Understanding Density What is density l Density is

Understanding Density

What is density? l Density is a comparison of how much matter there is in a certain amount of space. l Density is defined as the ratio of mass to the volume of a particular substance. This box is very dense with all of the molecules packed closely together.

Which one is more dense? l Which square is more dense?

Which one is more dense? l Which square is more dense?

Which one is more dense? l Now which one is more dense?

Which one is more dense? l Now which one is more dense?

Density is a physical property l Density is a physical property of matter l Each substance has a specific density which can be used to help determine what a substance is Gold has a density of 19. 30 g/cm 3 so it feels very heavy in comparison to other materials.

Water l Pure water has a density of 1. 0 g/m. L l Anything with a density greater than one will sink, less than one will float

What is density? l Density = mass OR volume mass ÷ volume. l Units for density: g or g cm 3 m. L ALWAYS REMEMBER UNITS! . l Why are these the units for density? l Mass is measured in grams, and volume can be measured in cubic centimeters (cm 3) or milliliters (m. L).

Mass over volume: The m at the top stands for mass, with the v at the bottom for volume.

Let’s try a density problem l Frank has a paper clip. It has a mass of 9 g and a volume of 3 cm 3. What is its density? l So divide the mass 9 g by the volume 3 cm 3 9 3 = 3 g/cm 3

Work this problem. l Jack has a rock. The rock has a mass of 6 g and a volume of 3 cm 3. What is the density of the rock? Mass = 6 Volume = 3 So 6 3 = 2 g/cm 3

Now, try one more. l Alicia has a watch. It has a mass of 4 g and a volume of 2 cm 3. What is the density of the watch? l 4/2=2 g/cm 3

Liquid Layers l If you pour together liquids that don’t mix and have different densities, they will form liquid layers. l The liquid with the highest density will be on the bottom. l The liquid with the lowest density will be on the top.

Liquid Layers l Check out this picture from your book. Which layer has the highest density? l Which layer has the lowest density? l Imagine that the liquids have the following densities: ¡ 10 g/cm 3. ¡ 6 g/cm 3. 3 g/cm 3. 5 g/cm 3. l What is the density of the green layer? l 10 g/cm 3

Liquid Layers – Try with your neighbor l Which liquid has the highest density? syrup l Which liquid has the lowest density? oil

Answer the following: l What is the formula for density? l What happens if you pour together liquids that have different densities? l What is the density of water? l Why does oil float on water?