Home

Chemistry

Acids and bases

Titration calculations

Videos

Summary

Exercises

Select Lesson

Exam Board

Select an option

Practical skills

The scientific method

How to plan experiments

Improving repeatability and reproducibility

Presenting results using tables and graphs

Analysing results: anomalies and correlation

Evaluating experiments

Modern analytical techniques II

NMR spectroscopy

Proton NMR spectroscopy

Chromatography

Combining analytical techniques

Organic chemistry III

Benzene: structure and combustion

Electrophilic substitution

Friedel-Crafts reactions

Phenols

Aliphatic and aromatic amines

Reactions of amines

Forming amides

Condensation polymers

Amino acids and zwitterions

Grignard reagents

Synthetic routes

Practical techniques

Percentage composition and combustion analysis

Organic chemistry II

Optical isomers and chirality

Aldehydes and ketones

Carboxylic acids: properties and reactions

Esters: formation, properties and uses

Acyl chlorides: formation and reactions

Kinetics II

Measuring rates of reaction

Determining reaction orders

The initial rates method

Rate equations and the rate constant

The rate determining step

Halogenoalkane reaction mechanisms

Activation energy and the Arrhenius equation

Transition metals

Transition metals: electron configuration and oxidation number

Complex ions: formation, shape and isomerism

Colours of inorganic ions and complexes

Chromium and its reactions

Ligand substitution reactions

Transition metals as catalysts

Redox II

Electrochemical cells and redox

Electrode potentials and calculations

The electrochemical series

Energy storage cells and hydrogen fuel cells

Redox titrations

Energetics II

Lattice enthalpies and Born-Haber cycles

Polarisation and the Pauling scale

Enthalpy change in solution

Entropy and calculating entropy change

Gibbs free energy change

Acid-base equilibria

Acids and bases

pH calculations

The ionic product of water

pH curves and indicators

Buffer solutions and calculations

Equilibrium II

The equilibrium constant

Partial pressure and gas equilibria

Le Chatelier's principle and equilibrium constants

Equilibrium I

Reversible reactions

Le Chatelier's principle

Kinetics I

Collision theory and rates of reaction

Calculating the rate of reaction

Catalysts and the Maxwell-Boltzmann distribution

Energetics I

Enthalpy changes and reaction profiles

Standard enthalpy changes

Hess's Law and enthalpy cycles

Calculating bond enthalpies

Modern analytical techniques I

Mass spectrometry

IR spectroscopy

Organic chemistry I

Basic concepts of organic chemistry

Organic reactions and mechanisms

Structural isomerism

Alkanes and free radical substitution

Fractional distillation of crude oil

Fuels: combustion and emissions

Alkenes: bonding and reactivity

Stereoisomerism

Reactions of alkenes

Addition polymerisation

Halogenoalkanes and their reactions

Alcohol: classification and reactions

Oxidation of alcohols

Organic techniques

Formulae, equations and amounts of substances

The mole and Avogadro's constant

Calculations involving gases

Empirical and molecular formulae

Balancing equations

Acid-base titrations

Calculating uncertainty and errors

Atom economy and percentage yield

Inorganic chemistry and the periodic table

Group 2: ionisation energy and properties

Thermal stability of nitrates and carbonates

Chemical properties of Group 7

Reactions with halogens

Halide ion reactions

Testing for ions

Redox I

Calculating oxidation numbers

Oxidation, reduction and redox reactions

Bonding and structure

Ionic bonding

Covalent bonding

Shapes of molecules

Giant covalent and metallic structures

Electronegativity and polarisation

Intermolecular forces: types and examples

Hydrogen bonding

Solubility

Predicting structures and properties

Atomic structure and the periodic table

The atom: history, structure and isotopes

Relative masses and mass spectrometry

Electronic structure: shells and orbitals

Atomic emission spectra

Ionisation energies

Ionisation energy trends

Periodicity

Explainer Video

Tutor: Alexander

Summary

Titration calculations

In a nutshell

The results of a titration can be used to calculate the concentrations of unknown solutions. This can also be done for diprotic acids.

Equations

Below are general equations you need to know. You will need to be able to use them for specific calculations.

