Kitchen Fun!

Milk

*Observe and explain changes occurring in milk due to biological influence.

Place 1/2 cup of milk in a container and place in a warm, dark place for about 3 days.

Hypothesis- I believe the milk will sour, smell badly, and get chunky, due to the warmth and the growth of bacteria.

I placed my milk on the top shelf of our coat closet, it is dark in there and as warm as the rest of the house. The first couple of days I did not see any significant change in appearance or smell. Today was day three and there were some changes, there was a thickish ring around the edge of the cup and the milk seemed thicker in general and definitely did not look as white as the nice fresh milk I had put in three days prior, it had some yellowish tint to it.  I stirred it up and it was thick and smelled slightly sour. When I dumped the milk out there was a thick but smooth white substance on the bottom of the cup that reminded me of yogurt. When I tasted the milk it tasted just fine... just kidding! Ha!

I expected more changes but I think that the closet I put the milk in could have been warmer, there wasn't enough warmth for bacteria to grow more rapidly. Because milk contains bacteria and also lactose which bacteria happen to thrive on, the lactose sugar is changed to lactic acid which tastes sour and causes curdling.

Fresh milk on day one: Nice and white, bubbles, smelled like fresh milk

Milk after three days: Yellowish, ring around cup, thick when swirled and stirred, slightly sour odor.

Juice

*Witness mixing action of molecules and describe the process.

In all pictures far left is room temperature, middle is ice water, and right is boiling hot water. I used Welch's grape juice.

My hypothesis is that the water will mix well into the room temperature and boiling water but maybe not as well into the ice water. 

Preparation

 




Top view after grape juice added

Front view after grape juice added

The grape juice immediately turned all three glasses of water shades of purple. In the first cup with the room temperature water it seemed to disperse well but after a few moments I could clearly see that it was clearer at the top of the glass which can be seen in the picture above. The middle glass is the ice water and again there is a clear separation at the top of the glass. The third cup was the boiling water and from my straight eye view it seemed to mix up the most evenly and was the most consistent in color. I think the colder water made the juice particles move more slowly which is why it took longer to disperse out and in the warm temperature and boiling water it was closer to the temperature of the room temp juice that I used and it was easier for the molecules to mix together. The ice water did seem to have the richest purple color below the separation.

Carrots

*Investigate cellular functions and cellular structures using a carrot.

My hypothesis for this experiment is that the carrot placed in the fresh water may expand some due to the water going into the carrot cells and causing them to burst. The carrot that is placed in salt water will have some shrinkage due to the salt water being hypertonic and drawing water out of the carrot cells.

Initial length and width of carrot pieces:
Piece 1- 4.125 inches long 7/8 inch wide
Piece 2- 4 1/4 inches long 7/8 inch wide

After-experiment length and width of carrot pieces
Piece 1- 4 1/2 inches long 7/8 inch wide
Piece 2- 4 inches long 3/4 inch wide

Carrots in water. Fresh water on left, salt water on right

Carrots prior to water baths.

Carrots after water bath

After 24 hours in the water, there were some changes. On the fresh water carrot the string was tighter then when I had first tied it the night before, the carrot was still very crisp and fresh feeling. The measurements grew a slight bit leading me to believe that some of the cells inside were burst because of the intake of water. Pure water is the most hypotonic solution so water would enter the cells, they would then swell and burst.

On the salt water carrot there was shrinkage. Because the salt water is hypertonic water diffused out of the carrot cells causing the shrinkage. The carrot was much softer then the fresh water carrot and the string had loosened up quite a bit.