WorksheetsA1: Chemical Properties and Electrolysis
Total questions: 98
Worksheet time: 49mins
Which statement best describes the amphoteric nature of Al2O3?
It reacts only with strong acids
It reacts only with strong bases
It reacts with acids and with bases
It does not react with acids or bases
Which formula represents alumina?
Al2O3
AlO2
Al(OH)3
Al3O2
When Al2O3 reacts with hydrochloric acid, which species in solution indicates its acidic–base behavior?
Precipitation of Al(s)
Formation of Al2(g)
Evolution of H2(g)
Formation of AlCl3(aq)
Which equation type shows acid–base behavior of metal oxides most clearly?
Balanced ionic equations
Unbalanced molecular sketches
Net energy diagrams
Empirical formula lists
Select the correct balanced ionic half-equation for reduction at the cathode in electrolysis of molten NaCl.
Na → Na+ + e−
2Cl− + 2e− → Cl2
Cl− → Cl + e−
Na+ + e− → Na
During electrolysis, which term names the positive electrode?
Electrolyte
Salt bridge
Anode
Cathode
Which condition is required for electrolysis to occur?
Solid ionic lattice
Molten or aqueous ions
Dry gaseous ions
Pure covalent liquid
As metal reactivity increases, how do electrolysis energy requirements change?
Decrease then increase
Become more demanding
Decrease significantly
Remain exactly constant
Match each species to its electrode process in electrolysis.
Na+ in molten NaCl
Reduction at cathode
Cl− in molten NaCl
Oxidation at anode
H+ in acid solution
Reduction at cathode
Which statement about transition metals is correct?
They never change oxidation state
They have a complete d subshell
They form coloured compounds
They cannot act as catalysts
Which characteristic is typical of transition metals?
Only +1 oxidation state
Always colourless ions
Variable oxidation states
No complex ion formation
Which description defines a complex ion?
Metal ion bonded to ligands by dative bonds
Neutral molecule with only covalent bonds
Metal atom with no surrounding ions
Anion formed by losing electrons
Which bond type holds ligands to a central metal ion?
Dative covalent bond
Metallic bond
Van der Waals forces
Ionic bond
Select all true statements about catalysts.
Increase reaction rate
Lower activation energy
Remain unchanged at end
Are consumed by reaction
Calcium hydroxide is used in acidic effluent treatment because it does what?
Neutralises excess acid
Forms coloured complexes
Reduces metal ions
Oxidises pollutants strongly
Which process is used industrially to purify alumina from bauxite before aluminium production?
Hall–Héroult electrolytic process
Kroll magnesium reduction process
Contact vanadium(V) oxide process
Bayer caustic digestion process
In the Hall–Héroult process, what is the main role of cryolite in the electrolytic cell?
Acts as a diaphragm separating products
Provides carbon anodes for oxidation
Lowers the melting point of alumina
Supplies sodium ions to the cathode
Which ore feedstock is commonly reduced in the Kroll process to obtain metallic titanium?
Sodium chloride brine solution
Alumina dissolved in cryolite
Rutile or ilmenite converted to TiCl4
Bauxite dissolved in caustic soda
Match each industrial process to its primary product.
Bayer process
Purified alumina
Hall–Héroult process
Aluminium metal
Kroll process
Titanium metal
Electrolysis of brine
Chlorine, hydrogen, NaOH
Which condition explains why titanium is produced by the Kroll process rather than direct electrolysis of TiO2?
Ti4+ forms insoluble salts in water
TiO2 melts too easily at low temperature
Titanium conducts poorly as a liquid metal
TiO2 is highly stable and difficult to electrolyse
During electrolysis of concentrated brine in a membrane cell, which products are obtained at the electrodes and in solution?
Solid sodium metal at the cathode
Aqueous sodium hydroxide in the cell
Oxygen gas at the anode
Chlorine gas at the anode
Hydrogen gas at the cathode
Which statement best distinguishes diaphragm and membrane cells for brine electrolysis?
