UNIT 4 - ORGANIC CHEMISTRY QUESTIONS AND ANSWERS

  What are R Chains - Correct Answers: Demonstrate the Length of the Carbon Chain What is used to show the movement of an electron pair (2)? - Correct Answers: A curly arrow What does the X represent? - Correct Answers: A Halogen (CnH2n+1X) Where is the R group located in a primary chain? - Correct Answers: At the end/start of the chain Where is the R group located in a secondary chain? - Correct Answers: In the middle of the chain Where is the R group located in a tertiary chain? - Correct Answers: Located in 3 regions of the chain forming a branched chain What are the forces between C-H bonds in a carbon chain? - Correct Answers: Van der Waals Forces (the weakest) Why does the halogen (X) bond to a carbon atom on a hydrocarbon chain? - Correct Answers: Carbon is partially polar (+ve) and the halogen is also partially polar (-ve) What is electronegativity? - Correct Answers: The ability of an atom to attract electrons in a covalent bond, towards itself (occurring due to nuclear charge, dependant on the amount of shells, and is strongest when there is no shielding) What is used o show the movement of one electron - Correct Answers: Half of a curly arrow What is a Nucleophile (Nu -ve)? - Correct Answers: Species (e.g., group) with a lone pair of electrons, and either a negative charge or with a bonded atom with a partially -ve charge Summarise a nucleophile in 2 points - Correct Answers: Has lone pair availability Electron pair donor How does a nucleophile react? - Correct Answers: It is attracted to an electron deficient atom to form a new covalent bond: by donating a pair of electrons Name 3 examples of nucleophiles and draw out their mechanism - Correct Answers: Ammonia (NH3) Cyanide (CN) Hydroxide (OH) Look up the mechanisms on the internet and use the available Flashcards that you made State the conditions needed in Fractional Distillation to produce refinery gas - Correct Answers: 50 degrees Celsius C1-C4 in hydrocarbon length State the conditions needed in Fractional Distillation to produce gasoline/petrol and its production abundance - Correct Answers: C5-C10 in hydrocarbon length 8%-10% abundance State the conditions needed in Fractional Distillation to produce naphtha - Correct Answers: 120 degrees Celsius C8-C12 in hydrocarbon length State the conditions needed in Fractional Distillation to produce kerosine - Correct Answers: C10 - C16 in hydrocarbon length State the conditions needed in Fractional Distillation to produce diesel oil and its production abundance - Correct Answers: 250 degrees Celsius C14 - C20 in hydrocarbon length Abundance of 45% State the conditions needed in Fractional Distillation to produce lubricating oil - Correct Answers: C20 - C50 in hydrocarbon length State the conditions needed in Fractional Distillation to produce fuel oil - Correct Answers: 350 degrees Celsius C50 - C70 in hydrocarbon length State the conditions needed in Fractional Distillation to produce bitumen - Correct Answers: C70 in hydrocarbon length Explain the meaning of substitution as applied to nucleophilic substitution in a haloalkane (1) - Correct Answers: It is the replacement of halogen by the nucleophile (halogen becomes halide ion) Suggest why cars filled illegally with fuel intended for tractors might emit harmful black fumes from the exhaust (3) - Correct Answers: Cars can take in petrol - short chain hydrocarbons Which require less oxygen to burn Tractors take in diesel - long chin hydrocarbons Incomplete combustion produces carbon monoxide Suggest why the cost of petrol has increased and he cost of diesel has decreased? (2) - Correct Answers: Crude oil consists of 8-10% of petrol only and has 45% of diesel How does thermal and catalytic cracking occur? (2) - Correct Answers: Thermal: Heating alkanes to a high temperature 700-1200K 7000KPa Catalytic: Lower temperature and pressure Uses a zeolite catalyst (silicon dioxide, or aluminium oxide) What are the products of thermal and catalytic cracking? (2) - Correct Answers: Thermal = Mixture of Alkanes and Alkenes Catalytic = branches alkanes, cycloalkanes, aromatics (benzene) List the emissions which are considered atmospheric pollutants: explaining how each is produced with