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CHEM 219 LATEST EXAM WITH
DETAILED QUESTIONS AND VERIFIED
ANSWERS
question-The solubility of a gas in a liquid generally - answer-increases with lowering temperature and increases with increasing pressure question-ionization energy moves - answer-up and to the right on the periodic table question-ionization energy is - answer-the energy required to remove an electron from an atom question-nonpolar does not dissolve - answer-polar question-a molecule is polar if - answer-it is not cute question-a molecule is nonpolar if it is - answer-cute question-density of gas equation - answer-D=MP/RT question-Standard Temperature and Pressure (STP) - answer-A temperature of 273 K and a pressure of 1.00 atm. and 22.414 L
question-a bond in which an electron pair is unequally shared by 2 atoms is - answer-polar covalent Sublimation - answer-solid to gas question-Condensation - answer-Gas to liquid question-Evaporation - answer-Liquid to gas question-Deposition - answer-gas to solid question-polar covalent is - answer-a type of bond that forms when electrons are not shared equally question-nonpolar covalent bond - answer-A type of covalent bond in which electrons are shared equally between two atoms of similar electronegativity. N=N question-order of IMFs from strongest to weakest - answer-H-Bonding > Dipole-Dipole > LDF question-can an atom be excited to a higher energy level? - answer-yes by absobring light energy question-How are frequency and wavelength related? - answer-They are inversely proportional
question-transfer of electrons occur between - answer-nonmetal and metal question-electron affinity is - answer-the energy needed to remove an electron from a negative ion to form a neutral atom or molecule question-Electronegativity - answer-how much an atom attracts electrons question-solid to a liquid and to a gas are - answer-endothermic question-gas to a liquid to a solid is - answer-exothermic What are hydrocarbons? - answer-Molecules composed of only the elements carbon and hydrogen question-What are the two major classes of hydrocarbons? - answer-Aromatic (benzene) and aliphatic (alkanes, alkenes, alkynes) question-What is the main source of hydrocarbons? - answer-Fossil fuels like coal, petroleum, and natural gas obtained by mining and drilling. question-What are Alkanes? - answer-They are saturated hydrocarbons because their skeleton is only composed of C-C single bonds.
question-How can alkanes exist? - answer-They can be linear, branched or exist in ring formations called cycloalkanes. question-Describe a higher/more complex alkane structure: - answer-They will have more carbons and/or increased structural diversity. question-What is the general formula of Alkanes? - answer-CnH2n+ question-The names of the alkanes reflect? - answer-The number of carbons present. question-How many isomers does each alkane have from 1- 10 - answer-1,1,1,2,3,5,9,18,35, question-Name the first ten prefix of alkanes: - answer-Methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane. question-As the molecular weight increases: - answer-The number of isomers increase. question-What does the suffix - ane mean? - answer-Denotes a saturated hydrocarbon. It is used for all acyclic saturated alkanes question-What is nomenclature? - answer-The naming of a molecular structure. Historically they were named after their source, now they are systemic.
Describes the position of substituents. question-What happens when two or more of the same type of substituents are present on the parent chain? Like 3 methyl groups - answer-Additional prefixes including the number are added. question-How would you describe finding 2,3 dimethylpentane? - answer-It is a 5 carbon chain, then it has substituents on numbers 2, 3 and those are methyl groups. question-How are IUPAC systematic names put together? - answer-Locant-(prefix) substituentparent question-If two or more different substituents are present on the parent chain then what happens?
- answer-They are listed alphabetically. Ethyl before methyl question-How are halogen atoms as substituents named? - answer-Change the - ine to - o, chlorine=chloro, bromine=bromo. question-propyl or n-propyl - answer-CH3CH2CH question-isopropyl - answer-CH3CHCH question-What does the squiggle bond mean? - answer-Point of attachment to the parent chain.
question-Butyl or n-butyl - answer--CH2CH2CH2CH question-sec-butyl - answer-CH3CHCH2CH question-isobutyl - answer- question-tert-butyl - answer- question-Isobutyl would be alphabetized as? While sec-butyl would be alphabetized as? - answer-I, B question-What does R represent? - answer-It is a generic/wildcard notation in organic structure. Any alkyl group. This is known as R-group notation. question-Why is R chosen? - answer-It is not on the chart anywhere. question-What is the important thing to know about the physical properties of alkanes. - answer- They will show similar trends in terms of their physical properties. question-What does the physical properties of a molecule refer to? - answer-Characteristics like melting point, boiling point, density, solubility.
question-What is the relationship between branching and VDWF? - answer-As you branch out you gain more surface area and lower the VDWF. Which lowers the BP and MP question-Alkanes can adopt different conformations, What does this mean? - answer-This means that it can change shapes as it can rotate around bonds. question-Hydrogen bonding and VDWFS are classifies as nonbonding intermolecular forces, what does this mean? - answer-That they are attractive forces between molecules that are not true bonds in the sense of sharing or donating. question-What are conformers? - answer-Different shapes of molecules that are derived by rotations of single bonds. question-What does the Newman projection do? - answer-It shows the conformation of molecules when looking down a particular bond axis. question-What is the difference in hydrogen placement between an eclipsed confirmation and a staggered one? - answer-The hydrogens do not overlap in staggered but they do in eclipsed. question-Certain conformers are called rotamers, why? - answer-They can simply be rotated into the other conformer. Used with newman projections question-Staggered vs. Eclipsed Conformers - answer-Staggered are generally more stable, because of the removed repulsion that occurs when electrons are aligned on top of each other in an eclipsed.
question-How do you name newman projections? - answer-Find the first carbon chain, attach it to the front carbon. The rest are substituents. Then attach it to the back carbon. Then attach the first carbon chain, the rest are substituents. question-Can conformers be isolated at room temp? - answer-No, because theres a lot of thermal energy, it starts the rapid inter conversion of conformers. Meaning it rotates back and forth question-What are cycloalkanes? - answer-Alkanes whose carbon skeleton forms a ring. (only c- c sigma bonds) question-Cycloalkanes that have 1 ring has the general formula of? - answer-Cn+H2n question-How are cycloalkanes named? - answer-With the prefix cyclo- in front of the corresponding alkane name question-What is the systemic approach when alkyl substituents are present? - answer-1. If only one substituent is present then no locants (numbers) are used.
