scientific method pp chem i
DESCRIPTION
TRANSCRIPT
Scientific MethodScientific Method
Put the steps in order…
Analyze Data Ask a Question
Experiment Hypothesis
Observation/ResearchConclusion
Theory
Scientific Law
Steps in the Scientific Steps in the Scientific MethodMethod
Observation Observation (ask (ask question)question)
HypothesisHypothesis ExperimentExperiment Analyze DataAnalyze Data ConclusionConclusion TheoryTheory Scientific LawScientific Law
ObservationsObservations
Gathered Gathered through your through your
sensessenses A scientist A scientist
notices notices something in something in their their natural natural
worldworld
ObservationsObservations
An An exampleexample of of an observationan observation
might be might be noticing that noticing that
heating CuCOheating CuCO33 a a gas is released.gas is released.
ObservationsObservations
Another Another exampleexample of an of an observationobservation
might be might be noticing that noticing that
every time that every time that your sister your sister
blows a bubble blows a bubble bigger than her bigger than her head, it POPS!head, it POPS!
HypothesisHypothesis
A suggested A suggested solution to the solution to the problem.problem.
Must be Must be testabletestable
PredictsPredicts an an outcomeoutcome
HypothesisHypothesis
An An example of a example of a hypothesishypothesis might be that might be that the bubble pops the bubble pops because of the because of the quality of the quality of the gum.gum.
ExperimentExperiment
A A procedure procedure to to testtest the the hypothesishypothesis
..
ExperimentExperiment
VariableVariable – – factor in the factor in the experiment experiment that is being that is being
testedtested
ExperimentExperiment
A good or A good or “valid” “valid”
experiment experiment will only will only test test ONE ONE variable!variable!
What is the Purpose of What is the Purpose of a Control?a Control?
Controls are NOT being tested
Controls are used for COMPARISON
EXAMPLE: What variables does one need to
account for if one were to design an experiment to test whether or not hot water dissolves salt faster than cold water? What would be the control?
Other Variables The factor that is changed
is known as the independent variable.
The factor that is measured or observed is called the dependent variable.
Example of Controls & Example of Controls & VariablesVariables
For example, suppose you want to figure out the fastest route to walk home from school.
You will try several different routes and time how long it takes you to get home by each one.
Since you are only interested in finding a route that is fastest for you, you will do the walking yourself.
What are the Variables in What are the Variables in Your Experiment?Your Experiment?
Varying the route is the Varying the route is the independent variableindependent variable
The time it takes is the The time it takes is the dependent variabledependent variable
Keeping the same walker Keeping the same walker throughout makes the throughout makes the walker a walker a control variable.control variable.
One more thing… it is best to make several trials with each independent variable.
How About Another Example? Pumpkin growers would like to
know if phosphorus has a key role in growing GIANT PUMPKINS!
THINK: How would you set up a controlled experiment?
Remember:Remember:
Two groups are used: the control & experimental
groups
There should be only one variable tested at a time.
Perform multiple trials
DataData Results of
the experiment
May be quantitative (numbers) or qualitative
DataData Must be
organized Can be
organized into charts, tables, or graphs
ConclusionConclusion
The answer to the hypothesis based on the data obtained from the experiment
RetestRetest
In order to verify the results,
experiments must be retested.
Theory Vs. Law supported by
many experiments.
can be modified Ex. - Einstein's
Theory of Relativity, Atomic Theory
•Summarizes a pattern in nature. •No known exceptions occur.•Ex. - Law of Universal Gravitation, Law of Conservation of Mass, Gas Laws
Ticket-Out-The-Door: CP You want to buy a new car. You are
interested in three different models (model 1, model 2, model 3). Today you are test driving the cars, and you want the car with the best gas mileage.
Independent Variable: Dependent Variable:
Ticket-Out-The-Door: CPHWithin a classroom setting, subjects were asked to listen to a guest instructor. All subjects were given a description of the instructor. Some subjects read a description containing the phrase “People who know him consider him to be a rather cold person...”, while other people read a description where the word “warm” was substituted for the word cold (otherwise, the descriptions were identical). After the lecture, subjects were asked to rate the instructor. Subjects who were told the instructor was warm gave him more favorable ratings compared to subjects who were told that the instructor was cold.