Density and Temperature

By: Erika Paiva period: G

Clarifying Important Terms


- Density is the ratio of an object's mass to its volume.
- Mass is the measure of the amount of matter that an object contains; the SI base unit for mass is the kilogram.
- Volume is a measure of the space occupied by a sample of matter.

The Key Concept

- The volume of most substances increases as the temperature increases.
- The mass remains the same despite the volume change and the temperature.
- The density of a substance generally decreases as its temperature increases.
- Density changes with temperature because the volume changes with temperature.
- When the temperature increases, The volume, the space occupied by the matter is getting bigger/increases, but the mass is staying the same, so it is becoming less dense.
- Over a certain range of temperature, the volume of water increases as its temperature decreases. Ice, or solid water, floats because it is less dense than liquid water.

Calculating Density


mass- units g, kg, ect..
volume- units cm3, m3, ect...
Density- units g/cm3, ect..

Problem:

A block of aluminum has a volume of 15.0 mL and a mass of 40.5 g. What is the density?

1. Analyze:list the known facts and the unknown.

Known
- mass= 40.5 g
- volume= 15.0 mL
Unknown
- density= ?

2. Calculate:solve for the unknown

- substitute the known information and calculate.

D= Mass/volume = 40.5 g/ 15.0 mL = 2.70 g/mL

3. Evaluate:does this make sense?

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Using Density to Calculate Volume

- What is the volume of a pure silver coin that has a mass of 14 g? The density of a silver (AG) is 10.5 g/cm3.

1. Analyze:List the knowns and the unknown.

Knowns
Mass of coin = 14g
Density of silver= 10.5 g/cm3

Unkown
Volume of coin= ? cm3.

- Solve this problem by using density as a conversion factor. You need to convert the mass of the coin into a corresponding volume. The density gives the following relationship between volume and mass.

1 cm3 Ag= 10.5 g Ag

- Notice that the known unit is in the denominator and the unknown unit is in the numerator.

2. Calculate:Solve for the unknown


- Multiply the mass of the coin by the conversion factor to yield an answer in cm3.
14 g Ag X 1 cm3 Ag/ 10.5 g Ag= 1.3 cm3 Ag.

3. Evaluate:Does this make sense?



Density work sheet

=
 
=

1.
a. 1.98 g/mL
b. 2 g/mL
c. 1.26 g/ mL
d. 7.8 X 10 ^-3 g/mL
e. 7.95 g/ml
2.
a. 3.54 ml
b. 316.6 ml

The rest of the worksheet doesn’t pertain to the chapter, so don’t do the rest of the problems