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Chemistry (OCR B - Salters) > DF > Flashcards

DF Flashcards

1
Q

What is the equation of Energy Transferred of Water, in an Enthalpy Reaction?

DF1

A

q = mcΔT
Energy transferred (kJ) = mass(kg) x specific heat capacity (J g^-1 K^-1) x temperature change (K)

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2
Q

What is an Endothermic Reaction?

DF1

A

When a reaction takes in energy from surroundings (ΔH = +n)

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3
Q

What is an Exothermic Reaction?

DF1

A

When a reaction releases energy to surroundings (ΔH = -n)

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4
Q

What are the definitions of Enthalpy Change of (Combustion, Reaction, Formation and Neutralisation) (CRFN)

DF1

A

ΔcH⦵298: 1mol of substance completely burnt in oxygen under STANDARD CONDITIONS
ΔrH⦵298: molar quantities of reactants in the equation react under STANDARD CONDITIONS
ΔfH⦵298: 1mol of compound formed from elements under STANDARD CONDITIONS, in STANDARD(naturally occuring) STATES
ΔneutH⦵298: 1mol of H+ ion reacting with 1mol of OH- ion to form 1mol of H2O under STANDARD CONDITIONS, in solutions of 1mol dm^-1

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5
Q

How do we measure enthalpy change?

DF2

A

Since we can’t always measure enthalpy change directly, we measure it indirectly through enthalpy cycles, ΔcH⦵298, ΔfH⦵298… due to Hess’ Law

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6
Q

Using Enthalpy Change of Combustion

DF2

A

ΔH1 = ΔH2 - ΔH3

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7
Q

Using Enthalpy Change of Formation

DF2

A

ΔH1 = -ΔH2 + ΔH3

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8
Q

Hydrocarbons with Benzene Rings

DF3

A

Aromatic compounds

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9
Q

Hydrocarbons without Benzene Rings

DF3

A

Aliphatic compounds

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10
Q

How to name a hydrocarbon

DF3

A
  1. Find the longest straight chain
  2. Find branched chains, order alphabetically
    (add positions, e.g. 2-methyl; prefixes depending on quantity, e.g. di-)
  3. Find functional groups, order alphabetically
    (add positions, e.g. 3-chloro; prefixes depending on quantity, e.g tri-)
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11
Q

What is a Homologous Series?

DF3

A

Series of Compounds with the same general chemical formula (e.g. CnH2n), similar in chemical properties but not in physical

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12
Q

What types of Structural formulae are there? How do you write them

A
  1. Full Structural
    ….H H
    H-C-C-H
    ….H H
  2. Shortened Structural
    CH3-CH3
  3. Further Shortened Structural
    CH3CH3
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13
Q

What do you call compounds with the same Cheimcal Formulae, but different Structural Formulae

DF3

A

Structural Isomers

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14
Q

Why do alkanes and water don’t mix?

DF3/DF6

A

Since water is polar (attracts other polar molecules), and hydrocarbons and non-polar. They form separate layers.

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15
Q

What causes bond length?

DF4

A

The attraction between nuclei and electrons and repulsion between nuclei at equilibrium. (Smaller bond lengths, stronger attraction.)

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16
Q

Properties of Bond Enthalpy

DF4

A
  1. Always positive
  2. Are averages
  3. Refers to energy required to break the attractive force of bonds
  4. Molecules are in gaseous states
17
Q

What are Bond Breaking & Bond Forming? Endothermic or Exothermic?

DF4

A

Bond Breaking - Endothermic
(energy to pull away from attraction)
Bond Forming - Exothermic

18
Q

What is Homogenous Catalysis?

DF5

A

Reactants and Catalyst are of the same physical state (e.g. both aqueous)

19
Q

What is Heterogenous Catalysis?

