A. Homogeneous Mixture- uniform throughout A. Homogeneous Mixture- uniform throughout B. One or more substances dissolved in another B. One or more substances dissolved in another C. Grouped by state C. Grouped by state Solid - metal alloys Solid - metal alloys Liquid – chemicals we use in experiments Liquid – chemicals we use in experiments Gas - air Gas - air

Solvent – the liquid in which something will be dissolved Solvent – the liquid in which something will be dissolved Solute – the substance (usually a solid) being dissolved Solute – the substance (usually a solid) being dissolved

What makes something dissolve? Solubility – the amount of a substance that dissolves in a given quantity of solvent at a certain temperature. Solubility – the amount of a substance that dissolves in a given quantity of solvent at a certain temperature. Determined by Determined by Temperature Temperature Pressure Pressure Nature of solute and solvent (Like dissolves like or polar dissolves polar.) Nature of solute and solvent (Like dissolves like or polar dissolves polar.) (click on curve for dissolving animations) (click on curve for dissolving animations)

How can you increase the rate of solubility? 1. Agitation- stir it 2. Temperature – Increase in temp usually causes an increase in solubility due to an increase in KE, this causes more collisions between liquid molecules and crystals. 3. Surface area – Increase in surface area will increase solubility – also due to more direct collisions between liquid and crystals.

Can an infinite amount of solute be dissolved in a given amount of solvent? No! No! 1. Saturated solution – contains maximum amount of solute for a given amount of solvent at a certain temp. 1. Saturated solution – contains maximum amount of solute for a given amount of solvent at a certain temp. 2. Unsaturated solution – contains less solute than a saturated solution. 2. Unsaturated solution – contains less solute than a saturated solution. 3. Supersaturated solution – contains more solute than theoretically possible 3. Supersaturated solution – contains more solute than theoretically possible

What if there is more solute than can be dissolved into a solution? Equilibrium is reached – same number of solute particles are solvating (dissolving) as desolvating (undissolving). Equilibrium is reached – same number of solute particles are solvating (dissolving) as desolvating (undissolving).

What about liquids? 1. Two liquids that dissolve in each other are called miscible. 1. Two liquids that dissolve in each other are called miscible. 2. Two liquids that don’t dissolve in each other are immiscible. Example: oil & water 2. Two liquids that don’t dissolve in each other are immiscible. Example: oil & water

Do gases dissolve the same way as solids? 1. Solubilities of gases are greater in cold water than in hot water. This is because bubbles form in warm water allowing dissolved gases to escape. 1. Solubilities of gases are greater in cold water than in hot water. This is because bubbles form in warm water allowing dissolved gases to escape. 2. Solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid – Henry’s Law. 2. Solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid – Henry’s Law.

Henry’s Law & Soda Pop If pressure is ↑↑↑ then CO 2 stays in the liquid (high solubility). If pressure is ↓↓↓ then CO 2 escapes the liquid (low solubility).

When does a supersaturated solution exist? 1. When the temp is raised in a saturated solution and excess solid is dissolved. If the system is cooled slowly then that excess may not crystallize but stay in the solution. So we call it supersaturated. 1. When the temp is raised in a saturated solution and excess solid is dissolved. If the system is cooled slowly then that excess may not crystallize but stay in the solution. So we call it supersaturated. 2. You can desupersaturate a solution by placing a crystal in it – this causes excess solute to crystallize. Now the system will reach a dynamic equilibrium. 2. You can desupersaturate a solution by placing a crystal in it – this causes excess solute to crystallize. Now the system will reach a dynamic equilibrium.

Is there an energy change when something is dissolved? Dissolving a solid in a liquid is usually endothermic. Dissolving a solid in a liquid is usually endothermic. Which means it will feel cool to the touch. Which means it will feel cool to the touch.

Why is water so good at dissolving things? Because water is polar it’s positive end is attracted to the negative end of polar covalent or ionic compounds. The negative end is attracted to positive ends. Because water is polar it’s positive end is attracted to the negative end of polar covalent or ionic compounds. The negative end is attracted to positive ends.

Try these Solve for x: Solve for x:1. 38 = x95 = x 2. If a recipe calls for 4 eggs and.5 cups of oil but you only have 3 eggs, how much oil will you need? (Set up a proportion.)

Solubility Curves

We can use the solubility curve to figure out a substance’s solubility at different temperatures. How many grams of KClO 3 will dissolve in 100g of water at 80 o C? How many grams of KClO 3 will dissolve in 100g of water at 80 o C? How many grams of NaNO 3 will dissolve in 400g of water at 50 o C? How many grams of NaNO 3 will dissolve in 400g of water at 50 o C?