The Scientific Method

A hypothesis is a possible explanation that answers the question. It is often pre- 

Once a hypothesis is formulated, an experiment is conducted to test the hypothesis. Experimentation is what distinguishes chemistry, and other experimental science, from other disciplines. In simple experiments, the researcher designs the experiment to examine one independent variable and attempts to hold all other variables constant. Again, using the battery example, if the experiment was designed to test battery life in flashlights, then battery life would be the dependent variable. It would be im-portant to define in exact terms the variable battery life and exactly how it would be measured. The researcher would then attempt to control all other variables, except for one indepen- 

This example also demonstrates why it is important to identify the important variables when formulating the hypothesis and designing the experiment. A few variables will generally be identified as important to control most variables will be ignored. For example, variables such as air pressure, rel- 

Once the experiment has been conducted and data collected and analyzed, a conclusion can be drawn concerning the original hypothesis. The experiment does not establish absolute truth concerning the hypothesis. A researcher should resist the temptation to state that the hypothesis was proven or not proven. In science, absolute truth can never be established. Results of an experiment may either support or not support the hypothesis. Ambiguous results can cause the researcher to modify the hypothesis and redesign the experiment. Even when the results are not ambiguous, an experiment is often repeated. One of the benchmarks of science is reproducibility. When an experiment is conducted and certain conclusions reached, another researcher should be able to repeat the same experiment and obtain similar results. 

This section contains a few chemical investigations that may be conducted at home. They are not full experiments, but they should provide useful activities that could be developed into a full-fledged experiment. Each illustrates basic concepts explained in the previous chapters. Most involve a few simple steps, while a few are more complicated. Again, the most important aspects of these activities are to be safe, have fun, and learn. Before actually trying to do the activity, read and understand the activity. Assemble all materials before starting and do the activity in a safe place. If chemicals are stored, label and mark the contents properly. Pay close attention to safety and dispose of used chemicals and materials safely. 

State the probiem and coiiect data (make observations). 

Observations may be qualitative (the sky is blue water is a liquid) or quantitative (water boils at 100 °C a certain chemistry book weighs 4.5 pounds). A qualitative observation does not involve a number. A quantitative observation is called a measurement and does involve a number (and a unit, such as pounds or inches). We will discuss measurements in detail in Chapter 5. 

Perform experiments. An experiment is something we do to test the hypothesis. We gather new information that allows us to decide whether the hypothesis is supported by the new information we have learned from the experiment. Experiments always produce new observations, and these observations bring us back to the beginning of the process. 

To explain the behavior of a given part of nature, we repeat these steps many times. Gradually, we gather the knowledge necessary to understand what is going on. 

The scientific method is spilling over into restaurant kitchens. Chefs are controlling for variables and keeping records in order to develop foods that are a surprise and a delight to the senses. This new field is known as molecular gastronomy and was founded by chemist and chef Herve This from the French National Institute for Agricultural Research in Paris and the late physicist Nicholas Kurti. 

The science of food is veiy old, dating back to at least the second century B.c. when observations were made on the density of meat. In the 1700s chemist Antoine Lavoisier, the father of modern chemistiy, did experiments on the preparation of meat stock. Benjamin Thompson (better known as Count Rumford) invented the double boiler and the percolating coffeepot. For the most part, early food science focused on preserving food by canning. Kurti made a presentation at the Royal Society of London in 1969 which began the change toward food as a science. Kurti said, I think it is a sad reflection on our civilization that while we can 

The molecular gastronomists are changing the way we understand food by one experiment at a time. Scientific method has given the culinary industry a makeover. 

Chocolate Chantilly incorporate air In a chocolate water emulsion. 

Chemists work together and also with other scientists to solve problems. As scientists conduct studies they ask many questions, and their questions often lead in directions that are not part of the original problem. The amazing developments from chemistry and technology usually involve what we call the scientific method, which can generally be described as follows  

This example illustrates two of the fundamental concepts of chemistry (1) matter is composed of various types of atoms, and (2) one substance changes to another by reorganizing the way the atoms are attached to each other. 

