Sunday, January 16, 2011

Lesson 18: DENSITY & MOLES

Density is the measure of mass per volume.

D = mass / volume

> density is commonly measured in g/L or g/mL.

EXAMPLE:
  • Water has a density of 1.0 g/mL. Determine the mass of 11.5 mL of water.
  • How many moles are in 11.5 mL of water?
           1.0 g   x   11.5 mL = 11.5 g = 12 g
            mL

           11.5 g   x    1 mol    = 0.64 mol
                             18.0 g

Density of Gases varies with temperature
  • At STP we can find density by:
                Molar Mass                      MM                         g/mol    
              Molar Volume              22.4 L/mol                  L/mol

EXAMPLE:
  • Determine the density of methane (CH4) @ STP.
               CH4    =    12.0 + 1(4)    =    16.0 g/mol

               16.0 g/mol      =    0.714 g/L
               22.4 L/mol


»Loureal Agustin.

posted by chemistry11 @ 9:48 PM

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