4) Acids and redox Flashcards
Define strong acid
an acid that dissociates completely in solution
Define weak acid
an acid that dissociates only partially in solution
Define base
a compound that neutralises an acid to form a salt
Define alkali
a type of base that dissolves in water forming hydroxide ions
Define neutralisation
chemical reaction in which an acid and a base react together to form a salt
acid + metal oxide / hydroxide / alkali ->
salt + water
acid + metal carbonate ->
salt + water + carbon dioxide
Define titration
a technique to accurately measure the volume of one solution that reacts exactly with another solution
Give 3 purposes of carrying out a titration
finding the concentration of another solution
identification of unknown chemicals
finding the purity of a substance
What piece of apparatus can be used to make up a standard solution?
a volumetric flask
Define standard solution
a solution of known concentration
Give the 5 steps to prepare a standard solution
- weigh solid
- dissolve solid in a beaker using less distilled water than will be needed to fill the volumetric flask to the mark
- transfer to volumetric flask, rinsing last traces of solution into the flask with distilled water
- carefully fill to graduation line (bottom of meniscus) dropwise with distilled water at eye-level
- invert several times to mix
Give a method for an acid-base titration procedure
- add a measured volume of one solution to a conical flask using a pipette
- add the other solution to a burette and record the initial burette reading
- add a few drops of indicator to the conical flask
- run the burette solution into the conical flask swirling throughout. the indicator changes colour at the end point (indicates when the volume of 1 solution reacts exactly with the volume of the second solution)
- record the final burette reading
A quick, trial titration is carried out first to find the approximate titre. The titration is then repeated accurately, adding the solution dropwise as the endpoint is approached. Further titrations are carried out until two accurate titres are concordant.
Define titre
the volume added from the burette when the volume of one solution has exactly reached with the solution
Define concordant
agree to within 0.10cm^3