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Lab Report: 2.4---2.5---2.6

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by

Shirley Hu

on 15 October 2014

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Transcript of Lab Report: 2.4---2.5---2.6

Lab Report:
2.4---2.5---2.6

General Overview
Analysis Questions
In conclusion...
Experimental Errors
Does mass change when the state of matter changes?
Mass:The amount of matter found by comparing a known amount to an unknown amount

BY:

Shirley

Hu

From the histogram, a cluster lies around zero. There are 2 outliers, but everything else is close to zero. The median is 0, the mean is 0.3, which is still close to zero, even with the outliers in the average calculation.
Experiment 2.1
We can see the overall trends with histograms. To get a better picture of the info, we combined both classes data so we had more to analyze.
HISTOGRAMS
Experiment 2.6

Even with less data, the overall trend seems to be right on or around zero. With only one outlier, where the data came from the same person who had the other outlier for 2.4, other than that, the majority of the data is situated around 0. Median is 0 and the mode is 0
Experiment 2.5

Individual Experiment Histograms
Class Data
NO.
When data varies, there could be procedural errors affecting the results.
In experiment 2.4, it could be possible that while weighing the ice/water, you didn't zero the balance correctly. Another problem could be if someone didn't weight it when it was completely melted.
In experiment 2.5, if you didn't zero the electronic balance with the cupcake wrap on it, then the result could be different.If someone spilled some sulfur or copper when putting it into the test tube, then the amounts would vary, therefore so would the results.
In experiment 2.6, if after you put the tablet in, you didn't close it fast enough, and gas escaped, the mass could be different. Again, there could be the issue that someone didn't calibrate their balance correctly.
Some things to think about
Ex 2.4: If you find condensation on the outside of the container what should you do? Why?

Ex 2.5: Why is it important to use a balloon in this experiment? Explain.

Do you think the substance left behind is sulfur, copper, or a new substance? What evidence do you have? Explain.
If you do find condensation, you should wipe it off, because the water doesn't come from inside the tube. It comes from the water vapor in the air, therefore might add mass to your result, producing inaccurate results.
It is important to use a balloon because the gas inside would expand when we heated it and either pop the stopper off or shatter the test tube. Both are very dangerous. With the balloon, the gas can expand.
I think that the left behind substance is a new substance. One clue is that the new substance changed color. Another clue is that often when a chemical change happens, gas might be a byproduct, and the balloon expanded indicating more gas.
when changing states of matter, the mass doesn't change. The data indicates that no change in mass happens the most often, and frequently, the results lied close to or on zero. The outliers are most likely due to the many possible procedural errors that someone might have made. The results that were surrounding zero can easily be explained by the sensitivity of the balance, little spills or incorrectly calibrated balances. There were more decreasing results, because it was easier to lose some then add some.
Again, the mode is 0, but this time, all of the data is less than or equal to 0. This could be due to the fact that it was difficult to put the cap of the test tube on quickly, so some people might have let more gas out than others. There weren't any outliers, and the median and mean were both close to 0.
The biggest major trend is the data surrounding 0. The mode and median are both 0. The mode is very noticeable, with 17 results. When the bin is a little farther from zero, there are less results. When the bin is even farther from zero, there are even less results.
Overall Class data
We conducted 4 closed system experiments in which we measured for the change in mass after a change in the state of matter or chemical reaction occured.
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