Lesson 2: The affect of Temperature on Change in State of Matter

1. Ask a question. 2. Gather background information. 3. Form a hypothesis (a guess). 4. Test your hypothesis by conducting an experiment. 5. Make observations and collect data. 6. Prove or disprove your hypothesis.

What happens to the temperature of water during a change in state of matter?

The three states of matter are  Liquid  Solid  Gas

Phase changes that occur in water are:  Melting – solid liquid  Freezing – liquid solid  Boiling – liquid gas  Condensation - gas liquid

If water is undergoing a change in state, then the temperature will… (choose one of the following)  change.  remain constant.

 Can we measure it?  Is it feasible (based upon real world observations)?

 Scientists use an experiment to search for cause and effect relationships in nature.  They design an experiment so that changing one thing cause something else to change in a predictable way.  These changing quantities are called variables. A variable is any factor, trait, or condition that can exist in differing amounts or types.  An experiment usually has three kinds of variables: independent, dependent, and controlled.

 The independent variable is the thing in the experiment that is changed by the scientist.  To insure a good experiment there can only one independent variable.  As the scientist changes the independent variable, he or she observes what happens.

 The dependent variable is what the scientist is observing.  Scientists observe the dependent variable to see how it responds to the change made to the independent variable.

 Controlled variables are quantities that a scientist wants to remain constant.  To know how your independent variable is affecting your dependent variable, all other things must be kept the same so that you can see if the independent variable really does have an effect on your dependent variable.

1. Put on safety goggles. 2. Set up equipment. 3. Add crushed ice to the beaker. 4. After about 10 seconds, start the data collection on the computer by pressing start. 5. Turn hotplate to high. 6. Stir ice gently periodically throughout the experiment. 7. Every 1 minute, record the temperature and physical state. 8. Heat the beaker until the water has boiled vigorously for 3 minutes and then press stop on the computer and turn off the hot plate.

IndependentVariable (What I change) DependentVariable (What I observe) ControlledVariables (What I keep the same) Temperature Physical state of water Frequency of stirring Frequency of stirring Keeping temperature sensor off the bottom of the beaker Keeping temperature sensor off the bottom of the beaker

Time(minutes) Physical State(s) 0SolidIce 1 Solid/ liquid Ice + water 2 Solid/ liquid Ice + water 3 4

 100 mL beaker  Glass stirrer  Hot plate  Clamp  Oven mitt  Temperature sensor  Laptop  Timer  Crushed ice  Safety goggles

 Goggles must be worn at all times! Even during set up and clean up!!!  Use oven mitt every time you touch the hot plate dial or the beaker being heated. Use the oven mitt when you are stirring the ice.  Electricity and water being used together! CAUTION!!! Keep electric wires and devices away from the beaker of water!