Density Most Dense Less Dense Least Dense

Mass tells us how much matter is in an object. (More mass means more atoms and molecules!) Balance Mass is measured in grams (g) using a scale or balance. Scale

Volume tells us how much space an object takes up. Volume is measured in milliliters (mL) using a graduated cylinder. Graduated Cylinders

Units of Volume 1 mL = 1 cm3 They are exactly the same! 1 milliliter (mL) is defined as the amount of space in a cube whose sides are all 1 cm in length. 1 cm 1 cm 1 cm This means that a milliliter is equal to a cubic centimeter 1 mL = 1 cm3 These units are completely interchangeable, but we often use cubic centimeters when referring to solid volumes. But doctors often say how many “cc’s” of medicine they need, and this just stands for cubic centimeters. This is because “cc” is easier to say and clearer to understand than “mL”, especially in an emergency room environment. They are exactly the same!

Density is the relationship between mass and volume Density is the relationship between mass and volume. It describes how tightly packed the particles in an object are!

Most Dense Least Dense Solids are the most dense state of matter while gases are the least dense!

Density Formula m D v Use the formula to derive all three ways of expressing this relationship. m v m D D = m = D × v v = If you can’t get back the original formula, you made your triangle wrong!

Density Formula g mL v m cm3 g v Units of D = The units for density contain the units for both mass and volume! Unit of mass? grams Units of volume? Since density equals mass divided by volume, the units of density are the units of mass divided by the units of volume! milliliters or cubic centimeters g mL v m cm3 g v Units of D = or

They are all equally packed together. They all have the same density! Which of the samples below is the most tightly packed together and therefore, the most dense? A B C They are all equally packed together. They all have the same density!

Different samples of the same substance will have the same density no matter how much of the substance is in each sample. 3 samples of the same substance are shown below along with their individual masses and volumes. Calculate the density of each. Mass = 17.50 g Volume = 13.0 cm3 Mass = 8.75 g Volume = 6.50 cm3 Mass = 35.0 g Volume = 26.0 cm3 Density = 1.35 g/cm3 Density = 1.35 g/cm3 Density = 1.35 g/cm3

3 samples of the water are shown below along with their individual masses and volumes. Calculate the density of each. Mass = 85.0 g Volume = 85 mL Mass = 40.0 g Volume = 40 mL Mass = 60.0 g Volume = 60 mL Density = 1.0 g/mL Density = 1.0 g/mL Density = 1.0 g/mL

The density of a substance is consistent The density of a substance is consistent. This means that density is a physical property that can be used to identify substances! Density 1.37 g/cm3 Photo by LHcheM

Complete the practice problems on your notes! 5.85 g D = m v D = D = 1.17 g/cm3 5.0 cm3

3.0 g D = m v D = D = 0.25 g/mL 12 mL 2.3 g D = m v D = D = 1.15 g/cm3 2.0 cm3