ox and reduction Flashcards
what happens when an atom undergoes oxidization?
loses electron/has a more positive charge
what happen to an atom when it is the reduction agent?
it is oxidizing/ loosing electrons
what happens when an atom undergoes reduction?
gains electrons/ more negative charge
what happen to an atom when it is the oxidation agent?
undergoes reductions/ gains electrons/ more negative charge
how do you determine which atom gets priority over charge?
the most electronegative charge
what oxidation state do Free elements have?
none/0
what charge does monoatomic ions have?
the charge displayed/given to them
what should the sum of the oxidation states add up too?
0/ they should cancel out unless told otherwise
when making oxidation half-reaction which sides do the electrons go on?
product side
when making reduction half-reaction which sides do the electrons go on?
reactant side
when making reduction half-reaction which sides do the electrons go on?
reactant side
when the two half equations add together what charge should it have?
o/ given charge
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what are the steps to balancing half reactions by mass?
1) First balance atoms other than O and H.
2) Balance O by adding H2O to side that lacks O.
3) Balance H by adding H+ to side that lacks H.
4) Finished if in acidic solution.
5) If in basic solution, add enough OH− to neutralize the H+, rewrite H+ + OH− as H2O.
6) Add to both sides.
7) Then cancel H2O on both sides.
what are the steps to balancing half reactions by charge?
1) add electrons on the product side for the oxidation agent
2) add electrons on the reactant side for the reduction agents
when do Displacement reactions happen?
when a stronger reducing agent replaces a weaker reducing agent. The reactivity series below list metals from strongest to weakest reducing agent
how do you check if something is a spontaneous reaction?
e(cell)=e(red) - e(oxd) needs to end up as a positive
what is the cathode?
the reduction agent
what is the anode?
the oxidizing agent
on which side is the cathode put on?
right/ product side
in which order is the anode presented?
left/ reactant side
what is the salt bridge?
ions that are not contributing just helping ions flow through
what other atom have to be in a solution in a electrochemical reaction
something that will return to the original charge
what is the redox method?
- Find the appropriate half-equations on the electrochemical series.
- Identify the chemical species that are reacting.
3.The strongest oxidant (top left) will react with the strongest reductant (bottom right) spontaneously. This is summarised in the ‘S’ configuration of Figure1.
4.Reduction is on the top of the S and oxidation is on the bottom (hence, RED SOX).
draw a galvanic cell reaction
look at phone
what must a cell diagram contain (galvanic cell reaction)?
two half-cells (including half-equations, spectator ions and ion movement)
an anode and a cathode (labelled with polarity)
an external circuit: consisting of wires and a voltmeter
an internal circuit: consisting of a salt bridge (demonstrating ion movement).
how do you Balancing Redox Reactions by the Half-Reaction Method?
1In this method, the reaction is broken down into two half-reactions, one for oxidation and another for reduction.
2Each half-reaction includes electrons.
Electrons go on the product side of the oxidation half-reaction—loss of electrons.
Electrons go on the reactant side of the reduction half-reaction—gain of electrons.
3Each half-reaction is balanced for its atoms.
Then the two half-reactions are adjusted so that the electrons lost and gained will be equal when added.
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how do you balance a redox reaction in basic solution?
same as acid solution plus
1 If in basic solution, add enough OH− to neutralize the a) H+, rewrite H+ + OH− as H2O.
Add to both sides.
b) Then cancel H2O on both sides
4. Balance each half-reaction, with respect to charge, by adjusting the numbers of electrons.
Electrons on product side for oxidation.
Electrons on reactant side for reduction.
5. Balance electrons between half-reactions.
6. Add half-reactions, canceling electrons and common species.
7. Check.
must the gas be in contact with the electrode when in a reaction?
yes
how can the The cell potential at standard conditions can be found?
E cell = E reduction − E oxidation
. Standard electrode potentials ( E °)
what is the formula for electromotive force (EMF)?
EMF = E ° reduction half-cell – E ° oxidation half-cell
what is a galvanic cell often called?
primary cell
what is a reachable battery called?
secondary cell
what is a electrolyte?
an ionic solution that carries charge between the electrodes
what are the key differences between an electrolytic cell and a galvanic cell.
1) Electrolytic cells occur in one container with a porous divider down the middle
2) Electrolytic cells use an electrolyte instead of a salt bridge. Electrolyte solution conducts the electricity.
3) Electrolytic cells use a power source to push electrons onto one of the electrodes. This is the negative electrode because it has a negative charge due to the electrons being pushed onto it.
4) Positive ions move towards the negative electrode to gain electrons. The oxidation number of the ion decreases from a positive number to zero, so it undergoes reduction. Reduction always occurs at the cathode. Therefore, reduction occurs at the negative cathode.
5) Negative ions move towards the positive electrode where they lose electrons. As the oxidation number of the ion increases from zero to a positive charge, it undergoes oxidation. Oxidation always occurs at the anode. Therefore, oxidation occurs at the positive anode.
6) The voltage required by an electrolytic cell must be greater than the EMF that the galvanic cell would generate on discharge. For example, a copper–zinc galvanic cell that produces a voltage of 1.1 V when discharging, requires more than 1.1 V to recharge
what is the difference between galvanic cell and primary cell?
a primary cell is non reversible where as a galvanic cell is Spontaneous redox reactions convert the chemical energy to an electric energy
