1) To know the steps of the Scientific Method.

2) To know how to generate good hypotheses.

Parsimonious

Empirical

Can be falsified

3) To understand basic intermolecular forces and their effects on the behavior of liquids.

4) To practice designing an experiment.

Identifying the variables

Outlining the procedures

5) To practice presenting data.

There are many different ways to experience the world around us. Educational theorists term these "ways of knowing." In this course we will be using a specific way of knowing, the scientific method. What is this way of approaching problems and how does it differ from other ways of knowing?

Within the scientific method, we are first concerned with the concept of "proof." The philosophical basis for how working scientists deal with proof was laid down by Pythagorus in ancient Greece. Pythagorus realized he was never sure that he knew something WAS, but he could certainly tell that something was likely NOT. However, when dealing with negative outcomes he quickly realized there were innumerable reasons to explain why something did not happen, and it was hard to tell which one was "true". To help to minimize this dilemma, Pythagorus proposed that all questions about the universe be stated as simple yes/no alternatives. Others took this idea and developed a set of rules which should be used in order to minimize the chance of making errors when asking questions about the world. This framework of rules has come to be known as the hypothetico-deductive method. Under this method, you make an observation about the world and propose an explanation for it. You then state this explanation in the form of a hypothesis, which is a statement that has a yes or no answer to it. By evaluating these yes or no statements, one might finally deduce the answer. Unfortunately, the Greeks enjoyed sitting around thinking, but did not want to dirty their hands running an experiment. The actual testing of hypotheses would have to wait until the Middle Ages

The next big step in the evolution the scientific method came from John of Occam, another famous philosopher. Occam noticed that any given observation about the world could be influenced by one's own biases and prior experiences. One never knew all of these factors in advance, and so could never be sure their observations and hypotheses would remain unbiased. Occam decided that the best way to reduce the possibility of bias was to make the smallest number of assumptions at all times. All observations should be subjected to "Occam's razor," a process where a scientist attempts to find an even simpler explanation for their observation. When a simpler explanation cannot be found, the scientist accepts that this is the simplest and least biased observation that can be made. This does not mean that the observation is correct, just that it is unbiased (also called parsimonious). This process came to be known as inductive reasoning and was seen as the first step in the scientific method. We now have two components of the current scientific method in place: 1) Inductive reasoning: placing observations about the world into an unbiased framework and 2) Hypothetico-deductive reasoning: making intelligent guesses about the world and testing them in a yes/no manner.

This is still not quite the process that we know as the current scientific method. The final piece fell to Bacon, a great philosopher and polymath. Bacon coined the term "empiricism", defined as that portion of the phenomena in the world that can be directly tested using physical measurements. Bacon perceived that most earlier scientists had failed because they never tested their guesses! How were they to know how accurate their ideas were unless they found a method to test them? Bacon suggested that all usable hypotheses should be based on Occam's razor, be two sided, and also be testable using physical measurements. He rejected questions about non-measurable phenomena as falling outside the realm of proper science (e.g. How many angels fit on the head of a pin etc.- thus, forever after, have the realms of religion and science been distinct).

Thus the process, as we know it today can be outlined as:

1.) One makes unprejudiced observations about the world

2.) These observations lead to questions

3.) These questions lead to the generation of testable hypotheses (i.e. possible answers for the questions). Remember an hypothesis is only useful in the scientific method if it can be proven false. This part of the process is termed inductive reasoning.

4.) One runs a test to disprove the hypothesis. We term this test an experiment. In an experiment the following terms and concepts will apply:

In order to create a scientifically sound experiment, the following terms and concepts will apply: One must attempt to control as much variation as possible during the experiment so that any variation observed can best be correlated with the hypothesis in question. Factors which control variation in an experiment are termed variables, of which there are two types: 1) Independent variables are those factors which govern change in other factors; 2) Dependent variables are the other factors they determine. It is crucial in an experiment that the scientists try as much as possible to control all of the independent variables except the one that is under study. These other independent variables are usually termed Control variables. For example, if one wished to determine the cause of obesity in humans and one guessed that the cause of obesity was inheritance, not lifestyle, one would have to run an experiment where inheritance was studied and lifestyle was controlled. Thus, genetic makeup is the independent variable under study, lifestyle is the control variable and body weight would be the dependent variable. It doesn't take much thought to realize that in our example experiment we are going to have a lot of control variables to worry about (such as age, racial background, gender, and all other factors that go into "lifestyle"). In one experiment we may be able to control all of these variables, but it is likely we will miss some. The goal is to create the cleanest and most controlled experiment possible to test the hypothesis in question.

Once the experimental variables have been defined, a testing procedure is developed. Scientists may be able to rely on procedures previously established by others or may have to develop a new set of methods for the particular experimental question. Either way, a precise set of steps must be laid out and followed in order to run a good experiment. An important component of your method is obtaining your sample. The sample is the subset of individuals that you will test during the experimental procedure. In our example of obesity, it is obviously impossible to test all obese people in the world. In order to run our experiment, we must choose a manageably sized subset of the total population that is sufficiently large and representative of the total population. Another crucial step in the procedure is determining the levels of treatment, or the values of the independent variable that will be tested. Going back to our example of obesity, imagine that you were testing a drug to see if it had the effect of lowering body weight in obese people. The doses of the drug chosen would be your levels of treatment. One usually uses control treatments, which are treatment conditions where the independent variable is not varied. In the case of a drug, the control condition would either be no treatment or a placebo treatment. This is done to insure that changes in the dependent variable are due to the independent variable and not some other factor.

We usually want to replicate any measurement we take in an experiment. If we only study one example we can't be sure if that response represents the normal response or represents an odd response. If we take the blood pressure of only one female subject, it may not be representative of blood pressure in typical females. Perhaps she had too much coffee for breakfast or has just completed a workout. By looking at a response several times we can help to determine this.

