Nature of Science

What does the word “Science” mean? The word “science” comes from the Latin term scientia, meaning knowledge. Reference: Wikipedia Encyclopedia

The Scientific Method Make an Observation, Ask a 2 Part (x,y) Question, or Define a Problem Do Some Research Propose a Reasonable Hypothesis (If/Than) Experiment (with Variables) Data Analysis Conclusion

What are Variables? Variables are part of the experiment you develop to test your hypothesis. They include anything that can change during the experiment. Control Variable: A part of the experiment that is not being tested and is only used to compare data Brainstorm_?__, Pick __?___, that is_?__, rest_?_. Independent Variable: The part that is changed by the person doing the experiment. Dependent Variable: The part that is affected by the independent variable. This variable does not change in the experiment and is the one that gets measured.

Lets Look at an Example: Krusty Krabs Breath Mints Mr. Krabs created a secret ingredient for a breath mint that he thinks will “cure” the bad breath people get from eating crabby patties at the Krusty Krab. He asked 100 customers with a history of bad breath to try his new breath mint. He had 50 customers (Group A) eat a breath mint after they finished eating a crabby patty. The other 50 (Group B) also received a breath mint after they finished the sandwich; however, it was just a regular breath mint and did not have the secret ingredient. Both groups were told that they were getting the breath mint that would cure their bad breath. Two hours after eating the crabby patties, 30 customers in Group A and 10 customers in Group B reported having better breath than they normally had after eating crabby patties.

Questions Which people were in the control group? Group B (no secret ingredient) 2) What is the independent variable (hint: this one changes)? The secret ingredient 3) What is the dependent variable (hint: this one gets measured)? Degree/amount of bad breath What should Mr. Krab’s conclusion be? The breath mint with the secret ingredient seems to reduce bad breath, but is not 100% accurate.

Pre-Lab: Conservation of Mass Take out a piece of paper Purpose: To relate observations of a chemical reaction to the law of conservation of mass Background: Define the Law of Conservation of Mass

The Law of Conservation of Mass The Law of Conservation of Mass states that mass, in a closed system, cannot be created nor destroyed, but can change form A closed system is one where there is no chemical exchange

↓ REACTANTS  PRODUCTS Sodium bicarbonate Acetic Acid (baking soda) + (vinegar) NaHCO3 CH3COOH ↓ H2O + CO2 + NaCH3CO2 (liquid) (gas) (solid)

Tonight’s Homework Complete the Scientific Method Handout Don’t forget that next class we’ll be doing the conservation of mass lab!