hydrocarbons and combustion reactions · 2018-03-09 · hydrocarbons •swbat name and draw...

Hydrocarbons and Combustion Reactions

Benchmarks

SC.912.P.8.7 Interpret formula representation of molecules and compounds in terms of composition and structure.

SC.912.P.8.8 Characterize types of chemical reactions, for example: redox, acid-base, synthesis, combustion, and single and double replacement reactions.

Objectives

Hydrocarbons

• SWBAT name and draw hydrocarbons with and without carbon-carbon double bonds.

• SWBAT explain why each element forms a specific number of bonds.

• SWBAT write chemical formulas for simple hydrocarbons.

• SWBAT draw and name basic hydrocarbon structures.

Combustion Reactions

• SWBAT classify combustion reactions.

• SWBAT write and balance combustion reactions.

• SWBAT recognize properties of carbon dioxide and oxygen gas.

Essential Question

Hydrocarbons

• What is the importance of the term organic chemistry?

Combustion

• How do combustion reactions work?

H.O.T Questions

Hydrocarbons

• Does organic mean one thing to shoppers and another to chemists?

• What would happen if you attempted to light carbon dioxide on fire?

• At the gas station, you might have noticed that there re different ratings of gas (87, 89, 91, 93), which identifies the specific ratio of octane based compounds. These fuels actually deliver the same amount of energy pertaining to combustions from (87-93). On the other hand, you might have noticed that race cars use alcohol based fuels such a methanol, which does deliver better combustion within a naturally aspirated car. Explain at the molecular level why the difference between octane and methanol changes the rate of combustion.

Combustion Reactions

• What does soot represent in the investigation?

• What can be used to put out an unwanted fire in a kitchen?

• This is a quick way to depict how many valence electrons atom(s) have

• Examples of Lewis Dot Structures:

Review- Lewis Dot Structure

• Valence electrons: These are the number of electrons

an atom has on their outer shell

• Remember each group (column) shares the same # of

valence electrons

Review- Valence Electrons

Mr. Dean

What is Organic Chemistry?

Chemistry of compounds that contain carbon

• Combine mainly with hydrogen, oxygen, and nitrogen

• Over 10 million compounds made with these 4 elements

95% of compounds contain carbon

• Form stable, covalent bonds with each other

Definitions

Hydrocarbons: these are compounds that only contain the elements CARBON and HYDROGEN.

Substituents: an atom or group of atoms taking the place of another atom or group or occupying a specified position in a molecule.

Valence electrons: electrons that exist on the outer most ring of an atom.

Determining the Structure of a HydrocarbonDecide how many carbons there will be in the molecules.

Hydrocarbon Name Number of Carbons

Methane 1

Ethane 2

Propane 3

Butane 4

Pentane 5

Hexane 6

Heptane 7

Octane 8

Nonane 9

Decane 10

Determining the amount of Hydrogens in a Hydrocarbons

• To determine the amount of hydrogens in a hydrocarbon Alkane (Single Bonded)

• To determine the amount of hydrogens in a hydrocarbon Alkene (Double bonded)

• To determine the amount of hydrogens in a hydrocarbon Alkyne (Triple bonded)

# of Hydrogens = (# of Carbons x 2) + 2

# of Hydrogens = # of Carbons x 2

# of Hydrogens = (# of Carbons x 2) - 2

Name that HydrocarbonNumber of Carbons Number of Hydrogens Hydrocarbon Name

8

5

4

2

6

3

9

18

10

6

14

8

20

12

Octane

Butane

Ethane

Hexane

Propane

Nonane

Pentane

1. Write draw the Carbon Backbone chain based on the name of the hydrocarbon making sure to connect each carbon with a single line (check the name list).

2. Use a single line to connect each carbon to a hydrogen. There should be no free carbons left.

Drawing Simple Hydrocarbons

C C C C C CC

Heptane

H H H H H H H

H H H H H H H

H

H

= 7 Carbons in chain = atleast 1 single bond

1. Write draw the Carbon Backbone chain based on the name of the hydrocarbon making sure to connect each carbon with a single line (check the name list).

2. Use a single line to connect each carbon to a hydrogen. There should be no free carbons left.

Drawing More Complex Hydrocarbons

C C C C C CC

Heptene

H H H H H H

H H H H H H

H

H

= 7 Carbons in chain = atleast 1 double bond

Notice that 2 Hydrogens are missing. Why?

1. Write draw the Carbon Backbone chain based on the name of the hydrocarbon making sure to connect each carbon with a single line (check the name list).

2. Use a single line to connect each carbon to a hydrogen. There should be no free carbons left.

Drawing EVEN More Complex Hydrocarbons

C C C C C CC

Heptyne

H H H H H

H H H H H

H

H

= 7 Carbons in chain = atleast 1 triple bond

Notice that 4 Hydrogens are missing. Why?

Akyl Groups

• Change the root name ending from –ane to -yl

• These are groups that will be attached to more complex carbon chains. Each group is named based on the length of its carbon-carbon chain.

