1 At the seven lab stations around the room are common examples of elements, mixtures, and compounds. Indicate if the sample is homogeneous or heterogeneous. Classify the material as an element, compound, mixture, or solution.
A substance (description):
homogeneous or heterogeneous:
element, compound, mixture, or solution:
B substance:
homogeneous or heterogeneous:
element, compound, mixture, or solution:
C substance:
homogeneous or heterogeneous:
element, compound, mixture, or solution:
D substance:
homogeneous or heterogeneous:
element, compound, mixture, or solution:
E substance:
homogeneous or heterogeneous:
element, compound, mixture, or solution:
F substance:
homogeneous or heterogeneous:
element, compound, mixture, or solution:
G substance:
homogeneous or heterogeneous:
element, compound, mixture, or solution:
2 Light a candle: examining how an element differs from a compound.
Materials: candle, heat source, beaker, ice cube
A Light a candle.
B Place a ceramic plate in the flame for a few seconds. Remove and observe the underside of the plate. Record observations.
C Invert a beaker over the flame and place an ice cube on top of the beaker. Wait approximately 1 minute. What happened? Record your observations.
D Without lifting the beaker, remove the ice cube and wipe dry the inverted bottom side of the beaker. Record observations of the inside of the beaker.
E Candles are made of a substance called paraffin. Is paraffin an element, compound or mixture?
F Is paraffin homogeneous or heterogeneous?
G Which element do you believe is deposited on the ceramic plate?
H What is the compound deposited on the inside of the beaker?
I What are three elements that are present in paraffin?
3 Modeling heterogeneous mixtures and phases. Materials: juice glass, tap water, paper towel, paper clips.
Ag Place a juice glass filled with water to the point of ready-to-overflow on a dry paper towel. Do not allow the paper towel to become wet.
Bg Predict the number of metal paper clips that can be added to the glass to make the water overflow.
Cg Add paper clips, one at a time, to the glass with water. Record the number of paper clips it takes to overflow the water. (You will know the water has overflowed if your paper towel becomes wet.)
Dg How did your prediction compare with the actual number of paper clips required to make the water overflow the glass? Calculate % prediction error.
Eg What are the phases present at the conclusion of the lab?
Fg What are the interfaces present in the glass?
Note to teachers: For the examination at the seven lab stations, I used beaten raw egg, metal slugs, gatorade, paint, bread, a rock, and baking soda. But, you could use whatever you want!
Also, for the candle lab, I used small wide candles (sturdy base, small flame). The flame was not very large and, thus, tongs were not required when holding a ceramic plate in the flame. Depending on the candle you use, you may want to use tongs to hold the plate.
Questions? Comments??
Terry Skovgard