Electrochemistry Flashcards
Is the oxidant (oxidising agent) being reduced or oxidised?
reduced
Is the reductant (reducing agent) being reduced or oxidised?
oxidised
What is water’s polarity and what intermolecular forces does it have?
very polar and a permanent dipole
When are electrochemical curves obtained?
when electrolysis causes a NET chemical reaction
What is electrochemistry?
ionic conduction in an electrolyte solution that is coupled to electronic conduction in a solid
Why is water a very polar molcule?
As oxygen is very electronegative and hydrogen is very electropositive. The oxygen has a small negative charge and the hydrogens have a small positive charge.
Reduction occurs at the….
Cathode
Oxidation occurs at the….
Anode
At what state does an electrochemical cell need to be to measure voltages?
A voltemeter measures voltages between two identical phases not at equilibrium
What is the cell voltage?
sum of several potential differences
Is the anode positive or negative in a galvanic cell?
negative
Is the cathode positive or negative in a galvanic cell?
positive
What is the cathode made of in a dry cell battery?
The cathode is a graphite rod surrounded by a mix of carbon paste and MnO2.
What is the anode made of in a dry cell battery?
the anode is zinc metal. MnO2 (manganese dioxide) is the electroactive material and carbon powder is just added to make it electrically conductive
What is the electrolyte in a dry cell battery?
The electrolyte is an aqueous solution of ZnCl2 and NH4Cl adsorbed on a some sort of inert felt pad
What happens when there are electrodes that are the same material, with different concentrations, which one will be an anode or the cathode?
The higher concentration will be a cathode.
The lower concentration will be an anode
What happens when there are electrodes that are the same material, with different concentrations?
Solution with higher concentration will deposit metal on electrode
Electrode in lower concentrated solution will corrode
When will electron transfer (voltage) cease?
when both sides have the same concentration
What is the anode in the lead-acid cell made of?
Made of spongy lead packed into a lead grid at the anode,
What is the cathode in the lead-acid cell made of?
red-brown lead(IV) oxide (PbO2) packed into a lead grid at the cathode and dlite sulfuric acid with about 35% H2SO4, by mass.
What is the equation for the water equation in corrosion?
2 H2O + 2 e -> H2(g)
2OH−(aq)
What is the equation for the oxygen equation in corrosion?
O2(g) + 4H+(aq) + 4e −> 2 H2O
What is the equation for corrosion in moist air?
O2(g) + 2H2O + 4e− 4OH−
