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Surface Area to Volume Ratio

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

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  1. Surface Area to Volume Ratio Principles of Physics

  2. Volume Volume • the amount of space taken up by matter • is measured in m3 Objects can have the same volume but different shapes

  3. 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.

  4. 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

  5. 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

  6. Which Will Burn? A steel nail? Steel wool? Why??????

  7. Which Will Dissolve Faster? Sugar cubes? Powered sugar? Why??????

  8. 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

  9. 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.

  10. 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

  11. 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

  12. 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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