Fluids

Density

 In the last activity, you discovered that no matter how much substance you used, the mass-to-volume ratio stayed the same. This ratio is density.

Density – A measure of the amount of matter (mass) per unit volume of a substance.

 Time for ... Mr. Edwards The Density Song

What is Density?

 You can use the particle theory to help explain density: ◦ Particles of a solid are usually more closely packed than particles of a liquid, which are more closely packed than particles of a gas.

◦ Therefore, solids are generally denser than liquids, which are denser than gases.

 Density is also affected by the type of particles a substance is made of.

◦ ◦ Oil and water are both liquids, but water is much denser.

Helium is much less dense than air.

Density & The Particle Theory

 Can you explain the science behind these experiments/demonstrations? Think of how density relates to the particle theory.

◦ Floating Egg ◦

HWK: Explain how density affects the results for each egg. Use a diagram to explain each.

◦ ◦ ◦ Floating/Sinking Coke?

Underwater Volcano - Density?

Ask yourself, why does this happen?

Density & The Particle Theory

 Density is determined by the following equation:

Density



Mass Volume

 The common units of measurement for density of solids and liquids are g/mL or g/cm , and for gases, kg/m .

 T/P/S: Based on the formula, how would you … a) Increase density? b) Decrease density?

c) Real-life examples?

Calculating Density

 An empty container has a mass of 50g. When 75mL of oil are placed in it, the total mass is 120g. Calculate the density of oil.

Given: mass of container = 50g mass of container & oil = 120g Volume of oil = 75mL 1.

Need to find mass of oil first: 2.

• Mass = 120g – 50g = 70g Use the formula to find density: • Density = mass/volume = 70g/75mL = 0.93g/mL • Therefore, the density of the oil is 0.9g/mL.

Calculating Density

Density of Some Common Materials

1.

Use the particle theory to explain densities in solids, liquids, and gases.

2.

Calculate the density of a diamond if the volume of the diamond is 0.50cm

and its mass is 1.75g.

3.

To prep for the upcoming lab, research the densities of:  Water, Rubbing Alcohol, Maple Syrup, Laundry Detergent, Vegetable Oil

Homework Questions

Fun with Density!

 It’s time for you to try one of the class’ density demonstrations. Complete each demonstration, but add an additional test: ◦ ◦ Floating Eggs – Test sugar Underwater Volcano – Cold Water in Hot Water  Make sure you create your own observation table to record your data. Think qualitative and quantitative data.

 Introduction: Seven Layer Density  Lab Prep: ◦ Read over lab handout ◦ ◦ Complete a hypothesis & variables Create the necessary tables for observations

Science Lab: Layer Liquid

Fluid

Water

Density Observations

Rubbing Alcohol Maple Syrup Laundry Detergent Vegetable Oil

Lab Chart Example - Liquids

Fluid/ Object

Air Bubble Wooden Bead Plastic Gem Bolt

Observations Density (Description)

Popcorn Kernel

Lab Chart Example – Gas & Solids