Do Now Convert the following to scientific notation: 16,000 .00123 Convert the following back to normal notation: 2.3 x 104 3.6 x 10-3 Find % error: A student measures the density of a metal to be .4 g/cm3. Her teacher tells her the density is .6 g/cm3 1.6 x 104 1.23 x 10-3 23,000 0.0036 D (%) = Diff from accepted value ---------------------------------------------------- x 100 Accepted Value D (%) = .2 g/cm3 ------------------------------------- x 100 .6 g/cm3 D (%) = 33% D (%) = .6 g/cm3 - .4 g/cm3 ----------------------------------------------------------------------------- x 100 .6 g/cm3 D (%) = 0.33% x 100

Density Review

Density is a measure of “mass per unit volume” or “how tightly packed” a material is. The formula is Density = Mass Volume measured in grams per cubic centimeter: g/cm3

Volume Units? Amount of space something takes up Rectangle or cube= length X width X height Example: L = 5 W= 2 H = 3 Volume? 30 cm3 Units?

Irregular solid: (anything you can’t measure L X W X H): Here are the steps to figure it out: Read the volume before Drop sample in water Read the volume after Subtract

Factors that Affect density Does the size of an object affect density? How does temperature affect density? How does the phase of matter affect density? No matter how much you have, if it’s the same material, same density When things are heated, they expand= less dense Least dense Most dense

As an object expands, density decreases (as size increases) As temperature increases, density decreases (water is the exception) As you go from solid to liquid to gas, density decreases (except water)

Density Problems D=M divided by V, M=D times V, V=M divided by D Density=mass volume Cover the variable you need- what’s left is your formula D=M divided by V, M=D times V, V=M divided by D M D V

Try These! 1. D= 3. D=4 g/cm3 5. D= 10 g/cm3 M= 7 g M= 12 g M= 40 g V= 14 cm3 V= V= 2. D= 8 g/cm3 4. D= 6. D=5 g/cm3 M= M= 32 g M= V= 2 cm3 V= 8 cm3 V=5 cm3 .5 g/cm3 3 cm3 4 cm3 4 g/cm3 16 g 25 g