5. Electricity And Chemistry Flashcards
what does the term electrolysis mean
the break down of a molten or aqueous ionic compound using electricity
what is the cathode and anode
cathode - negative electrode
anode - positive electrode
what is formed at each electrode in electrolysis
anode - metal or hydrogen
cathode - non metal
how can you predict whether a metal or hydrogen will form at the negative electrode during electrolysis of an aqueous compound
if hydrogen is above the metal in the reactivity series then the metal will form. if the metal is more reactive than hydrogen the hydrogen will form
what forms at each electrode during the electrolysis of molten lead(II) bromide
anode - bromine
cathode - lead
what forms at each electrode during the electrolysis of concentrated hydrochloric acid
anode - chlorine
cathode - hydrogen
what forms at each electrode during the electrolysis of concentrated sodium chloride solution
anode - chlorine
cathode - hydrogen
what forms at each electrode during the electrolysis of dilute sulfuric acid
anode - oxygen
cathode - hydrogen
how can the products of electrolysis of molten electrolytes be predicted
anode - non-metal element
cathode - metal element
predict what forms at each electrode during the electrolysis of molten zinc chloride
anode - chlorine
cathode - zinc
what forms at each electrode during the electrolysis of copper sulfate solution using inert electrodes
anode - oxygen
cathode - copper
what forms at each electrode during the electrolysis of copper sulfate solution using copper electrodes
anode - copper ions
cathode - copper
describe the electrolysis of copper (II) sulfate solution using carbon electrodes
- place the inert carbon electrodes into a beaker of copper sulfate solution
- connect ions gain electrons t the cathode to from pure copper. oxygen ions lose electrons at the anode to form oxygen gas
how can impure copper be purified using copper sulfate solution and copper electrodes
electrolysis:
- the anode is made of impure copper and the cathode is made of pure copper
- the electrodes are placed in a solution of copper sulfate
- the copper ions from the impure anode move to the cathode where they gain electrons and form pure copper
- impurities form as sludge below the anode
where do ions in the electrolyte move to during electrolysis
cations move towards the cathode
anions move towards the anode
what happens at the anode during electrolysis
the anions lose electrons to form their elements. this is oxidation
what happens at the cathode during electrolysis
cations gain electrons to form their elements. this is reduction
predict the products of electrolysis of concentrated potassium bromide soultion
anode - bromine
cathode - hydrogen
predict the products of electrolysis of concentrated copper iodide solution
anode - iodine
cathode - copper
predict the products of electrolysis of dilute zinc chloride solution
anode - oxygen
cathode - zinc
what is electroplating
a process in which a metal is coated with a layer of another metal
what are two reasons for using electroplating
- to increase resistance to corrosion
- to improve appearance
explain how the process of electroplating works
similar setup to electrolysis:
the metal being coated is the cathode. the metal that will form the exterior layer is the anode. the electrolyte solution must contain ions of the metal which will form the outer coating. a power supply is connected to both electrodes
write half equation for the reactions that occur at the electrodes when aqueous NaCl is electrolysed
cathode - 2H+ + 2e- –> H2
anode - 2Cl- + 2e-