Diaphragm increases cryolite solubility
Membrane prevents mixing of products
Diaphragm allows oxygen evolution only
Membrane produces solid sodium metal
Choose the equation that represents the anode reaction during brine electrolysis.
TiCl4 + 2Mg → Ti + 2MgCl2
Al3+ + 3e− → Al
2H2O + 2e− → H2 + 2OH−
2Cl− → Cl2 + 2e−
Why is alumina suitable for use in refractories?
Low melting point and high reactivity
High melting point and ionic lattice
Low electrical conductivity and volatility
Molecular structure and low hardness
Match each comparison to the preferred method or condition for efficient production.
Electrolysis vs metal oxide reduction
Choose based on product stability and energy
Concentrated solution vs molten compound
Molten often needed for ionic conduction
High pressure and concentration vs low
High often increases rate and yield
Large-surface-area catalysts vs small
Greater area increases catalytic efficiency
Batch process vs continuous process
Continuous favored for steady large output
Which pair correctly links a substance to a property guiding its industrial use?
Calcium hydroxide—oxidizes easily to TiCl4
Aluminium—low density and corrosion resistance
Hydrogen—forms ionic lattices in solids
Titanium—low melting point and volatility
Which general formula corresponds to alkanes with one ring or straight chains?
CnHn+2 for symmetric alkenes
CnH2n+2 for straight-chain alkanes
CnH2n for alkanes and cycloalkanes
CnH2n−2 for branched alkanes
Which statement best distinguishes alkanes from alkenes?
Alkanes contain a carbon–carbon double bond
Alkenes contain only single bonds
Alkenes are saturated hydrocarbons
Alkanes have sigma bonds only
Applying IUPAC rules, what is prioritised when selecting the parent chain in a hydrocarbon?
Chain placed alphabetically first
Chain with most substituents
Chain with most carbon atoms
Chain with lowest total locants
Which pair correctly matches representation and feature?
Displayed formula
Shows all bonds and atoms
Condensed formula
Groups atoms without all bonds
Skeletal formula
Lines for carbon framework, no H
Wedge–dash 3D
Solid/dashed wedges for 3D
Which are geometric stereoisomers of alkenes?
Chain and position forms
Cis and trans forms
E and Z forms
Primary and tertiary forms
In skeletal formulae, what convention is used for hydrogen atoms on carbon?
Hydrogens as circles on lines
Hydrogens shown on every carbon
Hydrogens are omitted
Hydrogens only on terminal carbons
Which feature makes an alkene symmetric with respect to the double bond?
No substituents on the chain
Even number of total carbon atoms
Same number of hydrogens in the molecule
Same groups on both double-bond carbons
What implication arises for products from reactions of asymmetric alkenes?
No stereoisomeric products form
Potential formation of regioisomers
Only one addition product possible
Reaction cannot proceed with halogens
Which statement about sigma bonds in hydrocarbons is accurate?
Occur only in alkenes
Have two lobes above and below
Arise from sideways p overlap
Formed by head-on orbital overlap
Which combination of orbitals gives sp3 hybridisation in carbon?
One s plus one p orbital
One s plus three p orbitals
Three s plus one p orbital
One s plus two p orbitals
Match hybridisation with typical bond angle and geometry.
sp3
109.5°, tetrahedral shape
sp2
120°, trigonal planar shape
sp
180°, linear shape
Which statements about hybrid orbitals are correct?
They cannot overlap to make sigma bonds
Each can host one shared electron
Same shape and energy for a given set
Unused p orbitals can form pi bonds
What bond angles are associated with three bonding electron pairs around a central carbon?
Approximately 120 degrees
Approximately 109.5 degrees
Approximately 104.5 degrees
Approximately 180 degrees
Which claim about bonds in alkanes and alkenes is correct?
Alkanes have only sigma bonds
Alkanes have sigma and pi bonds
Alkenes have sigma bonds only
Alkenes lack any sigma bonds
Which naming decision is part of IUPAC application to halogenoalkanes?
