hydrocarbons

alkynes

Unsaturated hydrocarbons that contain at least one triple bond are called alkynes. The name of specific alkynes always end in yne, with a prefix for the number of carbon atoms. Figure 9.12 shows the smallest alkyne, called ethyne, which has just two carbon atoms. Ethyne is also called acetylene. It is burned in acetylene torches, like the one in Figure 9.13. Acetylene produces so much heat when it burns that it can melt metal. Breaking all those bonds between carbon atoms releases a lot of energy. Alkynes may form straight or branched chains. They rarely occur as cycloalkynes. In fact, alkynes of all shapes are relatively rare, at least in nature.

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alkenes

Unsaturated hydrocarbons that contain at least one double bond are called alkenes. The name of a specific alkene always ends in ene, with a prefix indicating the number of carbon atoms. Figure 9.10 shows the structural formula for the smallest alkene. It has just two carbon atoms and is named ethene. Ethene is produced by most fruits and vegetables. It speeds up ripening and also rotting. Figure 9.11 shows the effects of ethene on bananas. Like alkanes, alkenes can have different shapes. They can form straight chains, branched chains, or rings. Alkenes can also form isomers, or compounds with the same atoms but different shapes. Generally, the physical properties of alkenes are similar to those of alkanes. Smaller alkenes, such as ethene, have relatively high boiling and melting points. They are gases at room temperature. Larger alkenes have lower boiling and melting points. They are liquids or waxy solids at room temperature.

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uses and sources of hydrocarbons

It is hard to overstate the importance of hydrocarbons to modern life. Hydrocarbons have even been called the driving force of western civilization. You saw some ways they are used in Figure 9.6. Several other ways are illustrated in Figure 9.15. Their most important use is as fuels. Gasoline, natural gas, fuel oil, diesel fuel, jet fuel, coal, kerosene, and propane are just some of the hydrocarbon compounds that are burned for fuel. Hydrocarbons are also used to manufacture many products, including plastics and synthetic fabrics such as polyester. The main source of hydrocarbons is fossil fuels coal, petroleum, and natural gas. Fossil fuels form over hundreds of millions of years when dead organisms are covered with sediments and put under great pressure. Giant ferns in ancient swamps turned into coal deposits. Dead organisms in ancient seas gradually formed deposits of petroleum and natural gas. You can read more about these sources of hydrocarbons in the chapter Introduction to Energy and at the URL below.

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aromatic hydrocarbons

Unsaturated cyclic hydrocarbons are called aromatic hydrocarbons. Thats because they have a strong aroma, or scent. Their molecules consist of six carbon atoms in a ring shape, connected by alternating single and double bonds. Aromatic hydrocarbons may have a single ring or multiple rings joined together by bonds between their carbon atoms. Benzene is the smallest aromatic hydrocarbon. It has just one ring. You can see its structural formula in Figure 9.14. Benzene has many uses. For example, it is used in air fresheners and mothballs because of its strong scent. You can learn more about benzene and other aromatic hydrocarbons at this URL: MEDIA Click image to the left or use the URL below. URL:

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what are hydrocarbons

Hydrocarbons are compounds that contain only carbon and hydrogen. Hydrocarbons are the simplest type of carbon-based compounds. Nonetheless, they can vary greatly in size. The smallest hydrocarbons have just one or two carbon atoms, but large hydrocarbons may have hundreds. The size of hydrocarbon molecules influences their properties. For example, it influences their boiling and melting points. As a result, some hydrocarbons are gases at room temperature, while others are liquids or solids. Hydrocarbons are generally nonpolar and do not dissolve in water. In fact, they tend to repel water. Thats why they are used in floor wax and similar products. Hydrocarbons can be classified in two basic classes. The classes are saturated hydrocarbons and unsaturated hydrocarbons. This classification is based on the number of bonds between carbon atoms. You can learn more about both types of hydrocarbons at this URL: (6:41). MEDIA Click image to the left or use the URL below. URL:

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saturated hydrocarbons

Saturated hydrocarbons contain only single bonds between carbon atoms. They are the simplest hydrocarbons. They are called saturated because each carbon atom is bonded to as many hydrogen atoms as possible. In other words, the carbon atoms are saturated with hydrogen. You can see an example of a saturated hydrocarbon in Figure Saturated hydrocarbons are given the general name of alkanes. The name of specific alkanes always ends in -ane. The first part of the name indicates how many carbon atoms each molecule of the alkane has. The smallest alkane is methane. It has just one carbon atom. The next largest is ethane, with two carbon atoms. The chemical formulas and properties of methane, ethane, and several other alkanes are listed in Table 9.2. The boiling and melting points of alkanes are determined mainly by the number of carbon atoms they have. Alkanes with more carbon atoms generally have higher boiling and melting points. This table shows only alkanes with relatively few carbon atoms. Some alkanes have many more carbon atoms. What properties might larger alkanes have? For example, do you think that any of them might be solids? Alkane Methane Ethane Propane Butane Pentane Hexane Heptane Octane Chemical Formula CH4 C2 H6 C3 H8 C4 H10 C5 H12 C6 H14 C7 H16 C8 H18 Boiling Point (C) -162 -89 -42 0 36 69 98 126 Melting Point (C) -183 -172 -188 -138 -130 -95 -91 -57 State (at 20C) gas gas gas gas liquid liquid liquid liquid

