Topic 2: Properties of Fluids

What is a Fluid? Anything that flows Has no fixed shaped Examples? Liquid or gas Examples?

Why care about fluids?

Your bicycle starts to make grinding noises as you pedal Your bicycle starts to make grinding noises as you pedal. What do you do? You are dehydrated from working out in the sun all day. What do you do? You are building a ship that needs to sail across the Atlantic Ocean. How do you know your ship will float? You are making caramel; how do you know when you have added enough sugar? You are working at a construction site and need to break apart some concrete. How do you do it?

Fluids make it easier to transport, process and use different kinds of materials Non-fluid materials can be behave like fluids if they are melted or dissolved Fluids can do work When they move, they do so with a force

Properties of Fluids

Solubility What makes a substance dissolve? Occurs because of the attraction between the different particles 2 parts to a solution: Solute The substance that dissolves Ex. In saltwater, the salt is the solute Solvent The substance that does the dissolving Ex. In saltwater, the water is the solvent http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/molvie1.swf

Solubility in g/100mL of Water @ 0°C Solubility is the maximum amount of a solute you can add to a fixed volume of solvent at a given temperature Creates a saturated solution No more solute is able to dissolve Solubility in g/100mL of Water @ 0°C Salt 35.7 Baking soda 6.9 Carbon dioxide 0.35 Sugar 180 Hydrogen 0.00019 Oxygen 0.007 Ammonia 92

Solubility is not a static property It can be manipulated What are some factors that you think will affect the rate of solubility of a substance?

Laboratory Activity 2: Manipulating Solubility Each group will investigate one factor that affects solubility Temperature Surface area Agitation Type of solute Type of solvent Groups will design and conduct an investigation and then share their findings with the class

Solubility & Particle Model How can we explain solubility in terms of particles? When 2 substances are mixed together, their particles interact If the substance is SOLUBLE... Particles of solute are attracted to the particles of the solvent are attracted to each other Solute dissolves in the solvent

Particles of solute are repelled by particles of solvent If the substance is INSOLUBLE... Particles of solute are repelled by particles of solvent Form distinct layers

Effect of Temperature Increases number of collisions between particles Increasing the temperature makes the particles move faster Increases number of collisions between particles Solute dissolves faster

Surface Area Smaller pieces have more surface area for the solvent particles to bump into Solute dissolves faster

Agitation Moves the particles around Increases the number of collisions between particles Solute dissolves faster

Type of solute / solvent Some particles have charges Polar molecules When mixed together, the charges interact Particles that have charges don’t like to mix with particles that don’t have charges (non-polar)