CCEA A-Level Chemistry 1110
Formulae, Equations and Amounts of Substance
Atomic Structure
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
Alkenes
Halogenoalkanes
Alcohols
Infrared Spectroscopy
Energetics
Kinetics
Equilibrium
Group II Elements and Their Compounds
Lattice Enthalpy, Entropy and Free Energy
Rates of Reaction
Equilibrium and Acid-Base Equilibria
Isomerism
Aldehydes and Ketones
Carboxylic Acids
Derivatives of Carboxylic Acids
Aromatic Chemistry
Spectroscopy and Chromatography
Volumetric Analysis
Transition Metals
Electrode Potentials
Amines
Amides and Polymers
Amino Acids and Proteins
Formulae, Equations and Amounts of Substance
Writing and balancing full and ionic equations
- 3 things to know
- Unit AS 1
Overview
Four state symbols and what each means, ionic equation and term spectator ion.
What you need to know
Answer each one before you reveal it.
Why can the formula of a compound never be altered to make an equation balance?
State the four state symbols and what each means.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What must be true of both sides of a correctly balanced chemical equation?
Model answer
The number of atoms of each element must be the same on both sides, and the total charge must be the same on both sides.
- 2
Why can the formula of a compound never be altered to make an equation balance?
Model answer
The formula is fixed by the bonding in the substance, so only the large numbers in front of the formulae may be changed.
- 3
State the four state symbols and what each means.
Model answer
The symbol (s) means solid, (l) means liquid, (g) means gas and (aq) means dissolved in water.
- 4
Balance the combustion of ethane in oxygen.
Model answer
The balanced equation is 2C₂H₆(g) + 7O₂(g) → 4CO₂(g) + 6H₂O(l).
- 5
Write the balanced equation for the reaction of sodium with water.
Model answer
The equation is 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g).
- 6
What is an ionic equation?
Model answer
An ionic equation shows only the ions and species that actually take part in the reaction, with the spectator ions left out.
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