Unit 1 - Chemical Changes and Structure (Oxidising and Reducing Agents)

Question 1

What is an reducing agent?

Answer 1

• Usually a metal or a negative ion.
• Loses/donates an electrons to another element or ion, reducing the other species.
• Is itself oxidised.

Question 2

In which group of the periodic table are the strongest reducing agents found?

Answer 2

Group 1 (the alkali metals), as they have low electronegativities and lose electrons very easily.

Question 3

Which molecule (not on the electrochemical series) is a good reducing agent?

Answer 3

Carbon monoxide (CO)

Question 4

Where are the strong reducing agents found on the electrochemical series?

Answer 4

Top right

Question 5

What is an oxidising agent?

Answer 5

• Usually a non-metal or positive ion.
• Cause oxidation reactions to take place.
• Gains electrons from other atoms or ions (is itself reduced).

Question 6

In which group of the periodic table are the strongest oxidising agents found?

Answer 6

Group 7 (the halogens), as they have high electronegativities and are more likely to gain electrons.

Question 7

Where are the strong oxidising agents found on the electrochemical series?

Answer 7

Bottom left

Question 8

What are oxidising agents commonly used for?

Answer 8

• Killing fungi and bacteria.
• Inactivating viruses.
• Forming aldehydes, ketones, and carboxylic acids from alcohol molecules.
• Breaking down coloured compounds, such as bleaching clothes and hair.

Question 9

What is a redox reaction?

Answer 9

A reaction in which both oxidation and reduction take place simultaneously.

Question 10

What is a displacement reaction?

Answer 10

A redox reaction where metals higher in the electrochemical series displace lower metals from a solution of their ions.

Question 11

What are the steps to balancing complex ion-electron equations?

Answer 11

1. Balance the non-oxygen and non-hydrogen atoms.
2. Balance the oxygen atoms by adding water molecules (H2O).
3. Balance the hydrogen atoms by adding hydrogen ions (H+).
4. Balance the charge by adding electrons (e-).

Question 12

What are some typical oxidising agents?

Answer 12

• Acidified potassium dichromate solution (orange to green).
• Acidified potassium permanganate solution (purple to colourless).
• Hot copper (II) oxide (black to brown).
• Fehling’s solution (blue to brick red).
  Tollen’s reagent (colourless to silver-mirror)