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Surface Area to Volume Ratio. Principles of Physics. Volume. Volume the amount of space taken up by matter is measured in m 3 Objects can have the same volume but different shapes. Surface Area. Surface Area the exposed size of an object is measured in m 2

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Surface area to volume ratio

Surface Area to Volume Ratio

Principles of Physics


Volume
Volume

Volume

  • the amount of space taken up by matter

  • is measured in m3

    Objects can have the same volume but different shapes


Surface area
Surface Area

Surface Area

  • the exposed size of an object

  • is measured in m2

    Example: The surface area of a cube is equal to the sum of the areas of each of its sides.


Surface area to volume ratio1
Surface Area to Volume Ratio

  • All four cubes have the same volume

  • By breaking the cube into multiple cubes the amount of surface exposed increases

  • Suppose you broke the block into 1 nm squares. How much surface area would be exposed?

    • 1 nm = 1/1,000,000,000 m

    • 6 x (1/1,000,000,000 m)2 x 10729=

      6,000,000,000 m2 = 1,482,632 acres

12

60,000 m2 = 14.8 acres

http://www.uwgb.edu/dutchs/EarthSC202Notes/ROCKCYCL.HTM


Surface area to volume ratio2
Surface Area to Volume Ratio

On a macro scale, the properties remain the same even if the size decreases

  • Ex: Sugar cubes and powdered sugar both dissolve in water

    On a nano scale, the properties change

  • Nano sugar may not dissolve at all

    For a nano sample: more atoms are at the surface because more of the sample is surface.

    For a macro sample: Just as many atoms can be inside as are on the surface


Which will burn
Which Will Burn?

A steel nail? Steel wool?

Why??????


Which will dissolve faster
Which Will Dissolve Faster?

Sugar cubes? Powered sugar?

Why??????


Surface area to volume ratio3
Surface Area to Volume Ratio

The more surface area a sample has the more of it that is available to change

  • Dissolving occurs when the solute is in contact with the solvent

  • When iron oxidizes it creates heat (flame), more surface area more oxidation occurs because there is a greater possibility of iron colliding with oxygen


Surface area to volume ratio4
Surface Area to Volume Ratio

Example

  • bending of a macro sample of copper occurs with movement of copper atoms of about 50 nm.

  • Copper nanoparticles smaller than 50 nm are considered super hard materials that do not exhibit the same ductility as the macro sample.


Surface area to volume ratio5
Surface Area to Volume Ratio

Example

  • Suspensions of nanoparticles are possible because the interaction of the particle surface with the solvent is strong enough to overcome differences in density, which usually result in a material either sinking or floating in a liquid.

http://en.wikipedia.org/wiki/Nanoparticle


Surface area to volume ratio6
Surface Area to Volume Ratio

Example

  • Nanoparticles often have unexpected visible properties because they are small enough to confine their electrons and produce quantum effects (photons are released/absorbed when electrons move within the atom

    • Gold nanoparticles appear deep red to black in solution.

http://en.wikipedia.org/wiki/Nanoparticle


For example
For Example

http://sidereus.org/MONEY/images/01-gold-bar.jpg

http://www.usagold.com/images/gold-coins-images.jpeg

As gold goes from a bar

to coins

to flakes

the color remains the same

As we hit the nanoscale, gold particles change in color depending on size

http://www.primidi.com/images/nano_gold_colors_1.jpg

http://www.amnh.org/education/resources/rfl/web/goldguide/images/flakes.jpg


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