Chapter 14 Polarity. Alkanes Are a simple group of hydrocarbons having the general formula C n H...
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Transcript of Chapter 14 Polarity. Alkanes Are a simple group of hydrocarbons having the general formula C n H...
![Page 1: Chapter 14 Polarity. Alkanes Are a simple group of hydrocarbons having the general formula C n H 2n+2.](https://reader036.fdocuments.in/reader036/viewer/2022062515/56649cfe5503460f949cf0d3/html5/thumbnails/1.jpg)
Chapter 14
Polarity
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Alkanes
• Are a simple group of hydrocarbons having the general formula CnH2n+2
![Page 3: Chapter 14 Polarity. Alkanes Are a simple group of hydrocarbons having the general formula C n H 2n+2.](https://reader036.fdocuments.in/reader036/viewer/2022062515/56649cfe5503460f949cf0d3/html5/thumbnails/3.jpg)
![Page 4: Chapter 14 Polarity. Alkanes Are a simple group of hydrocarbons having the general formula C n H 2n+2.](https://reader036.fdocuments.in/reader036/viewer/2022062515/56649cfe5503460f949cf0d3/html5/thumbnails/4.jpg)
Pentane (C5H12)
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Hexane (C6H14)
![Page 6: Chapter 14 Polarity. Alkanes Are a simple group of hydrocarbons having the general formula C n H 2n+2.](https://reader036.fdocuments.in/reader036/viewer/2022062515/56649cfe5503460f949cf0d3/html5/thumbnails/6.jpg)
How well do they stick together?
• hexane
• table salt
• methane
table salt > hexane > methanegreatest attractive weakest
attractive
forces forces
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How well do they stick together?
• hexane (liquid)
• table salt (solid)
• methane (gas)
table salt > hexane > methanegreatest attractive weakest
attractive
forces forces
![Page 8: Chapter 14 Polarity. Alkanes Are a simple group of hydrocarbons having the general formula C n H 2n+2.](https://reader036.fdocuments.in/reader036/viewer/2022062515/56649cfe5503460f949cf0d3/html5/thumbnails/8.jpg)
Table salt (NaCl)
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Methane and Hexane are Molecular
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They stick together through Van der Waals forces (not true bonds)
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Larger molecules have greater Van der Waals forces
Boiling Point = –161.7°C
Boiling Point = 68.7°C
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Rank the molecules from least to greatest Van der Waals forces?
• Hexane (C6H14)
• Methane (CH4)
• Hydrogen (H2)
• Water (H2O)
A A a a a a a a a a a a a
a a a a a a
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Did you get this order?
Hydrogen(H2) < Water(H2O) < Methane(CH4) < Hexane(C6H14)
A A a a a a a a a a a a a
a a a a a a
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It’s WrongHydrogen(H2) < Water(H2O) < Methane(CH4) < Hexane(C6H14)
A A a a a a a a a a a a a
a a a a a a
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The state of matter determines the attractive force?
• Methane (CH4) and Hydrogen (H2) are gases Water (H2O) and Hexane (C6H14) are liquids
A A a a a a a a a a a a a
a a a a a a
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The state of matter determines the attractive force?? H2 < CH4 < H2O < C6H14 ?
gases liquidsA A a a a a a a a a a a a
a a a a a a
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Boiling points can confirm your answers.
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Boiling Points
• Hydrogen has a boiling point -252.87 ºC.
• Methane has a of −161 °C
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Boiling Points
68.7°C 100°C
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Rank the molecules from least to greatest Van der Waals forces?
Hydrogen (H2) <Methane (CH4) < Hexane (C6H14) < Water (H2O)
A A a a a a a a a a a a a
a a a a a a
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What is the shape of a water molecule?
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A water molecule is bent. It therefore lacks symmetry.
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This makes a water molecule have different ends. This makes a water
molecule _____.
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This makes a water molecule have different ends. This makes a water
molecule polar.
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A water molecule is polar because it has oppositely charged ends.
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A polar molecule is called a dipoleA
A
A
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A
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Polar molecules act like little magnets. The oppositely charged ends attract.
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Van der Waals Forces are based on:
1. Size
2. Polarity
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Lucky for us water is polar
• Hydrogen has a boiling point -252.87 ºC.
• Methane has a of −161 °C
![Page 30: Chapter 14 Polarity. Alkanes Are a simple group of hydrocarbons having the general formula C n H 2n+2.](https://reader036.fdocuments.in/reader036/viewer/2022062515/56649cfe5503460f949cf0d3/html5/thumbnails/30.jpg)
Dipole Moment
• The dipole moment is a measurement of a molecules polarity.
• Example:
H2O and CO are both dipoles however water has a greater dipole moment.
![Page 31: Chapter 14 Polarity. Alkanes Are a simple group of hydrocarbons having the general formula C n H 2n+2.](https://reader036.fdocuments.in/reader036/viewer/2022062515/56649cfe5503460f949cf0d3/html5/thumbnails/31.jpg)
Polarity Demo: Hexane vs. Water
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Homework
• Chapter 14 Worksheet