MILK, JUICE, CARROT LAB

Milk: Record your hypothesis, observations, explanation, and factors here.

My Hypothesis: If the milk is left out in an open glass jar, in a warm, dark place for three days then it will curdle, turn yellow, thicken and smell sour, because the bacteria will multiply and change the purpose of the molecules in the milk.

Day 1: The milk was poured into the glass jar and left, no visible changes occurred less than twelve hours when I checked on it.

Day 2: 24 hours - The milk is starting to turn yellow and thicken on the surface. No changes in its odor yet.



Day 2 - the milk is starting to turn yellow and thicken



Day 3: 36 hours - The milk is visibly changing more. It has formed a thick, crust-like yellowish layer on the top, with less milk on the bottom. It has a foul, sour odor. I can see the curd on the top quite plainly.

 

Day 3 Side View



Day 3 Top View



Day 4: 48 hours - I forgot to throw the milk away and it started bubbling. It smelt pretty nasty too!



Day 4 - The milk started bubbling.



Explanation: The micro-organisms in the milk will become infected with bacteria which will multiply in the process of fermentation. Milk is made up of lactose (hence lactating Mother’s who breastfeed their babies), water, fats and proteins. The bacteria work and multiply to turn the milk’s lactose into lactic acid which sours the milk and turns it into thick clumps which is curd.

Juice: Write your observations and explanation here.

Tap Water at room temperature: When I poured the Grape juice into the glass jar of water it diffused rapidly and equally into the water. I tried it again using syringes filled with grape juice to slow down the diffusion and see it more clearly. It showed up better, but still diffused pretty equally in the water because the juice is basically at the same temperature as the water. This was the medium color purple in a short time. I wasn’t sure if I had slightly less Grape juice to make it this way, than the boiling water.



Tap water at room temperature allowed the
 Grape juice to diffuse rapidly.



Boiling Water: I again used the syringes filled with Grape juice and squirted them slowly into the boiling water. Because the Grape juice was colder, it was denser than the hot water so it formed streams of juice which diffused more slowly into the boiling water. The colder juice acted as a barrier to the hot water, but it quickly dissipated quickly and equalized in the water. This was the lightest color purple but in a short time.

Boiling water diffused the Grape juice a little slower.

Ice cold Water: When the stream of injected Grape juice hit the bottom of the glass jar of Iced water it looked darker than the surrounding water because it was hitting cold water. It did not dissipate as quickly as the others did. The juice particles moved slowly through the water and remained a darker purple for about two minutes before it was dissipated equally in the jar. This was the darkest color purple for the longest time.

Ice-cold water allowed me to see the Grape juice
 diffuse slowly, so it was visible to the eye
.The end result was that the solute
was a lot darker,
and it stayed like that for about
2 minutes before it dissapated evenly
 to match the other 2.

Carrot:  Record your hypothesis, tightness of string and texture observations and measurements, and what type of water caused shrinkage or expansion here.

My Hypothesis: If a carrot is placed in salt water then it will shrink because the salt solution is more concentrated on the outside than the carrots cells inside. The string will be looser than it started out.

On the other hand, if a carrot is placed in regular water then it will expand because the water will be drawn into the carrot. The string will be tighter as the carrot cells will have expanded.

Initial length and width of carrot pieces:

Piece 1: Salt Water - Length 90mm (3 ½”), Width 21mm (7/8”)

Piece 2: Tap Water – Length 83mm (3 ¼”), Width 21mm (7/8”)



Day 1: Carrots in salt water and tap water with string tied around
the width near the cut sides.



After-experiment length and width of carrot pieces:

Piece 1: Salt Water – Length 87mm (3  7/16”), Width 21mm (slightly loose string)

Piece 2: Tap Water – Length 83mm (3 ¼’), Width 22mm (string very tight and biting into the carrot)

In salt water - the carrot shrunk by about 2-3 millimeters in length.
The width didn't visibly show a difference - but the
string was slightly loose. This proved that the carrot
did shrink in the salt solution.



In the fresh tap water - the carrot didn't change in length, but the width
swelled by 1 millimeter and the string was tight and biting into the carrot.
This proved that the carrot swelled and took in extra water.






















Explanation: The carrot in the salt solution shrinks. The extracellular salt solution of the carrot is more concentrated (it is hypertonic) than the intracellular carrot cell solution. Therefore the water inside the carrots cells is drawn out by diffusion. This leaves the carrot depleted of water and it shrinks.

The carrot in the regular water will swell. The carrot cells will draw in (it is hypotonic) more water than is released and it will swell.