Unit 1-Oxidising And Reducing Agents

Question 1

What does an oxidising agent do?

Answer 1

• Oxidising agents cause oxidation reactions to take place
• They gain electrons from other atoms or ions (is itself reduced)

Question 2

What does a reducing agent do?

Answer 2

• Reducing agents lose (donates) electrons to another element or ion (reducing the other species)
• Is itself oxidised

Question 3

Elements at the top right of the Electrochemical series are strong…

reducing agents or oxidising agents?

Answer 3

Reducing agents

Question 4

Why are the strongest reducing agents the alkali metals??

HINT think electronegativity.

Answer 4

Alkali metals have low electronegativities and lose electrons very easily.

Question 5

Elements at the bottom left of the Electrochemical series are strong…

reducing agents or oxidising agents?

Answer 5

Oxidising agents

Question 6

Why are the strongest oxidising agents the halogens?

HINT think electronegativity.

Answer 6

The Halogens have high electronegativities and gain electrons very easily.

Question 7

Name an example of an oxidising agent which is not an element.

Answer 7

Group ions such as dichromate (Cr₂O₇^2-) and permanganate (MnO₄^-) ions are strong oxidising agents in acidic solutions.

Hydrogen peroxide (H₂O₂) is a molecule which is a strong oxidising agent.

Question 8

Name an example of a reducing agent which is not an element.

Answer 8

Some molecules such as carbon monoxide (CO) are also used in the chemical industry as reducing agents to help extract metals.

Question 9

Describe how to balance a complex ion-electron equation.

Answer 9

Balance the atoms that are already present on both sides.

If the number of oxygen atoms needs to be balanced, add the same number of water molecules to the opposite side (the side with the lower total oxygen).

Add twice the number of hydrogen ions (H+) as water molecules added to the opposite side.

Complete the equation by adding the total number of electrons needed to balance the overall electrical charge.

Question 10

ClO₃⁻ (aq) → Cl₂(g)

How would this equation be balanced?

Answer 10

ClO₃⁻ (aq) → Cl₂(g)

1. Balance chlorines

2ClO₃⁻ (aq) → Cl₂(g)

2. Add waters to balance 0xygens

2ClO₃⁻ (aq) → Cl₂(g) + 6H₂O(l)

3. Add H⁺ to balance hydrogens

2ClO₃⁻ (aq) + 12H⁺(aq) + 10e⁻ → Cl₂(g) + 6H₂O(l)