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# Surface Area to Volume Ratio - PowerPoint PPT Presentation

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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## PowerPoint Slideshow about ' Surface Area to Volume Ratio' - forrest-shields

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### Surface Area to Volume Ratio

Principles of Physics

Volume

• the amount of space taken up by matter

• is measured in m3

Objects can have the same volume but different shapes

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.

• 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

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

A steel nail? Steel wool?

Why??????

Sugar cubes? Powered sugar?

Why??????

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

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.

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

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

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