DENSITY

Wacky Soda Demo

WHY?

What have we experienced?

Mystery Liquids #1Did you discover more than one combination that would work?

What do you think the liquids are?

Mystery Liquids # 2What do you think keep the liquids separate?

Which layer was just water?

Give an example of two gases with different densities.

How do you know they have different densities?

In your science notebook….Today’s date: 3/21/2012

Title: Lava Lamp & Density

Draw a lava lamp and describe how you think the lamp works inside. (HINT: think about our density discussions)

Substance Mass (grams)

Volume (cm3)

Density (g/cm3)

Bar A 110 100

Bar B 95 100

Water 100g 100 cm3 1.0 g/cm3

Problem: Two different bars of soap are being investigated by a group of students. The students measured the mass and volume of each bar and recorded it below.•Calculate the density of each bar of soap. Show your work.

Homework Review

1.1 g/cm3Density =M/VBar A: 110g/100cm3 = 1.1 g/cm3

Bar B: 95g/100cm3 = 0.95 g/cm3 0.95 g/cm3

A

B

Step 1Read the problem.

Step 2Write the formula. “Copy”

Step 3Replace the words with the numbers and units.“Substitute”

Step 4Divide mass by the volume “Evaluate”

Step 5 Write the answer and include units.

If 96.5 grams (g) of gold has a volume of 5 cubic centimeters (cm3), than what is the density of gold?

Density = Mass/Volume

Density = 96.5 grams/5 cm3

Type in 96.5, hit ÷Type in 5, hit = 19.3

Density = 19.3 g/cm3

Finding Density using Math

Substance

Mass Volume

Formula/My Math Density

Air .026 g

20 cm3

Gasoline 21.0 g

30 cm3

Wood (oak)

34.0 g

40 cm3

Water (ice)

36.8 g

40 cm3

Water (liquid)

1.0 g

1 cm3

Aluminum

96.5 g

35 cm3

Steel 273.0 g

35 cm3

Silver 367.5 g

35 cm3

Gold 675.5 g

35 cm3

Platinum 752.5 g

35 cm3

Weight Volume Formula/My Math

Density Substance

1 .35 g

15,000 cm3

G

2.67 g

15,000 cm3

G

19.5 g 15,000 cm3

G

3200. g 2000 cm3

L

2000. g 2000 cm3

L

3600. g 2000 cm3

L

1800. g 2000 cm3

S

1840. g 2000 cm3

S

5600. g 3500 cm3

S

1. Density is a property of all matterMatter is any object that takes up space and has mass

2. Density measures how tightly packed the mass is in an object 

Density Facts

3. Density measures how much mass is squeezed into a space.

4. A dense object feels “heavy” for its size. A one –pound rock and a one-pound pillow have the same mass, but the rock is a lot denser; the rock takes up less space.

5. Densities of fluids, liquids and gases, can be compared usually by which fluid floats and which fluid sinks.

6. Densities can be measured by using MATH

The formula for density is d = densitym = mass (grams)v = volume (ml or cm3)

Density practice

Material Mass Volume Formula Density

Wood (oak) 34.0 g 40 cm3

Ironwood 51.2 g 40 cm3

Water 40 g 40 cm3

0.85g/cm3

1.28 g/cm3

Melting Ice Cube Lab

What happened to the ice when you first placed the cubes in the jars?

Describe the pattern the food color made in each of the jars… Why do you think there was a difference in the pattern?

Why did the food coloring ‘drop’ to the bottom of the fresh water jar?

Why did the food coloring stay on top of the salt water jar?

Why did the ice cubes stop melting in the salt water jar?

What will cause the salt water jar to eventually mix?