Density

What is density? Density is a comparison of how much matter there is in a certain amount of space. Comparison of MASS per VOLUME

Mass Amount of matter (atoms/molecules) in an object Measured with a triple-beam balance, gravity scale, or digital scale  Milligrams  Grams  Kilograms

60 g 300 g 5.7 g Total mass= ______ g 365.7

Volume Amount of space an object takes up  How large the object is  How much something can hold (capacity) Measured by calculation or water displacement

Volume by Calculation Any “regular” object has a formula that can be used to calculate its volume. “Regular” objects are shapes you have heard of, such as: Cubes, spheres, cylinders, cones, pyramids. Write THIS formula: V= L x W x H Units are ‘cubic’ cm 3 in 3 m 3

Volume by Calculation V = L x W x H V = 5in x 4in x 3in V = 60(in x in x in) V = 60in 3

Volume by Water Displacement “Irregular” objects do not have a formula to calculate their volume Use a method called Water Displacement

Volume by Water Displacement

DENSITY! Demonstration: Diet VS Regular How about this: Which square is more dense? Why?

More Density! Now which one is more dense? Why?

What is density? Density = mass OR mass ÷ volume. volume Mass (g) Volume (cm3 or mL) Units for density: g or g_ cm 3 mL ALWAYS REMEMBER UNITS!

Density Problems Together! Frank has a paper clip. It has a mass of 9g and a volume of 3cm 3. What is its density?  D= m/v  9g / 3cm 3  3 g/cm 3 Frank also has an eraser. It has a mass of 2g, and a volume of 4mL. What is its density?  D=m/v  2g/4ml  0.5 g/ml

Work on these problems with your neighbor! Jack has a rock. The rock has a mass of 6g and a volume of 3cm 3. What is the density of the rock?  6g / 3cm 3  2 g/cm 3 Jill has a gel pen. The gel pen has a mass of 8g and a volume of 2mL. What is the density of the gel pen?  8g / 2mL  4g/mL

Now, try these on your own. Alicia has a watch. It has a mass of 4g and a volume of 2mL. What is the density of the watch?  2 g/mL Mia has a wallet. It has a mass of 15g and a volume of 5cm 3. What is the density of the wallet?  3 g/cm 3

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

Liquid Layers Check out this picture from your book. Which layer has the highest density? Which layer has the lowest density? Imagine that the liquids have the following densities:  10g/cm 3.3g/cm 3.  6g/cm 3.5g/cm 3. Which number would go with which layer?

Liquid Layers – Try with your neighbor Which liquid has the highest density? Which liquid has the lowest density? Which liquid has the middle density?

Liquid Layers – Try on your own! Imagine that the liquids on the right have the following densities:  15g/cm 3 10g/cm 3  3g/cm 3 9g/cm 3  7g/cm 3 12g/cm 3 Match the colors to the correct densities. 3g/cm 3 7g/cm 3 9g/cm 3 10g/cm 3 12g/cm 3 15g/cm 3

Review What is the formula for density? What happens if you pour together liquids that have different densities? Will the liquid on the top have the highest or lowest density? Will the liquid on the bottom have the highest or lowest density?