Helen Hanson & John Macaluso Density



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tarix02.03.2018
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  • by

  • Helen Hanson &

  • John Macaluso


Density



Learning Check 1



Solution

  • Placing the mass and volume of the osmium metal into the density setup, we obtain

  • D = mass

  • volume



Volume Displacement

  • A solid displaces a matching volume of water when the solid is placed in water.

  • 25 mL



Learning Check 2

  • What is the density (g/cm3) of 48 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL?

  • 1) 0.2 g/ cm3 2) 6 g/m3 3) 252 g/cm3

  • 33 mL

  • 25 mL



Solution

  • 2) 6 g/cm3

  • Volume (mL) of water displaced

  • = 33 mL - 25 mL = 8 mL

  • Volume of metal (cm3)

  • = 8 mL x 1 cm3 = 8 cm3

  • 1 mL

  • Density of metal =

  • mass = 48 g = 6 g/cm3

  • volume 8 cm3



Methods for Finding Volume

  • The density can also be found by calculating the volume of an object and measuring its mass.



Density of a Cylinder

  • What is the density of a cylinder with a mass of 250.0g, a radius of 2.0 cm, and a height of 10.0 cm?



Density of a Cylinder

  • Vcylinder = лr2h = л x 5 x 5 x 10 (cm)(cm)(cm)

  • = 250л cm3

  • r = radius

  • h = height D = 250/(250л) g/cm3

  • D = m/V D =1/л g/cm3

  • m = 250.0 g D = 0.318 g/cm3





Learning Check 3

  • Which diagram represents the liquid layers in the cylinder?

  • (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL)

  • 1) 2) 3)



Solution

  • (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL)

  • 1)



Density as Conversion Factors

  • A substance has a density of 3.8 g/mL.

  • Density = 3.8 g/mL

  • Equality 3.8 g = 1 mL

  • Conversion factors:

  • 3.8 g and 1 mL

  • 1 mL 3.8 g



Density Connections



Learning Check

  • The density of octane, a component of gasoline, is 0.702 g/mL. What is the mass, in kg, of 875 mL of octane?

  • 1) 0.614 kg

  • 2) 614 kg

  • 3) 1.25 kg



Solution

  • 1) 0.614 kg

  • Unit plan: mL  g  kg

  • Equalities: 1 mL = 0.702 g and 1 kg = 1000 g

  • Setup:

  • 875 mL x 0.702 g x 1 kg = 0.614 kg

  • 1 mL 1000 g

  • density metric

  • factor factor



Learning Check

  • If blood has a density of 1.05 g/mL, how many liters of blood are donated if 575 g of blood are given?

  • 1) 0.548 L

  • 2) 1.25 L

  • 3) 1.83 L



Solution

  • 1) Unit Plan: g mL L

  • 575 g x 1 mL x 1 L = 0.548 L

  • 1.05 g 1000 mL



Learning Check

  • A group of students collected 125 empty aluminum cans to take to the recycling center. If each can has a mass of 3g what volume of aluminum can be made if the cans were melted (Hint: d = 2.7 g/mL)?

  • 1) 0.139L 2) 207 L 3) 4.85 L



Solution

  • 1) 1.0 L

  • 125 cans x 3g = 375g = mass

  • 1 can

  • So, V = mass = 375g = 139mL = 0.139L

  • density 2.7 g/mL



Learning Check

  • You have 3 metal samples. Which one will displace the greatest volume of water?

  • 1 2 3



Solution

  • 1) 25 g Al x 1 mL = 9.2 mL 2.70 g




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