
Chapter 3: Other Equipment..……………………………………………………………………..6
Chapter 4: Procedures…………………..…………………………………………………………9
Chapter 5: Results and Discussion………………………………………………………………..11
5.1 Table of Results……………………………………………………………………………....11
5.2 Discussion..………………………………………………………………………………......12
Chapter 6: Errors and Recommendation…………………………………………………………14
6.1 Errors…………………………………………………………………………………………14
6.2 Recommendation……………………………………………………………………………..14
Chapter 7: Conclusion……………………………………………………………………………15
References………………………………………………………………………………………..16

3. i
List of Figures:
Figure 1.1: Interaction between light, object, and the eye………………………………………….2
Figure 1.2: Absorbance of light in concentrated and diluted solution………………………….….3
Figure 2.1: Colorimeter with an open and closed lid………………………………………………4
Figure 2.2: Spectrometer’s parts…………………………………………………………………...5
Figure 3.1: NaCl…………………………………………………………………………………..6
Figure 3.2: Coffee powder and tea bag……………………………………………………………6
Figure 3.3: Plastic plate……………………………………………………………………………6
Figure 3.4: Spatula………………………………………………………………………………...6
Figure 3.5: Cuvette………………………………………………………………………………...7
Figure 3.6: Beakers………………………………………………………………………………..7
Figure 3.7: Digital balance………………………………………………………………………...7
Figure 3.8: HCl solutions…………………………………………………………………………..7
Figure 3.9: Fresh water…………………………………………………………………………….8
Figure 5.1: Absorbance of solution A and B versus wavelength…………………………………13

4. ii
List of Tables:
Table 1.1: Electromagnetic spectrum……………………………………………………….…….3
Table 5.1: Values of the color comparison method using APHA………………………………..11
Table 5.2: Values of the color comparison method using Gardner scale………………………..11
Table 5.3: Absorbance of solution A and B with different temperature and pH level…….……13

5. 1
Chapter 1: Introduction
1.1 Theory and definition:
Density and volume are some of the characteristics that defines a solution. Another characteristic
is color which is because of the interacting process between the rays of light, solution or object,
and the human’s sensitive eyes which is shown in figure 1.1. The human’s eye is very sensitive
and sent an impulse because of the radiant energy to the brain which translates visually (Lange,
n.d.). In order to measure the color of the solution, there is different ways where one of them is
related to transmittance and absorbance, while the other is related to color comparison methods.
Furthermore, not all the radiations and wavelength are visible to the human eye, for Table 1.1 the
visible wavelength ranges from 400-700 nm. When white light waves hit a solution, certain
wavelength is absorbed decreasing the intensity of the energy and the light seen by the eyes are
the beams that are not absorbed like in figure 1.2. The absorbance of the wavelength is due to the
solvent in the solution, so as the solvent’s molecules increase, absorbance increases
simultaneously. So, concentration, C in 𝑚𝑜𝑙𝑒/𝑚3
, and absorbance are directly proportional. For
instance, figure 1.2 shows that diluted solution transmits more rays than the concentrated solution
which helps in identifying the concentrated solution. Identifying the concentration by linking it to
the absorbance is defined as colorimetry (Sherwood Scientific Ltd, n.d.). Also, the lighter the color
which relates to less absorbance is linked to higher purity.
𝐶 =
𝑛
𝑉
▪ n is number of mole (𝑚𝑜𝑙𝑒)
▪ V is the volume (𝑚3
)

6. 2
Colorimetry is significantly important, for it used in different industries and fields like cosmatic,
medical, chemical. In the medical field, colorimeter is used to know the sugar, creatinine, Uric
acid in blood (Sherwood Scientific Ltd, n.d.). Another example is to ensure the appropriate quality
of the water by determining the solvents like chlorine, zinc, and oxygen. In other words, ensuring
the quality of the samples is one of the most important purposes of colorimeter. In the petroleum
industry, colorimetry is very influential, for it helps in determining organic chloride in crude oil,
sulfur in petroleum product, phosphorous in gasoline, and lead in primary reference fuel
(Nadkarni, 1991).
In order to determine measure the color in this experiment, color comparison scales are used. There
are a lot of scales like Iodine, EPC-scale, and Barrat- color scale (Lange, n.d.). Each scale is used
for a certain industry, for example in the cosmetic related products, ISO 2049 scale is used (Lange,
n.d.). The most wide-known and used scales are APHA color scale and the Gardner scale (Lange,
n.d.). Hazen is usually used for diluted, water-white solutions, and it aids in determine the purity
of the solution which is when the APHA is less than 10 (Lange, n.d.). Meanwhile, for darker,
concentrated solutions, Gardner scale give a better comparative analysis. The color gets darker as
the number increases, but one of its disadvantages is the lengthy space between 8G and 9G (Lange,
n.d.).
Figure 1.1: Interaction between light, object, and the eye (Brady, n.d.)

