Density!!!Thursday, February 2, 2012

Mass

=the amount of matter (stuff) in an objectUnits: grams (g), kilograms (kg)

= 137 grams or 0.137 kilograms

iPhone 4

Mass

What we use to measure mass:

Electronic Balance

Volume

= the amount of space occupied by an object

Units: mililiters (mL), liters (L), centimeter’s cubed (cm3)

= 2 liters or 2,000 mL

Volume

What we use to measure volume:

Graduated Cylinders

Measure from the bottom of the meniscus!

52.75 mL

Density = the amount of mass (stuff) in a given amount

of space=mass/volume (m/v)

Which more has more density? A or B?

A B

DensityIf density is equal to mass/volume, what do you think the units will be for density?

Units = g/cm3 or g/mL or kg/L

Density

Liquid Color Density

Rubbing Alcohol Red 0.79 g/mL

Vegetable Oil Yellow 0.92 g/mL

Water Blue 1.00 g/mL

Corn Syrup Green 1.33 g/mL

Honey Brown 1.42 g/mL

Why did the liquids make the order of layers that they did?

Because of their density!!!The less dense layers rose to the top, while the most dense layers sunk to the bottom, just like the materials in our planet!

If we wanted to determine the density of this rock, how could we do it?

Think about the calculation for density, and the instruments that are used to measure mass and volume.1. Use an electronic balance to measure the mass of the rock.2. Use the graduated cylinder to measure the volume of the

rock.3. Divide the two and get the rock’s density!

If we wanted to determine the density of this rock, how could we do it?

But wait! How could we get the rock’s volume by just putting it in the graduated cylinder???

If we wanted to determine the density of this rock, how could we do it?

We can’t silly! We’ve got to fill the graduated cylinder with water, measure its volume, and then add the rock and measure the volume again. The difference in volume is the volume of the rock. This is called the displacement method.

What is the volume of the

rock?

3 mL

If we wanted to determine the density of this rock, how could we do it?

If the mass of the rock is 5.0g and the volume is 3.0mL, what is the rock’s density?

1.7 g/mL