12.2 Galvanic Cells and Oxidation Numbers Flashcards
What is the combined oxidation sum of a neutral compound?
Clearly, if the compound is considered neutral, sum of oxidation numbers must be 0!
daily reminder to remember your states and standard state
What is the oxidation number of oxygen (99% of the time)?
Oxygen has an oxidation number of 2- apart from with peroxides and fluorine, where it is -1 and +x respectively.
What is the oxidation number of hydrogen?
+1 when with non-metals and -1 when bonded into metal hydrides
daily reminder to remember your states and standard state
What is the oxidation number of a simple ion?
This was common sense in class, the oxidation number for a single simple ion is simply the charge of the element on the periodic table.
e.g Cl oxidation number is -1
Does the sign come before or after the number in an oxidation number?
before, bitch. BEFORE.
What is the sum of oxidation numbers in a polyatomic ion? e.g SO4 (2-)
Sum of the oxidation number is equal to -2 or whatever the charge is.
What has happened to carbon as it charge has gone from -2 to +2 after a redox reaction?
If something gains charge, that means it loses electrons. Since carbon has gained a charge of +4, this means that it has lost 4 electrons.
Loss of electrons means oxidation. Therefore it has been oxidised, and therefore is the reductant.
What has happened to oxygen as it charge has gone from 0 to -2 after a redox reaction?
If something loses charge, that means it gains electrons. Since carbon has a new charge of -2, this means that it has gained 2 electrons.
Gain of electrons means reduction. Therefore it has been reduced, and therefore is the oxidant.
What is a galvanic cell? (you need to know this definition.)
Galvanic cells are electrochemical cells that convert chemical energy to electrical energy.
List the components of a galvanic cell. (as much as you can)
Anode, Cathode, Salt Bridge, Voltmeter, Electrolytes
What is the role of the cathode?
Remember, that the cathode is +
What do we associate with positive? A gain of electrons.
Thus, REDUCTION occurs at the cathode.
Similarly, if the flow of electrons goes from left to right, the cathode is on the right.
if the cathode reduces, then it is the oxidant
What is the role of the anode?
Remember, that the anode is -
What do we associate with negative? A loss of electrons.
Thus, OXIDATION occurs at the cathode.
Similarly, if the flow of electrons goes from left to right, the cathode is on the left.
if the anode oxidises, then it is the reductant
How is potential difference calculated and what is another term for EMF?
Find the more reactive substance, flip it and add it together. (On the periodic table).
If a substance is higher (more negative) on the emf table, is it the anode or the cathode?
ANODE BABY, Flip it, then add the emf of the cathode to it to get the potential difference.
Is the anode a reductant or oxidant?
Since the anode oxidises, it is the reductant
