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organic chem Flashcards

1
Q

Organic compounds (definition)

A

Compounds whose molecules contain a significant amount of carbon

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2
Q

Hydrocarbons

A

Compounds which contain only H and C

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3
Q

Fractional distillation

A

Peter Pan Never Kiss Donkey’s Little Fluffy Butt (Petroleum gas, Petrol, Naphtha, Kerosene, Diesel, Lubricating oil, Fuel oil, Bitumen)

[Heater at bottom]
Volatility increase upwards
Flow/ignite more easily upwards

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4
Q

Properties of carbon (2)

A
  • Each contains 4 valence electrons (tetravalent)
  • Can form strong bonds with each other to form long chain-like structures, stable
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5
Q

Prefix

A
  1. Methyl (CH3)
  2. Ethyl (CH2CH3)
  3. Propyl (CH2CH2CH3)
  4. Butyl (CH2CH2CH2CH3)

*increases by one CH2
*add di-/tri- etc if got more than one substituent

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6
Q

Parent

A
  1. Meth-
  2. Eth-
  3. Prop-
  4. But-
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7
Q

Suffix

A

*highest priority: suffix, others: prefix

  1. Alkanes: -ane
  2. Alkyl (alkane with one hydrogen removed): alkyl-
  3. Alkenes: -ene
  4. Carboxylic acids: carboxy-/-oic acid
  5. Alcohols: hydroxy-/-ol
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8
Q

Isomerism types (4) + definition

A

Phenomenon in which ≥2 compounds with the same molecular formula exist in different forms due to different arrangement of atoms in the molecule

Structural (atoms in diff order)
Skeletal (diff carbon skeletons)
Positional (diff position of func groups)
Functional (diff func groups)

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9
Q

Addition

A

2 reactants –> 1 product

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10
Q

Elimination

A

1 reactant –> 2 products

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11
Q

Substitution

A

2 reactants –> 2 products (exchange parts)

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12
Q

Alkanes (general formula, functional group, name)

A

C n H 2n+2
NIL
-ane

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13
Q

Physical properties (alkanes)

A
  1. State: gas at room temp (first 4)
  2. Solubility: soluble in organic solvents, insoluble in water
  3. Low mp/bp
  4. Low density
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14
Q

Trends in physical properties (alkanes, alkenes, alcohols)

A
  1. mp/bp increase
    - molecular size increase, electron cloud size increase
    - larger amount of energy needed to overcome the stronger intermolecular FOA between atoms
  2. viscosity/density increase
    - molecular size increase, stronger intermolecular FOA between atoms
    - molecules slide over each other less easily, more viscous and flow less easily
  3. flammability decrease
    - number of carbon atoms increase, boiling points increase, less flammable
    - % of carbon in alkane molecules increase, flame produced more smoky/sooty
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15
Q

Effect of branching on mp/bp (alkanes/alkenes/alcohols/carboxylic acids)

A

Branched chain lower

  • Branched chain more spherical in shape than straight chain
  • Less SA of contact between neighbouring molecules
  • Less energy needed to overcome intermolecular forces of attraction
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16
Q

Chemical properties (alkanes)

A

Generally unreactive, inert

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17
Q

Combustion of alkanes

A

Equation: CxHy (g) + O2 (g) –> H2O (g) + CO2 (g)
- Highly exothermic
- Complete produces water and CO2, - Incomplete produces soot (C) and carbon monoxide

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18
Q

Cracking of alkanes (definition, conditions, product, importance in oil industry)

A

Breaking down of long-chain hydrocarbons to form smaller, more volatile molecules

Conditions: 600ºC, SiO2/Al2O3 catalyst
Products: alkene + alkane/H2

Oil industry: greater supply/yield of fuels in demand

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19
Q

Cracking of paraffin (set-up)

Things to note:
a. Tilted boiling tube
b. Porcelain chips
c. Flame
d. Gas collection

A

Set-up
- Boiling tube: base is mineral wool soaked in liquid paraffin, middle is porcelain chips (directly over flame)
- Connected to beaker via delivery tube
- Delivery tube connected to inverted test tube (show production of gas)

Things to note
1. Tilted boiling tube: prevent paraffin and porcelain chips from reacting
2. Porcelain chips: catalyst, inc SA
3. Flame: needs high temperature
4. Gas collection: displacement of water (NOT gas syringe because hot air will expand it even without reaction)

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20
Q

Substitution of alkanes (reagents, conditions, products)

