Properties of Water Properties of Water ► Water is polar: Water is polar: Oxygen is more electronegative than Oxygen is more electronegative than Hydrogen. Hydrogen. ► Creates partial (+) charges at the Creates partial (+) charges at the hydrogen atoms & a partial (-) charge at hydrogen atoms & a partial (-) charge at the oxygen atom. the oxygen atom. Hydrogen bonds form between water molecules. Hydrogen bonds form between water molecules. ► The partial (+) end of one water molecule The partial (+) end of one water molecule is attracted to the partially (-) end of is attracted to the partially (-) end of another water molecule. another water molecule. ► Hydrogen bonds are weak! Hydrogen bonds are weak!
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Properties of WaterProperties of Water► Water is polar:Water is polar:
Oxygen is more electronegative than Hydrogen.Oxygen is more electronegative than Hydrogen.►Creates partial (+) charges at the hydrogen Creates partial (+) charges at the hydrogen
atoms & a partial (-) charge at the oxygen atoms & a partial (-) charge at the oxygen atom.atom.
Hydrogen bonds form between water molecules.Hydrogen bonds form between water molecules.►The partial (+) end of one water molecule is The partial (+) end of one water molecule is
attracted to the partially (-) end of another attracted to the partially (-) end of another water molecule.water molecule.
►Hydrogen bonds are weak!Hydrogen bonds are weak!
(-)++++
+++
+
+
+(+
)
(-)
++++
++++
++(+)
(-)
++ ++++ +
+
+
+
(+)
(-)
++
++ ++
+++
+
(+)
(-)
++++
++ +
+ +
+
(+)
(-)
+ ++ ++++
+
+
+
(+)
Hydrogen BondingHydrogen Bonding
Properties of WaterProperties of Water►Water’s polarity and hydrogen bonding Water’s polarity and hydrogen bonding
cause:cause: Capillary ActionCapillary Action High Surface TensionHigh Surface Tension High Specific HeatHigh Specific Heat SolubilitySolubility DensityDensity High freezing and boiling pointsHigh freezing and boiling points Low vapor pressureLow vapor pressure
Capillary ActionCapillary Action
►Capillary ActionCapillary Action►Water molecules are able to Water molecules are able to channel themselves in and channel themselves in and through small openings.through small openings.
►Allows water (and its dissolved Allows water (and its dissolved substances) to move through the substances) to move through the roots of plants and through the roots of plants and through the tiny blood vessels in our bodies.tiny blood vessels in our bodies.
►Causes the meniscus.Causes the meniscus.
Surface TensionSurface Tension►Surface TensionSurface Tension is the inward force is the inward force
that minimizes the surface area of a that minimizes the surface area of a liquid.liquid. Cohesion (sticking) between the Cohesion (sticking) between the
water molecules is caused by water molecules is caused by hydrogen bonding.hydrogen bonding.
Causes water droplets/beads.Causes water droplets/beads. Allows the water strider to “walk” Allows the water strider to “walk”
on water.on water.
Density of WaterDensity of Water
►The density of ice is less than water.The density of ice is less than water.►When frozen, the hydrogen bonds When frozen, the hydrogen bonds
arrange the water molecules into an arrange the water molecules into an open honeycomb shape.open honeycomb shape.
►What property of water causes the What property of water causes the occurrence in the picture below?occurrence in the picture below?
Density
►What property of water causes the What property of water causes the occurrence in the picture below?occurrence in the picture below?
Capillary Action
►What property of water causes the What property of water causes the occurrence in the picture below?occurrence in the picture below?
Polarity
SolutionsSolutions►A A solutionsolution is a mixture of two or more is a mixture of two or more
substances that are evenly substances that are evenly distributed at the molecular level.distributed at the molecular level. Coffee is a solution. What’s in it? Coffee is a solution. What’s in it? Can we see all the parts?Can we see all the parts?
2 Parts to All Solutions2 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 SolutionsProperties of Solutions►Miscible – liquids that can dissolve in Miscible – liquids that can dissolve in
each other.each other. EX: water/alcoholEX: water/alcohol
►Immiscible – liquids that can’t Immiscible – liquids that can’t dissolve in each other. dissolve in each other. EX: water/oilEX: water/oil
Aqueous SolutionsAqueous Solutions
►ElectrolyteElectrolyte – a substance that conducts – a substance that conducts an electrical current in aqueous solution.an electrical current in aqueous solution. WeakWeak electrolyte electrolyte – only part of the – only part of the
substance dissolves, therefore only a substance dissolves, therefore only a weak electrical current can be carriedweak electrical current can be carried
Strong Strong electrolyteelectrolyte – almost all – almost all dissolves, therefore strong current.dissolves, therefore strong current.
Non-electrolyteNon-electrolyte – a substance that – a substance that doesn’t conduct electrical currentsdoesn’t conduct electrical currents
►SolvationSolvation is the process of dissolving. is the process of dissolving.
solute particles are separated and pulled into solution
solute particles are surrounded by solvent particles
SolubilitySolubility►Solubility – the maximum amount of Solubility – the maximum amount of
solute that can be dissolved in a solute that can be dissolved in a given solvent at a given temperature.given solvent at a given temperature.
Types of SolutionsTypes of Solutions►Saturated solutionSaturated solution – a solution that – a solution that
contains the maximum amount of contains the maximum amount of solute…no more solute will dissolvesolute…no more solute will dissolve Ex: tea with a lot of sugar but not so Ex: tea with a lot of sugar but not so
much to where it falls to the bottommuch to where it falls to the bottom►Unsaturated solutionUnsaturated solution – more solute can – more solute can
dissolve.dissolve. Ex: tea with not enough sugarEx: tea with not enough sugar
Types of SolutionsTypes of Solutions
►Supersaturated SolutionsSupersaturated Solutions – a solution – a solution that contains more dissolved solute that contains more dissolved solute than is theoretically possible. Usually than is theoretically possible. Usually created by heating the solution and created by heating the solution and then slowly cooling it back down.then slowly cooling it back down.
Solutions with SolidsSolutions with Solids►Factors that affect the rate of solvation of solids:Factors that affect the rate of solvation of solids:
1.1. AgitationAgitation increases rate of dissolving by increases rate of dissolving by bringing more fresh solvent into contact with bringing more fresh solvent into contact with the solute.the solute.
2.2. Increasing Increasing temperaturetemperature increases rate of increases rate of dissolvingdissolving
3.3. Decreasing Decreasing particle sizeparticle size increases rate of increases rate of dissolving by allowing fresh more solvent to dissolving by allowing fresh more solvent to come into contact with more of the solutecome into contact with more of the solute
►Why? Because solvation only occurs at the Why? Because solvation only occurs at the surface. All of these increase the amount of surface. All of these increase the amount of solvent contacting the surface.solvent contacting the surface.
Solutions with GasesSolutions with Gases►Factors that affect solutions with Factors that affect solutions with
gases:gases: TemperatureTemperature
Most gases decrease in solubility Most gases decrease in solubility with an increase in temperature.with an increase in temperature.
PressurePressureThe solubility of a gas increase The solubility of a gas increase with increased pressure.with increased pressure.
EX: soft drinksEX: soft drinks
Solubility CurvesSolubility Curves►A solubility curve shows the A solubility curve shows the
dependence of solubility on dependence of solubility on temperature.temperature.
