1. Unit 1 Mix and Flow of Matter
Topic 4
Flow Rate and Viscosity
Remember to name and date your notes!

2. Viscosity
Viscosity describes a liquid’s thickness or thinness. The thicker the liquid, the higher the viscosity.
The time it takes for a fluid to run from one point to another is the flow rate.

3. The thicker a substance is, the higher the viscosity.
The thinner substance is, the lower the viscosity.

4. Viscous or not Viscous?
Viscous
Not viscous
Motor Oil
Water
Honey
Shampoo
Coffee
Vinegar
Molasses

5. DO NOT WRITE
The cosmetics industry must carefully regulate viscosity for:
Lipstick
Mascara
Nail Polish
Why?

6. Viscosity in Liquids
It is easier for particles of some fluids to slip past each other.
Water particles slip past each other easily compared to honey.
In honey, the particles are attracted to each other and slow down in passing.

7. DO NOT WRITE
The particles in thick liquids are VERY attracted to each other.
The particles in thin liquids are not very attracted to each other.

8. THE VISCOSITY OF A LIQUID DECREASES WHEN HEATED AND INCREASES WHEN COOLED.

9. Viscosity of Gases
Particles of gas are more likely to collide with one another than rub against each other.

10. Heated gases flow less quickly and smoothly because of increased number of collisions among particles at higher temps.

11. So, a heated gas has an increased viscosity, while a cool gas has a lower viscosity.
(This is the opposite of a liquid)