Viscosity: Thick or Thin? Chapter 4

Fluids Have the ability to flow Are liquids or gases

States of matter and the Particle Theory. The five major points of the particle theory of matter are: Copy the points down from your textbook on page 111

Substances are made up of particles Substances are made up of particles. The state of the substance depends on the arrangement of the particles. The Three States of Matter Gas No attraction between particles Far apart Random arrangement Vibrate Move quickly in all directions Solid Particles held tightly Very close together Regular arrangement Vibrate Can’t move from place to place Liquid Particles held weakly Very close together Random arrangement Vibrate Constantly move past each other

States of Matter: Solid Liquid Gas Definite Shape Definite volume Ex.: Liquid No Definite shape Ex. : Gas No definite shape No definite volume

Changes of State Gas Solid Liquid condensation sublimation vaporization sublimation melting Solid Liquid freezing

Two examples of vaporization are Evaporation ( slow vaporization) Boiling (rapid vaporization) What is the difference between vapor and gas?  vapor is a liquid at room temperature.  gas is a gas at room temperature. An example of sublimation is frozen carbon dioxide. ( Dry ice)

Assignment: Look and skim through Pg. 110-116 BLM 4-1, 4-3,4-9 Use the particle theory to explain why ice cubes form in your freezer. p. 110 At Home Activity (BLM 4-4)

Viscosity lab reminders Time 1:30:16 1 minute, 30.16 seconds  60 s + 30.16 s = 90.16 sec. Flow rate cm/sec 10cm ÷ 90.16 sec = 0.111 cm/s ( use 3 decimal places) Average  Sum of trials / number of trials (0.111 +0.125) ÷ 2 = 0.118 cm/s Ranking  flow rate : 1-fastest 4- slowest viscosity : 1- thickest 4- thinnest.

Flow Rate and Viscosity. Flow rate : How fast a fluid flows from one point to another. It’s measured in cm/s. Viscosity: resistance to flow A fluid with a high flow rate (runs quickly) has a low viscosity. (thin)

Flow Rate A liquid with a low flow rate (runs slowly) has a high viscosity. (thick) This is an inverse relationship. ( )

Viscosity Viscosity: resistance to flow High viscosity is thick Low viscosity is thin Viscosity affects the value of products (ex.medicine, food, paints) (Read this section in your text! pg. 120-121)

Factors that affect Viscosity: In liquids: Size and shape of particles (bulkiness) affect viscosity. Larger and bulkier particles will increase viscosity.

Factors that affect Viscosity: Internal friction (particles rubbing on each other) affects viscosity. Ex. Water particles move past each other easily but honey particles have more internal friction and do not move past each other as easily as water.

Factors that affect Viscosity Temperature: Viscosity decreases as a fluid is heated and viscosity increases as the fluid is cooled. This is an indirect relationship.

Factors that affect viscosity Continued… In gases: Size and shape of particles: Larger and bulkier particles increase viscosity.

Temperature and Internal friction High temperatures increase internal friction because the particles speed up and collide more frequently-therefore increase viscosity Cool temperatures keep internal friction and viscosity low.

Translation For gases, Viscosity increases as temperature increases and viscosity decreases as temperature decreases. It is a direct relationship.

Assignment: Read p. 118 – 119 (lab – flow rate) BLM 4-13(3only) , 4-23, 4-17 Pg. 122 CYU 1-4