redox. Flashcards
what colour is the [Co(H2O)6]2+ ion
pink (octahedral)
what colour is the [CoCl4]2- ion
blue
what would the color change be in this reaction Co(H2O)6 2+ + 4Cl⇌ CoCl4 2- + 6H2O
pink to blue
what are the metals present in brass?
- copper
- zinc
give one common purpose for brass and state the property of brass which makes it ideal for that purpose
- musical instrument -> bc shiny + attractive.
- coins -> non rusting
what happens when a rod of metal is dipped into a solution of its own emails.
an equilibrium is set up between the solid metal and the aq metal ions
what is a standard Hydrogen half cell made of (3)
HCl acid of 1mol dm3
Hydrogen gas at 100kPa
inert platinum electrode.
why is hydrogen half cell used as a standard half cell.
its easy to control its purity and reproducibility.
how can u make a simple salt bridge/
- soak a piece of filter paper in (aq) solution of KNO3 or NH4NO3
why are salt bridges necessary?
- they complete the circuit by connectint the 2 solutions –> they allow flow of ions and thus charge is transferred between the half cells.
THEY DONT REACT W./ ELECTRODES>
why might u use other standard electrodes occasionally
- platinum is EXPENSIVE
- they might be CHEAPER, easier and quicker to use and can provide just as good reference.
if a E value is more negative what does it mean in terms of oxidising or reducing power?
- it is better reducing agent
- easy to oxidise.
if a E value is more positive or more positive, what does it mean in terms of oxidising or reducing power?
- better oxidising agent (easier to reduce)
how do u calculate the emf of a cell from E values
E cell = E pos - Eneg
when would u use a pt electrode when trying to work out the E cell?
- when both the oxidised and reduced forms of the metal are in aqueous solution.