These are core ideas of chemistry, and we will have much more to say about them. 

Doing experiments to test the possible explanation (testing the hypothesis) 

Scientists call this process the scientific method. We will discuss it in more detail in the next section. One of life s most important activities is solving problems—not plug and chug exercises, but real problems—problems that have new facets to them, that involve things you may have never confronted before. The more creative you are at solving these problems, the more effective you will be in your career and your personal life. Part of the reason for learning chemistry, therefore, is to become a better problem solver. Chemists are usually excellent problem solvers, because to master chemistry, you have to master the scientific approach. Chemical problems are frequently very complicated—there is usually no neat and tidy solution. Often it is difficult to know where to begin. 

Science is a framework for gaining and organizing knowledge. Science is not simply a set of facts but also a plan of action—a procedure for processing and understanding certain types of information. Scientific thinking is useful in all aspects of life, but in this text we will use it to understand how the chemical world operates. As we have said in our previous discussion, the process that lies at the center of scientific inquiry is called the scientific method. There are actually many scientific methods, depending on the nature of the specific 

IBLG See questions from Chemistry An Overview and the Scientific Method  

In the last section we began to see how the methods of science are used to solve problems. In this section we will further examine this approach. 

Quantitative observations invoive a number. Quaiitative ones do not. 

When the ejqreriments have been completed and the data have been recorded, the next step in the scientific method is interpretation, meaning that the scientist attempts to explain the observed phenomenon. Based on the data that were gathered, the researcher formrrlates a hypothesis, or tentative explanation for a set of observations. Frrrther experiments are devised to test the validity of the hypothesis in as many ways as possible, and the process begins anew. 

After a large amount of data has been collected, it is often desirable to summarize the information in a concise way, as a law. In science, a law is a concise verbal or mathematical statement of a relationship between phenomena that is always the same under the same conditions. For example. Sir Isaac Newton s second law of motion, which you may remember from high school science, says that force equals mass times acceleration F = ma). What this law means is that an increase in the mass or in the acceleration of an object always increases the object s force proportionally, and a decrease in mass or acceleration always decreases the force. 

Hypotheses that survive many experimental tests of their validity may evolve into theories. A theory is a unifying principle that explains a body of facts and/or those laws that are based on them. Theories, too, are constantly being tested. If a theory is disproved by experiment, then it must be discarded or modified so that it becomes consistent with experimental observations. Proving or disproving a theory can take years, even centirries, in part because the necessary technology is not available. Atomic theory, which we will study in Chapter 2, is a case in point. It took more than 2000 years to work out this fundamental principle of chemistry proposed by Democritus, an ancient Greek philosopher. 

The three levels of studying chemistry and their relationships. Observation deals with events in the macroscopic world atoms and molecules constitute the microscopic world. Representation is a scientific shorthand for describing an experiment in symbols and chemical equations. Chemists use their knowledge of atoms and molecules to explain an observed phenomenon. 

The Chinese characters for chemistry mean the study of change.  

Science differs from other fields of study in the method that scientists use to acquire knowledge and the special significance of this knowledge. Scientific knowledge can be used to explain natural phenomena and, at times, to predict future events. 

The success of a natural law depends on its ability to explain, or account for, observations and to predict new phenomena. Copernicus s work was a great success because he was able to predict future positions of the planets more accurately than his contemporaries. We should not think of a natural law as an absolute truth, however. Future experiments may require us to modify the law. For example, Copernicus s ideas were refined a half-century later by Johannes Kepler, who showed that planets travel in elliptical, not circular, orbits. To verify 

Theory established unless later observations or experiments show inadequacies of model 

Revise h)q)othesis if experiments show that it is inadequate 

See Appendix A 1.6 for conventions regarding the use of significant figures in connection with measurements and the calculations involving measurements. Appendix 2 discusses methods for converting among various units. 