balanced equations (4) - Correct Answers: Carbon monoxide: incomplete combustions C3H8 + 3.5O2 — 3CO + 4H2O NOx: nitrogen and oxygen from the air combine N2 + O2 — 2NO Sulfur dioxide: SO2 + H2O — H2SO4 + 1.5O2 — H2SO4 Explain how petrol is obtained from crude oil (6) - Correct Answers: Crude oil is heated until vapouriest, through fractional distillation Liquid and vapour pass though the fractionating column: cooler liquid is then collected at the top Vapour then rises until they reach a tray which is cool enough for them to condense What acts like a catalyst in the ozone layer? - Correct Answers: CFCs Absorption vs Adhesion (from catalysts) - Correct Answers: Adsorption - molecules stick to catalyst Absorption - molecules are drawn to the catalyst What is the catalyst and use of the Harber process? - Correct Answers: Iron Making fertilisers What is the catalyst and use of the Ostwald process for making nitric acid - Correct Answers: platinum and rhodium Fertilisers and explosives What is the catalyst and use of the process of Hardening Fats? - Correct Answers: Nickel Making margarine What is the catalyst and use of the process in a Catalytic Converter - Correct Answers: Platinum and rhodium Removing pollutant gases What is the catalyst and use of the Hydration of ether to ethanol - Correct Answers: H+ ions (from H3PO4) Solvent, Chemical feed stock What is the catalyst and use of the esterification (making of esters) reaction? - Correct Answers: H= ions Making solvents What are the 4 stages of the Free radical mechanism? - Correct Answers: Initiation propagation 1 Propagation 2 Termination Outline the free radical mechanism using Cl2 - Correct Answers: (Full outline in Flashcards or on the internet) Initiation: Cl2 — Cl* + Cl* Propagation: Cl* + CH4 — HCl + *CH3 Propagation 2: *CH3 + Cl2 — CH3Cl + Cl* Termination: Cl* + Cl* — Cl2; *CH3 + *Cl — CH3Cl; *CH3 + *CH3 — C2H6 What is the condition needed for free radical mechanisms? - Correct Answers: UV Light What is the over all equation for the depletion of the ozone layer? - Correct Answers: 2O3 — 3O2 What are the steps to the formation of the ozone layer? - Correct Answers: O2 — *O* + *O* *O* + O2 — O3 O3 — *O* + O2 Steps 2 and 3 occur simultaneously Outline the entire process ofCFCs in the destruction of the ozone (O3) - Correct Answers: Initiation: CClF3 — Cl* + *CF3 Propagation: Cl* + O3 — ClO* + O2 Propagation 2: ClO* + O3 — Cl* + 2O2 Termination: Cl* + *CF3 — CClF3; Cl* + Cl* — Cl2; *CF3 + *CF3 — C2F6 What is a elimination reaction? - Correct Answers: A reaction where an atom or group of atoms is removed from a reactant, forming alkenes and water True or False: CFCs are naturally inert - Correct Answers: True Why are acids proton donors? - Correct Answers: have hydrogen ions that they can donate - bases then accept them What are the problems with elimination reactions? - Correct Answers: Mixture of products formed as he hydroxide ion can attack other substances due to more than 4 carbons on the halogenoalkane (halogen is not on end carbon) Outline a elimination reaction - Correct Answers: Search it up or found in Flashcards What are the conditions needed for a elimination reaction? - Correct Answers: NaOH aqueous solution Weak base (no ethanol) Warm temperature Primary or secondary R chains What are the conditions needed for a nucleophilic substitution reaction? - Correct Answers: NaOH ethanolic solution Strong base (ethanol) Hot temperature Tertiary R chains (always) What is the definition of a general formula? - Correct Answers: An algebraic formula that can describe any member of a family of compounds What is the definition of the empirical formula? - Correct Answers: The simplest whole number ratio of atoms of each element in a compound What is the definition of a molecular formula? - Correct Answers: The actual number of atoms of each element in a molecule What is the definition of the structural formula? - Correct Answers: Shows the atoms carbon by carbon, with the attached hydrogens and functional groups What is the skeletal formula? - Correct Answers: Shows the bonds of the carbon skeleton only with any functional groups (hydrogen and carbon atoms aren't shown) What is the displayed formula? - Correct Answers: A displayed