DF5

A

Reactants and Catalyst are of different physical states (e.g. solid catalyst with liquid or gaseous reactants)

20
Q

Process of Heterogenous Catalysis

DF5

A
  1. Reactant molecules ADSORBED into catalytic surface
  2. Bonds within reactant molecules WEAKEN & BREAK
  3. New covalent bonds form between Reactant molecules to form product
  4. Bond on catalytic surface WEAKENS, product DIFFUSES away
21
Q

How does Catalytic Poisoning occur?

DF5

A
  1. Poison molecules strongly bond to Catalytic Surface
  2. Catalyst unable to Catalyse poison
  3. Catalyst becomes Inactive
22
Q

What are σ-bonds and π-bonds?

DF6

A

σ-bonds - overlapping of s and p-orbitals, area with high electron density
π-bonds - side-to-side overlap of p-orbitals above and below atoms, area of negative charge

23
Q

Define Electrophiles

DF6

A

Electrophiles are…
- positive ions, or partially positive molecules
- …that are attracted to negatively charged regions
- …and will bond to lone pair of electrons through covalent bonding

24
Q

Name/ Draw the Mechanism of Electrophilic Addition

DF6

A
  • Bromine molecule closer to Ethene becomes partially positive
  • Lone pair of electrons are transferred from C=C to Brσ+ molecule, and electron pair from the Br molecule is transferred to Brσ- molecule
  • Forming a Carbocation, which attracts the Br- ion
  • Forming 2,3-dibromoethane
25
Q

Name the 4 Electrophilic Reactions learnt, their Conditions & Products.

DF6

A
  1. Bromine
    -decolourised in reaction
    -used to detect presence of unsaturated hydrocarbons
  2. HBr
    -under Room temperature
  3. Water at high temperature and high pressure (in steam)
    -with catalyst (phosphoric acid adsorbed into solid silica)
    -form ethanol
    -in laboratory, concentrated phosphoric acid is added and diluted with water (forms 2 products)
  4. Hydrogenation
    -react with platinum catalyst in ROOM temperature
    -in factories, react with finely divided nickel at 150C, at 5atm pressure to form unsaturated oils - margarines
26
Q

Define Polymer

DF7

A

long molecule made of many smaller molecules - monomers

27
Q

What are repeating units

DF7

A

Simplified monomers in polymers

28
Q

Types of Addition Polymerisation

DF7

A
  1. A-A: single repeating monomer
  2. A-B: two alternating monomers
29
Q

What & Why do we use Copolymerisation?

DF7

A
  • When a different monomer is added (A-A-B-A-A)
  • To change for desired properties of the polymer
30
Q

Define Molar Volume

DF8

A

Volume a mole of any gas under the same temperature & pressure is the same according to Avagadro.

31
Q

What are the Common Molar Volume Values?

DF8

A

Room temp: 24.0 dm^3 (298K; 1atm)
Standard temp: 22.4^3 (273K; 1atm)

32
Q

Equation with Molar Volume

DF8

A

amount of gas, n (mol) = volume, v (dm^3)/ molar volume, vr (dm^3)

33
Q

What is the Ideal Gas Equation?

DF8

A

PV = nRT
P = pressure (Pa)
V = volume (dm^3)
n = amount of gas (mol)
R = gas constant (8.31J K^-1 mol^-1)
T = temperature (K)

34
Q

What is Isomerism?

DF9

A

molecules with the same chemical formula, but different structural formula.

35
Q

What is Structural Isomerism & Stereoisomerism?

DF9

A

Structural: same chemical formula but differently arranged structures
Stereo-: same chemical formula and same structural formula

36
Q

What are the Types of Structural Isomerism?

DF9

A
  1. Chain Isomerism
  2. Position Isomerism
  3. Function Group Isomerism
37
Q

What are the Types of Stereoisomerism?

DF9

A
  1. E/Z Isomerism (cis/trans isomerism)
  2. Optical Isomerism (Y13)
38
Q

What is the E and Z in E/Z Isomerism mean?

DF9

A

E - across
Z - zame zide

Chemistry (OCR B - Salters) (2 decks)

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