The Effect of Different Cleaning Agents on Milk

Abdul Imtiaz, Sadia Supti, Yulin Liu

Professor Maryam Alikhani

Writing for Engineering

The City College of New York

October 3, 2018

 

 

Abstract

Surfactants in cleaning agents react with milk and break down the fat dispersed within. Four different types of cleaning agents were tested on milk, with food coloring added to facilitate the observation of the reaction. A drop of each agent was placed into the milk after it was poured into a plate (one for each cleaning agent) and had food coloring added to it. The time taken for the food coloring to cease movement was measured. Dish soap caused the most intense and longest duration of movement. It is possible that unexpected factors, such as chemicals in the food coloring, may have affected the experiment. The experiment may be retried with a specific class of cleaning detergents, such as different brands of dish soap, as well as a different type of food coloring.

 

Introduction

Mixtures can be split into two types: homogenous mixtures and heterogeneous mixtures. The milk sold in stores is generally a homogenized mixture of water, fat, and proteins. Milk is a colloid, which is a mixture that has particles that are of a certain size dispersed within another substance. Milk is specifically an emulsion, which is a colloid that has a liquid substance dispersed in another liquid substance (Brown et al., 2018).

Cleaning agents, such as soap and detergent, mainly consist of surfactants, which are substances that reduce the surface tension of the liquid they are added to (National Science Foundation, n.d.). This is part of the cleaning action of soaps. When dish soap is added to milk, the soap will reduce the surface tension of the water in the milk and will “break down” the fat. By adding food coloring to the milk beforehand, the reaction can be observed more easily. After adding soap to milk with food coloring, the food coloring will disperse and continue to move.

This experiment will test four different types of cleaning agents in the same process: dish soap, laundry detergent, hand soap, and shampoo. The time it takes until the food coloring stops visibly moving will be measured. By doing so, we can learn about how the different surfactants in the cleaning agents react with the milk.

Methods and Materials

Materials:

• 4 non-permeable plates
• 2 cups of whole milk
• 10 mL hand soap
• 10 mL shampoo
• 10 mL laundry detergent
• 10 mL dish soap
• 1 eyedropper
• 1 measuring cup
• Gloves (optional)
• 3 bottles of different types of food coloring
• 1 stopwatch

Cleaning agents                                                         (Sadia Supti,2018)

Experimental Procedure

1. Measure half a cup of milk using the measuring cup, then pour it into a plate.
2. Let the milk settle, then put 4 drops from each bottle of food coloring in the middle of the plate.
3. Using the eyedropper, put one drop of dish soap in the middle of the plate.
4. Have a partner start the stopwatch as soon as you finish step 3.
5. Watch the plate and wait until the food coloring stops moving, then stop the stopwatch.
6. Repeat steps 1-5 using the shampoo, laundry detergent, and hand soap in step 3.

 

The dish soap and laundry detergent had a noticeable effect when added to the milk, while the shampoo and hand soap did not.

Plate of milk with dish soap and food coloring added (Sadia Supti,2018)

Results

Cleaning Agent	Time (mm:ss)
Dish Soap	01:50
Shampoo	00:00
Laundry Detergent	00:52
Hand Soap	00:00

 

The time from the dropping of the cleaning agent into the milk until the food coloring stopped moving was to be measured, however, in the case of the shampoo and hand soap, the food coloring did not move at all. The food coloring in the plates where dish soap and laundry detergent were dropped into took 1 minute and 50 seconds, and 52 seconds, respectively.

Discussion

Based on the results, we can conclude that the cleaning agents did not all have the same effect on the milk. Dish soap caused the longest duration of food coloring movement, which suggests that it reacted the longest with the milk. On the other hand, the shampoo and hand soap did not cause any movement at all, which suggests that these two cleaning agents have different surfactants than those of the dish soap and the laundry detergent.

One problem that was encountered was with the food coloring. When it was put in the middle of the plate filled with milk, it should have stayed in the same place. However, it dispersed very quickly through the rest of the milk. This may have been due to certain chemicals in the food coloring, which may have affected the experiment.

Another problem encountered was the lack of intensity of the movement of the food coloring. While other demonstrations displayed a much more intense movement of the food coloring, the food coloring in our experiment moved relatively slow.

Conclusion

The different times in the results indicate that the cleaning agents have different surfactants and possibly different cleaning mechanisms. This makes sense, since the different cleaning agents are meant to be used for different purposes. The intensity and time of the measured movement may be an indicator of the effectiveness of the cleaning agent on the milk, however, an experiment like this is not the best way to measure it.

Since the cleaning agents varied so greatly, the differences in their effects were to be expected. It may be better to experiment with different types of dish soap instead, since dish soap is used to clean milk off of utensils and had the greatest effect. It would also allow us to know if it is only this type of dish soap that has such an effect, or if other kinds of dish soap have similar effects as well.

 

References

Brown, Theodore L., LeMay, Eugene H., Bursten, Bruce E., Murphy, Catherine J., Woodward, Patrick M., Stoltzfus, Matthew W. (2018). Chemistry: The Central Science. Harlow, United Kingdom: Pearson Education  Limited.

National Science Foundation. (n.d.). “Chemistry Now: It’s a Wash: The Chemistry of Soap”. [Video file]. Retrieved from https://www.nsf.gov/news/special_reports/chemistrynow/chem_soap.jsp