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shapes of alkanes

Structural formulas are often used to represent hydrocarbon compounds because the molecules can have different shapes, or structures. Hydrocarbons may form straight chains, branched chains, or rings. Figure 9.8 shows an example of an alkane with each shape. In straight-chain molecules, all the carbon atoms are lined up in a row like cars of a train. They form what is called the backbone of the molecule. In branched-chain molecules, at least one of the carbon atoms branches off to the side from the backbone. In cyclic molecules, the chain of carbon atoms is joined at the two ends to form a ring.

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isomers

Even compounds with the same number of carbon and hydrogen atoms can have different shapes. These compounds are called isomers. Look at the examples in Figure 9.9. The figure shows the structural formulas of butane and its isomer iso-butane. Both molecules have four carbon atoms and ten hydrogen atoms (C4 H10 ), but the atoms are arranged differently. Butane is a straight-chain molecule. Iso-butane is branched. You can see three-dimensional models of these two isomers at the URLs below. You can rotate the molecule models to get a better idea of their shapes.

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cycloalkanes

Ring-shaped alkanes are called cycloalkanes. They usually contain just five or six carbon atoms because larger rings are not very stable. However, rings can join together to create larger molecules consisting of two or more rings. Compared with the straight- and branched-chain alkanes, cycloalkanes have higher boiling and melting points.

unsaturated hydrocarbons

Unsaturated hydrocarbons contain at least one double or triple bond between carbon atoms. As a result, the carbon atoms are unable to bond with as many hydrogen atoms as they would if they were joined only by single bonds. This makes them unsaturated with hydrogen. Unsaturated hydrocarbons are classified on the basis of their bonds as alkenes, alkynes, or aromatic hydrocarbons.

instructional diagrams

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The diagram shows the chemical composition of four saturated hydrocarbons. It shows the chemical structure of four alkanes namely ethane, propane, butane and pentane with 2,3,4 and 5 carbon atoms respectively. All the above mentioned alkanes are straight chain compounds with 6,8,10 and 12 hydrogen atoms respectively.

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The diagram shows the molecular structure of Butane. Butane molecules have four carbon atoms and ten hydrogen atoms (C4 H10). Butane is classified as compounds that contain only carbon and hydrogen molecules, called Hydrocarbons. Saturated Hydrocarbons are the simplest Hydrocarbons. They are called saturated because each carbon atom is bonded to as many hydrogen atoms as possible and single bonds between carbon atoms. In other words, the carbon atoms are saturated with hydrogen. The diagram shows 3 carbon-carbon bonds and 10 carbon-hydrogen bonds. Their most important use is as fuels. Hydrocarbons are also used to manufacture many products, including plastics and synthetic fabrics such as polyester.

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The diagram shows the molecular structure of Hydrocarbons. Hydrocarbons can be classified into Saturated and Unsaturated Hydrocarbons. Saturated Hydrocarbons are the simplest Hydrocarbons. They are called saturated because each carbon atom is bonded to as many hydrogen atoms as possible and single bond between carbon atoms. In other words, the carbon atoms are saturated with hydrogen. As shown in the diagram, each carbon atoms are bonded to 3 hydrogen atoms and only one carbon atoms. In unsaturated hydrocarbons, The carbon atoms may have more than one bond to other carbon atoms and only 2 hydrogen atoms. Hydrocarbons are used to manufacture many products, including plastics and synthetic fabrics such as polyester. They are also used as fuels like Butane.

questions

Which statement about hydrocarbons is true?

a. They are the most complex type of carbon compounds.

b. They are all gases at room temperature.

-->  c. They generally do not dissolve in water.

d. none of the above

Which statement about hydrocarbons is false?

-->  a. All of them are polar compounds.

b. Most of them are obtained from fossil fuels.

c. Some of them are solids at room temperature.

d. They are the simplest type of carbon compounds.

The simplest hydrocarbons are

a. unsaturated hydrocarbons.

-->  b. saturated hydrocarbons.

c. aromatic hydrocarbons.

d. alkenes and alkynes.

