Which has more mass A 1 kilogram of

Which has more mass? A) 1 kilogram of feathers B) 1 kilogram of bricks They are the same! 1 kg = 1 kg

Which takes up more space? A) 1 kilogram of feathers B) 1 kilogram of bricks The Feathers

Measure matter by finding the density!

Which has the greater density? A) steel paper clip B) steel bar The density of steel is the same! Size doesn’t matter!

Density of Steel steel bar

Units for Density Metric Units: Solid: g/cm 3 Liquid: g/m. L Density of water is Memorize This! 1 g/m. L (at 4º C)

Which one floats? Why? • Density of Water: 1. 00 g/m. L • Density of Ice: 0. 92 g/m. L

Which of the following will float on water? Why is it good to know the density? Density helps you identify a substance All those less than 1. 0 g/m. L

Predict the correct “floating order” of the substances as they would appear in the “Density Column”. Substance Copper Corn oil Corn syrup Glycerin Mercury Plastic Rubber Tar Water Wood Density g/cm 3 8. 8 0. 925 1. 38 1. 26 13. 6 0. 93 1. 34 1. 02 1. 00 0. 7

Specific Gravity Density of Substance (g/cm 3) = 3 Density of Water (g/cm ) Specific gravity is the same as the density except: There are no units! Why? Because they cancel! Ex: Density of water: 1 g/cm 3 Specific Gravity of water: 1 (no units!)

What is the specific gravity? It is the same as the density but it has no units!

Calculating Density • Obtain mass using a balance. • Obtain volume by any of these methods. – Ruler: Volume = L x W x H – Graduated cylinder – Water displacement m “Magic Circles” d v d = m/v m=dxv v = m/d

1) Is the bar really gold or fool’s gold? Find the density of the bar if the mass is 1891. 4 g and the dimensions are 3. 50 cm by 8. 00 cm. • Gold has a density of 19. 3 g/cm 3 V=Lx. Wx. H D = M/V 1891. 4 g / 98. 0 cm 3 = 19. 3 g/cm 3 Yes it’s gold! What is the Specific Gravity? m d v

2) Is this liquid water, alcohol, or kerosene? Find the density of the liquid if the mass is 16. 98 g? Water 1. 0 g/m. L Alcohol 0. 79 g/m. L Kerosene 0. 82 g/m. L • Read the volume D = M/V 16. 98 g / 21. 50 m. L = 0. 7900 g/m. L It is alcohol! What is the Specific Gravity? m d v

3) Is the “Silver Surfer” really made of silver? We obtained a sample with a mass of 262. 5 g. Platinum 21. 5 g/cm 3 Silver 10. 5 g/cm 3 Tin 7. 3 g/cm 3 Find the volume by water displacement. d = m/v = 262. 5 g / 25. 0 cm 3 m d v = 10. 5 g/cm 3 It is Silver!

4) What is the volume in m. L of this syrup if it has a density of 0. 630 g/m. L and a mass of 78. 00 g? v = m/d = 78. 00 g ÷ 0. 630 g/m. L = 124 m. L m d v

5) What is the mass in grams of this lead pipe if it has a density of 11. 4 g/cm 3 and a volume of 55. 0 cc? m=dxv = 11. 4 g/cm 3 x 55. 0 cc = 627 g m d v