Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?
-
Upload
destini-lockey -
Category
Documents
-
view
218 -
download
2
Transcript of Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?
![Page 1: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/1.jpg)
Shapes Make A Lot of Difference
![Page 2: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/2.jpg)
Shapes Make A Lot of Difference!!
Why does “ice float on water”?
![Page 3: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/3.jpg)
Shape Makes A Lot of Difference
All these contain water. Why can water dissolve many things?
![Page 4: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/4.jpg)
Shape Makes A Lot of Difference
Why can I swim in water on a hot summer day but cannot step on sand for long?
What has shape got to do with all these observations? Let’s see…..
![Page 5: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/5.jpg)
Water’s Chemical Structure
Each water molecule consists of 2 atoms of hydrogen atoms bonded to an atom of oxygen. The chemical formula of water is H2O.
H
H
O
H
HH
O
O
O
H
H H
![Page 6: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/6.jpg)
Water’s Chemical Structure
The oxygen atom attracts the electrons shared with hydrogen atoms more strongly to itself. In effect, each hydrogen atom acquires a partial (+) charge. Oxygen acquires a partial (-) charge.
![Page 7: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/7.jpg)
Water’s Chemical Structure
The uneven distribution of electrical charges makes water a polar molecule. The two O-H bonds make an angle of 104.5o between them giving the molecule a triangular shape.
HH
O
104.5o
104.5o
104.5o
HH
H H
O
O
![Page 8: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/8.jpg)
Water Forms Hydrogen Bonds
Water molecules are attracted to each other creating hydrogen bonds. The attraction of the oxygen of one molecule to the hydrogen of another molecule forms the hydrogen bond.
H
O
H-bond
![Page 9: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/9.jpg)
More hydrogen bonds are formed when water molecules move closer to one another.
Water Forms Hydrogen Bonds
H-bonds
H-bonds
![Page 10: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/10.jpg)
In solid water or ice, the molecules form themselves into a well-ordered crystalline structure (hexagon) held by hydrogen bonds.
Water Forms Hydrogen Bonds
H-bonds
![Page 11: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/11.jpg)
Water –The Unique Solvent
Our experiment showed that water can dissolve different kinds of solids like salt, sugar, lime, and chemical salts like potassium nitrate and lead nitrate.
salt
sugar
lime potassium nitrate
lead nitrate
Water and
![Page 12: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/12.jpg)
Water –The Unique Solvent
Not only solids, water can dissolve different kinds of liquids. It can dissolve alcohol, vinegar, lye, and muriatic acid. But, it cannot dissolve oil and gasoline.
alcohol vinega
r
muriatic acid lye
oil gasoline
Water and
![Page 13: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/13.jpg)
Water –The Unique Solvent
Even gases dissolve in water but to a very limited extent. The bubbles coming out of the test tubes are gases that were dissolved in water under pressure.
carbon dioxid
e
oxygen
sulfur dioxide
chlorine
Water and
![Page 14: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/14.jpg)
Water –The Unique Solvent
Here is a sample data gathered from a library research. It was found out that the solubility of many salts increases with increase in temperature.
SubstanceSolubility (g solute/100g water)
10oC 30oC 50oC
Lead nitrate 48.3 66.0 85.0
Sodium chloride 35.8 36.3 37.0
Potassium nitrate 20.9 45.8 85.5
Potassium dichromate
7.0 20.0 34.0
![Page 15: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/15.jpg)
Solubility of Solutes at Varying Temperatures
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
10oC 30oC 50oC
Temperature
So
lub
ility
(g
so
lute
/ 1
00g
wat
er)
Lead Nitrate
SodiumChloridePotassiumNitratePotassiumDichromate
Water – The Unique SolventData has been translated into a bar graph to show the
comparative increase in solubility of the solutes at 10oC, 30oC, and 50oC.
![Page 16: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/16.jpg)
Water –The Unique Solvent
A bar graph of the data.
Solubilities of gases in water
0.000
2.000
4.000
6.000
8.000
1 0.000
1 2.000
1 4.000
1 6.000
1 8.000
Sul f ur dioxide Chlor ine Car bon dioxide Oxygen
Gases
Solu
bilit
ies
(g s
olut
e /
100g
wat
er) 10oC
30oC
50oC
![Page 17: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/17.jpg)
Water –The Unique Solvent
On the other hand, the solubility of many gases decreases with increase in temperature.
SubstanceSolubility (g solute/100g water)
10oC 30oC 50oC
Sulfur dioxide 16.210 7.800 0.393
Chlorine 0.997 0.572 0.393
Carbon dioxide 0.232 0.126 0.076
Oxygen 0.005 0.005 0.003
![Page 18: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/18.jpg)
Water – The Unique SolventData has been translated into a bar graph to show the
comparative increase in solubility of the gases at 10oC, 30oC, and 50oC.
