Scientific Method Chemistry Adapted from Stephen L Cotton

Scientific Method Chemistry Adapted from Stephen L. Cotton 1

The Scientific Method ØA logical approach to solving problems or answering questions. Ø Starts with observation- noting and recording information and facts and then a hypothesis is proposedan explanation for the observation; it must be tested by an experiment. 2

Steps in the Scientific Method 3 1. Observation (uses your senses) a) quantitative involves numbers = 95 o. F b) qualitative is word description = hot 2. Hypothesis (ideas-why) - possible explanation for the observation, or “educated” guess 3. Expermiment (the test) - gathers new information to help

Ø 4 Controlled Experiment-Must have a “controlled” experiment- designed to test the hypothesis only -can only test one “factor” at a time, that way results compared to the control can only be from what was changed not anything else

Ø We deal with variables, or factors that can change. Two types: A) Manipulated variable (or independent variable) is the one that we change B) Responding variable (or dependent variable) is the one observed during the experiment Ø For results to be accepted, the experiment needs to always produce the same result 5

4. Record and Analyze Data (the stuff) - record data in data tables and create graphs 5. Conclusion (so…) - draw a conclusion based on the evidence presented by the data Ø 6 only two possible answers: 1) hypothesis is right 2) hypothesis is wrong-start over with a new hypothesis

- Page 22 Using your senses to obtain information 7 Hypothesis is a proposed explanation; should be based on previous knowledge; an “educated” guess The procedure that is used to test the hypothesis Tells what happened A well-tested explanation for the observations; cannot be proven due to new discoveries

Law vs. Theory v. A law summarizes what has happened. v. A theory (or model) is an attempt to explain why it happened – this changes as new information is gathered. 8

- Page 16 Let’s examine some information from a graph. 88. 2% 440, 000 9 After lead was banned in gasoline, paint, and public water supply systems, less lead entered the environment.