Module 16 Flashcards
Define Oxidation number.
it is the charge that an atom in a molecule would develop if the most electronegative atoms in a molecule took the shared electrons from the electronegative atoms.
An atom has an oxidation number of -3 in one molecule, but it has an oxidation number of +3 in a second molecule. What can we say about the electronegativities of the other atoms that make up the 2 molecules.
the electronegativities of the other atoms in molecule one were lower than the atom in question, while the electronegativities of the atoms in molecule 2 were greater.
What must the oxidation numbers of all the atoms in a molecule add up to?
the sum of the oxidation numbers must equal the charge of the molecule
Define oxidation and reduction
Oxidation-the process by which an atom loses electrons
Reduction-the process by which an atom gains electrons
Would there ever be a case in which oxidation could occur without reduction?
No (atoms can’t loose electrons unless something else can gain them)
Is the anode of a battery positive or negative? what about the cathode?
Anodes are negative. Cathodes are positive.
When figuring out oxidation numbers, what rule do you use only as a last resort? Why is it only a last resort?
If all else fails assume that the atom’s oxidation number is the same as what it would take on in an ionic compound. The atoms that are most likely to follow this rule are in groups 3A, 6A, and 7A. This must be used as a last resort because there are many exceptions to it.
What are the 3 reactants needed for a lead-acid battery?
PbO2, Pb, & H2SO4
Why are some batteries rechargeable and others not?
because the internal structure of most batteries gets destroyed as the reaction proceeds. There is no way to reverse the destruction, so the battery is not rechargeable.
Name 2 differences between an alkaline dry cell and a lead-acid battery.
the alkaline cell has no aqueous solutions, but the lead-acid battery does. The lead-acid battery can be recharged; the alkaline cell cannot be recharged.
What are the sticks of metal in a simple battery called?
Electrodes
Is the atom that reduced the cathode or the anode?
Cathode (b/c electrons flow toward it)
Is the atom that oxidized the cathode or the anode?
Anode (b/c electron flow from it)
Does an alkaline battery contain an Acid?
No (an automobile battery does)
Does an alkaline battery contain several battery cells?
No (an automobile battery does)
