Density and Thickness

        The main ideas that we learned this past week were density and thickness. These main ideas go together because the experiment we did with thickness had two different types of aluminum foil, and one was more dense than the other. Some important things to know about density are the different ways to find density. One way to find density is to use the formula density=mass divided by volume. You could also use the formula that Dr. Finnan taught us, and if you have a graph you could use the slope of the line as the density. We did two experiments this week to help us learn the material. We did a experiment called density of gas, and thickness of a thin layer was the other.

       Experiment 1- Density of gas
The goal for the density of gas experiment was to find the density of gas and find how it compared to the density of water that we already know is 1g/mL. In our previous Alka-Seltzer experiment we saw that there were bubbles of gas floating out of the water. This shows us that gas is less dense than water, but we want to know by how much. The first thing that we did in the experiment was put 3/4 of a Alka-Seltzer tablet in a mini cupcake liner and filled a plastic bottle with 40mL of water. We put the plastic bottle and liner on the scale and got the mass of 68.944g. After that we put the tablet in the bottle with the liner. This is where the liner is important.  It is important because it allows the tablet to not touch the water and not react. While the tablet is floating on top we gently screwed on the top. Once the top was secured we started to shake, and swirl the bottle to make the tablet react. When the tablet was reacting the gas that was produced from the Alka-Seltzer went out a tube and into a larger plastic bottle filled with colored liquid. The gas may tip over the plastic cup so it is important to hold the cup. After we saw no more bubbles we marked on a piece of tape where the gas ended. Then we poured the water out. Next, we filled up to the line with water and found the volume with a graduated cylinder. After that we took the smaller plastic bottle with the 40mL of water and measured its mass again. The mass that we found was 68.556g. In order to find the density of the gas we had to use the formula mass divided by volume. The mass was the first mass subtracted by the second which was .388g and the volume was the number we found on the graduated cylinder which was 225mL. We divided .388  by 225 and got 0.001724g/cm3 with the four repeating. Since the numbers we divided only had three sig figs the final density of air is 0.00172g/cm3. We compared with the class and found that air is almost 600 times less dense than water!

40mL of water and 3/4 of a
Alka- Seltzer tablet

Dropping tablet in

Finding the mass of the tablet and water

Gas bubbles as we stir

Marking where gas starts

Holding down bottle

Pouring out colored liquid

Finding mass after reaction

Finding volume of water up to gas line

Our class' data

       Experiment 2- The thickness of a thin layer
In this experiment we are trying to find the thickness of something without using a ruler.The goal of the experiment was to find the thickness of regular tin foil vs. heavy duty tin foil. To start we had two equal sized squares of both kinds of tin foil. Then we massed both of them. With the mass we could calculate the volume. We then measured the length and height of both squares. After that we divided the length and height from the volume for both. That how we found the thickness.

Mass of regular foil

Mass of heavy duty foil

Our math done on the whiteboard

       Reflection-
We came to know and understand the ideas we learned this week by doing experiments, comparing with the class and taking two quizzes. The two quizzes were on density and reading scales. I still have questions about where the gas in the Alka-Seltzer comes from and why after mixing it with water it loses mass. I think my participation in this week's activities and experiments was very good.  Myself and one other person in our table group did most of the work. I would rate myself an 9 on the ideas we learned in class last week. I still need to work on word problems with density, mass, and volume. My ideas have changed this week, because now I know so many ways to do the same thing. Now I can measure the thickness without a ruler, and now I know so many ways to find density. A new thing I have to think about is how to go about finding the thickness or density and how to do that the most efficient way possible.