U2 exam revision Flashcards
Amphiprotic substances
HCO3-, H2O, HSO4-, H2PO4–, HPO42–
The concentration of ions in the solution is …..
(trend)
inversely proportional to the amount of light detected by the detector
Darker solution indicates …
in light spectrometry
= more light absorbed
polarity
imbalance/difference in charge on either side
Why filtration in gravimetric analysis?
To get rid of spectator ions that might have been mixed with precipitate
Assumptions in gravimetric analysis:
no errors occured, all sulphate was precipitated, none was lost
Improve reliability of gravimetric analysis:
repeat, add excess, dry thoroughly
Cathode carries what charge?
carries positive charge
which direction do electrons move through the salt bridge?
Anions move from anode to cathode
Strong acid
readily donates proton to water
What is the purpose of washing in gravimetric analysis?
Some precipitate sticks to sides of beaker, wahsing = all precipitate on filter paper
Gravimetric analysis: why wasn’t the yield 100%?
Some precipitate was lost, some may not have reacted
Why dilution in spectrometry?
To ensure the absorbance value fits calibration curve
Species that can act as both an odidising and reducing agent:
Fe2+ H2O, MnO2
horizontal parts on a phase graph of latent heat
contain a mixture of ice and water or water and steam
How does SHC allow the seasons to change slowly?
oceans absorb and release heat slowly as it takes a large amount to raise the temperature = climate gradually changes
In a redox reaction, would the solid metal increase in mass?
Depends on molar mass of the metal
How does zinc prevent the rusting of iron?
As it preferentially oxidises over iron
Why does the thickness of zinc in galvanised objects decrease over time?
Zinc ions washed away, zinc mass decreases
pH of water
always neutral, H3O+ is equal to OH-
Advantage of reducing volume of solution before gravimetric analysis.
less time to filter
Use of water that depends on SHC
coolant in car radiator