The last part of the name of a hydrocarbon compound indicates

-->  a. the number of bonds between carbon atoms.

b. the number of carbon atoms per molecule.

c. the shape of the hydrocarbon compound.

d. none of the above

The first part of the name of a hydrocarbon indicates the number of

a. bonds between carbon atoms.

b. branches in the molecule.

c. hydrogen atoms.

-->  d. carbon atoms.

Hydrocarbons are used in floor wax because they

a. resist scratches.

-->  b. tend to repel water.

c. dissolve well in water.

d. have high melting points.

Which of the following is an example of an unsaturated hydrocarbon?

a. methene

b. pentane

c. propane

-->  d. ethene

Alkanes with more carbon atoms generally have

a. higher boiling points.

b. lower boiling points.

c. higher melting points.

-->  d. two of the above

Aromatic hydrocarbons generally have

-->  a. a strong scent.

b. rings of four carbon atoms.

c. alternating double and triple bonds.

d. all of the above

Dead organisms in ancient seas gradually formed deposits of

a. coal.

b. petroleum.

c. natural gas.

-->  d. two of the above

Hydrocarbon compounds that are burned for fuels include

a. coal.

b. propane.

c. kerosene.

-->  d. all of the above

Fossil fuels include

a. wood.

b. charcoal.

-->  c. petroleum.

d. all of the above

All hydrocarbons are small chemical compounds.

a. true

-->  b. false

Hydrocarbons are generally nonpolar compounds.

-->  a. true

b. false

Isomers of a given compound always have the same properties.

a. true

-->  b. false

Hydrocarbons are compounds that contain only carbon and hydrogen.

-->  a. true

b. false

Heptane is an unsaturated hydrocarbon.

a. true

-->  b. false

The simplest hydrocarbons are the aromatic hydrocarbons.

a. true

-->  b. false

Butane has branched-chain molecules.

a. true

-->  b. false

The size of hydrocarbon molecules influences their properties.

-->  a. true

b. false

Butane and iso-butane differ in their number of hydrogen atoms.

a. true

-->  b. false

Any hydrocarbon ending in ane has only straight-chain molecules.

a. true

-->  b. false

Alkenes may form straight or branchedchains but not rings.

a. true

-->  b. false

Hydrocarbons are used to make synthetic fabrics such as polyester.

-->  a. true

b. false

The physical properties of alkenes are generally similar to those of alkanes.

-->  a. true

b. false

Alkynes are relatively rare in nature.

-->  a. true

b. false

Fossil fuels formed over millions of years from dead organisms.

-->  a. true

b. false

Ring-shaped unsaturated hydrocarbons

a. alkanes

b. alkenes

c. alkynes

d. hydrocarbons

e. isomers

-->  f. aromatic hydrocarbons

g. cycloalkanes

all compounds that consist only of carbon and hydrogen

a. alkanes

b. alkenes

c. alkynes

-->  d. hydrocarbons

e. isomers

f. aromatic hydrocarbons

g. cycloalkanes

unsaturated hydrocarbons with at least one double bond

a. alkanes

-->  b. alkenes

c. alkynes

d. hydrocarbons

e. isomers

f. aromatic hydrocarbons

g. cycloalkanes

ring-shaped saturated hydrocarbons

a. alkanes

b. alkenes

c. alkynes

d. hydrocarbons

e. isomers

f. aromatic hydrocarbons

-->  g. cycloalkanes

saturated hydrocarbons such as ethane

-->  a. alkanes

b. alkenes

c. alkynes

d. hydrocarbons

e. isomers

f. aromatic hydrocarbons

g. cycloalkanes

molecules with the same atoms but different shapes

a. alkanes

b. alkenes

c. alkynes

d. hydrocarbons

-->  e. isomers

f. aromatic hydrocarbons

g. cycloalkanes

unsaturated hydrocarbons with at least one triple bond

a. alkanes

b. alkenes

-->  c. alkynes

d. hydrocarbons

e. isomers

f. aromatic hydrocarbons

g. cycloalkanes

diagram questions

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How many shapes of Alkane is shown in the diagram?

-->  a. 1

b. 3

c. 2

d. 4

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What is represented in the following diagram?

-->  a. carbon

b. cyclic alkane

c. alkane

d. a hydrocarbon

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Which element are the hydrogen atoms connected to?

a. HC

b. None

c. CH

-->  d. C

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How many carbons are in the chain?

