Emergency learn Flashcards
What’s the oxidation number of O in OF₂?
+2
What’s the oxidation number of O in H₂O₂?
-1 (as it’s a peroxide)
What’s the oxidation number of H in NaH?
-1
Defn oxidation number
The oxidation number of an element is the charge an element has or appears to have when it is in a compound when certain rules are applied.
What’s the oxidation number of Group 7 elements?
-1 (but more electronegative +1)
What’s the oxidation number of H?
+1
How does the oxidation number of a reducing agent change during a redox reaction?
Is oxidised so the oxidation number will increase.
How do strong acids differ from weak acids in their behaviour in water according to the Arrhenius theory?
S: Fully dissociates to give hydrogen ions in solution.
W: Only slightly dissociates to give hydrogen ions in solution.
How do strong acids differ from weak acids in their behaviour in water according to the Bronsted-Lowry theory?
S: Good proton donor
W: Poor proton donor
Is the conjugate base of a strong acid or weak acid stronger?
Weak acid
What is an alkali?
A base that is soluble in water.
Give a problem with Arrhenius’ theory.
Excluded common bases such as NH₃.
Defn salt
A salt is formed when the H+ of the acid is replaced by a metal ion or ammonium ion.
Acid + Metal →
Salt + H₂
Acid + Metal oxide/hydroxide →
Salt + H₂O
Acid + Metal carbonate/hydrogen carbonate →
Salt + H₂O + CO₂
Metal + oxygen gas →
Metal oxide
Reactive metal + water →
Metal hydroxide + hydrogen gas
If Cl-, is there more or less electrons than Cl?
More
Name an instrument used to detect radiography.
Geiger-Muller tube
Give 3 uses of radioisotopes.
- Nuclear power
- Cancer treatment (using cobalt-60)
- Sterilisation (by radiation)
Give an example of alpha, beta and gamma emitters.
A: Americium-241
B: Carbon-14
G: Cobalt-60
Phosphate ion
PO₄³⁻
Manganate ion
MnO₄⁻
Hypochlorite ion
ClO⁻
Hydrogencarbonate ion
HCO₃⁻
Nitrate ion
NO₃⁻
Carbonate ion
CO₃²⁻
Why do metals generally have high electronegativity values?
As they are electropositive
Defn ionic bond
Formed due to the electrostatic attraction between oppositely charged ions caused by the complete transfer of electrons from one atom to another.
Why are ionic compounds crystalline?
Because they are made up of an orderly arrangement of oppositely charged ions which give rise to a lattice structure.
Why are ionic compounds solid?
There are extremely strong attractions between the oppositely charged ions which hold the ions tightly together giving a solid structure.
Why do ionic compounds have high boiling points/melting points.
The extremely strong attractions between the oppositely charged ions require large amounts of energy to break, hence ionic compounds have high b.p/m.p.
Give a sample of a flocculating agent.
Aluminium sulphate
Are ionic compounds soluble in polar compounds such as H₂O?
Yes
Why are ionic compounds soluble in polar solvents?
As the attraction between the ions in the compound and polar water are strong enough to pull the crystalline lattice apart.
Inert =
Unreactive
Defn pure covalent bonding
Occurs when electrons are shared equally between atoms.
Defn polar covalent bonding
Occurs when electrons are shared unequally between atoms.
Give 4 properties of covalent compounds.
- Usually gases or liquids
- Do not conduct electricity
- Insoluble in polar water
- Low melting and boiling points
Ionic bonding (table)
- Permanent dipole
- Ionic attractions
Pure covalent (table)
- Temporary dipole
- Van der Waals forces
Polar covalent (table)
- Permanent dipole
- Dipole-dipole attractions
Water, ammonia and hydrogen fluoride (table)
- Permanent dipole
- Hydrogen bonding
Defn polar molecule
The slight positive and slight negative poles of a molecule do not coincide.
Give two examples of molecules with polar bonds that are non-polar molecules.
- BH₃
- CH₄
Is the bonding in BF₃ ionic as expected?
No, sharing occurs
Why do ionic substances conduct electricity when molten or dissolved in water but not in the solid state?
Molten: ions are free to move
Solid: Ions not free to move
The diagram shows a thin stream of liquid flowing from a burette. A stream of water is deflected towards a positively charged rod whereas a stream of cyclohexane is undeflected. Account for these observation.
Polarity of water causes attraction to charged tod and non-polarity of cyclohexane means it is not affected by charged rod.
The diagram shows a thin stream of liquid flowing from a burette. A stream of water is deflected towards a positively charged rod whereas a stream of cyclohexane is undeflected. Explain what would happen in the case of the stream of water if the positively charged rod were replaced by a negatively charged rod.
Stream of water still attracted to rod as molecules arrange themselves with positive pole towards rod.
Defn hydrogen bonding (inter force of attraction)
A force of attraction thar occurs between molecules when hydrogen is bonded to a smaller more electronegative element such as O, F or N.
