The Scientific Method Chemistry CP

The Scientific Method The SCIENTIFIC METHOD is a logical, systematic approach to the solution of a scientific problem.

Steps of the Scientific Method 1. Make OBSERVATIONS 2. Form a HYPOTHESIS 3. Conduct an EXPERIMENT Record and COLLECT DATA Analyze your DATA and RESULTS 4. State your CONCLUSIONS

What makes the scientific method possible? At the root: humans are curious Experimental science is actually the search for cause and effect relationships in nature. If…... then…….

OBSERVATIONS YOU… Notice something and wonder why it happens See something and wonder what causes it Want to know how or why something works Ask questions about what you have observed Want to investigate

OBSERVATIONS Qualitative observations: Quantitative observations: Using your five senses – see, feel, sound, taste or smell Color, odor, shapes are all qualitative observations. Quantitative observations: Numeric data Temperature, mass, volume are all quantitative observations.

What’s wrong with the flashlight? OBSERVATIONS Suppose you try to turn on a flashlight and it does not light. Your observation leads to a question: What’s wrong with the flashlight?

HYPOTHESIS A hypothesis is an educated guess - a proposed explanation for an observation You guess or hypothesize that the flashlight needs new batteries.

HYPOTHESIS There are no right or wrong hypotheses Usually the more reasonable hypothesis becomes the one that is tested and verified A “correct” hypothesis can become a theory with support from further testing

EXPERIMENTS Test the hypothesis with an experiment An experiment is set of controlled observations. You can test your hypothesis by putting new batteries in the flashlight. If the flashlight lights, your hypothesis was true.

EXPERIMENTAL PROCEDURES Select only one thing to change in each experiment – the variable Independent variable: the one you will change Dependent variable: the one you will measure Change something that will help you answer your question(s) Test the effect of temperature on salt dissolving. Change/vary the temperature Measure how fast salt dissolves

EXPERIMENTAL PROCEDURES The procedure must tell how you will change this one thing and how you will measure the amount of change Each experiment should have a “control” for comparison so that you can see what the change actually did

EXPERIMENTS (Cont.) Experiments are done many times to guarantee that what you observe is reproducible Reduce the chance that you have made an experimental error or observed a random effect

DATA COLLECTION AND ANALYSIS Record your observations during the experiment. Quantitative Observations = Experimental Data Summarize what happened based on the analysis of the data or results: table or graphs a statement of what occurred

CONCLUSIONS Based on the results of your data analysis, conclusions can be drawn These conclusions help us confirm or deny the original hypothesis Sometimes you will need to revise your hypothesis if the original is “incorrect”

THEORIES Once a hypothesis is well-tested and reproducible, it may become a theory A theory is a well-tested explanation of a set of observations Sometimes a theory will be revised to explain new observations

SCIENTIFIC LAWS A scientific law is a statement of fact describing a set of observations. It is generally accepted to be true and universal. Examples: Law of Gravity, Law of Conservation of Mass, Law of Conservation of Energy