8.8 Properties of colloids Out-class reading Levine pp 402-405 13.6 Colloids
8.8 Properties of colloids Out-class reading: Levine pp. 402-405 13.6 Colloids
8.8.1 Optical property of colloids (I)Tyndall effect ol olution 1857, Faraday first observed the optical properties of Au sol 1871, Tyndall found that when an intense beam of light is passed through the sol the scattered light is observed at right angles to the beam Tyndall effect particles of the colloidal size can scatter light Distinguishing true solutions from sols
1857, Faraday first observed the optical properties of Au sol. sol solution Dyndall Effect: particles of the colloidal size can scatter light. (1) Tyndall effect 1871, Tyndall found that when an intense beam of light is passed through the sol, the scattered light is observed at right angles to the beam. 8.8.1 Optical property of colloids Distinguishing true solutions from sols
8.8.1 Optical property of colloids (I)Tyndall effect
(1) Tyndall effect 8.8.1 Optical property of colloids
8.8.1 Optical property of colloids (2)Rayleigh scattering equation 9丌2p 1=102242(n2+2ni +cos e Discussion (1) (2)v(concentration) ()r(distance) 4)2 6)6
(2) Rayleigh scattering equation: Discussion: (1) V (2) v (concentration) (3) r (distance) (4) (5) n (6) ( ) 1 cos 2 2 9 2 2 1 2 2 2 1 2 2 4 2 2 2 0 + + − = n n n n r vV I I 8.8.1 Optical property of colloids
8.8.1 Optical property of colloids (2)Rayleigh scattering equation Applications CP2 I= K 1. Colors of scattering and transition light 2. Influential factor for scattering intensity 3. Determine particle size and concentration 4. Red light for alarming
4 2 cV I = K Applications 1. Colors of scattering and transition light 2. Influential factor for scattering intensity 3. Determine particle size and concentration 4. Red light for alarming (2) Rayleigh scattering equation: 8.8.1 Optical property of colloids