Title

Phase and temperature changes over time

Jen Hinerman

Question

How will the temperature change over time?
How long will the chemical stay in each phase?
How will the data change with a 5%, 10% or 20% salt concentration?

Standards

3d. Students know the states of matter (solid, liquid, gas) depend on molecular motion.

3e. Students know that in solids the atoms are closely locked in position and can only vibrate; in liquids the atoms and molecules are more loosely connected and can collide with and move past one another; and in gases the atoms and molecules are free to move independently, colliding frequently.

High School Chemistry:

2d. Students know the atoms and molecules in liquids move in a random pattern relative to one another because the intermolecular forces are too weak to hold the atoms or molecules in a solid form.

4d. Students know the values and meanings of standard temperature and pressure (STP).

7a. Students know how to describe temperature and heat flow in terms of the motion of molecules (or atoms).

7c. Students know energy is released when a material condenses or freezes and is absorbed when a material evaporates or melts.

Experimental Design

Students will be measuring the temperature changes over time of distilled water and three salt water concentrations (5%, 10 %, 20%).  Students will be filling a beaker with ice of the differing solutions, recording the temperature every minute, graphing the results and comparing the graphs of each solution.

Time (minutes)

Dependent variables

Temperature (degrees Celsius)

Series

Compare the graphs of different salt water concentrations (5%, 10% and 20%)

Controls and Constants

The control would be distilled water.  The constants would be the same amount of ice (mass or volume) and the same heat setting on the the hot plate.

Materials

ice, beaker (200 mL), thermometer, hot plate

Procedures

1. Students will fill a beaker with crushed ice and place a thermometer into the ice and beaker, being carefull that the bulb of the thermometer doesn't touch the bottom of the beaker
2. Place the beaker onto a hot plate and turn the hot plate one
3. record the temperature every minute until the ice boils

repeat steps 1-4 for