2 b.p, 2 l.p
V-shaped
4 b.p, 0 l.p
Tetrahedral
3 b.p, 0 l.p
Triangular planar
3 b.p, 1 l.p
Pyramidal
2 b.p, 0 l.p
Linear
Linear bond angle
180°
V-shaped bond angle
104.5°
Triangular planar bond angle
120°
Pyramidal bond angle
107°
Tetrahedral bond angle
109°
What is Kc dependent on?
Temperature
Which word, reaction ‘shifts’ to or ‘moves’ to?
SHIFTS!
Write an equation for the manufacture of ammonia.
N₂ + 3H₂ ⇌ 2NH₃
What name to the process of the manufacture of ammonia?
Haber process
What are the ideal conditions for the Haber process?
Low temp, high pressure
Catalyst used in the manufacture of sulfuric acid.
Vanadium pentoxide
What is the effect of a catalyst on a reversible reaction?
Increases rate for both - reaches equilibrium faster
Colour flame of sodium
Amber/yellow
Colour flame of potassium
Lilac
Colour flame of copper
Blue/green
Colour flame of lithium
Crimson
Colour flame of strontium
Red
Colour flame of barium
Yellow/green
Give 3 limitations of Bohr’s theory.
- Does not take wave-particle duality into account.
- Does not allow for uncertainty
- Does not explain the discovery of sublevels
Absorption spectrum
Series of dark lines against a coloured background.
Emission spectrum
Series of coloured lines against a dark background.
Energy sublevel
A group of atomic orbitals within an atom, all of which have the same energy.
Aufbau principle
Electrons occupy the lowest available energy level.
Hund’s rule of maximum multiplicity
When two or more orbitals of equal energy are available, electrons fill them singly before filling them in pairs.
Pauli exclusion principle
No more than two electrons can occupy an orbital and this they can only do if they have opposite spin.
Exceptions to electronic configurations
Cr (4s1,3d5) and Cu (4s1, 3d10)
d-block element
An element whose highest energy electron enters a d orbital.
Transition metal
One that forms at least one ion with a partially filléid d sublevel.
Transition elements characteristics
- Variable valency
- Act as catalysts in many reactions
- Form coloured ions/compounds
Explain how the line emission spectrum of hydrogen arises and provides evidence for the existence of energy levels.
- In the ground state hydrogen occupies the lowest available energy level
- The electron can jump to a higher energy level if it receives heat
- Excited state is unstable so electron falls back to lower level and energy is emitted as photon
Explain how the expression E2 - E1 = hf links the occurrence of the visible lines in the hydrogen spectrum to energy levels in a hydrogen atom.
- E2 - E1: Energy difference between higher and lower level
- f = frequency of line in spectrum
- h is Plank’s constant, hf is a photon
- Each line is produced due to electrons falling from a particular higher level to particular lower level
Charle’s law
The volume of a fixed mass of gas, kept at constant pressure, is directly proportional to the absolute temperature.
Charle’s law math eqn
V1/T1 = V2/T2
Gay-Lussac’s Law
Gases always react with each other in simple whole number ratios when the volumes are measured at the same temperature and pressure.
Avogadro’s Law
Equal volumes of gases measured under the same conditions of temperature and pressure contain equal number of molecules.
The combined/general gas law
P₁V₁/T₁ = P₂V₂/T₂
Eqn of state for an ideal gas
PV = nRT (R = 8.31)
Give 3 assumptions of the kinetic theory of gases.
- Collisions are elastic - no overall loss of energy
- No attractive forces between the gas particles
- Average kinetic energy is proportional to the absolute temperature
Saturated
Contains only single bonds around carbon atoms.
Unsaturated
Contains a multiple bond between two carbon atoms.
Hydrocarbon
A compound that consists of the elements carbon and hydrogen.
Aliphatic hydrocarbons
Straight or branched-chained hydrocarbon molecules.
Aromatic hydrocarbons
Hydrocarbons that contain a benzene ‘ring’ in their structure.
Homologous series
A group of compounds, all members of the group contain the same functional group and successive members differ by CH₂.
Functional group
A group of atoms upon which the characteristic properties of a homologous series depends.
Common name for ethyne
Acetylene
Use of ethyne/acetylene
Cutting and welding metals
Alkanes reaction type
Free radical substitutions
Alkenes reaction type
Ionic addition reactions
Alkynes reaction type
Addition reactions
What is used in preference to benzene in the lab?
Methylbenzene
Why is ethene a gas at r.t?
As it has 2 carbon atoms and C2-C4 are gases.
Aromatic hydrocarbons uses - carcinogenic
- Solvents in the paints industry
- Basis of pharmaceuticals, detergents, dyes and herbicides
Chloroform IUPAC name
Trichlorometane
Are tertiary alcohols easily oxidised?
NO
Ethanol uses
- Solvent
- Sterilise
- As an oxygenate
What alcohols are soluble in water and why?
With smaller carbon chains as there is hydrogen bonding between the alcohol molecules.