formula shows how all the atoms are arranged and all the bonds between them What is a homologous series? - Correct Answers: A homologous series is a bunch of organic compounds that have the same general formula and similar chemical properties. What is the general formula for alkanes? - Correct Answers: CnH2n+2 How do you name an organic compound? - Correct Answers: 1. Count the number of carbons in the longest continuous chain following the functional group (stem) 2. suffix of the main functional group 3. Number the carbons in the longest carbon chain 4. Any side-chains or less important functional groups are added as prefixes at the start of the name (alphabetical order) What does a mechanism do? - Correct Answers: Breaks down a reaction into individual stages What are isomers? - Correct Answers: compounds with the same molecular formula but different structures and properties What are structural isomers? - Correct Answers: Compounds with the same molecular formula but different structural formula What are the types of structural isomers? - Correct Answers: Chain, Positional, and Functional Group isomers What are chain isomers? - Correct Answers: Chain isomers are a type of structural isomer. They have different arrangements of the carbon skeleton. Some are straight chains and others are branched in different ways. What are positional isomers? - Correct Answers: Positional isomers are a type of structural isomer. They have the same skeleton and the same atoms or groups attached but the group of atoms are attached to a different carbon atom. What are functional group isomers? - Correct Answers: Functional group isomers area type of structural isomer. They have the same atoms arranged into different functional groups. What are stereoisomers? - Correct Answers: Compounds with the same structural formula but with a different arrangement of the atoms in space. What qualities does an isomer need to have to be a stereoisomer? - Correct Answers: - double carbon bond - no rotation on the plane - E/Z isomerism Why do alkenes show E/Z isomerism? - Correct Answers: They have restricted rotation around their carbon-carbon double bonds What is a Z isomer? - Correct Answers: the groups of higher priority (higher atomic number) are on the same side of the double bond (both above or both below) What is a E isomer? - Correct Answers: an isomer where the functional groups are on different sides How do you use the CIP system to identify a E/Z isomer? - Correct Answers: 1. Assign a priority to the two atoms attached to each carbon in the double bond: look at the atoms that are directly bonded to each of the C=C carbon atoms. The atoms with the higher atomic number on each carbon is given the higher priority 2. To work out which isomer you have, just look at how the two higher priority groups are arranged Why would we use the CIP system? - Correct Answers: When the C=C bond is surrounded by 3 or 4 different groups When would you have to look at the next atom in the groups to work out which has the higher priority? - Correct Answers: If the atoms are directly bonded to the carbon are the same When do you know if you have drawn the same isomer twice? - Correct Answers: If you can switch between two drawings of a molecule, either by rotating the C-C single bonds or rotating the entire molecule, then you've drawn the same isomer twice What are cycloalkanes? - Correct Answers: saturated hydrocarbons made up of carbon atoms joined in rings What is a free radical? - Correct Answers: A molecule with at least one unpaired electron How do free radicals form? - Correct Answers: when a covalent bond splits equally giving one electron to each atom What are photochemical reactions? - Correct Answers: reactions started by UV light Why are CFCs banned? - Correct Answers: They damage the ozone layer What are the three main types of reactions of halogenoalkanes? - Correct Answers: Halogenoalkanes + Hydroxides = Alcohols Halogenoalkanes + Cyanide = Nitriles Halogenoalkanes + Ammonia = Amines True or False: iodoalkanes react fastest, and fluoroalkanes react the slowest - Correct Answers: True Why do iodoalkanes react the fastest? - Correct Answers: The C-I bond has the lowest bon enthalpy Easier to break Substituted more quickly