Solubilities of gases in water
0.000
2.000
4.000
6.000
8.000
1 0.000
1 2.000
1 4.000
1 6.000
1 8.000
Sul f ur dioxide Chlor ine Car bon dioxide Oxygen
Gases
Solu
bilit
ies
(g s
olut
e /
100g
wat
er) 10oC
30oC
50oC
![Page 19: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/19.jpg)
Water – The Unique SolventData has been translated into a bar graph to show the
comparative increase in solubility of the gases at 10oC, 30oC, and 50oC.
Solubilities of gases in water
0.000
2.000
4.000
6.000
8.000
1 0.000
1 2.000
1 4.000
1 6.000
1 8.000
1 0oC 30oC 50oC
Temperature
Solu
bilit
ies
(g s
olut
e /
100g
wat
er)
SulfurdioxideChlorine
CarbondioxideOxygen
![Page 20: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/20.jpg)
Water –The Unique Solvent
The graph shows that …
1. In general, the solubility of a solid in water increases with increase in temperature. The degree of increment varies with the nature
of the solid.2. The increase in solubility of sodium
chloride is relatively small, thus, a temperature increase has a slight effect on the solubility of sodium chloride in water.
3. The increase in solubility of potassium nitrate is relatively large, thus a temperature increase has a large effect on the solubility of potassium nitrate in water.
![Page 21: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/21.jpg)
Water –The Unique Solvent
The graph shows that …
1. In general, the solubility of a gas in water decreases with increase in temperature. The decrease varies with the nature of the
solute.
3. The solubility of oxygen is very, very small (almost negligible) and seem unaffected by
an increase in temperature.
2. Sulfur dioxide has the highest solubility under the same temperature, and experience the greatest decrease in solubility when its temperature is increased.
![Page 22: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/22.jpg)
Water – The Unique Solvent
A sodium chloride unit (NaCl) consists of a sodium ion and a chloride ion.
What happens when NaCl is added to water?
Na+ Cl-
![Page 23: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/23.jpg)
Water – The Unique Solvent
Several sodium chloride (NaCl) units make up a sodium chloride crystal.
Na+ Cl-
NaCl
![Page 24: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/24.jpg)
Water – The Unique Solvent
Water exerts an attractive force on NaCl - with the Cl side attracted to the H of water and the Na side to the O of water.
Cl-
H
O
Na+
![Page 25: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/25.jpg)
Water – The Unique SolventThe attractive force is strong enough to break the bonds between Na+ and Cl- ions, and the ions break away from their positions in the crystal. They are quickly surrounded by the water molecules.
![Page 26: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/26.jpg)
Water – The Unique Solvent
The same thing happens when other ionic substances like potassium chloride, calcium chloride, sodium nitrate, and polar substances like alcohol, vinegar and muriatic acid dissolve in water.
KCl
K+
Cl-K+
K+
Cl-
Cl-
![Page 27: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/27.jpg)
Water – The Unique Solvent
Write these:
1. Why is seawater salty? Where did the salts come from?
2. Water is a poor solvent to many nonpolar substances like oil and gasoline. They form layers with water usually occupying the lower layer. What is the effect of oil spills on rivers and lakes and the living things in it? 3. What is the effect of an increase in
temperature on the amount of dissolved oxygen in a river or lake?
![Page 28: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/28.jpg)
Some Applications
The high solubility of alcohol in water makes possible
a)the preparation of wines, colognes,perfumes, rubbing alcohol, etc..
b) the rapid spread of ethyl alcohol (from alcoholic drinks) in the body because the body is made up of 75% water.
![Page 29: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/29.jpg)
Some Applications
Fire caused by gasoline or oil cannot be put off by dousing it with water. Water will sink and formthe lower layer. The oil or gasoline will form the upper layer and spread out, exposing more of it to oxygen.
![Page 30: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/30.jpg)
Some Applications
The low solubility of oxygen in water limits its presence in water. This dissolved oxygen is used by fish and other organisms in rivers, lakes, etc.in order to live.
![Page 31: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/31.jpg)
Some Applications
An increase in temperature of the water will further reduce the dissolved oxygen, further lowering the available oxygen for these living things.
![Page 32: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/32.jpg)
Some Applications
Rainwater dissolves certain gases in air as it falls to the ground, seas, and oceans. As it flows through soil and rock formations, it dissolves many mineral salts and carries with it countless bacteria.
![Page 33: Shapes Make A Lot of Difference Shapes Make A Lot of Difference!! Why does “ice float on water”?](https://reader036.fdocuments.us/reader036/viewer/2022062515/56649cc25503460f9498975f/html5/thumbnails/33.jpg)
Well, these are all for today, class.
I hope you learned from the experiments we did and from the presentation.
Until our next meeting….. BYE!!