A

Reagents: alkane + halogens
Conditions: UV light
Products: halogenoalkanes + HX

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21
Q

Uses + sources of alkanes

A

Uses: fuel/paraffin wax/road surfacing

Sources: fractional distillation of crude oil

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22
Q

Alkenes (general formula, functional group, name)

A

CnH2n
C = C
-ene

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23
Q

Physical properties (alkenes)

A

Same as alkanes

24
Q

Sources of alkenes

A

Cracking of alkanes

25
Q

Combustion of alkenes

A

Same as alkanes BUT
Sootier flame (higher proportion of C)
Can also be used as fuel but C=C bond allows it to have other functions

26
Q

Hydrogenation of alkenes (reagents, conditions, products)

A

Reagents: H2, alkene
Conditions: 200ºC, nickel catalyst
Products: alkane

27
Q

Application of hydrogenation (margarine)

A

Polyunsaturated oil –> saturated fat

*Margarine mostly saturated fat but also with small amount of unsaturated fat

28
Q

Bromination (reagents, conditions, products, test for alkane/alkene)

A

Reagents: liquid bromine/bromine in tetrachloromethane
Conditions: rtp, absence of UV light
Products: halogenoalkane (Br)

Test:
(liquid) Add a few drops of bromine in tetrachloromethane to unknown compound in the absence of UV light.
(gas) Bubble unknown gas through bromine in CCl4 through delivery tube.
(observations) Reddish brown bromine decolourises when added to alkene.

29
Q

Hydration of alkenes (reagents, conditions, products)

A

Reagents: H2O (steam), alkene
Conditions: phosphoric (V) acid catalyst, 300ºC, 60 atm
Products: alcohol

30
Q

Addition polymerisation of alkenes (definition, reagents, conditions, bonds)

A

Definition: successive linking of ≥ 2 unsaturated monomers (alkenes) without loss of molecules
Reagents: alkenes
Conditions: high pressure, high temperature, catalyst
Bonds: double –> single covalent bond

*‘H’ structure for each repeat unit

31
Q

Alkanes vs Alkenes (2 similarities, 6 differences)

A

Similarities:
1. both hydrocarbons
2. both flammable, complete combustion in air to produce CO2 + H2O (g)

Differences:
1. Reactivity (alkanes unreactive, alkenes very reactive)
2. Reactions (alkanes substitution, alkenes addition)
3. Reaction with bromine (only alkenes decolourise bromine)
4. Flame (alkanes less smoky/sooty)
5. Polymerisation (alkanes no, alkenes addition polymerisation)
6. Bonds (alkanes C-C saturated, alkenes C=C unsaturated)

32
Q

Deduce chemical formula of alkanes/alkenes in oxidation

A

Use CxHy + O2 –> x CO2 + y/2 H2O

x = no. of moles of CO2 ÷ CxHy
y/2 = no. of moles of H2O ÷ CxHy

Mole ratio
CxHy : H2O
CxHy : CO2
C in CO2 : H in H2O (*must x2)

33
Q

Alcohols (general formula, functional group, name)

A

CnH2n+1OH
OH
hydroxy-/-ol

34
Q

Why are alcohols not alkalis?

A

Covalently bonded to carbon, does not dissociate

35
Q

Physical properties of alcohols

A
  1. State: liquid
  2. Solubility: first few soluble in water, is an organic solvent
  3. Low melting/boiling points (volatile)
  4. Low density
36
Q

Trends in solubility (alcohols, carboxylic acids)

A

Decrease.
- Hydroxyl groups form H bonds with water molecules. (hydrophilic, polar)
- More energy to overcome the H bonds within hydrophobic hydrocarbon part of molecule

37
Q

Preparation of ethanol

A
  1. Hydration of ethene
  2. Fermentation
38
Q

Fermentation (how it works, conditions, equations)

Points to note:
a. Why temp as such
b. Why stopper reaction flask
c. Why limewater
d. Why dilute ethanol
e. How to inc concentration

A
  • Breakdown of glucose (carbs) by yeast into ethanol + carbon dioxide
  • 37ºC, absence of oxygen
  • Temp: any higher enzymes denature and lose catalytic functions
  • Stopper: prevent oxidation of ethanol into ethanoic acid when in contact with surr air
  • Limewater: air lock, prevent CO2 from entering
  • Dilute ethanol: enzymes will denature if too concentrated (alcohol form H bonds with proteins, disrupt intramolecular H bonds giving it shape, affects active site)
  • Fractional distillation
39
Q

