The Density Challenge - Ms. Salzburg



The Density Challenge!!

CHALLENGE #1: Use the graph to study the Sink/Float line.

a. Find the slope of the Sink/Float line by selecting one point on the line and calculating its distance from the origin. (Use your graph on pg. 34R to help you out!)

Slope = Rise = Mass = _____________ grams =

Run Volume cm3

Objects graphed above the Sink/Float line __________ (sink/float) in water. Objects graphed below the Sink/Float line __________ (sink/float) in water.

The sink/float line represents the _____________ of water.

CHALLENGE #2: Let’s define density!

a. Density affects whether or not an object will float in water. The definition of density is mass per unit volume. We can write this definition as a math equation:

Density = Mass =

Volume

Explain what this definition means in your own words (you CANNOT use the words “mass” or “volume” in your explanation). OR Draw a picture to represent density and label it with captions.

CHALLENGE #3: Finding the density of water.

a. If you wanted to find the density of 50 mL of water, what would you do? Write the procedure for how you would find the density of 50 mL of water. [Hint: Think about how you can find the mass of water by itself.]

1. ______________________________________________________________________________

2. ______________________________________________________________________________

3. ______________________________________________________________________________

4. ______________________________________________________________________________

5. ______________________________________________________________________________

6. ______________________________________________________________________________

b. Using your procedures from Part A, find the density of 50 mL of water. Show your work below!

Hints:

• 1 mL = 1 cm3

• Do not include the mass of the graduated cylinder in your final calculations.

• Density = Mass / Volume

** Our team calculated the density of water to be: __________________________________________

From Challenge #1, the slope of the Sink/Float line in our graph is ________. In Challenge #3, we calculated the density of __________ to be approximately ____ g/mL. This proves that the density of __________ is the same as the _________ line. This also means that objects with a density greater than ____ g/mL will _________ (sink/float) and objects with a density less than ____ g/mL will _________ (sink/float) in ___________.

CHALLENGE #4: Remember the Floating Puzzles?

a. Think back to the puzzle with the soda cans.

• What was the volume of the soda cans? Check the information on the labels of the cans if you are not certain (this information on the can may be a close approximation!!).

Volume of Diet Coke: _________ mL

Volume of Regular Coke: _________ mL

• What other information would you need to calculate the density of each soda can? ______________

• Using the information you have learned about density, explain why one soda can floated and the other one sank? Make sure you include evidence to support your answer. Also, use the words: “mass”, “volume”, and “density” in your answer.

The volumes of the regular and diet cokes are _________. The volumes are ___________ (the same/different) and the masses are ___________ (the same/different). The regular coke ____________ (floated/sank), so the density of the regular coke has to be _______ (more/less) than the density of water. The diet coke __________ (floated/sank), so the density of the diet coke has to be _______ (more/less) than the density of water. The regular coke _________ (floated/sank) because it has a mass that is _______ (more/less) than the mass of the diet coke.

b. Now think back to the puzzle with the vials. Remember that the vials have the same mass (we checked the mass with the scales). Mass = _______ g

• Explain why one vial sank, while the other one floated. Remember to include evidence to support your answer. Also, use the words: “mass”, “volume”, and “density” in your answer.

The masses of the clear and black vials are _________. The masses are __________ (the same/different) and the volumes are ___________ (the same/different). The clear vial _________ (floated/sank), so the density of the clear vial has to be _______ (more/less) than the density of water. The black vial ___________ (floated/sank), so the density of the black vial has to be _______ (more/less) than the density of water. The clear vial ___________ (floated/sank) because it has a volume that is _______ (more/less) than the volume of the black vial.

Approximate where the two vials would be located on your sink-float graph. Draw the two data points on the graph. Remember to include the symbols for sink/float, the S/F line, and the exact mass of the vials.

[Hint: think about what we did on the graph with the cubes and cube combinations (pg.34R).]

CHALLENGE #5: Are the cubes made of pure gold or pure silver?

a. Using what you have learned about density, calculate the density of the shiny silver cube and the gold-colored cube. Show your work below. Find the masses of each block on your data table on pg. 32R.

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b. Now compare the densities you calculated to the densities of pure gold and pure silver given on the data chart. Remember, the cube is pure if the calculated density is the same as the density of the pure substance.

|Type of Block |Calculated Density of Block |Density of Pure Substance |Is the Cube Pure or Not Pure? |

| |(Get this from Part A) | |(Yes or No?) |

| | | | |

|Silver | |10.5 g/cm3 | |

| | | | |

|Gold | |19.3 g/cm3 | |

c. Compare the densities of the gold and silver cubes to the density of water (are they the same or different and why). Be as specific as possible (use the exact densities of the cubes and water in your answer).

The density of water is ___________. The density of the gold cube is ___________. The density of the silver cube is ___________. All the densities are ___________ (the same/different). The gold and silver cubes have densities that are __________ (more/less) than the density of water.

d. Based on this information, explain why the gold and silver cubes sink in water. Be sure to use as much scientific language as possible. (Use the words “mass”, “volume”, and “density” AND give the specific densities of the cubes and water.)

The gold and silver cubes sink in water because they have densities that are __________ (more/less) than the density of water. The density of water is ___________, but the density of the gold cube is ___________ and the density of the silver cube is ___________. The gold and silver cubes have densities that are __________ (more/less) than the density of water because the masses of the cubes are _________ (more/less) than the volume of the cubes.

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KEY

Mass (g)

Volume (mL)

Silver Cube (Aluminum block)

STEPS

1) Write the

density equation.

2) Plug the numbers into the equation.

3) Box your final answer.

Gold Cube (Brass block)

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