saturated hydrocarbons

shapes of alkanes

Structural formulas are often used to represent hydrocarbon compounds because the molecules can have different shapes and a structural formula shows how the atoms are arranged. Hydrocarbons may form straight chains, A) In a straight-chain molecule, all the carbon atoms are lined up in a row like cars of a train. The carbon atoms form the backbone of the molecule. B) In a branched-chain molecule, at least one of the carbon atoms branches off from the backbone. C) In a cyclic molecule, the chain of carbon atoms is joined at the two ends to form a ring. Each ring usually contains just five or six carbon atoms, but rings can join together to form larger molecules. A cyclic molecule generally has higher boiling and melting points than straight-chain and branched- chain molecules.

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whats in a name

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 other small alkanes are listed in the Table 1.1. The boiling and melting points of alkanes are determined mainly by the number of carbon atoms they have. Alkanes with more carbon atoms generally boil and melt at higher temperatures. 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 20 C) gas gas gas gas liquid liquid liquid liquid Q: The Table 1.1 shows only alkanes that have relatively few carbon atoms. Some alkanes have many more carbon atoms. What properties might larger alkanes have? A: Alkanes with more carbon atoms have higher boiling and melting points, so some of them are solids at room temperature.

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what are saturated hydrocarbons

Saturated hydrocarbons are hydrocarbons that contain only single bonds between carbon atoms. They are the simplest class of 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 the Figure 1.1. In this compound, named ethane, each carbon atom is bonded to three hydrogen atoms. In the structural formula, each dash (-) represents a single covalent bond, in which two atoms share one pair of valence electrons. Q: What is the chemical formula for ethane? A: The chemical formula is C2 H6 .

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questions

the melting points of saturated hydrocarbons are determined mainly by their number of

a) double bonds.

b) hydrogen atoms.

-->  c) carbon atoms.

d) none of the above

which saturated hydrocarbon has the chemical formula c2h6?

a) methane

-->  b) ethane

c) propane

d) butane

which saturated hydrocarbon has eight carbon atoms?

a) pentane

b) hexane

c) heptane

-->  d) octane

methane has a higher boiling point than ethane.

a. true

-->  b. false

some alkanes are solids are room temperature.

-->  a. true

b. false

diagram questions

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