TEMA PARA LA MATERIA DE QUÍMICA...t/t

1. Density
QBA Miguel A. Castro Ramírez

2.  Why did the liquids settle in a specific order?
 Why did some object float while some sunk.
 Whycan some heavier objects float while
some lighter objects sink?

3. Density…
 Is a property of all
matter: solids, liquids
and gases.
 Is found by dividing an
object’s mass by its
volume.
 Units for mass: _____
 Units for volume: _____

4. Density…
 Measures how tightly
matter is packed within
an object
 Symbol = rho (ρ)

5. Calculating Density
Mass
---------- = Density
Volume

6. Examples
 A block with a volume  Mass = 52.5 g
of 15 cubic centimeters
has a mass of 52.5  Volume = 15 cm3
grams. What is its
density?
 Divide!
Mass
------------
 Density = 3.5 g/cm3
Volume

7. Examples
 A die (1.0 cm on each  Mass = 3.6 g
side) has a mass of 3.6
g. What is its density?  Volume = 1.0 cm3
Mass  Divide!
------------
Volume  Density = 3.6 g/cm3

8. Examples
 Youhave a piece of metal with a volume of
245 cm3 and a mass of 612 g. Is it aluminum
(which has a density of 2.70 g/cm3)?
A 14.0 cm3 ice cube has a density of 12.83 g.
What is the density? Compare this to the
density of water. What does this tell you
about the ice?

9. Examples
 A jar has a volume of  Oxygen: 0.00133 g/cm3
953 cm3. If a scientist
measures the mass of  Nitrogen: 0.00117 g/cm3
the gas in the jar at
0.158 g, what gas is
probably in the jar?  Helium: 0.00016 g/cm3
 0.000166 g/cm3  Hydrogen: 0.00008
g
/cm3

10. Examples
 A jar has a volume of  Oxygen: 0.00133 g/cm3
953 cm3. If a scientist
measures the mass of  Nitrogen: 0.00117 g/cm3
the gas in the jar at
0.158 g, what gas is
probably in the jar?  Helium: 0.00016 g/cm3
 0.000166 g/cm3  Hydrogen: 0.00008
g
/cm3