States of Matter Labs

Over the course of a week or two weeks, we completed three labs in order to observe physical and chemical changes and properties of difference substances. A physical change is the change of appearance or form of a substance, while a chemical change occurs when a substance changes into one or more new substances.

Observing a Candle and Pouring a Gas

In this lab, we began by observing the physical and chemical properties of the small, yellow candle. Physical properties include that it was yellow, striped, and small. Chemical properties were unable to be determined. Then, we recorded new observations after the candle was lit. The physical properties of the lit candle include that it was becoming shorter because of melting, more of the wick was being exposed, and the tip became black. The chemical properties of the candle were that it was burning and melting. For the second part of this lab, we used a larger candle. While it was being lit, we created a mixture of baking soda and vinegar, causing a chemical change in this substance. When we carefully tipped the beaker of the mixture over the flame, it burned out. This was because of the carbon dioxide in the beaker. The candle went through a slight chemical change, because the top was a little charred. The reaction between the carbon dioxide and the flame was a physical change, because the form of the flame changed, for it disappeared.


Roasting a Marshmallow!

The second experiment was roasting a marshmallow over the bunsen burner. To begin, we observed small marshmallows to determine the physical and chemical properties. Then, we burned larger marshmallows over the burner to create the black char, and the rest was caramel-colored and gooey on the inside. The charred part of the marshmallow tasted bitter and, for lack of a better word, burnt. The remainder of the marshmallow tasted gooey and sweet. The object went through a chemical change, because burning it created the char substance. It also went through a physical change, because of the golden brown color that appeared when the marshmallow was lightly roasted.


Changes of Sugar

For this lab, we began by observing the four sugar cubes to determine their properties. Then, we were required to crush them with the mortar and pestle until it became a powder. A physical change had taken place because the cube had been broken down, changing form. For the second part of the lab, we began by placing two of the sugar cubes into the test tube and lighting the Bunsen burner. We held the test tube near the burner and watched the sugar burn. Very quickly, it caramelized, turning into a golden-brown color that seemed to be a bubbling liquid. Then, just as quickly, it became black and hard. Shortly after it went through this change, a yellow-colored smoke came out from the test tube, and the process was almost complete. After the test tube took a moment to cool down, Mrs. Rousseau carefully broke the test tube so we could observe it more closely. The black substance took up about half the test tube, taking its shape. The substance was hard, but easy to break, and the texture was exactly the same as the sugar cube. The sugar cube had liquidated, then solidified. It went through physical and chemical changes.



The labs allowed us to observe changes in physical and chemical property and each built on to our knowledge about changes in states of matter. Overall, it was fun to complete experiments with fire.

Separating a Mixture - Lab Procedure

In order to complete this lab, my group went through the following procedure:

1. Remove the two red toothpicks from the cup with your fingers.

2. Remove the beans with the spoon (make sure you remove all of them).

3. Use the funnel and filter paper to isolate the water in the flask.

4. Remove the small piece of glass near the bottom of the cup.

5. Use a small amount of water in the flask and boil it on the hot plate for 5-10 minutes.

6. Remove the iron filings from the cup using the magnet, leaving the sand alone in the cup.

7. Use the magnifying glass to identify the buildup on the side and bottom of the flask after the water has boiled.

8. Identify each of the seven objects. You should have found glass, iron filings, toothpicks, water, salt, sand, and beans.

Frog Dissection

I completed this dissection online, because I was absent on the two days that this task was completed. The following website was used to give me a thorough understanding of the dissection of a frog: http://frog.edschool.virginia.edu/Frog2/ To begin, the website provided photos of the incisions of the frog, followed by the identification of each organ. It specifically explained how the organs should look, and it also included photos and videos to complete the visual. This tool allowed me to see the whole of the dissection without completing it myself, and it was very helpful when preparing for the test.
This task, like the worm dissection, helped us compare life systems of other organisms to human life systems. Though I personally dislike dissections, they have allowed me to expand on my knowledge of life systems and how alike organisms are. I am curious to see how further dissections will work out for me.

 
(photo from http://true-wildlife.blogspot.com/2011/02/frog.html)

The Immune System Animated Movie

The Immune System
by: broadwaybound37


Information received from "Human Biology and Health," published by Prentice Hall Science.

Animation created on XtraNormal.com

Digestion Lab

This lab was completed to observe how substances in your stomach work together to digest food. Each of the four test tubes represented a stomach. In test tube A was pepsin, which is a control. This means that it is a significant component in the digestion process. In test tube C was hydrochloric acid, which is also a control. In test tube B was a mixture of pepsin and water, while test tube D contained a mixture of hydrochloric acid and pepsin. Also, in each test tube were three cubes of egg whites, being the food that would be digested. The "digestion system" that was most successful was the one in test tube D. This is because the two controls together make for a faster digestion. Controls, by themselves, can not function correctly; they need support from eachother or another substance, such as water. This lab allowed us to see a model of the digestion system in action and how it really works.

Chicken Wing Dissection - Class Response

Today, the class observed as Mrs. Rousseau dissected a chicken wing to show us the makeup of tissues. We observed the tissues and what other tissues they attach to. The skin is an epithelial tissue, and it attaches to muscle tissue. Fat also attaches to muscle tissue. When we were observing the muscles in the wing, Mrs. Rousseau located the two that bend and straighten the elbow joint. The flexor bends the joint, then the extensor pulls in the bone in the other direction to straighten it. We observed this movement and made a connection to a human arm flexing. We were able to see muscles, tendons, joints, and ligaments working together. When it came down to the bone, we observed the cartilage, which is connected to the bone. This was cut open, and we observed the bone marrow, which was a red color. We discovered and observed many parts, though we did not see any nerves. This observation of this dissection was helpful in making connections to a human body and better understand makeups of the human body.

October 11, 2011 - Diffusion Experiment

In science class yesterday, we completed a diffusion experiment. To begin, a beaker was filled halfway with water. Then, a teaspoon of corn starch was placed into a plastic bag, which was secured shut and submerged in the water in the beaker. The last step of the preparation was to drop iodine into the water. After sitting for about fifteen minutes, the iodine should have diffused into the plastic bag, which is permeable to liquid substances. The mixture of iodine and water should have entered the plastic bag, changing the starch from a translucent white color to a dark purple color. However, only a small portion of the bag's contents were changed to the purple color, and it was a lighter shade than expected. This may have been because the iodine was not given enough time to complete the full process of osmosis. When this experiment was put in place for an extended period of time by Mrs. Rousseau, the process worked out, and the iodine diffused into the starch. Overall, this experiment was a great way to learn about osmosis and diffusion.