Janice VanCleave’s Crazy, Kooky, and Quirky Chemistry Experiments
The Scientific Method Scientists identify a problem or observe an event Then they seek solutions or explanations through research and experimentation By doing the experiments in this book you will learn to follow experimental steps and make observations You will also learn many scientific principles that have to do with chemistry In the process the things you see or learn may lead you to new questions For example perhaps you have completed the experiment that studies how you can use the sun to separate salt from water Now you wonder how humidity might affect the process That’s great All scientists are curious and ask new questions about what they learn When you design a new experiment it is a good idea to follow the scientific method 6 Janice VanCleave’s Crazy Kooky and Quirky Chemistry Experiments IntroduCtIon
1 Ask a question 2 Do some research about your question What do you already know 3 Come up with a hypothesis or a possible answer to your question 4 Design an experiment to test your hypothesis Make sure the experiment is repeatable 5 Collect the data and make observations 6 Analyze your results 7 Reach a conclusion Did your results support your hypothesis Many times the experiment leads to more questions and a new experiment Always remember that when devising your own science experiment have a knowledgeable adult review it with you before trying it out Ask him or her to supervise it as well 7 Introduction
expando Purpose To observe the effects of expanding gas Materials empty 2-liter plastic soda bottle timer ½ cup 125 ml tap water 1 tablespoon 15 ml dishwashing liquid saucer NOTE This experiment requires a freezer Procedure 1 Place the empty soda bottle in a freezer for two minutes or more 2 While you are waiting mix the water and dishwashing liquid together in the saucer 3 Remove the soda bottle from the freezer and dip its open end in the soapy water 4 Stand the bottle on a table and observe what happens NOTE If a soap bubble does not form over the mouth dip the bottle in the soapy water again Results A soap bubble forms over the mouth of the bottle Why As the temperature of molecules decreases molecular motion decreases and the cohesive force increases pulling the molecules closer together Cooling caused the air molecules inside the bottle to move closer together removed from the freezer the cold air inside it heated up 8 Janice VanCleave’s Crazy Kooky and Quirky Chemistry Experiments
and the air molecules moved farther apart Some of the air was forced out of the bottle and pushed on the soap film across the mouth of the bottle making a soap bubble 9 Expando
