Stoichiometry

End point

point at which a colour change occurs during a titration

Equivalence point

point at which the reaction has occurred as per the stoichiometric ratio of the balanced equation

Aliquot

A fixed colume of liquid measured by a pipette

Titre

volume of liquid delivered from a burette to reach the end point of a titration

Concordant titres

three or more titres that fall within 0.1mL of each other

Primary standard

substance used to make a primary standard solution

Primary standard solution

solution of precisely known concentration

Titration

quantitative technique used to find the concentration and/or concentrations of solutions

Volumetric analysis

quantitative technique used to determine unknown concentrations of solutions

Indicator

A substance that changes colour to indicate a pH range

Meniscus

Curved upper surface of liquid

Criteria for primary standards

• Be obtainable in pure form

• Not react with the atmosphere

• Have accurately known formula

• Be inexpensive

• Have a high molar mass

Why can’t sodium hydroxide be a primary standard?

because it reacts with the atmospheric co2

Anhydrous

Random errors in titrations

• incorrect volume measurement

• incorrect visual identification of end point

• contamination of glassware

Systematic errors in titrations

• incorrect weighing of substance

• incorrect concentration of standard solution

• equivalence and end points do not align accurately

• rinsing apparatus with inappropriate substance

What effect does rinsing burette with water have on unknown solution in conical flask

overestimated - number gotten in experiment is bigger than true value

What effect does rinsing burette with water have on unknown solution in burette

underestimated - number gotten in experiment is smaller than true value

What effect does rinsing pipette with water have on unknown solution in burette

overestimated - number gotten in experiment is bigger than true value

What effect does rinsing pipette with water have on unknown solution in conical flask

underestimated- number gotten in experiment is smaller than true value

What effect does rinsing conical flask with solution have on unknown solution in burette

underestimated- number gotten in experiment is smaller than true value

What effect does rinsing conical flask with solution have on unknown solution in conical flask

overestimated - number gotten in experiment is bigger than true value

What effect does missed indicator end point have on unknown solution in burette

underestimated- number gotten in experiment is smaller than true value

What effect does missed indicator end point have on unknown solution in conical flask

overestimated - number gotten in experiment is bigger than true value