Oxidation-Reduction Reactions

These flashcards cover key concepts related to oxidation-reduction reactions as discussed in the lecture notes.

What happens to an atom if you change the number of protons?

It becomes a different element.

What happens to an atom if you change the number of electrons?

It becomes an ion of the same element.

What are oxidation-reduction reactions commonly known as?

Redox reactions.

What is an oxidation number or oxidation state?

It is the same thing as the charge on an ion.

In the reaction 2Na (s) + Cl2 (g) → 2 NaCl (s), what type of reaction is it?

It is a redox reaction.

What is a half-reaction?

One half of the total redox reaction, either oxidation or reduction.

What happens to the charge on sodium from reactants to products in its oxidation half-reaction?

Sodium's charge increases (becomes more positive).

What happens to the charge on chlorine from reactants to products in its reduction half-reaction?

Chlorine's charge decreases (becomes more negative).

Where are the electrons written in an oxidation half-reaction?

On the product side.

Where are the electrons written in a reduction half-reaction?

On the reactant side.

What is the substance that is oxidized called?

The reducing agent.

What is the substance that is reduced called?

The oxidizing agent.

What does gaining electrons signify in a reaction?

It signifies reduction.

What does losing electrons signify in a reaction?

It signifies oxidation.

What type of reactions can also be oxidation-reduction reactions?

Single replacement, synthesis/combination, decomposition, and combustion.

What type of reaction is NOT an oxidation-reduction reaction?

Double replacement reactions.

What is the first step in writing redox half-reactions?

Find the charges/oxidation states of all elements.

What charge do elements written alone have?

They have a charge of zero.

What does the law of conservation of charge state regarding electrons?

Electrons must be balanced in the half-reactions.

In a voltaic cell, what is the electrode at which oxidation occurs called?

The anode.

In a voltaic cell, what is the electrode at which reduction occurs called?

The cathode.

What does a voltaic cell convert?

It converts chemical energy into electrical energy.

What does an electrolytic cell convert?

It converts electrical energy into chemical energy.

What happens to the charges in the two half-cells of a voltaic cell?

They become unbalanced, causing movement of ions through the salt bridge.

What is the movement of electrons in a voltaic cell?

From the anode to the cathode.

What kind of reaction is thermodynamically favorable in a voltaic cell?

Chemical reactions that release energy.

How do charges of the electrodes differ in a voltaic cell and an electrolytic cell?

Anode is negative and cathode is positive in a voltaic cell; the opposite in an electrolytic cell.