Combustion of alcohols

A

Forms CO2 + H2O (g)
Highly exothermic, good as fuels BUT less energy efficient than alkanes (less E/unit mass)
- one O alr present, supply less, greater enthalpy change (release more heat)

40
Q

Primary vs Secondary vs Tertiary alcohols

A

Pri: func group to 1st C atom
Sec: func group to other C atoms
Tertiary: extra substituent

41
Q

Oxidation of alcohols (reagents, set-up, conditions, observations)

A

Reagents: acidified KMnO4
Set-up: round bottom flask with condenser (keep condensing and vaporising)
Conditions: heat under reflux
Observations: purple acidified KMnO4 turns colourless (Mn2+ reduced to Mn)

OR by air (produces CO2 + H2O)

42
Q

Carboxylic acids (general formula, functional group, name)

A

CnH2n+1COOH (n can be 0)
COOH
carboxy-/-oic acid

43
Q

Physical properties of carboxylic acids

A
  1. State: liquid
  2. Solubility: C1-4 very soluble, C5 slightly soluble (form strong H bonds with water molecules)
  3. High mp/bp
  4. High density
  5. Good electrical conductivity (simple molecular structure, dissociate to produce mobile H+ ions when dissolved in water, charge carriers)
44
Q

Trends in mp/bp (carboxylic acids)

A

Increase
- SMS, molecules held together by H bonds in addition to van der Waals’ FOA, more E to overcome

45
Q

Carboxylic acids + reactive metals (products)

A

Products: Salt + H2 (g)

*Salt formed = carboxylate eg CH3COONa (substitute H in COOH), ie sodium ethanoate
*CH3COO-

46
Q

Carboxylic acids + carbonate (products)

A

Products: Salt + H2O + CO2

*Carboxylate formed eg (HCOO)2Ca ie calcium methanoate

47
Q

Carboxylic acids + base (products)

A

Salt + H2O

*Carboxylate formed eg (C2H5COO)3Al ie aluminium propanoate

48
Q

Esters (functional group, physical appearance, solubility)

A

COO
Sweet smelling and colourless
Insoluble in water, soluble in organic solvents

49
Q

Esterification (type of reaction, reactants, conditions, equation, naming)

A

Type of reaction: condensation (loss of water molecule)
Reactants: carboxylic acid, alcohol
Conditions: strong conc acid eg H2SO4, heat
Equation: alcohol + carboxylic acid ⇌ ester + H2O
Naming: alcohol then acid ie methanol + ethanoic acid ⇌ methyl ethanoate

50
Q

How to increase yield in esterification

A

Increase concentration of reactants (alcohol/carboxylic acids)
Remove product to shift equilibrium to right to produce more product

51
Q

Role of concentrated sulfuric acid in esterification

A
  1. Catalyst
  2. Dehydrating agent; removes water as it forms to shift equilibrium to the right to increase yield of ester
52
Q

Polymers (definition, types)

A

Large molecules with high relative Ar, monomers (repeat units) covalently bonded through polymerisation

53
Q

Condensation polymerisation (definition)

A

Polymer formed when ≥ 2 types of monomers undergo covalent bonding with the loss of a small molecule eg H2O/HCl

54
Q

Condensation polymerisation; nylon, synthetic (products, monomers, type of bond, application)

A

Products: polyamide + H2O

Monomers: dicarboxylic acid, diamine

Type of bond: amide/peptide linkage (OH from COOH carboxyl grp of carboxylic acid + H from H2N amine group from diamine)
O = C - N - H

Application: resistant to attack by fungus/chemicals, used to make fabric/clothing like strong ropes and socks

55
Q

Condensation polymerisation; ester, synthetic (products, monomers, type of bond, application)

A

Products: polyester + H2O

Monomers: dicarboxylic acid, diol

Type of bond: ester bond (OH from COOH carboxyl func group in dicarboxylic acid + H from OH hydroxyl func group in diol)
O = C - O

Application: resistant to attack by chemicals/fungus, does not crumple easily, clothing materials (but combined with cotton as it is more absorbent and cool), plastic bottles, audio/video tapes

56
Q

Pros of synthetic polymers (4) + 2 examples of synthetic polymers

A

Nylon + terylene

  1. Cheap
  2. Light
  3. Durable
  4. Moulded into different shapes
57
Q

Cons of synthetic polymers (2)

A
  1. Burying (takes up landfill space, unsightly, leaching, pollute groundwater)
  2. Incineration (release toxic gases, global warming)

chem y4 (1 decks)

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