Lowest locants for substituents
Choose chain with fewest carbons
Ignore halogen prefixes
Use common names before systematic
Carbon in ethene exhibits which hybridisation and approximate H–C–C bond angle?
sp2 and about 120°
sp2 and about 90°
sp3 and about 109.5°
sp and about 180°
Which trend correctly compares carbon–carbon bond length and bond strength as the number of bonds increases from single to double to triple?
Both length and strength decrease
Bond length increases, bond strength decreases
Both length and strength increase
Bond length decreases, bond strength increases
Select the correct ordering of bond lengths for C–C in alkane, alkene, and alkyne.
alkane > alkene > alkyne
alkyne > alkene > alkane
alkane = alkene = alkyne
alkene > alkane > alkyne
Which statement about sigma and pi bonds is correct?
Sigma and pi are equal in strength
Pi is stronger than a single sigma bond
A pi bond exists without any sigma bond
Sigma is stronger than a single pi bond
Match hybridisation to ideal geometry and bond angle.
sp3
tetrahedral, ~109.5°
sp2
trigonal planar, ~120°
sp
linear, ~180°
In benzene, how are the sigma and pi systems arranged?
Sigma bonds in ring plane, pi delocalised above and below
Pi bonds in ring plane, sigma delocalised above and below
Only pi bonds around the ring, no sigma bonds
Alternating sigma bonds with isolated localised pi bonds
Which factor most increases boiling point within a homologous series of alkanes and alkenes?
More branching increases surface contact
Greater chain length raises intermolecular forces
Smaller molecular size increases attractions
Fewer electrons increase dispersion forces
How does branching in isomeric alkanes typically affect boiling point?
Branching only affects alkenes
Branching lowers boiling point
Branching has no effect
Branching raises boiling point
Which statements are true for factors controlling intermolecular force strength in hydrocarbons?
More electrons strengthen attractions
Presence of pi bonds always increases polarity
Shorter chains weaken London forces
Larger surface area enhances dispersion
Identify the three named stages of a free radical substitution in alkanes.
Initiation
Homolytic fission forming radicals
Propagation
Radicals react to sustain chain
Termination
Radicals combine to end chain
Which condition commonly promotes initiation in halogenation of alkanes?
UV light or high temperature
Low temperature and darkness
Strong base catalyst
Acidic aqueous medium
During free radical substitution of methane with chlorine, which step produces chloromethane?
Propagation via CH3• reacting with Cl2
Initiation forming Cl• radicals
Termination combining CH3• and Cl•
Propagation via Cl• abstracting H from CH4
Electrophilic addition to alkenes begins with which interaction?
Radical attacks the sigma bond
Nucleophile attacks the sigma bond
Electrophile attacks the pi bond
Base abstracts allylic hydrogen
Which statements are correct regarding heterolytic bond fission and curly arrows?
Double-headed arrows indicate lone pair motion
Single-headed arrows depict pair transfer
Curly arrows show electron pair movement
Heterolysis gives ions rather than radicals
Arrange carbocation stability from least to most stable.
methyl carbocation
least stable
primary carbocation
more stable than methyl
secondary carbocation
more stable than primary
tertiary carbocation
most stable
Why is a tertiary carbocation generally more stable than a secondary carbocation?
Fewer substituents reduce steric hindrance
Greater alkyl electron donation and hyperconjugation
Resonance from hydrogen atoms stabilises
Tertiary has lower positive charge magnitude
In addition of HBr to propene, which major product forms and why?
1-bromopropane via steric blocking
2-bromopropane via radical mechanism
1-bromopropane via more stable primary carbocation
2-bromopropane via more stable secondary carbocation
Which description correctly matches polymer names to their monomers?
poly(ethene)
ethene monomer
poly(propene)
propene monomer
polystyrene
styrene monomer
PVC
chloroethene monomer
PTFE
tetrafluoroethene monomer
In free radical addition polymerisation of ethene, what initiates chain growth?
