Chemistry is the study of matter and the change it undergoes. The change is divided up into two classes, chemical change and physical change. In a physical change, one or more physical properties of a substance are altered without their being any new substances formed as a result. Some examples of physical properties include, size, shape, color, and physical phase. An example of a physical change is melting an ice cube.
A chemical change results in the formation of one or more of new substances. These new substances change the chemical properties and composition from the original substance. A chemical change is a creation of a new product and usually is irreversible. Some chemical properties include oxidation, flammability, heat of combustion, and reactivity with other chemicals. An example of a chemical change is the formation of rust on iron.
The purpose of this lab is to be able to distinguish these physical and chemical changes and describe the changes in detail using observation skills.
1. After sorting out my supplies, I put my safety goggles on as well as a pair of protective gloves.
2. I took the 24- well plate and began filling a well half way with 6 M HCl and a second well on the same plate filling it also half way, but this time I used 6 M NaOH. To ensure accuracy I was playing close attention to the placement of these chemicals in the well plate. I took the pipets labeled “HCl” and “NaOH” and used it to suck up the proper chemical that matched the labeled pipet.
3. I gathered four small test tubes, the 24- well plate used previously, and each of the substances to be tested. I placed the micro test tubes into the wells of the 24- well plate. In this lab the substances I am testing in the order are Magnesium (Mg), Copper (Cu), Zinc (Zn), Magnesium Oxide (MgO), Copper Carbonate (CuCO3), Copper Nitrate (CuNO3)2, and Sodium Chloride (NaCl).
4. For each of the four test tubes there are four different steps required. I took ONE of the substances and placed small amounts into each of the test tubes. I then followed the four steps I listed below.
My test tube #1 is always first on the left side when referring to anatomical positioning.
Test Tube #1:
I examined and noted the color and order of the substance.
I obtained a box of matches and lit the burner fuel wick. Picking up the test tube with a clamp, I then cautiously heated the sample slightly above the flame. I allowed the test tube to cool off before placing it back into the well plate preventing the plastic to melt.
Test Tube #2:
Using the pipet I added cold water to the second test tube, just enough to cover the substance that I was testing. Picking up the test tube with the clamp, I cautiously held the test tube slanted slightly on an angle (away from myself) so the flame was directed to the top of the water just long enough that it began to boil, observing the solubility in hot water.
I tore off a small piece of red and blue litmus paper. After the solution cooled, I took the glass stirring rod and transferred a small drop of the solution onto the litmus paper. After noting my results, I cleaned off the stirring rod.
Test Tube #3:
I grabbed the pipet that was set aside previously that was labeled HCl and added about 6 drops to the sample and followed by stirring the sample. For safety precautions, I held the test tube with a test tube holder in case I was to experience an exothermic reaction. After recording my reactions, I cleaned the glass stirring rod.
Test Tube #4:
I took the other pipet set aside labeled NaOH and added also about 6 drops to the sample and followed by stirring the sample.