Researching Chemistry Flashcards
What are the types of Titrations
acid-base
redox
complexometric
How to determine the end point of an acid base titration
use indicator with relevant pH
How to make a primary standard
calculate mass of primary standard required
weigh standard by difference approximately and then accurately in a standard flask
add small vol of deionised water in a standard flask until it dissolves
Transfer to standard flask
add rinsings
stopper and invert
Characteristics of a primary standard
high purity - if not, solution would have lower conc
be stable in air and solution - true conc < calc. value
readily soluble in solvent - conc not as expected
large GFM - large uncertainty in mass weighed out
Examples of a primary standard
sodium carbonate
hydrated oxalic acid
potassium iodate
What are accurate results
in close agreement with the true/ accepted value
what are precise results
in close agreement with each other
What is the DILUTION calculation
C1V1 = C2V2
What to do if the dilution question is ION SPECIFIC
multiply unknown value by number of ions in the formula
What is the use of a control
to VALIDATE an experiment
Steps to a BACK TITRATION
Use titration calculation to calculate number of moles of formula IN BOTH CALCULATIONS
ratio it to SUBSTANCE ASKED
Work out actual moles and subtract value from answer 2
Scale to 1 mole
work out mass
What is gravimetric analysis
determining the mass of an element in a compound by PRODUCING A PRECIPITATE
What does a desiccator do?
prevents sample from absorbing water in air
-DOES NOT REMOVE WATER FROM SAMPLE
How to work out the value of a substance in a hydrated compound
work out the mass of water after evaporation
calculate moles of salt and water
calculate ratio
How are organic compounds prepared
through REFLUX
