Presentation on theme: "Surface Area to Volume Ratio"— Presentation transcript:
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 m2Example: 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 volumeBy breaking the cube into multiple cubes the amount of surface exposed increasesSuppose you broke the block into 1 nm squares. How much surface area would be exposed?1 nm = 1/1,000,000,000 m6 x (1/1,000,000,000 m)2 x 10729=6,000,000,000 m2 = 1,482,632 acres1260,000 m2 = 14.8 acres
5 Surface Area to Volume Ratio On a macro scale, the properties remain the same even if the size decreasesEx: Sugar cubes and powdered sugar both dissolve in waterOn a nano scale, the properties changeNano sugar may not dissolve at allFor 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 changeDissolving occurs when the solute is in contact with the solventWhen 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 Examplebending 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 ExampleSuspensions 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.
11 Surface Area to Volume Ratio ExampleNanoparticles 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 atomGold nanoparticles appear deep red to black in solution.
12 For Example As gold goes from a bar to coins to flakes As gold goes from a barto coinsto flakesthe color remains the sameAs we hit the nanoscale, gold particles change in color depending on size