Electrolysis Flashcards
What is electrolysis?
- passing electric current through electrolyte
- causes ions to move to electrodes
- positively charged ions -> negative electrode
- negatively charged ions -> positive electrode
- ions are discharged at electrodes
- produces elements
What is an electrolyte?
- liquid or solution that can conduct electricity
What is the charge of the non metal ion in electrolysis?
- negative
What is the charge of a metal ion in electrolysis?
positive
Give a half equation for the formation of Br2 at the positive electrode
2Br- -> Br2 + 2e-
Give a half equation of the formation of Mg at the negative electrode
Mg2+ + 2e- -> Mg
Why does aluminium need to be extracted from electrolysis?
- it is too reactive to be extracted by reduction with carbon
Label a diagram of the electrolysis of aluminium
label a diagram of the electrolysis of lead bromide
Why is cryolite added to aluminium oxide?
- to lower the melting point
- reduces energy costs
Why does the carbon anode need to be replaced frequently?
- carbon reacts with oxygen produced to form carbon dioxide
What is an aqueous compound?
- dissolved in water
What is the rule for the product of the negative electrode in the electrolysis of aqueous solutions?
- hydrogen is produced is metal is more reactive than hydrogen
What is the rule for the product of the positive electrode in the electrolysis of aqueous solutions?
- oxygen is produced unless solution contains halide ions (group 7)
Describe the test and expected observations for the hydrogen
- put lit splint near the gas
- products squeaky “pop” sound = hydrogen is present
