Solutions Why does a raw egg swell or shrink when placed in different solutions? SAVE PAPER AND INK!!! When you print the notes on PowerPoint, print "Handouts" instead of "Slides" in the print setup. Also, turn off the backgrounds (Tools>Options>Print>UNcheck "Background Printing")!

Homogeneous Mixtures: Solutions Homogeneous Mixtures are uniform throughout. Solutions are homogeneous mixtures of two or more substances uniformly spread throughout a single phase. Example: Salt Water Example: Salt Water – if you add salt to a glass of water – if you add salt to a glass of water and stir, the mixture soon looks and stir, the mixture soon looks like pure water. like pure water. -- In salt water the salt is the solute, -- In salt water the salt is the solute, the substance that dissolves. Water the substance that dissolves. Water is the solvent, the substance in is the solvent, the substance in which the solute dissolves. which the solute dissolves.

Parts of a Solution SOLUTE – the part of a solution that is being dissolved (usually the lesser amount) SOLVENT – the part of a solution that dissolves the solute (usually the greater amount) Solute + Solvent = Solution SoluteSolventExample solidsolid Alloys (brass, steel) solidliquid Salt water gassolid Air bubbles in ice cubes liquidliquid “suicides” (mixed drinks) gasliquid Soft drinks gasgasAir

Water– A Universal Solvent The structure of water helps it dissolve charged particles. dissolve charged particles. Water is polar (the shared electrons are not (the shared electrons are not evenly spread throughout). evenly spread throughout). The oxygen atom is partially negative, and the hydrogen negative, and the hydrogen atom is partially positive. atom is partially positive. Example: When sodium chloride (table salt) dissolves in water, positively charged sodium ions are attracted to the partially negative oxygen atoms of water.

Factors That Affect Dissolving Which will dissolve faster??? Which will dissolve faster??? 1.Solutes with a larger surface area dissolves faster. dissolves faster. VS.

2. Stirring or shaking a solution helps the solute dissolve faster. Example: Example: When you add sugar to tea. When you stir or shake the sugar into the tea, it moves the dissolved sugar away from the other sugar crystals. Now more tea molecules can surround the sugar and interact with the solid, so the sugar crystals dissolve faster.

Solubility Differences More solid will dissolve as temperature increases temperature increases Less gas will dissolve as temperature increases

3.Solutes dissolve faster when the solvent is HOT. When a substance is heated, When a substance is heated, its particles move faster. its particles move faster. As a result, there are more As a result, there are more collisions between particles collisions between particles causing them to dissolve causing them to dissolve faster. faster.

Using Solubility Tables About 112g What mass of sodium nitrate will dissolve in 100cm3 of water at 50°C?

More Solubility Tables How much oxygen will dissolve in 100g water at 80C°? How much oxygen will dissolve in 100g water at 10C°? 0.5 mg 1.2 mg

A.Saturated solutions are holding as much solute as possible at a given temperature B. Saturated has some solid on the bottom A.Unsaturated solutions will be able to dissolve more. B.Supersaturated solutions are holding more than they should be able to at a given temperature C. unsaturated & supersaturated are completely dissolved

Because SUPERSATURATED SOLUTIONS contain more solute than is possible to be dissolved supersaturated solutions are unstable. Supersaturation is only temporary, and usually accomplished in one of two ways: Supersaturation is only temporary, and usually accomplished in one of two ways: 1. Warm the solvent so that it will dissolve more, then cool the solution 2. Evaporate some of the solvent carefully so that the solute does not solidify and come out of solution. It’s easy for a supersaturated solution to become saturated.

IONIC COMPOUNDS Compounds in Aqueous Solution Many reactions involve ionic compounds, especially reactions in water or aqueous solutions. aqueous solutions. KMnO 4 in water K + (aq) + MnO 4 - (aq)

How do we know ions are present in aqueous solutions? The solutions conduct electricity! They are called ELECTROLYTES HCl, MgCl 2, and NaCl are strong HCl, MgCl 2, and NaCl are strong electrolytes. Strong electrolytes electrolytes. Strong electrolytes dissociate completely (or nearly dissociate completely (or nearly so) into ions. so) into ions. Aqueous Solutions

Some compounds dissolve in water but do not conduct electricity. They are called nonelectrolytes. Examples include: sugarethanol ethylene glycol Examples include: sugarethanol ethylene glycol

Electrolytes in the Body  Electrolytes carry messages to and from the brain as electrical signals  The body maintains cellular function with the correct concentrations of electrolytes Make your own g sugar One liter of warm water Pinch of salt 200ml of sugar free fruit squash Mix, cool and drink

Colligative Properties When a solute is added to a solvent, the properties of the solvent are modified. These changes are called COLLIGATIVE PROPERTIES. Vapor pressure decreases Melting point decreases Boiling point increases Osmosis is possible (osmotic pressure) COLLIGATIVE PROPERTIES depend only on the number of solute particles relative to solvent particles, not on the kind of solute particles.

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