The hypothesis is then used to make a prediction that can be tested by performing an experiment. 

Scientists learn about chemistry in three ways. They observe, or watch, substances. They study substances and they do experiments. They try to make substances change and then record what happens. Scientists carefully plan how they learn about chemistry. They often use a system called the scientific method to answer questions they might have. 

The scientific method is very important. It allows scientists to learn about how things work. 

Scientists begin the scientific method by asking a question. 

They research information about their question, or problem. When gathering information, scientists use observation to watch what they are studying very carefully. They might write down, or record their observations when collecting the information. Scientists call this information data. They also collect data by reading other scientists books and journal articles. The Internet is another useful tool for gathering information. 

A scientist carefully records data during an experiment. 

This book is written from a perspective that was developed as the result of 37 years of industrial research at The Dow Chemical Company that focused on inventing, developing, and implementing industrial separation and purification processes. The work process for research and development is the scientific method, which will now be described. 

The main problem in distillation process control is to separate and purify chemical components in liquid and vapor streams while shedding the disturbances that are imposed on the distillation column. The opportunity is to separate the components from a feed stream into new vapor and liquid streams that have increased economic value at a cost that is competitive with other producers. Conducting research in a large corporation provides the opportunity to apply the results of improved performance to many distillation towers in many different businesses. 

Distillation is a mature technology that is well developed and tested by the scientific method. Two comprehensive books have been written by Kisteb on the design and operation of distillation columns. The control of distillation columns has been widely studied for many years, many papers have been written, and several books have been published on the subject such as the one by Buckley, Luyben, and Shunta. There is a large body of information to search and understand in the state of the art of distillation and process control. 

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The scientific method, as mentioned, involves observation and experimentation (research) to discover or establish facts. These are followed by deduction or hypothesis, establishing theories or principles. This sequence, however, may be reversed. The noted twentieth-century philosopher Karl Popper, who also dealt with science, expressed the view that the scientist s work starts not with collection of data (observation) but with selection of a suitable problem (theory). In fact, both of these paths can be involved. vSignificant and sometimes accidental observations can be made without any preconceived idea of a problem or theory and vice versa. The scientist, however, must have a well-prepared, open mind to be able to recognize the significance of such observations and must be able to follow them through. Science always demands rigorous standards of procedure, reproducibility, and open discussion that set reason over irrational belief. 

The scientific method is taught starting in elementary school. The first step in the scientific method is to form a hypothesis. A hypothesis is just an educated guess or logical conclusion from known facts. It is then compared against all available data and its details developed. If the hypothesis is found to be consistent with known facts, it is called a theory and usually published. The characteristics most theories have in common are that they explain observed phenomena, predict the results of future experiments, and can be presented in mathematical form. When a theory is found to be always correct for many years, it is eventually referred to as a scientific law. However useful this process is, we often use constructs that do not fit in the scientific method scheme as it is typically described. 

For more discussion of the application of the scientific method to chemistry see... 

The first of these statements is close to the way Vladimir Markovnikov expressed it in 1870 the sec ond IS the way we usually phrase it now These two statements differ in an important way—a way that is related to the scientific method... 

Adherence to the scientific method is what de fines science The scientific method has four major el ements observation law theory and hypothesis... 

A theory is our best present interpretation of why things happen the way they do The modern ver Sion of Markovnikov s rule which is based on mecha nistic reasoning and carbocation stability recasts the rule in terms of theoretical ideas Mechanisms and explanations grounded in them belong to the theory part of the scientific method... 

It IS worth remembering that a theory can never be proven correct It can only be proven incor rect incomplete or inadequate Thus theories are always being tested and refined As important as anything else in the scientific method is the testable hypothesis Once a theory is proposed experiments are designed to test its validity If the results are con sistent with the theory our belief in its soundness is strengthened If the results conflict with it the theory IS flawed and must be modified Section 6 7 describes some observations that support the theory that car bocations are intermediates in the addition of hydro gen halides to alkenes... 

