101 FLAVORS ICE CREAM





02/12/04


Pd.6


H.MATTER &ENERGY


LAB 2


TOPIC: CHEMISTRY PHYSICAL PROPERTIES-freezing point depression-the effect of salt on the freezing point of ice


PURPOSE:


To observe a phase change and analyze it on a molecular level.


To determine what happens to the freezing point when salt is added to ice.


DATA TABLE:


TEMPERATURE


ICE WITHOUT SALT ADDED


-3°C


ICE WITH SALT JUST ADDED


-5°C


ICE AND SALT AFTER PHASE CHANGE OF ICE CREAM


-5°C


BEGINNING ICE CREAM MIXTURE


10 °C


ENDING ICE CREAM MIXTURE


-1.5°C


ANALYSIS:



o After approximately 8-10 minutes in an ice/salt mixture the cream change its phase from liquid phase to solid phase and became ice cream.
o 10 minutes after adding the salt the phase of the ice changed form solid to liquid and the temperature decreased.



CONNECTIONS/TEXTBOOK RESEARCH:


1. The kinetic molecular Theory explains the forces between molecules and energy that they possess. Molecules are in constant motion. This motion is different for the 3 states of matter. In the solid state the molecules are held close to each other by their attractions of charge. They will bend or vibrate, but will stay close to each other. In the liquid state molecules will flow over one another, but stay toward the bottom of the container. Motion is a bit more random than of solid. In the gas state molecules are in continual straight-line motion. The kinetic energy of the molecules is greater that the attractive force between them, thus they are much farther apart and move freely of each other.


When molecules collide with each other, or with the walls of a container, there is no loss of energy.


2. At standard pressure the freezing point of pure water in Celsius is 0°C, in Fahrenheit is 32°F and in Kelvin is 273 K.


3. The freezing point of water drops with the addition of salt because adding salt to water breaks the hydrogen bonding in water therefore lowering the freezing point of water.


4.


5.


6.


7.


CONCLUSIONS:








BIBLIOGRAPHY: The information has been founded in the books “Focus on Physical Science” and www.sciencebyjones.com/heat_notes_full_copy.htm