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.
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?”
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.
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.
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.
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