Properties of Water ► Water is polar:  Oxygen is more electronegative than Hydrogen. ► Creates partial (+) charges at the hydrogen atoms & a partial (-) charge at the oxygen atom.  Hydrogen bonds form between water molecules. ► The partial (+) end of one water molecule is attracted to the partially (-) end of another water molecule. ► Hydrogen bonds are weak!

(-) (+) (-) (+) (-) (+) (-) (+) (-) (+) (-) (+) Hydrogen Bonding

Properties of Water ► Water’s polarity and hydrogen bonding cause:  Capillary Action  High Surface Tension  High Specific Heat  Solubility  Density  High freezing and boiling points  Low vapor pressure

Capillary Action ► Capillary Action ► Water molecules are able to channel themselves in and through small openings. ► Allows water (and its dissolved substances) to move through the roots of plants and through the tiny blood vessels in our bodies. ► Causes the meniscus.

Surface Tension ► Surface Tension is the inward force that minimizes the surface area of a liquid.  Cohesion (sticking) between the water molecules is caused by hydrogen bonding.  Causes water droplets/beads.  Allows the water strider to “walk” on water.

Density of Water ► The density of ice is less than water. ► When frozen, the hydrogen bonds arrange the water molecules into an open honeycomb shape.

► What property of water causes the occurrence in the picture below? Density

► What property of water causes the occurrence in the picture below? Capillary Action

► What property of water causes the occurrence in the picture below? Polarity

Solutions ►A►A►A►A solution is a mixture of two or more substances that are evenly distributed at the molecular level. CCCCoffee is a solution. What’s in it? CCCCan we see all the parts?

2 Parts to All Solutions ► ► Solvent – The part of the mixture present in the greatest amount (part doing the dissolving). ► ► Solute – The part or parts of the mixture present in the lesser amount (part being dissolved). ► ► “Like Dissolves Like” ► ► Polar substances dissolve in other polar substances. ► ► Non-polar substances dissolve in other non- polar substances.

Properties of Solutions ► Miscible – liquids that can dissolve in each other.  EX: water/alcohol ► Immiscible – liquids that can’t dissolve in each other.  EX: water/oil

Aqueous Solutions ► Electrolyte – a substance that conducts an electrical current in aqueous solution.  Weak electrolyte – only part of the substance dissolves, therefore only a weak electrical current can be carried  Strong electrolyte – almost all dissolves, therefore strong current.  Non-electrolyte – a substance that doesn’t conduct electrical currents

Strong Electrolyte Solution Weak Electrolyte Solution

Solvation ► Solvation is the process of dissolving. solute particles are separated and pulled into solution solute particles are surrounded by solvent particles

Solubility ► Solubility – the maximum amount of solute that can be dissolved in a given solvent at a given temperature.

Types of Solutions ► Saturated solution – a solution that contains the maximum amount of solute…no more solute will dissolve  Ex: tea with a lot of sugar but not so much to where it falls to the bottom ► Unsaturated solution – more solute can dissolve.  Ex: tea with not enough sugar

Types of Solutions ► Supersaturated Solutions – a solution that contains more dissolved solute than is theoretically possible. Usually created by heating the solution and then slowly cooling it back down.

Solutions with Solids ► Factors that affect the rate of solvation of solids: 1.Agitation increases rate of dissolving by bringing more fresh solvent into contact with the solute. 2.Increasing temperature increases rate of dissolving 3.Decreasing particle size increases rate of dissolving by allowing fresh more solvent to come into contact with more of the solute ► Why? Because solvation only occurs at the surface. All of these increase the amount of solvent contacting the surface.

Solutions with Gases ► Factors that affect solutions with gases:  Temperature  Most gases decrease in solubility with an increase in temperature.  Pressure  The solubility of a gas increase with increased pressure.  EX: soft drinks

Solubility Curves ► A solubility curve shows the dependence of solubility on temperature.