Gravimetric Analysis Flashcards
1
Q
Gravimetric Analysis
A
- selective precipitation employing an excess ion causing unknown ppt to be created and quantitatively analyzed
- addition in a controlled manner to understand unknown
- mass of ppt and identity of ppt used to calc unknown ion based on total mass
2
Q
Precipitation
A
- indicator, excess ion, urea combined in beaker, solution heated
- ppt and supernatant poured through crucible (sintered glass filter) and washed
- ppt and crucible dried to constant mass which is then used to calculate something ab ion
3
Q
Volatilization
A
- volatile sample (easily evaporated) chemically separated or decomposed by heating and measuring mass difference (mass pre-heat and post-heat)
- other materials in sample found by combusting sample and measuring g (CO2 or SO4) produced.
4
Q
Electrogravimetric/ electroplating analysis
A
- weighs solids plated on electrode
- sample w/ metal deposits on electrode, current run through
- know done when no mass chng btwn trials
5
Q
Potentiometry
A
- measures electric potential (voltage) in sample w/ constant current (amperage) btwn electrodes
6
Q
Amperometry
A
- measures current (amperage) in sample w/ constant voltage (electric potential) btwn electrodes
7
Q
Conductometry
A
- measures conductance while AC current constant btwn electrodes
- conductivity meter
8
Q
Voltammetry
A
- measures chng in current while electric potential varied
9
Q
Polarography
A
- voltammetry subtype, uses liquid metal electrode (mercury)
10
Q
Coulometry
A
- measures electricity consumption (coulombs) during electrochem rxn
11
Q
Advantages of gravimetric analysis
A
- precise when done correctly
- no standards to calibrate required
- low instrumental error
- little expensive equipment required
12
Q
Disadvantages of gravimetric analysis
A
- only analyze for one ion at a time
- modern instrumental methods flash combustion and gas chromatography are superior methods to reg combustion analysis
- DETAIL ORIENTED methods, slight mistep means disaster
