Lab Experiment 1: Combining Elements

September 13, 2008 Combining Elements Julie Anne A.

Day 1, Period 4

Purpose: To practice observation skills by describing changes that occur when chemicals are combined.


Materials:
· 1 large test tube
· 10 mL of water
· 20 mL of vinegar
· 3 raisins
· 5 g or 2 scoops of baking soda
· Timer




Procedure:
1. Pour 10 mL of water into a large test tube.
2. Add 20 mL of vinegar.
*Record Observations*
3. Add the raisins.
*Record Observations*
4. Slowly add 5 g of baking soda.
*Immediately record observations and describe changes at 1 min, 3 min, and 5 min.


Data and Observations:
Step 2:
Water and vinegar
The water became cloudier and the strong smell of the vinegar became slightly weaker.


Step 3:
Adding the raisins
Bubbles were form on the raisins. The mixture became a bit clear. The vinegar still has its odor.
*The raisins are still at the bottom. This is the picture before the addition of the baking soda.


Step 4:
Adding the baking soda
A lot of fizz was formed in the mixture and bubbles were on top of it. Two raisins floated for a few seconds on top of the mixture. There are bubbles going upward. The smell of the vinegar was not as strong as it was in the second step.
*Baking soda was added. The mixture has bubbles on top of it.*

*The mixture started to bubble up and rise*
*The mixture was rising*


Step 4:
1 min
One raisin floated for a long time and it was followed by the other two raisins and while the three raisins were floating, bubbles were going upward. The vinegar odor became weaker.
*This one raisin floated for a long time while the other two tried to float. I notice some discoloration of the raisin here.


Step 4:
3 min

One raisin was on top for a long time while the other two floats for a few second and drops. There were also still bubbles that had the upward motion. The vinegar odor is gone.
*As you can see, one raisin was one top and the other two stayed at the bottom but those two floated too but only for a few seconds.


*Inside of the test tube*

Step 4:
5 min

After five minutes, three raisins floated then two of them dropped. At 05:40, three raisins floated but after about fifteen to seventeen seconds they started to float again. By this time, the mixture is very cloudy and there’s completely no vinegar smell.

***The End***

Questions:
1. List and describe the different changes you observed in the beaker.

There were a lot of changes that occur in this experiment. Before combining the water and the vinegar, the water was very clear and the vinegar had a very strong odor that you can smell it even if you are a few centimeters away from it. After combining the vinegar and the water, the water became cloudy and the strong smell of the vinegar became cloudy and the vinegar’s strong smell became slightly weaker. The raisins looked like normal raisins before it was added to the mixture. When it was combined with the mixture, little bubbles were formed on them and they stayed at the bottom of the test tube. Also, the mixture became a bit clearer. The baking soda had solid quite fine grains. When it was added to the mixture, it reacted with the mixture and fizz and bubbles were created on top. In addition to that, the mixture became cloudier and started to rise. Furthermore, when the baking soda reached the bottom of the large test tube, bubbles were going in an upward motion. Moreover, raisins were floating on top for a few seconds and some floated for a long time. Finally, the vinegar odor was very weak.

2. What happened to the solid baking soda that you added to the beaker?
The baking soda was still in its solid form and it stayed at the bottom of the test tube.

3. Describe and explain what happened to the raisins after the baking soda was added.
When the baking soda was added to the mixture, the raisins floated up and dropped after a few seconds. Also, I noticed a pattern regarding the raisins’ movement. One raisin stayed on top for a long time while the other two stayed at the bottom. However, after about 15 to 17 seconds, the two raisins would float and they would dropped again after about 15 seconds. I think the movement of the raisins was caused by the upward motion of the bubbles that were created by the reaction of vinegar and baking soda.

Conclusion:
The experiment today improved my observation skills because before this project, I didn’t really pay attention to the detailed description of how something felt and how something looked like. However, when I started to write my observations, I had to jot down a lot of words and I didn’t know what to add to my list so I started examining the mixture carefully to fully see the detail of it. I started to use some of my five senses and I learned that by using them, I could prolong the details in my observations. Also, in this experiment, I learned that the reaction between the baking soda and the vinegar was so strong that it can move the raisins.