Uncle Tom's Milk

Case Study 1
Uncle Tom lives in Frankfurt, Germany. There, milk is delivered in glass bottles to the doorstep of almost every house. Each milk bottle is sealed with a heavy paper cap. The milk bottles have to be brought quickly into the house, especially when outside temperature is below freezing.

One day, Uncle Tom forgot to bring in the milk bottles into the house. When he realized and went out to check on the milk, he found that the bottles were opened and the milk was all over the ground. It was a cold winter.

Problems With the Case Study

Problem 1:
“Each milk bottle is sealed with a heavy paper cap.”
Paper Caps? Shouldn’t it be metal caps?

Problem 2:
What is the freezing point of the milk?
“the milk was all over the ground. It was a cold winter.”
“temperature is below freezing.”
The exact freezing point of milk (also called the melting point) varies slightly according to the individual cow, the breed, the time of day / season that the milk is collected, the type of feed that the cow recieves, etc. The majority of cows produce milk with a natural freezing point of -0.5250 and -0.5650 C, with an average of about -0.5400 C.

Predict Why the Cap Came off the Bottle

Maybe milk is like water. It freezes and expands when the temperature is below a certain temperature.
Therefore, it could be that the milk expanded, while the bottle contracted, causing the bottle to break. However, the milk would not be spilt all over the floor. It would be frozen in a lump.

Do you think the Cold weather had any effect on the milk?

Yes. The cold weather caused the bottle, cap and milk to contract. However, the liquid reached its freezing point and froze while the solids continued to contract. The liquid, upon freezing, expanded, while the solids were contracting. In the end, there is too much pressure between the bottle and frozen milk, resulting in the bottle cracking and breaking.

Conclusion

Water expands upon freezing...

Why does water/liquid/milk expand when frozen?

Water's behavior is caused by its molecule's bonding. One water molecule is made up of two hydrogen and one oxygen atom. Hence, H2O. Because of how the atoms share electrons, a water molecule is slightly positively charged at the hydrogen atoms, and slightly negatively charged at the oxygen atom. The molecule's charged ends attract the oppositely charged ends of other water molecules.
In liquid water, as molecules slip-slide past each other, bonds form, break, and re-form. But by the time water has cooled to 4 C, the molecule's energy has dropped until they are very near one another. So each H2O molecule forms more stable hydrogen bonds, with up to four fellow molecules. By 0 C. (32 F.), the H2O molecules are lined up in a frozen crystal lattice, an open hexagonal (six-sided) shape...

Uncle Tom's Milk

Case Study 1
Uncle Tom lives in Frankfurt, Germany. There, milk is delivered in glass bottles to the doorstep of almost every house. Each milk bottle is sealed with a heavy paper cap. The milk bottles have to be brought quickly into the house, especially when outside temperature is below freezing.

One day, Uncle Tom forgot to bring in the milk bottles into the house. When he realized and went out to check on the milk, he found that the bottles were opened and the milk was all over the ground. It was a cold winter.

Problems With the Case Study

Problem 1:
“Each milk bottle is sealed with a heavy paper cap.”
Paper Caps? Shouldn’t it be metal caps?

Problem 2:
What is the freezing point of the milk?
“the milk was all over the ground. It was a cold winter.”
“temperature is below freezing.”
The exact freezing point of milk (also called the melting point) varies slightly according to the individual cow, the breed, the time of day / season that the milk is collected, the type of feed that the cow recieves, etc. The majority of cows produce milk with a natural freezing point of -0.5250 and -0.5650 C, with an average of about -0.5400 C.

Predict Why the Cap Came off the Bottle

Maybe milk is like water. It freezes and expands when the temperature is below a certain temperature.
Therefore, it could be that the milk expanded, while the bottle contracted, causing the bottle to break. However, the milk would not be spilt all over the floor. It would be frozen in a lump.

Do you think the Cold weather had any effect on the milk?

Yes. The cold weather caused the bottle, cap and milk to contract. However, the liquid reached its freezing point and froze while the solids continued to contract. The liquid, upon freezing, expanded, while the solids were contracting. In the end, there is too much pressure between the bottle and frozen milk, resulting in the bottle cracking and breaking.

Conclusion

Water expands upon freezing...

Why does water/liquid/milk expand when frozen?

Water's behavior is caused by its molecule's bonding. One water molecule is made up of two hydrogen and one oxygen atom. Hence, H2O. Because of how the atoms share electrons, a water molecule is slightly positively charged at the hydrogen atoms, and slightly negatively charged at the oxygen atom. The molecule's charged ends attract the oppositely charged ends of other water molecules.
In liquid water, as molecules slip-slide past each other, bonds form, break, and re-form. But by the time water has cooled to 4 C, the molecule's energy has dropped until they are very near one another. So each H2O molecule forms more stable hydrogen bonds, with up to four fellow molecules. By 0 C. (32 F.), the H2O molecules are lined up in a frozen crystal lattice, an open hexagonal (six-sided) shape...