• Always number starting from the side that is closest to a substituent.

• When writing the name always list the substituents in alphabetical order.

Number of

Carbons1 2 3 4 5 6 7 8 9 10

prefix meth- eth- prop- but- pent- hex- hept- oct- non- dec-

Molecule Name

methyl ethyl propyl butyl pentyl hexyl heptyl octyl nonyl decyl

• Geneva, Switzerland 1892

• International Union of Pure and Applied Chemistry

• IUPAC System of Nomenclature• (isobutane, isopentane are common names)

Hydrocarbon Nomenclature (IUPAC)

C

Hydrocarbon Nomenclature Rules (IUPAC)1. Find and name the longest chain in the parent compound and number each carbon. If it only has single bonds the name end in –ane. If it has a double bond the name will end in –ene.(Root name)

Example:

C C C C C

C

C

C

CC1 2 3 5 764

Hydrocarbon Nomenclature Rules (IUPAC)

2. Make a note of the alkyl groups attached to the chain.

Example:

C C C C C

C

C

C

CC

C

C

Hydrocarbon Nomenclature Rules (IUPAC)

C C C C C

C

C

C

CCC C C C C

C

C

C

CC1 2 3 5 764

2nd and 6th Carbon:Methyl groups

4th Carbon:Ethyl group

3. Determine the number of the carbon that the group(s) is/are attached to. Must use the lowest number possible for each attached group.

Example:

Hydrocarbon Nomenclature Rules (IUPAC)4. Name the attached groups there are on the chain. Combine like groups.

Example:

C

C C C C C

C

C

C

CCC C C C C

C

C

C

CC1 2 3 5 764

Prefixes1 – mono-2 – Di-3 – Tri-4 – Tetra-5 – penta-6 – hexa-7 – hepta-8 – octa-9 – nona-

4-ethyl6-methyl

2-methyl 2,6 di-methyl

5. If there are more than two or more different substituents, list them in alphabetical order with the numbers. Name the hydrocarbon.Example:

Hydrocarbon Nomenclature Rules (IUPAC)

C

C C C C C

C

CCC C C C C CC

4-ethyl-2,6-di-methylheptane

Naming Hydrocarbons with Akyl Groups

C C C C C

C

H H H H H

H H H H

H

H

H

H

H

Naming Hydrocarbons with Multiple Akyl Groups

C C C C C

C

H CH3 H H

H H H H

HH

H

H

H

H

H

H

C

Complete Independent Practice Worksheet #1

Independent Practice

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Mr. Dean

Definitions

Combustion Reaction: occurs when a hydrocarbon (compound made up of hydrogen and carbons) reacts with oxygen. Usually produces Carbon dioxide (CO2) and water (H2O)

Reactants: a substance that takes part in and undergoes change during a reaction.

Products: substances that are produced after the reaction has taken place.

Information on Combustion Reactions

• Combustion is considered a chemical change.

• Fire/Burning flame are general signs that a combustion reaction is taking place.

• An incomplete combustion reaction happens when there is not enough oxygen in the reactants and produces CO instead of CO2

Balancing EquationsTips for combustion reactions

1. Predict the products of the combustion equation (CO2 and H2O—Always!!!)

2. Balance the carbon and hydrogen atoms on both sides of the equation.

3. Then, balance the oxygen atoms. ...

4. Finally, balance anything that has become unbalanced.

Balancing Equations will always follow what law?

Law of Conservation of Mass

Balancing Combustion Reactions

__C3H8 + __O2 →

Reactants Products

:C:

:H:

:O:

__ CO2 __ H2O+What will this type of reaction always produce?

Properties of Carbon Dioxide

• Colorless/odorless gas

• Extinguishes flames (used in fire extinguishers)

• Produced by living organisms as a product of cellular respiration.

• Covalently bonded compound

• Carbon dioxide is used by the food industry, the oil industry, and the chemical industry.

Properties of Oxygen

• Colorless/odorless gas

• Essential for breathing and cellular respiration

• Produced by plants during the process of photosynthesis.

• Highly Reactive when in contact with flames

• Covalently bonded molecule

Practice Problem #1

Name C4H10

____________________

Balance the Chemical Equation:__C4H10 + __O2

Draw the structure of C4H10

Practice Problem #2

Name C6H14

____________________

Balance the Chemical Equation:__C6H14 + __O2

Draw the structure of C9H20

Practice Problem #3

Name C9H20

____________________

Balance the Chemical Equation:__C9H20 + __O2

Draw the structure of C9H20

Complete Independent Practice Worksheet #2

Complete Independent Practice Worksheet #3

Independent Practice

Exit Slip

1. Draw the Lewis dot structure for Lithium (Li).

2. How many hydrogens are in a hydrocarbon with 6 Carbon atoms?

3. What is the name of the hydrocarbon from the Question 2?

4. Write the chemical formula of the hydrocarbon?

5. Draw the structure of the Hydrocarbon from Question 2.