Pre lab discussion
a- chemical change
b- chemical change
c- physical change
d- chemical change
e- physical change
2. Change in color, gas, light or smoke and heat.
3.Becuase if the temperature changes you can notice it better this way.
4. I will use goggles and cloves all the time, I also need to point dangerous materials away from other people and I should be specially cautious with hydrochloric acid.
Problem- How can you recognize and differentiate between physical and chemical changes?
X= A change that occurred (add tearing paper)
1.Melting candle wax
2.Burning candle wick
6. Heating CuSO4 and 5H2O
Chemical changes in- color, gas, light, smoke, or heat, burning
Physical changes in- texture, boiling point, and melting point
Addendum to report
1. Name two possible indications that a chemical change has occurred, using examples from this investigation.
A. Two possible indications a chemical change has occurred are burning and a change in color, for example when the paper burned and smoke was released,
it was a chemical change. Also, when we dried out Copper Sulfate Pentahydrate, the color changed from blue to white but then, we added a couple drops of water to the substance and the color was changed back to its original state but since the color changed, we came to the conclusion it was a chemical change.
2. Why are you instructed to feel the outside of the test tube after two chemicals are mixed, as in Steps 5 and 6 of this investigation?
A. After we mixed two chemicals and felt the outside of the tube, the temperature was warm meaning it was a chemical change since heat was created. For example, in step 5, we mixed HCL and Mg and touched the test tube and it was warm.
3. Indicate whether following changes are chemical or physical A. Physical change, no new substance is created and the texture does change
B. Chemical change, the burning candle released smoke showing how a new chemical was made.
C. Physical change, tearing paper is a physical change because their is nothing that shows a chemical change occurred but the tearing and change of texture shows a physical change.
D. Chemical change, burning paper released smoke and the paper changed color as it burned.
E. Physical change, if the water is removed by evaporation you still have NaCl making no new substance.
F. Chemical Change, when you mix this two you create precipitation, so this shows its chemical.
Chemical change, adding these two substances produced a gas making it a chemical change.
H. Physical Change, no chemical change only changes that are physical occurred you grinded the substances.
I. Chemical change, this created anhydrous copper sulphate.
4. Sodium chloride dissolves in water, leaving a clear homogeneous mixture with no physical evidence of the crystals with which you stand. Describe an experiment that you could perform to separate the sodium chloride from the water?
A. To separate the sodium chloride from the water we could evaporate the water leaving only the sodium Chloride.
5. How would the experiment you designed in response to question 4 differ if some sand was mixed in with the sodium chloride before it was added to the water?
A. I would use a filter to separate the sand from the mixture then I could evaporate the water leaving the sodium Chloride and the sand separated.