Redox Reactions
What does the word "Redox" means?
the word "Redox" Means "Reduction and Oxidation"
What does the pH Scale means?
The pH Scale ranks different aqueous solutions based on their acidity levels
Name the type of reaction: H₂ + Cl₂ → 2HCl
Synthesis reaction
Balance: H₂ + O₂ → H₂O
2H₂ + O₂ → 2H₂O
Identify the change: Ice melting to water
Physical change
Why the Oxidation state is important?
The Oxidation state are important as they help us keep track of where each electron is moving in compound
The pH Scale range from_____,_____being highly acidic and ___ being very basic. ____ ties right in the middle as a neutral solution
0-14, 0, 14
Identify the reaction type: 2KClO₃ → 2KCl + 3O₂
Decomposition reaction
Why do we balance chemical equations?
To satisfy the law of conservation of mass: atoms are neither created nor destroyed.
How can you tell a chemical change has occurred?
Signs include color change, gas production, temperature change, or formation of a new substance.
What is the definition of Oxidation?
The opposite of an atom being reduced. This is when an atom loses electrons
What are the two types of Ions of all solutions contains?
Hydroxide and Hydronium Ions
Predict the products and type of reaction: Na + H₂O → ?
NaOH + H₂; this is a single replacement reaction
Balance: Al + O₂ → Al₂O₃
4Al + 3O₂ → 2Al₂O₃
Classify the change: Iron rusting
Chemical change
In the reaction Zn + Cu²⁺ → Zn²⁺ + Cu, identify which substance is oxidized and which is reduced, and explain how you know using electron transfer.
Zinc (Zn) is oxidized because it loses electrons to form Zn²⁺. Copper ions (Cu²⁺) are reduced because they gain electrons to form Cu.
solution with a pH of 4 is 1,000 times more acidic than a solution with a pH of 7 because the pH scale is logarithmic, and each decrease of one pH unit represents a tenfold increase in acidity.
A solution with a pH of 4 is 1,000 times more acidic than a solution with a pH of 7.
Given Zn + HCl → ZnCl₂ + H₂, explain why this is a single replacement reaction.
Zinc replaces hydrogen in HCl, forming a new compound
The unbalanced equation is: Fe + Cl₂ → FeCl₃. Determine the coefficients and explain your reasoning.
2Fe + 3Cl₂ → 2FeCl₃. Each FeCl₃ has 1 Fe and 3 Cl atoms, so 2 Fe and 3 Cl₂ molecules balance the Cl.
Explain why dissolving salt in water is a physical change, but baking a cake is a chemical change.
Dissolving salt only separates ions but doesn’t form a new substance. Baking a cake involves chemical reactions that produce new substances
Why does a redox reaction always involve both oxidation and reduction? Use a real-world example (such as rusting or batteries) to support your explanation.
A redox reaction always includes both oxidation and reduction because electrons lost by one substance must be gained by another. For example, in a battery, one material loses electrons while another gains them, allowing electric current to flow.
Two solutions differ by 2 units on the pH scale. Explain how their hydrogen ion (H⁺) concentrations compare, and predict how this difference would affect the rate of a chemical reaction that is sensitive to acidity
A 2-unit pH difference means the lower-pH solution has 100× more H⁺ ions, which changes the reaction rate in pH-sensitive reactions.
Compare combustion and synthesis reactions in terms of energy change and products. Give a real-life example of each.
Combustion reactions release a large amount of energy and produce CO₂ and H₂O (e.g., burning gasoline). Synthesis reactions may absorb or release energy depending on the compounds and produce one product from two or more reactants
Compare the difficulty of balancing combustion vs. synthesis reactions, and explain why balancing combustion reactions sometimes requires fractional coefficients
Combustion reactions often involve O₂ and multiple products (CO₂, H₂O), making balancing more complex. Fractional coefficients can simplify balancing before multiplying to whole numbers.
Evaluate this scenario: a candle burns, producing heat, light, water vapor, and CO₂. Identify all physical and chemical changes.
The melting wax is a physical change; burning wax producing CO₂ and H₂O is a chemical change. Both occur simultaneously