properties of water
DESCRIPTION
Properties of Water. Primarily due to polarity. Molecule two hydrogen atoms and one oxygen atom v-shaped triangular molecule hydrogen bonds Polarity properties. Intro to water. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/1.jpg)
Primarily due to polarity
Properties of Water
![Page 2: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/2.jpg)
Intro to water
•Molecule
•two hydrogen atoms and one oxygen atom
•v-shaped triangular molecule
•hydrogen bonds
•Polarity
•properties
![Page 3: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/3.jpg)
*Intro to WaterWater is a molecule made up of two hydrogen atoms and one oxygen atom. It has the formula H2O. When oxygen and hydrogen combine (H-O-H) they form a v-shaped triangular molecule. While water molecules are electrically neutral, the oxygen atom holds a small negative charge and the two hydrogen atoms hold small positive charges. Water molecules are attracted to each other, creating hydrogen bonds. These bonds determine almost every physical property of water and many of its chemical properties too. Scientists believe this unusual electrical balancing, called polarity, gives water some of its remarkable properties
![Page 4: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/4.jpg)
*Terms to know by the end of the lesson
Polarity Hydrogen bondCohesionAdhesionSurface tensionCapillary action
![Page 5: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/5.jpg)
Water Physical Properties (review)
•At what temperature in Celsius does water start boiling?
•At what temperature in Celsius does water start melting?
•At what temperature in Celsius does water start freezing?
•What is the density of water?
![Page 6: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/6.jpg)
Water has a high specific heat capacity•Water has the ability to absorb a lot of heat with a relatively small increase in temperature
•Water has one of the highest specific heat capacity
This allows marine organisms to avoid drastic temperature fluctuations in the seawater.
This allows orchards grown on the coast to survive hot summers and severe winters.
http://www.youtube.com/watch?v=qeDZQ9-gsjY
![Page 7: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/7.jpg)
Water “acts” like a magnet
![Page 8: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/8.jpg)
Water molecule is V-shaped - BENT
![Page 9: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/9.jpg)
Thinking critically
If matter expands when heated, and contracts when cooled, why does ice expand (increase in volume) when water freezes?
![Page 10: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/10.jpg)
When water freezes, it goes from a mixed up liquid state where all these V's are just sliding around each other, to an ordered crystalline solid state where all the V's have to connect with each other in nice orderly solid shapes.
![Page 11: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/11.jpg)
The closest and easiest solid crystal shape for something that exists as a 104.5 degree V is a hexagonal (really tetrahedral in 3D) crystal. Think of it as a flat hexagonal snowflake shape, but it really goes in three dimensions. The water molecules want to do this because to them it "feels" nicer--that is: they feel less strain and they can get into a lower energy state by getting into this nice orderly hexagonal crystal.
![Page 12: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/12.jpg)
“Why ice floats “
Critical Thinking:If ice were more dense than liquid water, how would this impact the survival of the marine life?
(The floating layer of ice insulates the liquid water below, so that it wouldn’t freeze – this makes the ocean environment to easier to live in)
![Page 13: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/13.jpg)
![Page 14: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/14.jpg)
H2O is Polar
•As we know – water is neutral
(equal number of e- & p+ = zero Net Charge)
•But because the O atom is more electronegative than the H atoms – electrons spend more of their time nearer the oxygen. (O atom attracts more than its “fair share” of electrons).
•This gives water a slight overall charge. The oxygen end “acts” negative.
The hydrogen end “acts” positive.
•This charge is called polarity
![Page 15: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/15.jpg)
Oxygen “pulls” closer to it creating positive and negative sides of the polar molecule.
![Page 16: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/16.jpg)
Water is Polar
![Page 17: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/17.jpg)
Water is a universal solvent
•Water can dissolve more substances than any other solvent.
•Give examples of substances that water can dissolve.
•The dissolving power of water is very important for life on Earth. Wherever water goes, it carries dissolved chemicals, minerals, and nutrients that are used to support living things.
![Page 18: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/18.jpg)
![Page 19: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/19.jpg)
“Like dissolves like”(due to its polarity)
Water (polar) + Styrofoam (non-polar)
Acetone (nonpolar) + Styrofoam (non-polar)
![Page 20: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/20.jpg)
Hydrogen Bonds (Formed between a highly Electronegative atom of a polar molecule and a hydrogen
(O-H)
Opposites
attract
![Page 21: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/21.jpg)
This model to show the attraction between H and O –
hydrogen bonding
![Page 22: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/22.jpg)
Forces due to polarity
• Cohesion
• Adhesion
![Page 23: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/23.jpg)
Cohesion (water is sticky)Attraction between particles of the same substance ( why water is attracted to itself)•Results in Surface tension (a measure of the strength of water’s surface)Produces a surface film on water that allows insects to walk on the surface of water
![Page 24: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/24.jpg)
Surface Tension
•Inside a drop of water polar water molecules attract to each other in a random fashion
•At the surface of the drop, water does not attract to the air
•A unified layer of molecules at the surface creates surface tensionThere the water behaves like an flexible sheet allowing denser objects to “sit” on the surface.
