4.1 CHECK and REFLECT

4.1 CHECK and REFLECT

1. Name two properties of matter.
- malleability
- solubility

2. What are the two categories of pure substances in the matter classification tree shown in Figure 4.5 on page 143?
- elements
- compounds

3. How is an element different from a compound?
An element cannot be chemically broken down into any simpler substance, whereas a compound can be as they are elements that have been chemically combined to form one substance.
5. What is the relationship between an element's atomic number and the number of protons in the nucleus of each of its atoms?
An element's atomic number equals the number of protons and neutrons in said atom.

7. What is an ion?
An ion is a positively or negatively charged atom/group of atoms.

13. Suppose you place a kettle on the stove and boil some water. Is the steam that forms evidence of a chemical change or a physical change? Explain.
This is evidence of a physical change because an substance's boiling point is a physical property The substance is not reacting with anything, but simply changing its structure and evaporating.

15. Describe three things about atoms that you did not know before starting work on this section.
I learned that:
- bromine is the only non-metal that is a liquid at room temperature
- neutrons are 1837 times the weight of an electron
- flash point is a chemical property

Mythbusters Science

Mythbusters Science

Season 1, Episode 1

“Ice Bullet, Exploding Toilet, Who Gets Wetter?

The Myth: If caught in a rainstorm, you will stay drier by running for shelter, instead of walking.

Experimental Setup: The Mythbusters set up a controlled experiment to compare the amount of rainwater absorbed by walking versus running a set distance.

Background Questions:

1.      Define, in your own words, each of these steps of the scientific method:

Question – The initial reason for the experiment (what the experimenter wants to find out).

Hypothesis – Experimenter’s theory/guess on what will happen and why.

Experiment – The process in which the experimenter tests his hypothesis.

Analysis – Considers all data and looks for relationships between the variables. Experimenter tries to understand what happened in the experiment and why.

Conclusion – Experimenter comes up with an answer to the question based on the results of the experiment.

2.      The question to be answered by this segment of Mythbusters is “Do you get wetter by walking or running in the rain”? Given this question, what hypothesis do you have?

I think that you would get wetter by walking in the rain because you spend more time in the rain, rather than when you are walking.

3.      Explain why a hypothesis is not just a guess.

A hypothesis is not just a guess because you must consider your background knowledge, as well as logic and reasoning, to come up with a hypothesis. However, when one guesses, you just say what you feel is right, without any backup or reasons.

4.      The Mythbusters have two options: conduct the experiment indoors in controlled conditions, or outdoors in nature. What are the pros and cons of each?

Indoors – There are a reduced number of uncontrollable variables (such and wind and consistency of rainfall). However, the rain will be man-made and unnatural.

Outdoors – There are natural raining conditions, but uncontrollable and unpredictable conditions.

5.      What is the independent variable to be tested in this experiment?

The independent variable is the speed of the person in the rain (whether they are running or walking).

6.      What is the dependent variable to be measured in this experiment?

The dependant variable is how much the person in the rain absorbs.

7.      A controlled experiment such as this one always has an experimental group and a control group. What is the difference between the two?

The control group is the test subject(s) that are not given the experiment. This allows the experimenter(s) some data of what normally happens so that they can compare the experiment results and see the differences.

The experimental group is test subject(s) that are given the experiment so that the experiment can observe what effects the experiment has.

8.      The goal of a controlled experiment is to only alter the variable that is to be tested, leaving all others constant. What variables do the Mythbusters account for in their experiment design?

-          Wind

-          Speed of walking/running

-          Rain consistency

-          Perspiration

-          Overalls’ consistent weight

9.      Ho was the experiment that the two meteorologists designed different than that of the Mythbusters?

They did not have a controlled environment, nor did they specify the length of the run; they simple compared the ratios.

10.  Adam and Jamie each did 4 trials: walking without wind, running without wind, walking with wind, and running with wind. Do you think this is enough data? Explain how sample size can affect the outcome of an experiment.

This may not be enough data as they only did two trials for each condition. This small sample size provides a distorted view as they have limited data to examine. Had they conducted the experiment more times, then they could get a better idea, an average, of the results.

11.  This is the data table based on the Mythbuster’s results. Calculate the amount of water absorbed in each trial, and the water absorbed per second for each trial.

Trial	Wind	Time (s)	Initial Mass of Suit (g)	Final Mass of Suit (g)	Water Absorbed (g)	Water Absorbed Per Second (g/s)
Adam walk	No	18.28	757	785	28	̴ 1.53
Jamie walk	No	17.84	757	790	33	̴ 1.85
Adam run	No	7.06	757	799	42	̴ 5.95
Jamie run	No	6.59	757	793	36	̴ 5.46
Adam walk	Yes	17.40	757	789	32	̴ 1.84
Jamie walk	Yes	17.56	757	788	31	̴ 1.77
Adam run	Yes	6.98	757	801	44	̴ 6.30
Jamie run	Yes	6.51	757	790	33	̴ 5.07

12.  Calculate the average amount of water absorbed in the running and walking trials:

Avg. Water Absorbed (Running) = 38.75 g

Avg. Water Absorbed (walking) = 31 g

13.  Based on the data recorded in the table above, generate a scatterplot graph. Mark the walking trials on the graph with an “x”, and the running trials with an “o”. The independent variable should go on the x-axis, and the dependent variable on the y=axis. Label both axis!

14.  Finally, generate a bar graph based on the average water absorbed running and walking.

15.  Give one advantage and one disadvantage of displaying you data is a scatterplot graph.

Advantage – A scatterplot shows the specific points (data) of the experiment.

Disadvantage – A scatterplot does not show the relation between the points.

16.  Give one advantage and one disadvantage of displaying your average data in a bar graph.

Advantage – A bar graph shows the difference between the two sets of data.

Disadvantage – A bar graph does not show the relation of the independent/dependent variables.

17.  What conclusion did the Mythbusters make as a result of this experiment? Did their conclusion agree or disagree with that of the two meteorologists? Which do you think is a more accurate conclusion? Explain your choice.

The Mythbusters concluded that you get wetter if you run through the rain. This is the opposite conclusion of the meteorologists, as they concluded that you get wetter when walking. I think that the Mythbusters’ conclusion is more accurate as they had a controlled environment.

18.  Extra Credit! The Mythbusters redesigned this experiment in Episode 38: Mythbusters Revisited (found in the Third Season of Mythbusters), and collected different data. Watch this segment and explain how they changed their experimental procedures. Do you fell their data form the second attempt is more or less reliable? Explain why.

This time, the Mythbusters used natural rain instead of artificial rain. They also added caps to their outfit so they could measure how much rain was absorbed. Instead of doing the trial in one direction, they did two.

I think that this data is less reliable, even though it is the same as the meteorologists’ results. All though the rain was natural, the conditions such as wind and amount of rain could have changed during the experiment so their data could be incorrect.