Key term
CCEA AS-Level Chemistry 1110
Formulae, Equations and Amounts of Substance
Atomic Structure
Topic overviewProtons, neutrons and electronsAtomic number, mass number and the composition of ionsIsotopes and relative isotopic massRelative atomic, molecular and formula massMass spectra and relative atomic mass calculationsMass spectra of diatomic elementsElectronic configuration and the building up principleOrbitals, electron spin and orbital shapesThe s-, p-, d- and f-blocks of the Periodic TableIonisation energies and their equationsTrends in ionisation energy as evidence for shells and subshells
Bonding
Topic overviewIonic bonding and electron transferDot and cross diagrams for ionic compoundsCovalent bonding and the shared pairLone pairs and co-ordinate bondingDot and cross diagrams for covalent molecules and ionsThe octet rule and its limitationsElectronegativity and bond polarityMetallic bonding
Intermolecular Forces and Structure
Shapes of Molecules and Ions
Redox
The Halogens
Acid-Base Titrations
Qualitative Tests
Formulae and Amounts of a Substance
Nomenclature and Isomerism in Organic Chemistry
Alkanes
Topic overviewAlkanes as saturated hydrocarbonsBoiling points of alkanes and van der Waals' forcesBoiling points of branched isomersComplete and incomplete combustion of alkanesPollutants from alkane fuels and the atmosphereCatalytic convertersRadicals, homolytic fission and heterolytic fissionFree radical substitution of alkanes
Alkenes
Topic overviewUnsaturated hydrocarbons and the bromine water testSigma and pi bonds in the carbon–carbon double bondElectron density at C=C, reactivity and catalytic hydrogenationAddition of chlorine and bromine to alkenesAddition of hydrogen chloride and hydrogen bromideElectrophiles, heterolytic fission and the addition mechanismCarbocation stability and Markovnikov additionAddition polymerisation of alkenes
Halogenoalkanes
Topic overviewClassification and boiling points of halogenoalkanesLaboratory preparation of a halogenoalkane from an alcoholNucleophiles and hydrolysis with aqueous alkaliReactions with ammonia and with potassium cyanideRelative rates of hydrolysis and carbon–halogen bond enthalpyElimination using ethanolic potassium hydroxideCFCs and the ozone layer
Alcohols
Infrared Spectroscopy
Energetics
Topic overviewExothermic and endothermic changesStandard conditions and the standard enthalpy changeEnthalpy level diagramsStandard enthalpies of combustion and formationStandard enthalpy of neutralisationMeasuring enthalpy changes by experimentEnthalpy calculations using q = mcΔTHess's Law and enthalpy cyclesIndirect enthalpy calculations using Hess's LawAverage bond enthalpies and their limitations
Kinetics
Equilibrium
Group II Elements and Their Compounds
Topic overviews-block character and electronic configurationTrends in atomic radius and first ionisation energyReactions of the elements with oxygen, water and dilute acidsThe oxides and their reactions with water and dilute acidsThermal stability of the carbonates and hydroxidesUses of magnesium oxide, calcium carbonate and limeSolubility trends and solubility curves
Formulae and Amounts of a Substance
- 5 subtopics
- 15 things to know
- Unit AS 2
What Formulae and Amounts of a Substance covers
Formulae and Amounts of a Substance is examined in Unit AS 2, Further Physical and Inorganic Chemistry and an Introduction to Organic Chemistry, and drawn on again in Unit AS 3, Basic Practical Chemistry. It covers empirical and molecular formulae, calculating formulae from composition data, molar gas volume and reacting gas volumes, percentage yield and atom economy.
Where it is assessed
Unit AS 2
Further Physical and Inorganic Chemistry and an Introduction to Organic Chemistry, and again in Unit AS 3, Basic Practical Chemistry.
Check the CCEA specification ↗The 5 subtopics
Each one has its own page. CCEA AS Chemistry students sit this topic in the first year.
- Empirical and molecular formulaeTerm empirical formula, term molecular formula and empirical formula of benzene, C₆H₆.Open →
- Calculating formulae from composition dataRecall questions on the method for an empirical formula from masses or percentages, why moles are found before the ratio is taken, dividing through by the smallest figure, handling a ratio ending in .5, and going on to a molecular formula from the relative molecular mass.Open →
- Molar gas volume and reacting gas volumesTerm molar gas volume and avogadro's law.Open →
- Percentage yieldTerm percentage yield, expression used to calculate a percentage yield and theoretical yield of a reaction.Open →
- Atom economyTerm atom economy, expression used to calculate atom economy and percentage yield and atom economy.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen by mass. Deduce its empirical formula.
Key term
A hydrocarbon is 85.7% carbon and 14.3% hydrogen by mass and has a relative molecular mass of 56.0. Deduce its molecular formula.
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Give four reasons why the yield of a preparation falls below 100%.
Key term
Define the term empirical formula.
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Define the term molar gas volume.
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Why must each molar mass be multiplied by its balancing number in an atom economy calculation?
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Define the term molecular formula.
Key term
State the value of the molar gas volume at room temperature and pressure.
Key term
Define the term percentage yield.
Numbers
Calculate the atom economy of the hydration of ethene, C₂H₄ + H₂O → C₂H₅OH.
Key term
How is the molecular formula of a compound related to its empirical formula?
Key term
Why is the molar gas volume the same for every gas?
Numbers
State the expression used to calculate a percentage yield.
Numbers
Calculate the atom economy for calcium oxide in the reaction CaCO₃ → CaO + CO₂.
Take Formulae and Amounts of a Substance further
The same content, four other ways.
Questions from this topic
Each one with the model answer underneath.
- 1
Define the term empirical formula.
Model answer
The empirical formula is the simplest whole-number ratio of the atoms of each element present in a compound.
- 2
Define the term molecular formula.
Model answer
The molecular formula gives the actual number of atoms of each element present in one molecule of a compound.
- 3
How is the molecular formula of a compound related to its empirical formula?
Model answer
The molecular formula is a whole-number multiple n of the empirical formula, where n is the relative molecular mass divided by the empirical formula mass.
- 4
State the empirical formula of benzene, C₆H₆.
Model answer
The empirical formula of benzene is CH.
- 5
State the empirical formula of glucose, C₆H₁₂O₆.
Model answer
The empirical formula of glucose is CH₂O.
- 6
Why can an ionic compound such as sodium chloride only be given an empirical formula?
Model answer
Sodium chloride is a giant lattice with no separate molecules, so its formula can only state the simplest ratio in which the ions are present.
What is inside Levo
Six ways to work the same material.
Formulae and Amounts of a Substance revision questions
- Is Formulae and Amounts of a Substance examined at AS in CCEA Chemistry?
- Yes. It sits in Unit AS 2, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.
- What does Formulae and Amounts of a Substance cover in CCEA AS-Level Chemistry?
- 5 subtopics: empirical and molecular formulae, calculating formulae from composition data, molar gas volume and reacting gas volumes, percentage yield and atom economy. Each one has its own page with questions and model answers.
- How is Formulae and Amounts of a Substance organised?
- By the CCEA 1110 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Formulae and Amounts of a Substance, on a schedule.
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