Conceptual Chemistry Density Preview 2015 Send to Gene Easter
G LEaster@sbcglobal.net by June 2. 2015 Put your email here so I can email it back.
Thanks. Name your attachment your last name and Density
Name_______________ Grade______
1. Create a concept map for density put the major concepts in circles near the top and
minor ones below. Connect the circles with descriptors. Descriptors go on the
arrow lines.
This just a start for you. Change it any way you want. More correct
branching the better Gene
Density
Mass
divided
volume
units of
grams
measurement
ml
cm3
2. My meter stick has a volume of 120 cm3 and a mass of 60 grams.
A. I want you to divide the mass by the volume of my meter stick and tell me what is the
meaning of this division and you can’t use the word per in your answer. A / is per. What
use can be made of the concept?
B. Also divide the volume by the mass and tell me what is the meaning of this division.
Also you can’t use the word per in your answer. Who would use such a concept?
3. How are density of a substance and concentration of solutions similar and different?
How does density relate to the everyday world?
Gene Easter GLEaster@sbcglobal.net
2015_____
4. Discuss how you would approach teaching the concept of density to your students.
Please list activities and pre and post assessments and the grade level of your students.
I would teach ___ grade.
5. Plastics make up 30% of city solid waster by volume. There are six types of plastic
that can be recycled, but these different types cannot be melted together to create new
plastic products. For this reason, most plastic containers and other disposable plastic
products are marked with a number 1-6 which appears inside the recycle symbol and
indicates the plastic type.
Number
1
2
3
4
5
6
Your task here is to design an activity for your students to separate
the 6 plastic types using density. Pay close attention the density ranges
of each material.
Plastic(chemical name)
Density(g/cm3) Example product
polyethylene terphthalate (PETE)
1.35-1.39
soda bottles
high density polyethylene (HDPE) 0.95-.97
milk jugs
polyethylene
1.16-1.42
Ziploc bag
low density polyethylene (LDPE)
0.92-.94
catsup bottle
polypropylene (PP)
0.89-.91
sour cream container
polystyrene (PS)
1.04-1.07
clear deli containers
Liquids to use: Name chemical
Water( 25 oC)
ethanol
corn oil
glycerol
corn syrup
solution 33%sugar
2:1 isopropyl alcohol/water
Density(g/cm3)
0.997
0.789
0.925
1.26
1.38
1.12
0.95
6. A graduated cylinder was weighted dry, then filled to the 25.0 cm3 mark with a liquid
and weighed again. From the data below calculate the density of the liquid. Show your
work.
Mass of the dry graduated cylinder –28.31 g
Mass of the cylinder with the liquid—48.43 g
Volume of the liquid in the cylinder—25.0 cm3
Be careful of significant Figures. Which is the least precise? Do not use per or/.
Thanks.
7. Solids and Holes
Gene Easter GLEaster@sbcglobal.net
2015_____
Willard had a thin, uniform solid piece of material. He placed the material in water
and it floated. He took out the material and punched holes all the way through it.
What do you think Willard will observe when he puts the material with holes back in
the water? Circle your prediction.
A. It will sink.
B. It will barely float.
C. It will float the same as it did before the holes were punched in it.
D. It neither sinks nor floats. It will bob up and down in the water.
Explain your thinking. Describe the “rule” or reasoning you used to make your
prediction.
8. Two ice cubes are floating in water:
After the ice melts, will the water level be:
Gene Easter GLEaster@sbcglobal.net
2015_____
a.
b.
c.
Higher?
Lower?
Same?
9. What is the reason for your answer to question 8?
a.
b.
c.
d.
e.
Water is more dense in its solid form (ice).
Water molecules displace more volume than ice molecules.
The water from the ice melting changes the water level.
When ice melts, its molecules expand.
The weight of the water displaced is to the weight of the ice.
10. Density question
One characteristic that can be used to identify pure metals is density. If you
determine the density of a pure metal, you can determine what the metal is, as
shown in the table below.
Suppose that you have been given a ring and want to determine if it is made of pure
gold or you got stiffed. Design a procedure for determining the density of the ring.
Explain the steps you would follow, including the equipment that you would use,
and how you would use this equipment to determine the ring's density.
Sorry about the_gram/cm3 I lifted the question as a pic. Please do not use / or per in your
answer._________________________________________________________________
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TIMSS test question for 8th grade
Gene Easter GLEaster@sbcglobal.net
2015_____