It can be said that science is the art of budding models to explain observations and predict new ones. Chemistry, as the central science, utilizes models ia virtually every aspect of the discipline. From the first week of a first chemistry course, students use the scientific method to develop models which explain the behavior of the elements. Anyone who studies or uses chemistry has, ia fact, practiced some form of molecular modeling. 

Our discussion to this point has been confined to those areas in which the governing laws are well known. However, in many areas, information on the governing laws is lacking. Interest in the application of statistical methods to all types of problems has grown rapidly since World War II. Broadly speaking, statistical methods may be of use whenever conclusions are to be drawn or decisions made on the basis of experimental evidence. Since statistics could be defined as the technology of the scientific method, it is primarily concerned with the first two aspec ts of the method, namely, the performance of experiments and the drawing of conclusions from experiments. Traditionally the field is divided into two areas ... 

The scientific method has been successfully used throughout human history to enlighten us to our natural world and beyond. Since the earliest days there have been... 

However, like the scientific method, the engineering method is an interative process and embedded in the engineering method is the systematic use of the scientific method itself to predict behavior of a prototype device or process. This means both methods require the use of trial and error. The interdependency of irtiil and error was explained by someone who said. One cannot have trail and error without error. ... 

Fieser, The Scientific Method A Personal Account of Unusual Projects in War and Peace , Reinhold, NY (1964) 4) Ellern (1968)... 

Scientists pursue ideas in an ill-defined but effective way called the scientific method, which takes many forms. There is no strict rule of procedure that leads you from a good idea to a Nobel prize or even to a publishable discovery. Some scientists are meticulously careful, others are highly creative. The best scientists are probably both careful and creative. Although there are various scientific methods in use, a typical approach consists of a series of steps (Fig. 6). The first step is often... 

FIGURE 6 A summary of the principal activities that constitute a common version of the scientific method. At each stage, the crucial activity is experiment and its comparison with the ideas proposed. 

Author s comment] Because a general rendition of the Scientific Method cannot be cast in legally watertight wording, all possible outcomes of a series of measurements and pursuant actions must be in writing before the experiments are started. This includes but is not limited to the number of additional samples and measurements, and prescriptions on how to calculate and present final results. Off-the-cuff interpretations and decisions after the fact are viewed with suspicion. 

The next several chapters will deal with the philosophy of experimental designs. Experimental design is at the very heart of the scientific method without proper design, it is well-nigh impossible to glean high-quality information from experimental data collected. No amount of sophisticated processing or chemometrics can create information not presented within the data. 

The Sherlock Holmes stories often are read as the triumph of the scientific method of deduction. There is, though, another, darker interpretation to be advanced. That is the frustration of science and technology in changing everyday social practice. Throughout the canon, Holmes is consistently thwarted by the standard operating procedures of the Scotland Yard "regulars." He also is annoyed—and even disturbed—by the inability of Victorian... 

This passage is about the process by which scientists prove theories, the scientific method. 

The scientific method usually refers to either a series or a collection of processes that are considered characteristic of scientific investigation and of the acquisition of new scientific knowledge. 

The scientific method begins with observation. Observation often demands careful measurement. It also requires the establishment of an operational definition of measurements and other concepts before the experiment begins. 

The experiments that reject a hypothesis should be performed by many different scientists to guard against bias, mistake, misunderstanding, and fraud. Scientific journals use a process of peer review, in which scientists submit their results to a panel of fellow scientists (who may or (8 0) may not know the identity of the writer) for evaluation. Peer review may well have turned up problems and led to a closer examination of experimental evidence for many scientists. Much embarrassment, and wasted effort worldwide, has been avoided by objective peer review, in addition to continuing the use and proving the necessity of the scientific method. 

Learning the Scientific Method Through the Historical Approach. School Science and Math, 53, 637-43 (1953). 

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