At the end of the experiment you determine if the results obtained (usually number-based results called data) support or refute your hypothesis. There are two factors at work in an experiment: 1)accuracy (validity), a measure of how closely experimental results conform to the actual value of some variable; and 2) precision (reliability), the ability to get the same result over and over again. In a game of darts, accuracy would be how close one gets to the bull's eye while precision is how close together the individual darts are. We need to determine if our experiment suffers from lack of either precision or accuracy and whether this invalidates our results. If our experiment seems to pass muster on this issue we then need to assess what it means to support or refute our hypothesis.

5.) If the hypothesis is proven false, the hypothesis is likely modified and tested again. The process is ongoing and never truly gives one an answer that is "right", it only gives an outcome that may likely be so. Proof for a scientist is failure to disprove. When you next hear the statement that a group of scientists has "proved" something to be, realize that you are hearing misinformation, this cannot be done in science, we can only show that something is not. If enough people over enough time fail to show that something is not, we must accept that it might be so.

So, there it is, in a nutshell. We will be running a simple experiment today in lab which will help us to reinforce these concepts since they need to be used to be fully appreciated.

Since this material in this course is based on the above method, we thought you might want some practical experience in its use. We will undertake a simple exercise which will simultaneously help to test your scientific reasoning skills as well as reinforce some chemical properties discussed in lecture.

Use the Drop worksheet as a guide through this activity. Do this experiment in groups, the more discussion, the better.

Each lab table will have four clear solutions in 250 mL erlenmeyer flasks. They are labeled 3M KCl, H₂O, isopropanol and ethanol. You will also notice droppers, pippetors, rulers and glass slides have been placed at each station.

Observe the four different liquids. Make note in particular of how you would describe their similarities and their differences. Once you have been able to describe their differences, design an experiment to in some way measure their differences (using only the equipment set before you). In following the scientific method, you may find it helpful to make some additional preliminary observations. The solutions are non-toxic, but it is not suggested that you taste them. As an example, what happens to each liquid when placed on the back of your hand? These observations MAY SUGGEST to you a physical characteristic (eventually to become your dependent variable) that can be quantified (measured).

Decide how to conduct your activity to minimize error. Determine what your control variables might be, what your dependent variable will be and what your independent variable will be. You may need to run some practice trials to work out any kinks. Carefully observe and record all that occurs.

Complete the Drop Worksheet. This sheet will guide you through each stop of the scientific method, starting with making some basic observations. When you get to the end of the activity, you will need to use the additional references about intermolecular bonds provided in the appendix of this document by your instructor as well as your lecture textbook to formulate some discussion and explanation of your findings

The WORKSHEET is due next week (Week of January 31 in lab). Hand in one report per group.

References:

Carey, S.S. 199. A Beginner's Guide to the Scientific Method. 2 ed. Prentice-hall, Englewood Cliffs, NJ.

Morgan, J.G. and M.E.B. Carter. 1993. Investigating Biology: A Laboratory Manual for Biology. Benjamin/Cummings, New York, New York.Wynn, C.M. and A.W. Wiggins. 1997. The Five Biggest Ideas in Science. John Wiley & Sons. New York, New York.

INFORMATION FOR DROP WRITE UP

The information presented below is a review of basic chemistry that you will have covered in CHEM 120. You will use this information to explain your results from the "Scientific Method activity"

Introduction:

Properties of liquids and solids (i.e. condensed states of matter) are determined by the attraction/repulsion between molecules. Attractive and repulsive forces are determined by the bonds that hold the molecules together.

For review of the types of bonds WITHIN molecules (i.e. intramolecular bonds):

Read Appendix B in Sherwood, particularly pages B1 - B9 

About intermolecular bonds in the four solutions:

The bonds that make up water are polar covalent, and therefore, water molecules tend to orient themselves so that the oxygens are closest to the hydrogens of other water molecules (Figure 1). The interaction between water molecules is called hydrogen bonding. Although significantly weaker than the polar covalent bonds of the water molecule itself, they are sufficiently strong that water has a relatively high surface tension (Table 1). Beading up on a surface decreases the surface area to volume ratio, maximizing the interaction of each water molecule with another water molecule and decreases the interaction of water molecules with the air. When a salt is dissolved into water, the ionic bond between K⁺ and Cl^- is disrupted. This is because the dipole of the oxygen in the water molecule is sufficiently strong to disrupt the ionic bond (and also because of the tendency of entropy in the system to increase--the order of a salt crystal is low in entropy). Therefore, the nature of the intermolecular bonds is between an ion K⁺ or Cl^- and the dipoles of water (Figure 2). This ion-dipole interaction is stronger than the dipole-dipole interaction between water molecules. Finally, although hydrogen bonding does occur between the molecules of both ethanol and isopropanol (Figure 3), the extent of hydrogen bonding of both is less than in water. In addition, because isopropanol is a branched chain alcohol hydrogen bonding is less extensive than that of ethanol. The presence of the functional -OH group is significant, consider that Ethane, which is Ethanol without the -OH group has a boiling point of -89C vs the 69 C boiling point of Ethanol!

Figure 1 Water (Sherwood, Figure B-6)

Figure 2 3M KCl in water

Figure 3 Ethanol and Isopropanol

 Table 1

Surface tension: is defined as the amount of energy required to stretch or increase the surface of a liquid by a unit area. In general, liquids with stronger intermolecular forces have higher surface tensions.

Substance	Temperature (C)	Surface tension g
Ethanol	20	24.05
Isopropanol	20	21.7
Water	18	73.05
3M KCl	20	78.5

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