-->  a. 4

b. 2

c. 3

d. 1

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If two carbon atoms were joined using double bond in the hydrocarbon shown in diagram, what would be the result?

a. cyclic hydrocarbon

b. unsaturated hydrocarbon

-->  c. saturated hydrocarbon

d. nothing would change

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What is formed when each carbon atom is bonded to as many hydrogen atoms as possible?

a. alkanes

b. simple hydrocarbon

c. alkene

-->  d. saturated hydrocarbons

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How many C are there in butane?

a. 4

b. 5

-->  c. 3

d. 6

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How many hydrogen atoms are in butane?

a. 8

b. 14

c. 12

-->  d. 10

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How many carbon atoms are there in butane?

a. 5

b. 3

-->  c. 4

d. 6

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What would happen to the boiling point of alkanes as the number of carbon atoms per molecule increases?

a. The boiling point does not change even if the number of carbon atom increases.

b. The boiling point is doubled every time the number of carbon atom increases.

c. The boiling point decreases as the number of carbon atom increases.

-->  d. The boiling point increases as the number of carbon atom increases.

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How many carbon atoms are present in (b)?

a. 9

b. 11

c. 12

-->  d. 10

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How many more double bonds than saturated fatty acid does unsaturated fatty acid have?

a. 4

b. 2

c. 3

-->  d. 1

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What is the difference between the saturated and unsaturated hydrocarbon?

a. nothing

b. saturated has triple bond Carbon

-->  c. unsaturated has double bond carbon

d. saturated has double bond Carbon

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How many carbon atoms are there in propane?

a. 4

-->  b. 3

c. 2

d. 5

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How many hydrogen atoms are there in methane?

-->  a. 4

b. 2

c. 1

d. 3

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What has each formula going down the list gained?

a. One oxygen

b. One hydrogen

c. Three carbons

-->  d. Two hydrogen

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How many hydrogen atoms make up methane?

a. 2

b. 5

-->  c. 4

d. 3

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How many Hydrogen Atoms are there in methane?

a. 2

-->  b. 4

c. 8

d. 6

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How many carbon atoms are there in ethane?

a. 3

b. 4

c. 1

-->  d. 2

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The figures below represent which type of bond?

a. cycloalkanes

-->  b. Alkynes

c. alkenes

d. aromatic hydrocarbons

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How many carbon atoms are there in 1-Hexyne?

a. 5

b. 7

-->  c. 6

d. 3

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How many carbon atoms are there in 2-hexyne?

a. 4

b. 7

-->  c. 6

d. 5

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What compound is needed to create ethanol out of methanol?

-->  a. Methylene CH2

b. Methylidyne CH

c. Carbide C

d. Methyl CH3

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What connects C to OH?

-->  a. chemical bond'

b. line

c. physical bond

d. bond

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How many hydrogen atoms are present in ethanol?

-->  a. 5

b. 4

c. 6

d. 3

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What type of alkane is Pentane?

a. Isopentane

b. Cyclic Alkane

c. Branched Chain Alkane

-->  d. Straight-Chain Alkane

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How many carbon atoms are found in a molecule of Isopentane?

a. 12

b. 8

c. 4

-->  d. 5

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How many saturated hydrocarbons are shown?

a. 1

b. 2

c. 5

-->  d. 3

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How many carbon atoms are there in pentane?

a. 4

b. 6

-->  c. 5

d. 3

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The following structures of pentane are what?

-->  a. Isomers

b. Cyclic

c. Alkene

d. Chiral

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How many carbons and hydrogen are in this diagram?

a. 15 and 36

b. 10 and 30

-->  c. 17 and 35

d. 2 and 1

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Identify the hydrocarbon that consists of triple bond between two carbon atoms.

-->  a. unsaturated hydrocarbon

b. none

c. saturated hydrocarbon

d. both saturated and unsaturated hydrocarbon

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How many bonds the carbon has to make to be stable?

a. 5

b. 3

-->  c. 4

d. 6

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How many carbon atoms are there in a saturated hydrocarbon?

a. 1

-->  b. 3

c. 4

d. 2

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A saturated hydrocarbon with three carbon atoms has how many hydrogen atoms in the molecule?

a. 7

b. 6

c. 4

-->  d. 8

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How many carbon molecules are present?

a. five

b. two

-->  c. four

d. eight

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How many carbon atoms are in the diagram?

-->  a. 4

b. 3

c. 1

d. 2

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How many carbon atoms does cyclobutane have?

-->  a. 4

b. 8

c. 1

d. 12

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How many hydrogen atoms does cyclobutane have?

a. 4

b. 6

-->  c. 8

d. 10

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How many links are present with each Carbon atom?

a. 3

b. 2

c. 1

-->  d. 4

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From the diagram, identify the smallest alkane.

a. butane

-->  b. ethane

c. propane

d. methane

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How many carbon atoms are needed to form propane?

-->  a. 3

b. 4

c. 1

d. 2

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How many carbon atoms does propane have?

a. 2

b. 1

-->  c. 3

d. 4

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How many maximum bonds can carbon have?

a. 3

-->  b. 4

c. 2

d. 5