Objective One: The Nature of Science
- 2. • Science involves asking questions about the natural world (the world we see around us) and finding answers to those questions • Specifically, scientists use the Scientific Method to try and answer questions in a fact-based, methodical way • Scientists use Experiments, Research, Building a Models, etc., to try and find an answer to their questions
- 3. • Never work alone in a lab • Never eat, drink, or apply makeup in a lab • Know where safety equipment in located in lab • Never mix chemicals unless directed by your teacher • Never work on a experiment not assigned by your teacher • Report any accidents, hazards, or spills to your teacher right away • Always handle chemicals with care—do not return to original container • Never taste, touch, smell, or substance in the lab—if you are told to do so, waft fumes toward you with your hand • Tie back long hair, roll up loose sleeve—put on any safety equipment given by your teacher, including safety goggles and gloves • Always wear an apron or lab coat—never wear shorts or sandals in the lab • Never pour chemicals down the drain without checking with your teacher— dispose of chemicals and contaminated materials in appropriate containers • Handles animals as directed by your teacher—do not conduct an investigation of animals unless told to do so by your teacher • Never remove an animal from the lab unless told to do so by teacher • Never capture an animal from the wild or release to the wild • Animals must be properly cared for—they should be given appropriate food, water, housing, space, lighting and temperature
- 4. • Safe goggles • Beakers • Test tubes • Tongs • Pipet • Forceps • Petri Dish • Microscope
- 5. Bad Question: Which brand of toothpaste tastes best? (opinion-based) Good Question: How do factors such as temperature and surface area affect the speed of chemical change in effervescent antacid tablets dissolved in water. (fact-based)
- 6. • Problem/Question: How long does it take antacid tablets to dissolve in water and does temperature and surface area effect that chemical change? • Research/Observation: Other substances like sugar dissolve faster in hot water vs. cold water. Sugar also dissolves faster in smaller pieces vs. larger pieces. • Hypothesis: We hypothesize that the rate of chemical change (time it takes to dissolve) of the reactant (the antacid tablets) will increase as the temperature and surface area increases. • Experiment: We will put different-size tablets in different temperature water and record the speed of chemical reaction (time it takes to dissolve.) • Analysis/Conclusion: We will analyze our Hypothesis: Educated guess about what we results to see if we can confirm or if we think will happen in our experiment fail to confirm our hypothesis.
- 7. Gather the tools and equipment needed to conduct the experiment and measure the results
- 8. • Variable: anything in a experiment that can change • You want to keep variables the same except the ones you are testing • EX: We will use only one tablet per trial and using the same amount of water per trial • Independent Variable: The things we change in the experiment (EX: size of tablet and temperature of water.) Measurements must be precise. • Control: normal conditions we can compare our results to (Trial 2)
- 9. bubbling stops—in other words, when we can no longer see any visible reaction. When timing the reaction, the most reasonable unit to use is seconds. To keep a record of our data, we’ll make a data table. We’ll have one column for each temperature and one row for each surface area. Remember, this is not the only way to organize our data. I think we’re ready now. Let’s begin! Finally! If you’ll drop the antacid tablet into the water, I’ll time the reaction. Then you can record the data in our table. No problem! Here’s our data organized in a data table. Reaction Times Water Temperature Cold (2°C) Warm (26°C) Hot (82°C) Small (w hole tablet) 144 s 51 s (cont rol) 27 s Surface Area M edium (3 pieces) 42 s 40 s 9s Large (pow der) 20 s 14 s 8s
- 10. • Independent Variable: The Variable that we changed during the experiment. Plotted on the horizontal axis (x) • Dependent Variable: The variable that changes as a result of the independent variable. The result of the experiment. EX: Reaction time (time it takes tablet to dissolve.) Plotted on the vertical axis (y)
- 11. • Reaction time decreased as temperature increased • Reaction time decreased as surface area increased • Conclusion: Our experiment supported our hypothesis that the rate of chemical change will increase as the temperature and surface area of the reactant increases
- 12. Although our experiment supported our hypothesis, it did not PROVE our conclusion…WHY? • Theory: A general explanation of a set of observations based on testing hypotheses. Explains how things happen in nature. • A theory is supported by lots of data collected from many different experiments and observations • Theories can change over time as scientists gather more info • EXAMPLE: Scientists in the past thought that the world was flat and that the sun revolved around the earth, later through scientific observation and processes, they realized that the earth is round and that the earth revolves around the sun • An action or sets of actions about the universe that has always been observed as true. Must be simple, universal, and absolute. • EXAMPLE: Law of gravity, E=MC(squared), etc.