1.2:
The Scientific Method
The scientific method is a systematic approach followed by all scientific disciplines. It follows six main steps – making an observation, asking a question, building a hypothesis, conducting experiments, the interpretation of data, and finally, the derivation of a conclusion.
The scientific method starts with an observation and a question to help understand that observation. For example, the French chemist Antoine Lavoisier observed the phenomena of combustion. He formulated a question to understand what happens when something is burned. Where does the matter go?
The third step in the scientific method is building a hypothesis – a tentative explanation for the observation in question, that can be tested. In response to his question of “Where does the matter go?”, Lavoiser hypothesized that in a chemical reaction, the matter was neither created nor destroyed. A good hypothesis is also testable and falsifiable. A testable hypothesis is one that makes predictions that can be confirmed by experimentations or observations. It is falsifiable when it can be refuted by experimentation.
The fourth step in the scientific method is experimentation and data collection. Experiments are observations or measurements conducted under controlled environments such as temperature, pressure, or volume. This step investigates how well the real world fits that predicted by the hypothesis.
Some experiments and observations are qualitative – describing how a process happens. Others are quantitative – measuring or quantifying something about the process.
Lavoisier tested his hypothesis by heating mercury in a closed setting. This led to the formation of a reddish substance. His experiments were quantitative, so he carefully recorded the mass of reactants and the products in the closed system as well as separately.
The fifth step is data interpretation and analysis – evaluating whether the results support or refute the hypothesis and if further experimentation is needed. Lavoisier observed that the total mass of the jar and its contents before and after the reaction remained the same, although the mass of the red product was greater than that of the original mercury.
The final step is to draw a logical conclusion and decide whether to accept or reject the hypothesis. If the results support the hypothesis strongly, then it is accepted. It may also be put to further testing or refined by asking new questions, and conducting new experiments.
From his experiments, Lavoisier concluded that since the total mass of the jar remained unchanged during the reaction, the oxygen in the jar had combined with the mercury to form the new product, now known as mercury(II) oxide. This conclusion strongly supported his hypothesis on the conservation of mass – that the total mass of the objects remains unchanged during the process of burning.
However, if a hypothesis is disproved, then scientists may formulate a new hypothesis by taking cues from the failed experiments, and start afresh.
Even though we see the scientific method as a series of steps, new information or ideas might cause a scientist to back up and repeat steps at any point during the process. Thus, the scientific method is an iterative process.
1.2:
The Scientific Method
Chemistry is an empirical science. Scientists often pose questions to understand the chemistry in everyday life and seek answers to these questions. To achieve this, scientists follow a definitive series of steps that together make up the Scientific Method. This approach involves making observations, asking questions, building a hypothesis, conducting experiments, analyzing results, and forming a conclusion.
Observation and Question
The first step in the scientific method is observing a phenomenon in the physical world. Next, a question is posed to better understand that phenomenon. For example, the question could be: “Which freezes faster, plain water, or water with salt added to it?”
Hypothesis
The next step is to formulate an explanation for the particular observation. This tentative interpretation for a set of observations that acts as a guide for understanding the observed phenomenon is called a hypothesis. For example, for the question above, a hypothesis could suggest that adding salt alters the freezing point of plain water.
Scientists often use earlier research and literature to begin their investigation and formulate a hypothesis that could be tested through experiments. A strong hypothesis is both testable and falsifiable. It is considered testable if it can be proven right, and falsifiable if it can be disproven—in which case, the scientist must modify or discard the hypothesis.
Experimentation
The third step is designing and conducting experiments to test the validity of the hypothesis. Experiments are measurements and observations carried out under controlled conditions. Some observations and experiments are qualitative (describing how a process happens), while many are quantitative (measuring or quantifying something about the process). To test the salt-water hypothesis, the scientist can take two glasses with equal amounts of water, at room temperature. A spoonful of salt can be added to one of the glasses, and both glasses placed into the freezer. The status of water in each glass can be observed every 15 minutes and the time taken for each glass of water to become completely frozen can be recorded.
The experimental design is a critical step in the scientific method. Care should be taken to control the number of variable factors so that the effect of a specific factor in question can be monitored.
Result Analysis and Conclusion
The next step is to analyze the results of the experiments and conclude whether these results validate the hypothesis or not. If the conclusion is that they do, then the hypothesis is accepted and might be subjected to further experimentation to answer new questions. When a hypothesis is proven wrong, a new hypothesis can be proposed, and the process continues.
In the salt-water example, the results indicate that saltwater takes more time to freeze than plain water. This provides the conclusion that water with salt freezes at a slower rate than plain water. Thus, the results validate the hypothesis.
This text is adapted from Openstax, Chemistry 2e, Section 1.1: The Scientific Method.