- If more than one is present. It is put in order question-What is angle strain? - answer-When bond angles deviate from their ideal values by being stretched or compressed question-What is torsional strain? - answer-When cyclic molecules must assume conformations that have eclipsed interactions
question-Alkanes can be used as ______ - answer-Solvents due to being inert. question-The sigma bonds in alkanes are: - answer-covalent non-polar. question-The two reactions alkanes go under are? - answer-Combustion (Oxidation) and substitution. question-What happens in combustion (oxidation) - answer-Burning as fuel. CH + O always makes CO2 and H2O. It is exothermic. question-If a fossil fuel is combusted in a partial oxygen atmosphere, what will happen? - answer-Oxidation will be incomplete and it will produce carbon monoxide (spark) question-What happens in a radical halogenation reactions (substitutions)? - answer-This is to reintroduce reactivity into an alkane. Halogen atoms (Cl or Br) are substituted for hydrogen atoms. The product is an alkyl halide (haloalkane) Heat or UV light is used. question-Chlorinated vs Bromination? - answer-When Chlorine is used and when Bromine is used.
question-How can radical halogenation be represented: - answer-R-H + X-X - > R- X + H-H question-What are polyhalogen compounds? - answer-Compounds that contain more than 1 halogen atom. question-Why is radical halogenation only used when simple specific alkyl halides are required?
- answer-As the structure grows, the mixture of products becomes even more complex and becomes challenging to separate the product mixture to obtain the desired isomers. question-What is an Alkene? - answer-An alkene is unsaturated hydrocarbon with at least one C=C bond question-What does it mean to be an unsaturated hydrocarbon? - answer-They have a lower hydrogen to carbon ratio than their saturated counterparts. question-What is the formula for for Alkenes? - answer-Cn+H2n question-What is an alkyne? - answer-unsaturated hydrocarbon with at least one triple bond question-What is the formula for alkynes? - answer-CnH2n- 2 question-Olefins are ___ while acetylenes are ____? - answer-Alkenes, alkynes
question-How do you draw cis/trans isomers? (To find out what they are) - answer-if the double carbon is at the end it wont be possible. But if you the lines next to the C=C going in the same direction cis, opposite trans. question-The triple carbon bonds of alkynes are: - answer-sp with linear shape. The remaining 2 p make 2 pi bonds. question-What is distillation? - answer-separates liquids with different boiling points question-What is an addition reaction? - answer-It adds atoms or groups of atoms to each carbon of the multiple bonds. question-How is bromine used for finding alkenes? - answer-The orange brown that normally appears when bromine is added to compounds is dispersed when added to alkanes.Canbe. ualitative question-What happens when you add water to an alkene? H + OH - answer-It converts an alkene into an alcohol question-What happens if you add acid to alkenes? - answer-The H is attached to a carbon and the A is attached to the other. question-What it is H-A supposed to mean in the addition of acids? - answer-H is the acid A is the rest H-A
question-With alkenes: H-OH H-Br Br H What kind of reactions are these? - answer-Hydration Addition of an acid Halogenation Hydrogenation question-Hydration reactions of alkenes will look like? - answer-The product is an alcohol creates - anol at the end H-OH question-Halogenation reactions look like: - answer-Adding chlorine and bromine easily question-Hydrogenation reactions look like: - answer-Referred to as a reduction and produces cis isomers. question-What happens if you add hydrogen to alkenes? - answer-It converts to an alkane. Because it become saturated. Also known as a reduction. It requires a coinage metal as a catalyst
They are stable and don't have many reactions. Referred to as - arenes. question-What is Benzene? - answer-The primary aromatic hydrocarbon. Six membered ring of carbon atoms containing three altering C=C bonds within the ring question-What is the structural formula of Benzene? - answer-They originally thought that the double bonds were just moving so fast that you couldn't get it at a certain place. We now know that it is just spread out. Planar question-What is the geometry of Benzene? - answer-Each of the six carbons are sp2 hybridized with 120 bonds and trigonal planar geometry. question-Since Benzene is stable, what can its symbols look like? - answer-Regular hexagon with three lines. Hexagon with a circle(the carbons are moving). -----C6H _______Φ -----Ph question-Toluene - answer-benzene with CH question-Phenol - answer-Benzene ring with - OH question-Anisole - answer-benzene with OCH
question-Benzoic acid - answer-C6H5COOH question-Aniline - answer-benzene with NH question-Benzaldehyde - answer-benzene with CHO question-How do you use IUPAC nomenclature of Aromatic Compounds? - answer-1. The parent compound is benzene and the name of the substituent group is added before it.
- When two substituents are present, the prefixes ortho, meta, and para are used to describe 2,3,4 carbons respectively. (1,2. 1,3. 1,4.)
- If there are 3 or more then locants, numbers are used question-Where is ortho, meta and para on benzene? - answer-1, 5 are ortho. 2, 4 are meta. 3 is para. question-What are polycyclic aromatic hydrocarbons? - answer-They are composed of more than one benzene rings that are fused together, sharing two or more carbons. Nepthalene. Anthracene. Pyrene. question-What are typical reactions of Aromatic Compounds? - answer-They are usually unstable, lacking reactivity. Because they are conjugated they only undergo one reaction. EAS.