7. 3
Table 1.1: Electromagnetic spectrum (Brady, n.d.)
Figure 1.2: Absorbance of light in concentrated and diluted solution (AUS, n.d.)

8. 4
Chapter 2: Apparatus
Figure 2.1: Colorimeter with an open and closed lid
Colorimeter measures the solution’s which is in the cuvette absorbance of wavelength from a light
source. This apparatus is an 1870s invention by Duboscq where there are two types of colorimeter
that are photometer, transmission percentage or absorbance’s measurement apparatus, and
densitometers, primary color’s density measurement apparatus (GE Healthcare Life science,
2013). As figure 2.2 shows the process of how spectrometer, colorimeter, measures absorbance. A
light source transmits a white light which passes through the collimator and then the prism allows
the existence of different wavelengths. After that, a single wavelength 𝜆 passes through the slit
and the cuvette. The intensity decreases due to absorbance of the wavelength where this
absorbance is detected by a microprocessor and displayed. Furthermore, when a single beam
passes through the slit, the colorimeter is called a single beam colorimeter. However, double beam
colorimeter is usually used for color comparison methods where different scales can be chose (GE
Healthcare Life science, 2013). A monochromator selects a specific band of wavelength from the
light source (GE Healthcare Life science, 2013).
Touch screen
Cuvette slot
Lid
Power button

9. 5
Figure 2.2: Spectrometer’s parts (GE Healthcare Life science, 2013)

10. 6
Chapter 3: Equipment Used:
Figure 3.1: NaCl
Figure 3.2: Coffee powder and tea bag
Figure 3.3: Plastic plate
Figure 3.4: Spatula
Figure 3.5: Cuvette

11. 7
Figure 3.6: Beakers
Figure 3.7: Digital balance
Figure 3.8: HCl solutions
1 2 3 4 5 6

12. 8
Figure 3.9: Fresh water
▪ Cuvette: The solution to be tested is usually poured in it and then it is placed in the cuvette’s
slot. The cuvette can be disposable or made from glass.
▪ Beakers: can contain distilled water, coffee, and tea
▪ Spatula: used mix and add NaCl and coffee into the plastic plate and the beaker
▪ Digital balance: to measure the weight of salt
▪ Fresh water used to calibrate the apparatus
▪ HCl solutions: solutions with different shade of yellow and different concentrations of
hydrogen chloride.
▪ Plastic: hold either salt or coffee to be weighed on the digital balance.

13. 9
Chapter 4: Procedures:
A lot of solutions that are used in this experiment do not need preparations like HCl solutions
1,2,3,4,5 and 6, but other need preparations.
Preparation of brine solution:
▪ Plug in the digital balance and calibrate it by placing a plastic plate on it
▪ Use a spatula to put 36 g of salt, NaCl, on the plastic plate
▪ Then, put the salt in a beaker full of water
▪ Mix the solution using a spatula
Prepare Tea:
▪ Put a tea bag in a beaker full of warm distilled water
▪ Use a spatula to mix
Prepare Coffee (Diluted/concentrated)
▪ Put a coffee powder in a beaker full of warm distilled water, put more for the
concentrated option
▪ Use a spatula to mix
Using Colorimeter:
▪ The apparatus should be plugged
▪ Turn ON the apparatus by pressing the power button
▪ Wait a few minutes until it finishes the start up where it does a self-automatic check
▪ After the checkup, it makes a sound signifying the end of the checkup
▪ Press on color measurement on the touch screen
▪ Calibrate to assure that the apparatus is working appropriately
▪ Bring a beaker filled with fresh water

14. 10
▪ Pour it in a cuvette, but not till the rim or edge where 5% is empty
▪ Make sure that the cuvette’s surface is dry
▪ If it is not, dry it with a tissue
▪ Slide the lid, put the cuvette in the cuvette slot
▪ According the Hazen’s scale, the value should be zero
▪ For light colored solutions, choose Hazen Scale
▪ Wear gloves when dealing with HCl solution
▪ Pour HCl solution 1 to a cuvette where 5% is empty
▪ Make sure the surface is dry, if not dry it with a tissue
▪ The value should be 21 according to Hazen’s scale
▪ After recording the value, get rid of the solution by pouring it in the sink to prevent any
unwanted accidents
▪ Repeat the same procedures using Hazel scale for brine solution and HCl solution 2 and 3;
make sure to calibrate using fresh water before each solution
▪ For darker colored solution, choose Gardener scale
▪ Repeat the same procedure done for HCl solution 1 for darker colored solutions which are
HCl solution 2,3,4 and tea and coffee; make sure to calibrate using fresh water before each
solution
▪ After recording the different values
▪ Clean the different equipment used cuvettes, beakers, and the spatula
▪ Unplug the apparatus
▪ Cover it with the plastic cover

