Chem 219: Module 2 Exam with 100% Correct Solutions

Chem 219: Module 2 Exam with 100% Correct Solutions What are hydrocarbons? - Answer -Molecules composed of only the elements carbon and hydrogen What are the two major classes of hydrocarbons? - Answer -Aromatic (benzene) and aliphatic (alkanes, alkenes, alkynes) What is the main source of hydrocarbons? - Answer -Fossil fuels like coal, petroleum, and natural gas obtained by mining and drilling. What are Alkanes? - Answer -They are saturated hydrocarbons because their skeleton is only composed of C-C single bonds. How can alkanes exist? - Answer -They can be linear, branched or exist in ring formations called cycloalkanes. Describe a higher/more complex alkane structure: - Answer -They will have more carbons and/or increased structural diversity. What is the general formula of Alkanes? - Answer -CnH2n+2 The names of the alkanes reflect? - Answer -The number of carbons present. How many isomers does each alkane have from 1-10 - Answer -1,1,1,2,3,5,9,18,35,75 Name the first ten prefix of alkanes: - Answer -Methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane. As the molecular weight increases: - Answer -The number of isomers increase. What does the suffix -ane mean? - Answer -Denotes a saturated hydrocarbon. It is used for all acyclic saturated alkanes What is nomenclature? - Answer -The naming of a molecular structure. Historically they were named after their source, now they are systemic. Why is nomenclature important? - Answer -Because we cannot remember all the prefixes since a MF composed of carbons can have several different patterns of connectivity. What is it meant by the systemic approach? - Answer -There are now methods of naming molecules so that they all have unique names. You can then determine the structure from only the name and viceversa. IUPAC rules for naming branced alkanes: - Answer -1. Find the parent name by identifying the longest continuous chain of carbons.2. Number the parent chain. (begin at the end of the chain nearest to the first branch.) 3. If there are two equally long continuous chains, select the one with most branches. 4. If the first branch point is the same distance, choose the one that gives the lowest substituents. 5. If the substituents are both equidistant then choose the numbering so the substituent goes with the higher alphabetic priority. How are linear alkanes named? - Answer -By combining the prefix indicating the number to the suffix - ane. What is a substituent? - Answer -Any group attached to the parent chain. What are alkyl groups? - Answer -Saturated hydrocarbon substituents. You drop the -yl for -ane. A one carbon substituent is a methyl group,