Analysis of ions Flashcards
where are galvanic cells in everyday life
they are found in everyday electronic devices, such as mobile phones and calaculators, as a source of electricity
in electronic devicezs, where does the electricityy come from?
galvanic cells, the source of energy comes from a spontaneously occuring redox reaction between two metals
what are the componenets of a galvanic cell
two half cells and two electrodes (anode and cathode), salt bridge, voltmetre and wire
what differs between the two half-cells
one has a negatively charged electrode (anode) so oxidation occurs and the other has a posiitvely charged electrode (cathode) so reduction occurs
acronym to remember where reduction/oxidation occurs in galvanic cells
REDCAT and ANOX
REDCAT ANOX
reduction occurs at the cathode, anode is the site of oxidation
two functions of the salt bridge
prevents build up of charge in each half cells and connects two solutions of the half cells to allow for ion flow
how does the salt bridge prevent build up of charge
the anion of the salt in the salt bridge will go to the halfcell of oxidation as it is becomingg positvely charged and the ccation of the salt will go to the site of reduction as it is gaining electrons
what are tthe electtrodes
each electrode is a solid metal immersed in a solution of that same metals cations, the electrodes are connected by a wire
what is tthe flow of electrons in a galvanic cell
the anode loses electrons, which then travel through the exterrnal circuit and to the cathode which gains the electrons
what is the function of the wire in galvanic cells
to connect the electrodes for electricity output
how does the mass of the two half-cells change
the half cell will the anode will undergo oxidation, so loses electrons and therefore decreases in mass, whereas the half-cell with the cathode will undergo reduction, so gains electrons and therefore increases in mass
what type of reactions are redox reactions
exothermic
how do galvanic cells convert energy
they convert chemical energy into electrical energy
when is water toxic
when water contains high concentrations of salt ions, it is toxic to plants, animals and humans
how is the salinity of water tested
we test the electrical conductivity of a sample of water
how does testing the electrical conductivity of water show the salinity
because pure water is a poor conductoe but saline water with a high concentration of ions will have a higher conductivity
hydroscopic salts
salts that absorb water from its surroundibngs and have it within their chemical formula
water of crystallisation
the molecules of water bonded into the crystals of a salt, which have crystallised out of water, forming a hydrated salt
when salt crystals are formed in the absense of water, the salt is considered…
anhydrous
the dot between a salt and H2O in a formula represnts
used in hydrated ssssalts and is used to indicate that water of crystalliation molecules are bonded to tthe salt
CuSO₄.5H₂O is called
copper (II) sulfate pentahydrate as each copper sulfate molecule is bonded to five water molceules
how can the water of crystallisation be removed
by heating the hydrated salt and making it anhydrous