15. 11
Chapter 5: Results and Discussion
5.1 Results:
Table 5.1: Values of the color comparison method using APHA
Fluid Hazen’s scale
Fresh water 0
Brine solution 2
HCl
Solution 1 21
Solution 2 97
Solution 3 198
Table 5.2: Values of the color comparison method using Gardner scale
Fluid Gardner’s scale
Tea 6.9
Coffee Concentrated >18
Diluted 17.1
HCl
Solution 4 2.2
Solution 5 4.7
Solution 6 8

16. 12
5.2 Discussion:
Beer-Lambert formula is shown below:
𝐴 = 𝜖𝐶𝐿
▪ A is the absorbency
▪ 𝜖 is the molar extinction coefficient
▪ C is the concentration
▪ L is the pathlength
In this experiment, color is measured using APHA and Gardner scale where APHA is used for
lighter solutions and Gardner is used for darker solutions. For instance, HCl solution 3 is much
more concentrated and darker, more yellowish, than HCl solution 1 and 2. Similarly, for Gardner
scale concentrated coffee ( >18) has a higher color value than diluted coffee (17.1). It can be
deduced, as the concentration increases absorbance increases which is proven in Beer-Lambert
formula. Also, pathlength and absorbance are directly proportional. Additionally, the wavelength
of the light is another factor which affects absorbance. For instance, in figure 5.1 different
wavelengths have different absorbance. In the solution, the molecule which absorbs the light is
referred to as chromophore. So, the nature of the chromophore or the solvent affect absorbance
since different solvents react and absorb differently. For example, tea ,6.9 in Gardner scale, and
diluted coffee, 17.1 in Gardner scale Additionally, number of absorbing species in the solution
affect the absorbance. For example, figure 5.1 shows the usage of two species x and y lead to
different values for absorbance. The experiment is usually done in room temperature and the
thickness is specified. However, when the thickness increases, the absorbance increases.
Moreover, increasing temperature results in more absorbance (Hanrahan, 2013). Another factor is
pH effect where a reduction leads to an increase in absorbance (Hanrahan, 2013). HCl solution 1

17. 13
is less acidic than HCl solution 2, so HCl solution 2 has less pH level leading to higher rates of
absorbance. Table 5.3 validates the relationship between pH level and temperature with
absorbance. Also, when APHA is less than 10, the solution is characterized by being purer which
is verified by the results (Lange, n.d.). For instance, APHA of brine is 2 which is less than HCl
solution 1 (21).
Figure 5.1: Absorbance of solution A and B versus wavelength (Kittipanyangam & Eguchi,
2019)
Table 5.3: Absorbance of solution A and B with different temperature and pH level
(Hanrahan, 2013)

18. 14
Chapter 6: Errors and Recommendations
6.1 Errors:
▪ The cuvette’s surface is not dry
▪ The cuvette is not clean and has dust
▪ Scratches on the cuvette
▪ Not the same type of cuvette is used
▪ The cuvette is full to the rim with the tested solution
▪ Forgetting to calibrate using fresh water before each solution
▪ Not using a fresh water to calibrate
▪ Turbidity of the solution
▪ Finger prints on the cuvette
6.2 Recommendations:
▪ Make sure to dry the surface leaving no fingerprints
▪ Chose a cuvette with no cuts and with a smooth surface
▪ Use the same type of cuvette
▪ Leave 5% of the cuvette empty
▪ Calibrate using fresh water to minimize side reactions
▪ Make sure that the solution is clear

19. 15
Chapter 7: Conclusion
Liquids have diverse properties like volume, density, viscosity, and color and understanding their
characteristics is a very important step into understanding the composition and the behavior of the
solution. Color number aids in knowing the solution’s purity and determining the solution. There
are different color scales. Hazen and Gardner color scales are the most used scales. There are many
factors that affect the absorbance of the wavelength by a solution including pH, concentration,
temperature, and the thickness of the solution. In petroleum industry, colorimeters are widely used
and known.

20. 16
References
AUS. (n.d.). Colorimetry. Retrieved from: https://www.ausetute.com.au/colorimetry.html
Brady, R. (n.d.). Theory of color measurement. Geelong: Deakin University.
GE Healthcare Life science. (2013). Spectrometry. UK: General Electric Company.
Hanrahan, G. (2013). Environmental Chemometrics: Principles and Modern Applications. New
York: Taylor & Francis group.
Kittipanyangam, S. &, Eguchi,K, (2019). Design of a multi-component analysis system based on
fuzzy Theory. International Journal of Innovative. 15(5). DOI: 10.24507/ijicic.15.05.1763
Lange, B. (n.d.). Objective colour assessment and quality control in chemical, pharmaceutical, and
cosmetic industries. UK: Dr Lange.
Nadkarni, R. A. (1989). Modern Instrumental Methods of Elemental Analysis of Petroleum
Products and Lubricants. Philadelphia: American Society for Testing and Materials.
Sherwood Scientific Ltd. (n.d.). A Guide to Colorimeter. England: Sherwood Scientific.