![Page 25: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/25.jpg)
Surface tension (cohesion)
•Can be seen as water droplets form
•Helps insects walk across water
![Page 26: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/26.jpg)
Adhesion•Attraction between two different substances.
•Water will form hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton
•Adhesion Causes Capillary Action, which gives water the ability to “climb” structures.
![Page 27: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/27.jpg)
*Adhesion
*Can be seen as water droplets form on the spider web (another polar surface)
Form spheres & hold onto plant leaves
![Page 28: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/28.jpg)
*Capillary action
*We know that gravity is ALWAYS pulling on objects with mass
*Yet water can move up a paper towel with relative ease – How can this happen?
*Because the positive and negative charges in the paper attract the polar water molecules (adhesion)
*This property of adhesion is called capillary action.
![Page 29: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/29.jpg)
Explain the following water properties in both words and drawings(2 min)Polarity-Like dissolves like-Heat capacityWater acts as a magnet-Trade notebooks with your partner write one constructive comment in your partner’s notebook. Hand them back their notebook( 1min)
Warm up: 2/25/13
![Page 30: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/30.jpg)
• How do heterogeneous and homogeneous mixtures differ?(Left Side)
Salt solution and Oil in water
2 min - Quick Write: Based on your prior knowledge about mixtures, explain why a salt solution is classified as a homogeneous mixture and a mixture of oil and water is said to be a heterogeneous mixture.
White boards activity:
Homo- or Hetero - ?
COKE
AIR
STEEL
A JAR OF PENNIES
Coke (mixture of CO2 gas, water, sugar, caramel color, food flavorings)
Air (mixture of O2 and N2)
Steel (alloy – mixture of Fe and C)
A jar of pennies and nickels
• Notes
![Page 31: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/31.jpg)
By the end of the day you will know:
•Solute
•Solvent
•Solution
•Soluble
• Insoluble
• Immiscible
•Separation
•Solvation
•Factors affecting the rate of dissolution
Next notes…
![Page 32: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/32.jpg)
Complete the sentences.
When you put salt into water it______. The salt dissolves because it is ________in the water. The substance which dissolves is called the ______. The substance that does the dissolving is called the _______. When something dissolves you get a _______. Water is a ________. Salt is a ________. When a substance does not dissolve it is________Dissolution of salt in water
http://www.nsf.gov/news/special_reports/chemistrynow/chem_water.jsp
![Page 33: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/33.jpg)
• Animation - Dissolution of an Ionic compound (results in dissociation) and a covalent compound (no dissociation)
http://www.chem.ufl.edu/~itl/4411/react/dissolution_of_cmpds.swf
• Animation – Strong electrolyte (complete dissociation into ions) – many ionic compounds – conduct electricity - (+ strong acids and bases – will cover in more detail in Bundle 11)
http://www.chem.ufl.edu/~itl/4411/react/04M05AN1.MOV
• Animation – Weak electrolyte (partial dissociation) – weak acids and bases (if a conductivity meter is used - light is not as bright (dim) compared to a strong electrolyte)
http://www.chem.ufl.edu/~itl/4411/react/04M05AN2.MOV
• Animation – Non-electrolyte ( no dissociation) - no disruption of its molecular (covalent) structure – does not conduct electricity
http://www.chem.ufl.edu/~itl/4411/react/04M05AN3.MOV
![Page 34: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/34.jpg)
The dissolved components of ionic and covalent compounds are:
a.All ionsb.Ions for ionic and molecules for covalent
compoundsc.Ions for covalent and molecules for ionic
Checking for understanding
![Page 35: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/35.jpg)
The dissolution of KNO3 and C3H6O (acetone) in water occurs:a.Molecules by molecules for both KNO3 and
C3H6Ob.Ion by ion for KNO3 and molecule by
molecule for C3H6Oc.Ion by ion for C3H6O and molecule by
molecule for KNO3
![Page 36: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/36.jpg)
Based on your observations of the dissolution process on the animation, how do you think substances get dissolved?
a.Each solvent molecules gets separated from other molecules and is surrounded by ions in ionic substances or molecules in covalent substances
b.Each ion in covalent substances and each molecule in ionic substances gets separated from other molecules or ions and is surrounded by solvent molecules
c.Each ion in ionic substances and each molecule in covalent substances gets separated from other molecules or ions and is surrounded by solvent molecules.
![Page 37: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/37.jpg)
Warm up 2/25/13For the following reaction
• identify the products as insoluble or soluble.Na2CO3 + CaCl2 CaCO3 + 2NaCl
•Classify the type of reactionActivity
Sketch the process of dissolution of calcium chloride. Find a partner - compare each other’s drawings – make corrections if needed(4min)
![Page 38: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/38.jpg)
Factors that Affect the Rate of Dissolution Pre-assessment:If you wanted to dissolve a substance in water as quickly as possible what could you do?
![Page 39: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/39.jpg)
The three methods to increase the rate of
dissolving for a solid are?
•Heat it! •Crush it!
