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
Acid-Base Titrations
Titration calculations
- 3 things to know
- Unit AS 1
Overview
Recall questions on the sequence of steps in a titration calculation, working concentrations for hydrochloric and sulfuric acid against sodium hydroxide, the sodium carbonate reaction, converting between mol dm⁻³ and g dm⁻³, finding a degree of hydration, diluting a vinegar before titration, and the effect of common procedural errors.
What you need to know
Answer each one before you reveal it.
25.0 cm³ of 0.100 mol dm⁻³ sodium hydroxide is neutralised by 22.50 cm³ of hydrochloric acid. Calculate the concentration of the acid.
Write the equation for the reaction of sulfuric acid with sodium hydroxide and state the mole ratio.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Describe the general sequence of steps in a titration calculation.
Model answer
The moles in the known solution are calculated from its concentration and volume, the balanced equation gives the moles of the other reactant, and that value is used with its volume or mass to find the unknown quantity.
- 2
25.0 cm³ of 0.100 mol dm⁻³ sodium hydroxide is neutralised by 22.50 cm³ of hydrochloric acid. Calculate the concentration of the acid.
Model answer
The alkali is 2.50 × 10⁻³ mol and the reaction is one to one, so the acid concentration is 2.50 × 10⁻³ ÷ 0.02250 = 0.111 mol dm⁻³.
- 3
Write the equation for the reaction of sulfuric acid with sodium hydroxide and state the mole ratio.
Model answer
The equation is H₂SO₄(aq) + 2NaOH(aq) → Na₂SO₄(aq) + 2H₂O(l), so one mole of the acid reacts with two moles of the alkali.
- 4
What volume of 0.100 mol dm⁻³ sodium hydroxide is needed to neutralise 25.0 cm³ of 0.0500 mol dm⁻³ sulfuric acid?
Model answer
The acid is 1.25 × 10⁻³ mol and needs twice that in alkali, so 2.50 × 10⁻³ ÷ 0.100 = 0.0250 dm³, which is 25.0 cm³.
- 5
Write the equation for the reaction of sodium carbonate with hydrochloric acid.
Model answer
The equation is Na₂CO₃(aq) + 2HCl(aq) → 2NaCl(aq) + H₂O(l) + CO₂(g).
- 6
25.0 cm³ of sodium carbonate solution requires 23.40 cm³ of 0.100 mol dm⁻³ hydrochloric acid. Calculate the concentration of the carbonate.
Model answer
The acid is 2.34 × 10⁻³ mol, so the carbonate is half that at 1.17 × 10⁻³ mol, giving 1.17 × 10⁻³ ÷ 0.0250 = 0.0468 mol dm⁻³.
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