Density, Mass and Volume

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Density, Mass and Volume
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Experimental Objectives

• Determine the density of a solid
• Aluminum,Al
• Lead, Pb
• Copper, Cu
• Iron, Fe
• Determine the density of a solution
• Unknown water/ethyl alcohol mixture
• Identify mixture.

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Determine the density of a solid

• Determine mass of solid Electronic Balance
• Weigh dish
• Doors closed
• Tare balance
• Determine volume of solid Displacement of water

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Volume of solid by displacement of water

• Begin with DRY solid sample
• Completely submerge sample
• Verify that no air bubbles are observed on the
  submerged object.

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Graduated Cylinder

• Record volume with one estimated digit and
  remember units.
• 6.62 mL

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Precaution

• Tilt the graduated cylinder and gently slide the
  metal down the side.
• Dropping the metal into the graduated cylinder
  can lead to broken glass.

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Safety Reminder

• Notify instructor of all injuries after first
  administering appropriate immediate first-aid.
• Cut  immediately flush with running water
• Dispose of broken glass in broken glass
  container.
• Wear safety glasses at all times.
• Wear closed toed shoes, long pants and complete
  upper body coverage.

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Determine the density of a liquid

• Obtain a known volume sample pipet
• Determine the mass of the sample balance
• Three Trials

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Obtain a known volume sample - Pipet

• Obtain about 45 mL of assigned solution in a 50
  mL beaker
• Pipet 10.0 mL into a dry vial
• Rinse pipet with solution discard rinse
• Pipet from beaker into vial
• Keep lid on vial to minimize evaporation

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Determine the mass of the sample - balance

• Obtain mass of dry vial and cap
• Pipet solution
• Obtain mass of vial, cap, and solution
• Record masses to 4 decimal places and remember
  UNITS

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Waste handling

• Return metal samples to back of lab
• Dispose of liquids down the sink
• Water
• Water/ethyl alcohol solution

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Calculate Density
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Evaluate Accuracy of Metal Densities

• Obtain theoretical value of metal densities for
  CRC or online resource.

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Identify composition of water/ethyl alcohol
solution

• Density is a physical property that can be used
  to identify a substance
• Density or water/ethyl alcohol solutions page 32
  of lab manual.

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Next Week

• Waters of Hydration
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