Word equations	Symbol equations
$concentration\ =\ \frac{moles}{volume}$	$c\ =\ \frac{n}{v}$
$moles\ =\ concentration \times\ volume$	$n\ =\ c \ \times \ v$

Variable definitions

Quantity name	Symbol	Unit Name	Unit
$concentration$	$c$	$moles\ per\ decimeter\ cubed$	$mol\ dm^{-3}$
$moles$	$n$	$mole$	$mol$
$volume$	$v$	$decimetre\ cubed\ or\ centimetre\ cubed$	$dm^3\ or\ cm^3$

Titration results to calculate concentrations

Titration results can be used to calculate the concentration of an unknown acid or base.

Make sure to carry out the titration to the nearest $0.05cm^3$ and repeat until concordant results are achieved.

Chemistry; Acids and bases; KS5 Year 12; Titration calculations — 1. Burette containing acid, 2. Clamp stand, 3. Known volume of alkali containing indicator

Example

$12.50 \ cm^3$ of $1.20\ mol\ dm^{-3}\ HCl$ was required to neutralise $20 \ cm^3$ of $KOH$ solution. Calculate the concentration of the $KOH$ solution.

$HCl\ +\ KOH\ \rightarrow\ KCl\ +\ H_2O$

Convert $cm^3$ to $dm^3$ .

$\frac{12.50\ cm^3}{1000}\ =\ 0.0125\ dm^3$

$\frac{20\ cm^3}{1000}\ =\ 0.020\ dm^3$

Calculate the number of moles of $HCl$ :

$n \ (HCl)\ =\ c\ \times\ v \\ n \ (HCl) = 1.20\ \times\ 0.0125\ =\ 0.015\ mol$ 

From the equation, $1$ mol of $HCl$ is neutralised by $1$ mol of $KOH$ . Therefore the moles of $HCl$ and $KOH$ are equal. Now the concentration can be calculated.

$c\ (KOH)\ =\ \frac{n \ (KOH)}{v}\ =\ \frac{0.015}{0.020}\ =\ \underline{0.75\ mol\ dm^{-3}}$

Diprotic acids release two protons

A diprotic acid is an acid that releases two protons in solution. Diprotic acids neutralise a base in two stages.

Example

Some examples of diprotic acids include; sulfuric acid $(\underline{H_2}SO_4)$ , carbonic acid $(\underline{H_2}CO_3)$ , oxalic acid $(\underline{H_2}C_2O_4)$ .

$H_2SO_4\ \rightarrow\ HSO_4^-\ +\ H^+\ \rightleftharpoons\ SO_4^{2-}\ +\ H^+$ 

Calculating concentrations of diprotic acids

Calculating the concentration of a diprotic acid is almost the same as calculating the concentration for a monoprotic acid.

Example

$20 \ cm^3$ of $H_2SO_4$ is neutralised by $15.50 \ cm^3$ of $1.6\ mol\ dm^{-3}\ NaOH$ . Determine the concentration of the sulfuric acid.

Firstly, the volumes must be converted from $cm^3$  to $dm^3$ :

$\frac{20\ cm^3}{1000}\ =\ 0.020\ dm^3$

$\frac{15.50\ cm^3}{1000}\ =\ 0.0155\ dm^3$

Calculate the moles of $NaOH$ :

$n \ (NaOH)\ =\ c\ \times\ v \\ n \ (NaOH) = 1.6 \times\ 0.0155\ =\ 0.0248\ mol$

Calculate the moles of $H_2SO_4$ from the moles of $NaOH$ :

$H_2SO_4\ +\ 2NaOH\ \rightarrow\ Na_2SO_4\ +\ 2H_2O$

$H_2SO_4:NaOH \\1:2$

You can see from the ratio of sulphuric acid to sodium hydroxide, the moles of sulphuric acid is half of that of sodium hydroxide.

$\frac{0.0248\ mol}{2}\ =\ 0.0124\ mol$

Since the moles of sulphuric acid is known, the concentration can be calculated.

$c \ (H_2SO4)\ =\ \frac{n\ (H_2SO_4)}{v}\ =\ \frac{0.0124}{0.020}\ =\ \underline{0.62\ mol\ dm^{-3}}$

The concentration of sulphuric acid is $\underline{0.62\ mol\ dm^{-3}}$ .

Learn with Basics

Length:

Unit 1

Mole calculations and Avogadro's constant - Higher

Unit 2