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on 1 May 2014

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Transcript of CHEMISTRY 124


Erin Lee Manolas 18675743
Carlene Marais 18472567
Aqeelah Martin 17574706
Raya Stavreva 18696058

1. Problem: How well does glue made from milk protein (casein) work and how efficient is it over time at varying temperatures?
2. Background Information…What you need to know about our Moo Glue…

• Milk contains the protein casein, this is the underlying reason why we are able to make glue out of milk.

• Casein’s protein molecules are long and stringy and contain lots of sticky points which makes it effective as a glue.

Casein works best when solid in curds which is why we add vinegar to obtain the dissolved casein in a solid form.

• Vinegar is acidic and lowers the pH of the milk. This denatures the casein turning it into a solid form.

3. Hypothesis: Glue made from milk protein will work well and the efficiency of this glue will improve over time, more so at room temperature than that of the fridge temperature.
Stage 1- Forming of the glue

color- off yellow

texture- small lumps in clear liquid

smell- sour/ acidic

curdles formed- small solid lumps
Conducting the Experiment…
• Casein’s optimal temperature is 40⁰, which is closer to room temperature than that of the fridge.

• We use 2% low fat milk because fat in milk interferes with the bonds necessary for an efficient glue.

• We use heat as a catalyst in this experiment and don’t let the mixture boil because this will dissociate curds into particles which will be too fine to obtain an efficient glue.

• Once we obtain our curds the purpose of the baking soda is to neutralise the remaining vinegar in the curds.
color - white

texture- "cheese-like"

smell- none ( slightly smells like yoghurt

curdles formed- medium size

stickiness- elastic/rubber-like
Stage 2- glue formed
( no addition of bi- carbonate)
color- off white/grey

texture- watery/foaming/frothy (like beaten egg whites)

smell- none

curdles formed- none

stickiness- sticky, but very watery
Stage 3- Glue formed
(addition of water and bicarbonate)
For this experiment we have devised our own efficiency scale, using normal prit as our refrence, which we have used to describe how "sticky" our glue is compared to normal prit
1- You can pull the piece of paper apart with no damage and no difficulty to pull apart paper

2- You can pull the paper apart with very little damage and little to no effort needed to pull paper apart

4- You can pull paper apart with great damage and much is needed to pull paper apart

5- You can’t pull the paper apart without extreme damage thus great effort is needed to pull paper apart
3- You can pull apart the paper with small damage and effort is needed to pull paper apart

Trial 1:

Trial 2:
Graphs of results:

Trial 1:
Trial 2:
Restating our hypothesis:
Our hypothesis was correct in stating that : " the glue made correctly from milk protein (casein) will work well and efficienty of this glue will improve over time, more so at room temperature than that of the fridge temperature".
There was a glitch in our first trial, for our 10 minute interval the efficienty of the glue was lower than the initial efficienty.
So what happend?
didn't apply a constant amount of glue to each page
glue having time to set at room temperature, as we prepared the diffrent samples
The samples we prepared weren't done so in any particular order
Ways to improve the results:
To do more than two attempts to obtain accurate results

to record the time imediatly after the sample (glue on paper) has been completed; and not to wait until all the samples are completed

Use a constant amount of glue when applying the glue to the sample

Use powder milk instead of liquid milk. powdered milk makes the strongest glue-milk, because it contains a high protein content (casein)
Thank you !
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