Aldehydes general formula
RCHO
Ketones general formula
R₁COR₂
Name the aromatic aldehyde that is found in almond oil of almond kernals
Benzaldehyde - C7H6O
Propanone common name
Acetone
Carboxylic acid general formula
RCOOH (carbonyl group C = O)
hydroxyl group C - OH
Name the acid found in nettle stings**
Methanoic/formic acid
Ethanoic acid uses
Used in varnishes and found in vinegar
What’s used as a food preservative?
- Propanoic acid
- Benzoic acid
Esters general formula
R₁COOR₂ (R₂ cannot be hydrogen)
Condensation reaction
Occurs when two different molecules combine to form a more complex molecule with the production of a smaller such as H₂O.
Perfumes made from
Esters
First ionisation energy
The minimum amount of energy required to remove the first most loosely bound electron from a mole of isolated atoms of an element in its neutral gaseous ground state.
Ionisation down a group
Decrease
Ionisation up a group
Increase
The smaller the radius (distance from the nucleus)
The greater the energy
Noble gases (ionisation energy)
Highest
Alkali metals (ionisation energy)
Lowest
Stability of sublevels
- Full sublevel is most stable
- Half filled is the next most stable
Equation for first ionisation energy
X(g) → X+(g) + e-
Explain why there is an increase in ionisation energy values for the first eight ionisation energies in magnesium.
- Increasing positive charge
- Decreasing radius
Second ionisation energy
X+ → X²+(g) + e-
Would it take more or less energy to remove the most loosely bound electron from an atom if that electron were not in its ground state? Explain
Less as it had already gained energy - further from nucleus.
An element has a low ionisation energy value and a low electronegativity value. What does this information tell you about how reactive the element is likely to be, and what is likely to happen to the atoms of the element when they react?
Very reactive
- Would be oxidised
What other experimental evidence do we have for the existence of energy levels in atoms?
The line emission spectrum
Reforming
Involves changing straight chained hydrocarbons into branched chained hydrocarbons or cyclic hydrocarbons.
Catalytic cracking
Involves changing long chained hydrocarbons for which there is low demand, into short chained hydrocarbons for which there is high demand.
Auto-ignition
The early explosion of a petrol-air mixture caused by increasing pressure in the engine.
Residue uses
- Bitumen for road surfacing
- Heavy industrial fuel
- Used in catalytic cracking
Kerosene uses
Fuel for planes and paraffin lamps/stoves
Naptha uses
Petrol and feedstock for petrochemical industry
Light gasoline uses
Motor fuel / petrol
Gas uses
- Refinery fuel
- Liquefied to form propane or butane gas (LPG)
Gas oil and heavy gas oil
- Diesel oil
- Lubricating oil for engines
C1-C4
Gas
C5-C10
Light gasoline
C7-C10
Naptha
C10-C14
Kerosene
C14-C40
Gas oil and heavy gas oil
C35 +
Residue
Why are mercaptans added?
To give a smell to be able to detect leaks
LPG makeup
Propane and butane
2 reference hydrocarbons in organic chem, petrol
2,2,3 trimethylpentane and heptane
Dehyrdrocyclisation
Involves the conversion of straight-chained hydrocarbons to form ring compounds.
Isomerisation
Involves changing straight-chained hydrocarbons into branched-chained hydrocarbons.
Why is lead in the form of tetraethyl lead added to petrol?
To allow the petrol to run smoothly.
What is collected in the separating funnel (clove oil exp.)
Mixture of clove oil and water
What is an emulsion?
Two immiscible liquids mixed without a boundary.
Name a suitable organic solvent for use in the liquid-liquid extraction of clove oil?
Cyclohexane
Identify the hydrocarbon gas produced by anaerobic bacterial decomposition of either waste or vegetation.
Methane
Give a major use of methane.
Fuel
What is the advantage of adding tetraethyllead to petrol?
To increase the octane number of the fuel
Give one major use of ethene gas.
The manufacture of PVC
How do the molecules of the naphtha fraction differ from the molecules of the gas oil fraction?
Naphtha has a shorter carbon chain.
What two changes to the hydrocarbon molecules occur during dehydrocyclisation?
- Removal of hydrogen
- Ring formation
Give two reasons why oxygenates are added to petrol.
- Raise octane number
- Less pollution
Equation for the production of ethyne.
CAC₂ + 2H₂O → C₂H₂ + Ca(OH)₂
Two impurities of calcium dicarbide
CaS and Ca3P₂
Impurities in ethene gas collected
PH3 and H₂S
LEARN DIAGRAM IN ORG 4! FRACTIONATION OF CRUDE OIL
DONEEE
Ionic addition reaction
Occurs when two substances react together to form one main product.
Chloroethene produces
PVC
Ethene + water →
Ethanol
Polymerisation reaction
A polymer is a very long chained molecule that is made when many thousands of small-chained molecules, called monomers, join together.
Free radical substitution
Occurs when an atom or a group of atoms are replaced by another atom or group of atoms. There are two products.
Mechanism of free radical substitution stages.
- Initiation
- Propagation
- Termination
State one safety protection when separating the funnel. (Clove oil exp.)
Work in fume-cupboard
