Density

Fluids and Density Lava, water, and syrup are examples of fluids. A fluid is any form of matter that can flow. Liquids and gases are fluids since they do not have a fixed shape (Examples: juice, carbon dioxide, cytoplasm, blood). Solids are not fluids. Lava, water, and syrup are examples of fluids.

Solid, Liquid and Gas Density Density is the measure of the amount of matter in a given volume of a substance. Density describes how closely packed together the particles are in a material. As substances gain energy, spaces between particles increase, and density decreases. Describe the spacing of the particles in the solid block, liquid water, and gaseous air.

Density and the Particle Theory The more matter that is “packed” into a substance, the denser it is. Gold has more matter packed into it than foam, so gold is denser than foam. The state of a substance also affects its density. Not all solids have the same density. The same is true for liquids and gases. Water is much denser than oil Helium is less dense than air

Layers of Fluids Fluids that do not mix layer themselves according to their density. Less dense fluids “float” on top of more dense fluids. Can you list the objects, in this beaker, from most dense to least dense? oil ball water

Layers of Fluids At sea level, there are lots of oxygen molecules to breathe Going higher = less oxygen (need masks) At high altitudes, air density is low Less friction for airplanes at higher elevations! (= less fuel needed)

Density and Water Most substances are denser in their solid form than in their liquid form. This is because the particles move more slowly and get closer together. However, water is an exception (ice floats on water). Creates an insulating barrier against cold temperatures. If water gets colder than 4°C, the particles move farther apart, it gets less dense and ice forms. If ice didn’t behave this way, lakes would freeze solid in the winter from the bottom up. If that happened, all the plants and fish would die.

Calculating Density Both mass and volume are required when calculating density. To calculate density, divide an object’s mass by its volume. Density can be used to distinguish one substance from another.

Calculating Density Answer the following: What is the density of a 4 cm3 rock that has a mass of 24 g? A 5 ml sample of motor oil has a mass of 4.5 g. What is the density of the motor oil?

Calculating Density Density can be calculated using the following formula: Answer the following: What is the density of a 4 cm3 rock that has a mass of 24 g? D = 24 g = 6 g/cm3 4 cm3 A 5 ml sample of motor oil has a mass of 4.5 g. What is the density of the motor oil? D = 4.5 g = 0.9 g/ml 5 ml

activity on pg 24 of txt