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Chemistry Presentation. Standards 9a and 9b Experimentation. Standard 9a and 9b. Plan and conduct a scientific Investigation to test a hypothesis. Evaluate the accuracy and reproducibility of data. What does the word hypothesis mean?. Hypothesis is an educated guess.
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Chemistry Presentation Standards 9a and 9b Experimentation
Standard 9a and 9b • Plan and conduct a scientific Investigation to test a hypothesis. • Evaluate the accuracy and reproducibility of data
What does the word hypothesis mean? • Hypothesis is an educated guess. • It has to be something you can test not just an opinion • Example: Cold water freezes faster than hot water.
There are 3 types of variables in an experiment. • Control variable: variables that are kept the same throughout the whole experiment. • Independent variable: Also called the experimental variable or manipulated variable. It is the thing the scientist is changing. • Dependent variable: what the scientist is measuring. It responds to what is being done with the experimental variable.
A good experiment only tests 1 variable at a time • It’s important to test 1 variable at a time so you know exactly what is causing your results.
Doing an experiment more than once is good. • Experiments need to have reliable data so that good conclusions can be made. • Reproducibility is when you repeat an experiment or measurement the same way you get the same answer. • Multiple trials help ensure reproducibility because errors can be seen more easily.
Your turn: Read the Following procedure carefully • EXPERIMENTAL PROCEDURE • Fill 3 containers with 300 milliliters of cold tap water. • 2. Add 10 grams of salt to container 1; stir. Add 20 grams of salt to Container 2; stir. Add no salt to container 3. • Place the 3 containers in a freezer. • Check the containers every 15 minutes. Record your observations.
What is the experimental variable? • EXPERIMENTAL PROCEDURE • Fill 3 containers with 300 milliliters of cold tap water. • 2. Add 10 grams of salt to container 1; stir. Add 20 grams of salt to Container 2; stir. Add no salt to container 3. • Place the 3 containers in a freezer. • Check the containers every 15 minutes. Record your observations.
What is probably the dependent variable? • EXPERIMENTAL PROCEDURE • Fill 3 containers with 300 milliliters of cold tap water. • Add 10 grams of salt to container 1; stir. Add 20 grams of salt to Container 2; stir. Add no salt to container 3. • Place the 3 containers in a freezer. • Check the containers every 15 minutes. Record your observations.
What is a control variable? • EXPERIMENTAL PROCEDURE • Fill 3 containers with 300 milliliters of cold tap water. • Add 10 grams of salt to container 1; stir. Add 20 grams of salt to Container 2; stir. Add no salt to container 3. • Place the 3 containers in a freezer. • Check the containers every 15 minutes. Record your observations.
What is a possible hypothesis? • EXPERIMENTAL PROCEDURE • Fill 3 containers with 300 milliliters of cold tap water. • Add 10 grams of salt to container 1; stir. Add 20 grams of salt to Container 2; stir. Add no salt to container 3. • Place the 3 containers in a freezer. • Check the containers every 15 minutes. Record your observations.
Where is there a possible error? Freezing Time Results Trial 1 Trial 2 • 10 grams 10 minutes 13 minutes • 20 grams 13minutes 13 minutes • No salt 8 minutes 8 minutes