Base deprotonates the monomer
Electrophile attacks the sigma bond
Carbocation inserts into the chain
Radical adds to the C=C pi bond
During hydration of ethene to ethanol, which catalyst and mechanism are typically involved?
Phosphoric acid, electrophilic addition
Nickel catalyst, radical substitution
Sulfuric acid, nucleophilic substitution
Alkaline medium, elimination
Which statement best describes addition polymerisation of ethene to form poly(ethene)?
Ethene chains crosslink via UV-initiated radical curing
Ethene molecules condense releasing small water molecules
Ethene rings form by intramolecular cyclisation steps
Many ethene molecules join by double bond opening
Match each polymer to its typical monomer or key feature.
PVC
Monomer: chloroethene (vinyl chloride)
PTFE
Monomer: tetrafluoroethene
Poly(ethene)
Monomer: ethene
During catalytic cracking of long-chain alkanes, what are the usual conditions?
Aqueous acid in reflux apparatus
Strong base under cold conditions
Low temperature and high pressure
High temperature with zeolite catalyst
Which products are commonly formed by cracking of hydrocarbons?
Aromatic nitriles
Carbon dioxide only
Alkenes like ethene
Shorter-chain alkanes
Write the balanced equation for complete combustion of propane (C3H8).
2C3H8 + 7O2 → 6CO + 8H2O
C3H8 + O2 → CO2 + H2O
C3H8 + 3O2 → 3CO + 4H2O
C3H8 + 5O2 → 3CO2 + 4H2O
Which statement about incomplete combustion of alkanes is correct?
Forms carbon monoxide and soot
Produces only carbon dioxide
Requires excess oxygen supply
Always yields alkenes as by‑products
Hydration of ethene to form ethanol in industry typically uses which conditions?
UV light and peroxide initiator
Steam and phosphoric acid catalyst
Dry hydrogen with nickel catalyst
Aqueous base at room temperature
Which statement correctly contrasts thermal and catalytic cracking?
Thermal requires high pressure; catalytic no pressure
Thermal produces only alkanes; catalytic only alkenes
Thermal uses zeolite catalyst; catalytic uses steam only
Thermal uses higher temperature; catalytic lowers temperature
Which statement best describes standard conditions used for enthalpy data?
100 kPa and 298 K
1 kPa and 273 K
1000 kPa and 298 K
101 kPa and 310 K
Which unit is correct for standard enthalpy change values?
kJ mol−1
J mol−2
J g−1
kJ L−1
In thermochemistry, what is meant by the system?
The laboratory room
The measuring instruments
Everything except products
The reacting chemicals
Which sign convention is correct for an exothermic enthalpy change?
Zero ΔH
Positive ΔH
Alternates by catalyst
Negative ΔH
During an endothermic process, what happens to the surroundings’ temperature?
It fluctuates randomly
It stays exactly constant
It increases slightly
It decreases overall
Which pair correctly matches process type to heat flow direction?
Exothermic
Heat flows to surroundings
Endothermic
Heat flows from surroundings
From surroundings to system
Endothermic heat direction
From system to surroundings
Exothermic heat direction
Which features are shown on an enthalpy reaction profile diagram?
Reactants and products levels
Activation energy peak
Catalyst lowering Ea
Bond polarity arrows
Which statement about catalysts on reaction profiles is accurate?
They reverse endothermic reactions
They lower the activation energy
They make ΔH more negative
They raise the reactant enthalpy
Define the standard enthalpy of combustion, ΔH°c.
Enthalpy change when one mole burns completely in oxygen
Enthalpy change when one mole dissolves fully in water
Energy released when one gram ignites in air
Heat absorbed when one mole reacts without oxygen
Which factor can prevent complete combustion in practice?
Excess catalyst presence
High activation energy
Limited oxygen supply
Non‑standard conditions
Why is ΔH°c = 0 kJ mol−1 for oxygen gas?
