Section 3.0 The Properties of gases and liquids can be explained by the Particle Model of Matter

Viscosity Viscosity is a measure of a fluid’s resistance to flow. Viscosity is determined by a fluid’s internal resistance or friction. The higher the viscosity, the “thicker” the fluid.

The Particle Model How can we explain viscosity using the particle model of matter? Recall that in a liquid, these particles roll, and slide over each other (in a gas they move even more easily!) The greater the attraction between these particles, the less easily they “roll” and the more viscous the fluid is.

The effect of temperature on viscosity Temperature increases, viscosity decreases

The Particle Model How can we explain what just happened using the particle model of matter? Hint: What happens to the distances between particles as energy is added? Hint: What happens to the attraction between particles as their separation increases? Hint: What happens to the speed at which these particles now slide or roll?

Why do you think there are “summer motor oils” and “winter motor oils” for cars?

3.1 Viscosity and the Effects of Temperature One property of fluids is how they move or flow. How quickly fluids flow is a property called VISCOSITY! VISCOSITY is determined by a fluids internal resistance, or friction that keeps it from flowing. The greater the friction or rubbing between particles, the higher the viscosity. Fluids with a high viscosity do not flow as easily as fluids with a low viscosity HIGH VISCOSITY = do not flow easily

Identify fluids that you use, and describe what would happen if they were thicker or thinner. Record them in a chart! Fluid Thicker Thinner Shampoo - Hard to get out of bottle - Would probably use more to wash hair

The Effect of Temperature on VISCOSITY! Temperature is one factor that can have a big effect on viscosity! What would happen to the viscosity of fluids if it were heated? Cooled?

Measuring Viscosity with the Ramp Method Using the ramp method to measure viscosity… Pour a fluid down a ramp and time how long it takes to get to the bottom of the ramp Pour the same amount of another fluid down the same ramp and time it. You can then compare the viscosities of different fluids! This can also be used to test the effect of temperature on viscosity!

Understanding Viscosity and Temperature RECALL VISCOSITY Understanding Viscosity and Temperature RECALL VISCOSITY. . . - Viscosity is a fluids internal resistance or friction that keeps it from flowing. HIGH VISCOSITY = more friction TEMPERATURE INCREASES = VISCOSITY DECREASES TEMPERATURE DECREASES = VISCOSITY INCREASES In the Particle Model of Matter, a liquid is made of particles that can slide and roll over each other. When heat is added to the liquid, the particles slide and roll more quickly. The fluid now flows more easily. Its viscosity decreases! If temperature of a liquid drops, the particles slow down. Viscosity Increases!

Homework! Check and Reflect page 41 #’s 1-5 http://www.youtube.com/watch?v=28-oXZo8iUA