A LABORATORY PROTOCOL ON THE CHEMISTRY EXPERIMENT CARRIED OUT BY SPANISH  STUDENTS OF ESCUELA PROFESIONAL “LA SALLE” PATERNA (VALENCIA)

“MAKING GLUE’’ 

1.INTRODUCTION

Chemistry has always used food to obtain other substances to improve our lives. For example, substances like sea salt, steel and glucose, or medicinal products such as food supplements and other products based on natural products to prevent hair loss (aloe vera, almond oil, etc.) or against insomnia (valerian, melatonin, camomile and different vitamins).

Chemistry is essential for life.

Knowing that plastics are organic materials produced fromraw materials such as cellulose, carbon, etc., we think that, just as some resins from some trees are used as glue, we can state our hypothesis.

HYPOTHESIS

We believe you could also get glue from a milk protein, called casein, because the solid particles are so small and they do not sediment and remain in suspension. These particles are called micelles; they are precipitate when they come into contact with an acid such as vinegar.

2.OBJECTIVE:

We will separate the casein from the milk and make a white glue.

3.MATERIALS USED

    • Beaker 250 ml

    • Glass agitator

    • Funnel and filter paper

    • Graduated cylinder

4.PRODUCTS USED

    •     Skimmed milk

    •     Vinegar

    •     Sodium bicarbonate

5.PROCESS

Step 1:

Put 125 ml of milk into the 250 ml beaker.


Step 2:

Add 25 ml of vinegar (acid solution)


Step 3:

Heat the mix slowly and shake it often until it starts to form small lumps.

Step 4:

Stop the heating and continue shaking until more lumps appear.

Step 5:

Wait for the lumps to seat themselves

Step 6:

Filter by gravity.

 Step 7:

Gently press the filter paper to drain the liquid

Step 8:

Return the solid material to the empty beaker

Step 9:

Add 30 mL of water and shake

Step 10:

Add ½ teaspoon of baking soda to neutralize the excess vinegar. Note the gas bubbles that appear. If necessary, add more bicarbonate until no more bubbles form.

6.RESULTS

Milk protein coagulates due to the effect of acidity and heating. The casein is presented in the form of lumps or precipitate.

The excess vinegar is neutralised by the action of the sodium bicarbonate, producing carbon dioxide bubbles

7.QUESTIONS

    1. What is a plastic? It is an organic material produced with natural products.

    2. What is the function of vinegar? Vinegar causes proteins, called caseins, to stick together, turning into little balls, called clumps.

8.CONCLUSION

Thanks to this practice we can demonstrate that it is possible to separate the casein from the milk to get a homemade glue, as we suggest in the hypothesis.

PERSONAL COMMENTS

It is possible to manufacture plastics that are not petrochemical and thus avoid environmental damage.

REFERENCES

This practice and experiment are taken from: https://servicios.educarm.es/templates/portal/images/ficheros/etapasEducativas/secundaria/5/secciones/513/contenidos/10263/experimentos_de_qumica.pdf (Pages 51, 52, 53 Experiment 16)

Photo 1: https://www.youtube.com/watch?v=vAkLAe5jOw4

Photo 2 : http://206a1-danielitzaes-tenorio-gutierrez.blogspot.com/2011/05/pegamento-con-leche.html

Photo 3: https://www.youtube.com/watch?v=PQTdNDzcYow