Lab 2B

Prompt: Summarize the purpose of the lab. Report your average atomic mass for Candium and answer the four concluding questions from your lab manual in your post.

Summary: The goal of this lab was to go through a number of steps to find the average atomic mass for the element Candium. This was achieved by counting the different isotopes(regular m&m's, peanut m&m's, and pretzel m&m's) and then averaging their individual masses. The average atomic mass for our sample of Candium was 1.413 amu.

1. Our atomic mass would be different because our sample sizes would have different numbers of each of the isotopes. Because the calculation for average atomic mass is based on the percentage of each isotope, if you had different percentages of the isotope your atomic mass number would be different.

2. If larger samples were used the difference between my sample and other group's samples would be smaller. When sample size is increased, your result is more accurate and representative of the correct value.

3. No. The average atomic mass is an average of all the isotopes, so it is not the exact weight of any of the isotopes, so if you weighed an isotope it would most likely not be the average atomic mass.

4.

Lab 2A

Prompt: Post a picture of your favorite chromatogram you produced. Answer the five questions from the lab manual in your post.

1. It is important that you use a wick to transport water instead of direct contact with the filter paper as it is essential that the water spreads evenly and from the same point(i.e. the center). If the filter paper was in direct contact with the water in the cup you wouldn't be able to see the pigment bands as the water wouldn't be spreading from the same point so the bands would not be visible as the water would be dispersing in different directions.

2. Some variables that affect the pattern of the colors produced on the filter paper include marker type, brand, design drawn on filter paper, and concentration of ink.

3. Ink separates into different pigment bands because when the black ink comes into contact with water, the ink starts to spread. Some pigments travel further than others, creating the bands.

4. When I walked around looking at other students colored filter papers, I noticed a lot of blue pigment bands. The type of blue I saw in all the filter papers was a light blue that looked very similar in every paper, so it was probably made from the same pigment/compound. There are common pigments in different pens because the same company creates a lot of the pens or markers and probably reuses pigments.

5. If the markers weren't water-soluble, the pigments would not separate with the water. Water-soluble markers are meant to break down with water, which explains why the ink broke down on the filter paper with the water. If the experiment was modified to be conducted with permanent markers you would need to have a different solute with added chemicals that is able to break down the permanent ink.

Lab 1B

Prompt: Write a brief post that details the procedure you designed for Part II: Determining the Thickness of Aluminum Foil. Include information on how you determined the thickness, and be sure to include your thickness in mm.


To determine the thickness of the aluminum foil, we first had to do part 1 of the procedure which was calculating the density of aluminum by using an aluminum block. To find the density, we first had to find the volume. We did this by using the water displacement method, which is where you have a graduated cylinder with water to a certain measurement and after dropping the object you are trying to find the volume of in the water, you calculate the increase in the measurement of the water. The increase is the objects volume.Our aluminum object had a volume of 23 mL. Next we weighed the object on a scale. The mass of our object was 67.48 g. Using the mass and volume we had found, we were able to calculate the density using the density formula(d=m/v). The density of our object was 2.9 g/cm^3. 
Now that we knew the density of aluminum we could begin part II. We began by setting up the density equation, except instead of volume we put the equation for volume, so it looked like this: density=mass/length x height x width. At this point we could only insert in the 2.9 we had found as the density of aluminum in the density location in the equation. We then measured the length and height of the aluminum foil, which were 11.1 cm for length and 9.9 cm for height. Next we weighed the aluminum foil which had a mass of.45 grams. So now our equation was: 2.9=.45/ 11.1 x 9.9 x width. With that we were able to calculate the equation using the steps detailed in the picture. The answer we got was in centimeters, so we then moved the decimal point one to the right to account for that giving us a final answer of .014 mm for the width of our aluminum foil.

Lab 1A

Lab 1A

Introduction: 
The goal of this lab was to determine the mass of a plastic block by using a given density and measurements for the volume by using a centimeter ruler. Density is how compact a material is and can be found using the formula: Density=Mass/Volume

Procedure:
 We measured the length, width and height of the block using a centimeter ruler to determine the volume. We then multiplied the density by the volume to determine the mass. Next, we took the block to the scale to determine how far off our calculated mass was from the actual mass. Luckily, we were under the 2% off range on our first try so we did not have to repeat the procedure.

Data:

• Length: 7.5 cm.
• Width: 3.3 cm.
• Height: 2.4 cm.
• Calculated volume: 59.4 cm.^3
• Density(given): 1.42 g/cm^3
• Experimental Mass: 84.3 grams
• Actual Mass: 85.0
• Percent error: .8%

Conclusion:

We fulfilled the lab successfully on our first try. Possible error could have been in the measurement of our block, as even being off by a few millimeters would have effected our result. This lab gave us a better understanding of the formula for density and how to calculate it when not given all the information.