DENSITY . D = m/v (g/cm 3 ) Mass usually expressed in grams Volume usually expressed in cm 3 or liters, etc. Density. Density = amount of matter per unit volume Density is the ratio of mass to volume If the volume stays the same and the mass increases . . . the density will increase
D = m/v (g/cm3)
To calculate Density, you have to know how to properly measure!
1. If the glassware is marked every 10 mLs, the volume you record should be in mLs. (Example A)
2. If the glassware is marked every 1 mL, the volume you record should be in tenths of mLs.
3. If the glassware is marked every 0.1 mL, the volume you record should be in hundredths of mLs. (Example B)
the volume you write in your lab report should be 13 mL
Buret marked in 0.1 mL: you record volume as 0.67 mL
Davis, Metcalfe, Williams, Castka, Modern Chemistry, 1999, page 46
High pressure systems indicate a colder more dense air mass that will……. SINK!!!
Denser layers to less dense layers…..
Ice vs. water…..
Wouldn’t you like to have a bunch of THIS dense material?
at 40C and 1 atm(pressure)
in other words, the greatest density of water is at 40C
EX: cubes, cylinders, spheres, cones, etc.
Use a graduated cylinder
Add water to a predetermined level - record.
Gently drop in the irregularly shaped object.
Read the graduated cylinder – record.
Subtract the first water level from the second – this is the volume
SINK or FLOAT
In Water (D = 1.0 g/mL)