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Density is a measure of the quantity of mass of a substance that occupies one unit of volume.
Remember: Changes in temperature and pressure have little effect in the densities of liquids and solids.
Also: generally an increase in temperature will increase the volume of the sample while the mass remains constant, thus the density will decrease
- Density= mass
- volume
Density's units are grams/liters or grams/centimeters cubed
Formula for determining Density:
- determine which part is missing and which part you know (i.e. either the mass, volume, or density is what you are trying to determine)
- write out the formula that you need to use (Density= mass/volume)
- plug the numbers you are given into the formula and write a constant for the part you are trying to determine
- multipy or divide to determine the answer
- check to make sure you have the right answer in the right units with the correct number of significant figures!
Example
Question:
A piece of lead has a mass of 22.7 grams and occupies a volume of 2.00 liters. What is the density of the lead?
Solution:
- Determine what you have and what is missing
- mass=22.7 grams, volume=2.00 liters,
- density is what is missing
- Density=mass
- volume
- X=22.7 grams
- 2.oo liters
X=11.4 grams/liters
Now Try it on Your Own
Question:
A piece of silver has a mass of 7.o grams and occupies a volume of 2.9 liters. What is the density of the silver?
Answer:
The density of the silver is 2.4 grams/liters