It is already in its standard state
It has zero activation energy
It contains no chemical bonds
It cannot undergo oxidation
Define the standard enthalpy of formation, ΔH°f.
Enthalpy change when one mole forms from elements in standard states
Energy change when one mole vaporizes from liquid state
Enthalpy when elements combine under any conditions
Heat change when one mole dissolves from solid salts
Which reason can prevent formation of the desired product in practice?
Zero temperature surroundings
Alternative products possible
Non‑standard conditions used
High activation energy barrier
Why is ΔH°f = 0 kJ mol−1 for elements in their standard states?
They cannot form compounds under standard conditions
Their bonds contain no energy whatsoever
They are defined as reference state enthalpy zero
They are the most stable at any temperature
Which statement best describes specific heat capacity of water used in calorimetry?
Energy to raise 1 g by 1 K
Energy to raise 10 kg by 1 K
Energy to raise 1 kg by 1 K
Energy to raise 1 kg by 10 K
What numerical value is used for the specific heat capacity of water in calorimetry calculations?
1.00 kJ kg−1 K−1
8.36 kJ kg−1 K−1
2.09 kJ kg−1 K−1
4.18 kJ kg−1 K−1
In Q = mcΔT, what does m represent in a solution calorimetry experiment?
Volume of the gas evolved
Mass of the calorimeter
Moles of solute added
Mass of water present
A student dissolves a salt in water and measures temperature change directly. Which situation is this?
Heat change within water
Adiabatic reaction vessel
Heat transfer to water
Heat loss to surroundings
Which measurements are needed when heat from a reaction is transferred to water?
Specific heat capacity of water
Change in water temperature
Volume of the gas produced
Heat capacity of the calorimeter
Mass of water used
Which equation allows calculation of heat transferred to water during a reaction?
Q = mcΔT
ΔH = ΔU + pΔV
ΔH°r = ΣΔH°f(products) − ΣΔH°f(reactants)
q = nΔH
Which statements about enthalpy changes are correct?
Combustion enthalpies are exothermic
They show reaction rate directly
Sign and size suggest feasibility
Hydration enthalpies are always exothermic
Formation enthalpies can be exo or endo
Which factors influence the magnitude of an ion’s standard enthalpy of hydration?
Calorimeter volume
Gas constant value
Solution viscosity
Ion charge and size
What symbol denotes standard enthalpy change of hydration?
ΔH°r
ΔH°hyd
ΔH°comb
ΔH°f
Which statement about interpreting enthalpy change data is valid?
Sign indicates heat flow direction
Size shows exact reaction rate
Endothermic means energy released
Exothermic indicates positive ΔH
Which relation connects enthalpy change to internal energy for processes with volume change at pressure p?
ΔH = cpΔT
ΔU = ΔH + pΔV
ΔH = Q − W
ΔH = ΔU + pΔV
Using Hess’s Law, which expression gives standard enthalpy change of reaction from formation data?
ΔH°r = ΣΔH°c(products) + ΣΔH°c(reactants)
ΔH°r = ΔU + pΔV
ΔH°r = ΣΔH°f(reactants) − ΣΔH°f(products)
ΔH°r = ΣΔH°f(products) − ΣΔH°f(reactants)
Using combustion data with Hess cycles, which expression is correct?
ΔH°r = ΣΔH°c(reactants) − ΣΔH°c(products)
ΔH°r = ΣΔH°c(products) − ΣΔH°c(reactants)
ΔH°r = ΣΔH°f(products) − ΣΔH°f(reactants)
ΔH°r = mcΔT
Match each calorimetry concept to its description.
Indirect temperature measurement
Heat transferred to/from water
Direct temperature measurement
Heat change occurs within water
Q = mcΔT variables
m, c, ΔT and meanings
Specific heat capacity of water
4.18 kJ kg−1 K−1 value
Which statement about hydration enthalpy recognition is most accurate?
It is enthalpy when liquids evaporate
It is enthalpy when gases condense
It is enthalpy when solids dissolve
It is enthalpy when gaseous ions dissolve
