Density

​Density

By Tania Murphy

Density is a measure of mass per unit volume.

- The density of an object is found by taking the mass of the object and dividing it by the volume of the object.

- Because density is derived by using 2 measurements and not one, density is called a "derived value" (not a diretly measured value

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- if the mass goes up and the volume stays the same the density goes up

- if the mass goes down and the volume stays the same then the density goes down

Density Conceptually

the object with the more "stuff" shoved into a particular amount of space is "more dense" than an object (of the same size) with less "stuff" shoved in it

- if the volume goes up and the mass stays the same the density goes down.

Density Conceptually

the object with the more "stuff" shoved into a particular amount of space is "more dense" than an object (of the same size) with less "stuff" shoved in it

- if the volume goes up and the mass stays the same the density goes down.

Density Conceptually

Drag and Drop

Both of the blocks have the ​

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. The block on the right has ​

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and therefore a ​

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than the block on the left. The block on the right has a​

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and therefore, the block on the right has a ​ ​

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Drag these tiles and drop them in the correct blank above

same volume

more green particles

greater mass

greater mass per unit volume

lower mass per unit volume

higher  density

Drag and Drop

If I were to add more particles to the cube on the left then the ​

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and if I were to remove particles from the cube on the right then the ​

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. If I were to decrease the volume of the cube on the left then density would​

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and if I were to increase the volume of the cube on the right then the density would ​

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.

Drag these tiles and drop them in the correct blank above

density would decrease

density would increase

increase

decrease

The units of density often depend on the state of matter under consideration.



The units are typically as follows:

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Units for Density

​Gas = g/L
Liquid = g/mL
Solid = g/cm³

Match

Match the following substances with the most appropriate unit for density:

• solid copper

• liquid water

• oxygen gas

g/cm³

g/mL

g/L

• g/cm³

• g/mL

• g/L

Less dense objects will float and more dense objects will sink (this is basically Archimedes Principle)

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​Why does an object float?

Drag and Drop

We know that object on the ​ right is ​

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than the liquid because it ​

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and the object on the left is ​

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than the object because if ​

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.

Drag these tiles and drop them in the correct blank above

more dense

sinks

less dense

floats

​You can use the density formula to solve for density, mass, or volume.

Multiple Choice

Rank the objects from MOST dense to LEAST dense.

• left, center, right

• right, center, left

• left, right, center

• right, left, center

• center, left, right

Multiple Choice

Put the liquids in order from most dense to least dense?

• 4, 3, 2, 1
• 1, 2, 3, 4
• 3, 4, 2, 1, 
• 4, 3, 1, 2

Multiple Choice

Jack has a rock. The rock has a mass of 14g and a volume of 2cm³. What is the density of the rock?

• 7 mL
• 7 g/cm³
• 28 g/cm³
• 1/7 g/cm³

Multiple Choice

Frank has an eraser. It has a mass of 4.0g, and a volume of 2.00cm³. What is its density?

• 8.0 g/cm³

• 2.0 g/cm³

• 2 g/cm³

• 8.00 g/cm³

Multiple Choice

Why do objects sink or float in H₂O?

• Because their densities are higher or lower than compared to water

• Because their densities are using gravity to pull down

• Because their densities are heavier or lighter

• Because their mass and volumes are equal

Multiple Choice

Ethanol has a density of 0.789 g/cm 3 .

What is the mass of 225 cm³ of ethanol?

• 178g

• 285g

• 0.004 g

• 225.789g

Multiple Choice

A cup of sugar has a volume of 237 ml. What is the mass of the cup of sugar if the density is 1.59 g/ml? Answer to the correct number of sig figs.

• 377. g

• 376.8 g

• 0.007 g

• 0.785 g

Multiple Choice

A block of aluminum has a density of 2.70g/cm³ . What is the volume of 40.5 g of aluminum?

• 15 cm³

• 109 cm³

• 15.0cm³

• 40.5 cm³