Warm-Up Sept. 11

Density POGIL Activity September 11, 2014

Warm-Up Sept. 11

1. How many sig figs in each of the numbers. State the rules you used to get your answer.

a. 6.74 10-4 ______ Rule _____

b. 1.7040 109 ______ Rule _____

c. 3.005 102 ______ Rule _____

2. Write the following numbers in scientific notation.

a. 0.00590 ________

b. 3041000 ________

×

x

x

3. Write the following numbers in expanded format.

a. 4.804 108 ______________

b. 9.11 10-7 ______________

4. Compute the following using sig figs. Show work.

a. (4.2 103) (1.6 104)

b. (6.89 104) + (9.24 105)x x

×x

×

x


DensitySeptember 10, 2014

What is density?


What is density?• Model 1: Mass and Volume

1. How Many Dots in each cube?

A1: 16

A2: 64

A3: 4

A4: 16

What is density?• 2. Based upon Model 1, what is mass?

> How many dots are in a cube

• 3. What can you infer about how much mass each dot represents?> Each dot has the same size, so they

represent the same amount of mass


What is density?• 4. As volume increases on the graph’s X-

Axis, what changes about each cube? What evidence from Model 1 supports your thoughts?> The size of the cube increases. Cubes

A2 and B2 are larger than A1 and B1 and they contain more dots

What is density?• 5. Use the following data to calculate the

volume for each of the cubes.

CUBE VolumeA1 8 cm3

A2 32 cm3

B1 8 cm3

B2 32 cm3

Pull

Pull

6. What are the units for volume? Why?- cm3 because you have to add the exponents why you multiply cm1 + cm1 + cm1


What is density?• 7. With your group members, create your

own definition of volume.> Amount of space the cube takes up

Pull

Pull

• 8. What is similar about objects A1 and A2?> Tightly packed, a lot of dots,

not much empty space• 9. What is similar about objects B1

and B2?> More space between dots, less

packed

What is density?• 10. Based upon your prior knowledge for

density and the ideas you summarized in questions 8 and 9, create a definition for density with your group members.

Pull

PullDensity is the

amount of mass (dots) in a certain amount of space (size of cube).


• 1. Which object is more dense and which is less dense? WHY!?

• The first cube is more dense. Has more matter in same amt of space

Summarizing Questions

• 2. On the graph below, a line has been added to show the density of water. Based upon its density, explain which objects you think will sink and which will float and why.

Summarizing Questions

Material A sinks

Material B floats


Liquid Layers• Oil floats on top of water.

Explain why and draw a picture (using dots like in Model 1) to show why this is the case.> Oil is less dense than

water

water

oil

• 4. What is the same between Object C & D?Why is this (based on picture)?

Calculating Density

Pull

Pull

C has less matter in it, but also has smaller volume


• 5. How was density calculated using mass and volume values?

Calculating Density

PullPull

DIVIDING MASS BY VOLUME

Calculating density?• 6. Come up with a formula for calculating

density (based on the numbers in Model 2)..• Density = mass OR mass ÷ volume

volume

• Units for density: g ; g cm3 L M

D V ÷×


Calculating density?• 7. Do you think that objects C and D are

made out of the same or different material? Explain using evidence from Model 2.

Yes, it is the same material because density is a definite property and does not change for a certain substance.

M

D V ÷×

Calculating Density

• 8.

M

D V ÷×

16 g / 8 cm3 = 2 g/cm3

64 g / 32 cm3 = 2 g/cm3

4 g / 8cm3 = 0.5 g /cm3

16 g/ 32 cm3 = 0.50 g/cm3


Calculating Density• 9. Calculate density for the following objects:> a. A 114 gram box that has the

dimensions: length =3 cm, width = 3 cm, height = 7cm

> b. A rock which has a mass of 60 grams and a volume of 20 mL

> c. An unknown liquid with a mass of 10 grams and a volume of 15 mL

M

D V ÷×

114 g / 63 cm3 = 1.8 g/cm3

60 g / 20 mL = 3 g/mL

10 g / 15 mL = 0.7 g/mL

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Warm-Up Sept. 11