3.1 Viscosity and the Effects of Temperature 3.0 The properties of gases and liquids can be explained by the particle model of matter 3.1 Viscosity and the Effects of Temperature

The particle model of matter All matter is made up of tiny particles. Different substances are made up of different particles The tiny particles of matter are always moving and vibrating. The particles in matter may be attracted to each other or bonded together The particles have spaces between them

Fluids… Remember that fluids does not always mean liquids… Fluids can be both liquid and gases. A fluid is any matter that has no fixed shape (it takes the shape of its container!) So how are fluids useful?

What type of fluids have we used?

What is Viscosity? Imagine a styrofoam cup with a hole in the bottom. If I then pour honey into the cup I will find that the cup drains very slowly. That is because honey's viscosity is large compared to other liquids' viscosities. If I fill the same cup with water, for example, the cup will drain much more quickly.

Viscosity is a measure of a fluid's resistance to flow Viscosity is a measure of a fluid's resistance to flow. It describes the internal friction of a moving fluid. A fluid with large viscosity resists motion because its molecular makeup gives it a lot of internal friction. A fluid with low viscosity flows easily because its molecular makeup results in very little friction when it is in motion.

So Again…What is Viscosity? Viscosity: how fast/quickly a fluid flows It is determined by a fluids internal resistance or friction The greater the friction or rubbing between particles in any fluid, the higher the viscosity Fluids with higher viscosity do not flow as easy as fluids with a low viscosity.

The Ramp Method Simple! Pour a fluid down a ramp and time how long it takes for the fluid to get to the bottom Use this to calculate the viscosities of different fluids

The effect of temperature on viscosity As the temperature of a liquid increases, its viscosity decreases. When a fluid is heated, the particles will slide and roll more quickly, thus making it flow more readily, making it’s viscosity decrease (Remember the particle model of matter?) If the temperature drops, the particles slow down, thus viscosity increases (the fluid flows more slowly).