•Stir it!
![Page 40: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/40.jpg)
How can you achieve the following:
•Increased number of collisions between solvent and solute
•Agitation
•Increased surface area
•Increased kinetic energy
![Page 41: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/41.jpg)
Notes –Solubility
•the amount of solute that will dissolve in a given amount of solvent at a specified temperature and pressure (for gases)
•grams of solute per grams of solvent
•grams of solute per 100ml of solvent
![Page 42: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/42.jpg)
Example: at 25.0 0C, the solubility of sodium chloride is 35.0 grams per 100 ml of water. You can dissolve up to 35.0 grams of sodium chloride in 100 ml of water. If you add more than 35.0 grams the solid will simply not dissolve.
![Page 43: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/43.jpg)
Based on solubility we can have three types of solutions:
•Unsaturated – a solution that could dissolve MORE solute at a specific temperature
• Saturated – a solution that contains the MAX amount of solute that can dissolve at a specific temp (stable)
Visual evidence: a small quantity of un-dissolved solute remains in solution
•Supersaturated – a solution that contains more dissolved solute than a saturated solution. (Prepared by heating the solvent, adding solute, and cooling slowly – very unstable)
DEMO. Supersaturated solution of Sodium Acetate
![Page 44: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/44.jpg)
Gra
ms
solu
te/1
00 g
H2O
NaClO3
KNO3 KBr
NaCl
TemperatureTemperatureGra
ms
of
solu
te p
er
10
0 g
of
wate
r
![Page 45: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/45.jpg)
How much solute will dissolve?
Gra
ms
solu
te/1
00 g
H2O NaClO3
KNO3 KBr
NaCl
Temperature
• A solubility curve shows the amount of each solute that will dissolve in 100g H20 at each temperature.
• Saturated is on the line.
• Unsaturated is below the line.
• Supersaturated is above the line.
![Page 46: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/46.jpg)
How much solute will dissolve?
•A solubility curve shows the amount of each solute that will dissolve in 100g H20 at each temperature.
•Saturated is on the line.
•Unsaturated is below the line.
•Supersaturated is above the line.
Gra
ms
solu
te/1
00 g
H2O
Saturated
![Page 47: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/47.jpg)
•What is the solubility of KNO3 at 60 oC in 200 g of H2O?
•How many grams of KBr can dissolve in 300 gr of H2O at 100 oC?
G
ram
s so
lute
/100
g H
2O NaClO3
KNO3 KBr
NaCl
Temperature
![Page 48: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/48.jpg)
*How much solute will dissolve? *A solubility curve
shows the amount of each solute that will dissolve in 100g H20 at each temperature.
*Saturated is on the line.
*Unsaturated is below the line.
*Supersaturated is above the line.
Gra
ms
solu
te/1
00 g
H2O
Unsaturated
![Page 49: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/49.jpg)
Gra
ms
solu
te/1
00 g
H2O
How much NaClO3 would you have to add to 100 g of water at 50oC to make a saturated solution?
50o
Look at the intersection.
Approx. 140 – 142 g
![Page 50: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/50.jpg)
Mini Lab: WHAT FACTORS INFLUENCE DISSOLUTION
Surface Area (Solid Solute)
1) Record the time 1 sugar cube needs to dissolve in 200 ml of tap water. ______
2) Crush 1 sugar cube in the mortar & pestle. Record the time the crushed sugar cube needs to dissolve in 200 ml of tap water. _____________
Temperature (Solid Solute)
3) Obtain 200 ml of warm water from the front lab table. Color one side of the sugar cube with a Vis-A-Vis marker. Add the sugar cube to the warm water & record the time the cube needs to dissolve. _____________
4) Obtain 200 ml of cold water from the front lab table. Color one side of the sugar cube with a Vis-A-Vis marker. Add the sugar cube to the cold water & record the time the cube needs to dissolve.___________
Stirring (Solid Solute)
5) Place 1 sugar cube in 200 ml of tap water. Record the time the cube needs to dissolve without stirring.______________
6) Place 1 sugar cube in 200 ml of tap water. Record the time the cube needs to dissolve while you stir the solution._____________
![Page 51: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/51.jpg)
Homework: Lab analysis questions1) How do you increase the surface area of a solid?
2) How is surface area of a solid solute related to dissolution? WHY?
3) How is temperature related to the dissolution of a solid solute? WHY?
4) What effect does stirring have on the dissolution of a solid solute? WHY?
![Page 52: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/52.jpg)
Checking for understanding
![Page 53: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/53.jpg)
The Great Soda Mystery!
1. What is the difference between the hot soda and cold soda? Why?
2. As temperature _______,
solubility of a gas ______.
3. Does pressure affect the amount of gas in the soda? How?
4. As pressure _____, solubility of gases ______.
![Page 54: Properties of Water](https://reader035.vdocument.in/reader035/viewer/2022062519/56815491550346895dc2a05c/html5/thumbnails/54.jpg)
•In general solubility of solids increases with increasing temperature.•Solubility of gases in water decreases with increasing temperature.