Redox Reactions in Chemistry

What is the process where electrons are lost to another chemical species called?

What is the process where electrons are received from another chemical species called?

In a redox reaction, oxidation and reduction occur separately.

What do we call a chemical species that causes another substance to undergo oxidation?

What do we call a chemical species that causes another substance to undergo reduction?

What is the oxidation state assigned to free elements?

What is the sum of oxidation states in a neutral atom equal to?

The chemical species whose oxidation state increases undergoes ________.

The chemical species whose oxidation state decreases undergoes ________.

What is used to show the movement of electrons in redox chemistry?

Where are electrons found in an oxidation half-equation?

Where are electrons found in a reduction half-equation?

What is the first step to write a balanced redox half-equation?

To balance oxygen in redox equations, you need to add ________.

To balance hydrogen in acidic conditions, you usually add ________.

Redox Reactions Overview

Redox reactions are characterized by the transfer of electrons between molecules.
They involve simultaneous oxidation (loss of electrons) and reduction (gain of electrons).

Definitions in Redox Chemistry

Oxidation: Loss of electrons; often associated with the gain of oxygen atoms.
Reduction: Gain of electrons.
Oxidizing Agent (Oxidant): Substance that causes oxidation in another substance.
Reducing Agent (Reductant): Substance that causes reduction in another substance.

Oxidation States

Indicate the relative charge on an individual atom during reactions.
Useful for identifying redox reactions.
Common Rules:
- Free elements and elements bound to themselves have an oxidation state of zero.
- Oxidation states of single atoms equal their charge.
- Sum of oxidation states in a neutral molecule equals zero.
- Polyatomic ions have oxidation states equal to their overall charge.

Calculating Oxidation States

Example: In sulfur trioxide (SO₃), sulfur's oxidation state can be determined through balancing total charges.
Hydrogen usually has an oxidation state of +1, while oxygen typically has an oxidation state of -2.

Redox Half-Equations

Used to illustrate the movement of electrons in reactions.
Two half-equations exist: one for oxidation (electrons on the product side) and one for reduction (electrons on the reactants side).

Writing and Balancing Redox Half-Equations

Steps to write half-equations:
- Balance the equation.
- Assign oxidation numbers.
- Add electrons as needed to balance charges.

Balancing Redox Equations with KOHES Method

Key Elements:
- Balance all elements except oxygen.
Oxygen: Balance by adding water molecules.
Hydrogen: Balance by adding hydrogen ions (H⁺) in acidic conditions.
Electrons: Consider oxidation states and add electrons to the appropriate side of the equation.
States: Indicate the physical states of all reactants and products.

Explore the fundamentals of redox reactions and equations in this quiz. Understand the definitions of oxidation and reduction, and how they involve the transfer of electrons. Perfect for students looking to deepen their knowledge in chemistry.