Chemical and Physical Properties of Baking Soda and Chalk.

Procedure:        Materials – 3 glass slides, chalk, baking soda, water, hydrochloric acid, medicine dropper, hotplate, permanent marker, and tongs.

1. Divide two slides into two sections.  Label one side H2O and the other HCL.
2. Use a blank slide to scrap chalk dust onto one of the slides on both sides.
3. Drop five drops of water onto the H2O side and Five drops of hydrochloric acid on the HCL side.
4. Put the slide onto the hotplate and wait until the water has evaporated, and record the results
5. Repeat steps 2-4 with hydrochloric acid
6. Clean up your lab station.

Hazards:        Always wear your safety goggles when working with any type of chemical.  Be sure to tie your hair back to be sure that you do not obscure your view.  Be sure to be cautious when working with the hot plates.  Remember, hot and cold glass look alike, always give the hot glass plenty of time to cool off.  If  burned immediately rise your burn with water.  If a chemical is splashed into your eye or gets on skin be sure to wash it off immediately via eye wash station or soap and water.  Report all spills toe the teacher immediately

Data and Observations:

Questions:        

1. How did the samples of chalk change? After the liquid evaporated, the chalk became thick looking and not as transparent
2. How did the samples of baking soda change? The baking soda looked as if it had crystal patterns in it.
3. List four mixtures and classify each as resulting in a physical change or a chemical change.  Was you hypothesis correct? Explain. Chalk and water: physical, Chalk and hydrochloric acid: chemical, baking soda and water: physical, baking soda and hydrochloric acid: chemical
4. Which observations proved when a chemical change occurred and when it did not? The fizzing proved that a chemical change occurred.
5. What can you infer from your observations of the substances remaining after hydrochloric acid was mixed with chalk and baking soda? The HCL sparked a chemical change with the chalk and bakingsoda.
6. What is the difference between a chemical and a physical change? Physical – change in color, shape, no change in chemical makeup.  Chemical – change in temp, bubbling occurs, change in chemical make-up
7. Does fizzing always indicate the occurrence of a chemical change? Yes, fizzing indicates a chemical change because it is a characteristic of a chemical change
8. Identify any physical and chemical changes of water in the water cycle. Chemical – evaporation Physical – condensation
9. List physical and chemical changes that occur when gasoline enters an automobile engine andburns.  Gas (liquid) + burning = fuel for car (gas)

Conclusion:        The lab seemed to be very responsive and informative.  The purpose was to identify physical and chemical changes when water and hydrochloric acid was mixed with baking soda and chalk and heated to evaporation.  I discovered that when Baking soda as well as chalk is mixed with hydrochloric acid and burned a chemical change takes place.  I also learned that when the same two substances are mixed with water and burned, a physical change takes place.