Gcse Chemistry oxidation and reduction.

Last updated about 4 hours ago

10 questions

Gcse Chemistry oxidation and reduction.

Last updated about 4 hours ago

10 questions

Carbon + oxygen → carbon dioxide
The carbon has gained oxygen and has been _____________ 

Other Answer Choices:

oxidised

reduced

CH₄ + 2O₂ → CO₂ + 2H₂O
The carbon has gained oxygen so has been _____________ 
The hydrogen has gained oxygen so has been _____________ 

Other Answer Choices:

oxidised

reduced

CuO + H₂ → Cu + H₂O

The copper in Copper (II) oxide has lost oxygen and has been ____________ 
The hydrogen has gained oxygen and has been _____________ 

Other Answer Choices:

reduced

oxidised

Mg +CuSO₄ → MgSO₄ + Cu
In a metal displacement reaction even though there has been no gain or loss of oxygen we can still identify what has been oxidised and what has been reduced.
The metal in the element has been oxidised.
The metal in the compound has been reduced.
Mg has been _____________
The copper (in copper sulfate ) has been ____________.

Other Answer Choices:

oxidised

reduced

2K(s) + Br2(ℓ) → 2KBr(s)
The potassium atoms have lost electrons and been _____________
This means that the bromide ions have been ____________
K →K+ +e- (loss of electrons so _____________) 
2Br⁻ → Br₂ +2e⁻ (gain of electrons so ____________ )

Other Answer Choices:

reduced

oxidised

In oxidation and reduction reactions for non-metals.
The non-metal atoms gain electrons to for negative ions and are therefore being ____________.
The negative non-metal ions lose electrons and are therefore being _____________
2I⁻ + Br₂ → I₂ + 2Br⁻
The iodide ions have lost electrons and have been _____________
The chlorine atoms have gained electrons and have been ____________  
  

Other Answer Choices:

oxidised

reduced

Oxidation and reduction can also be thought of in terms of the gain or loss of electrons.
Reduction is gain of electrons
Oxidation is loss of electrons
Cu²⁺ + 2e⁻ → Cu
The copper ions has been ____________ (gained electrons).
Mg →Mg²⁺ +  2e⁻
The magnesium metal atoms have been _____________ (lost electrons)

Other Answer Choices:

oxidised

reduced

Zinc oxide + aluminium  → aluminium oxide + zinc
The zinc in zinc oxide has lost oxygen and has been ____________
The aluminium has gained oxygen and has been _____________ 
Zn2+ + 2e⁻→ Zn
The zinc ions have gained electrons and have been ____________ 
Al → Al3+ + 3e⁻
The aluminium atoms have lost electrons and have been _____________ 

Other Answer Choices:

reduced

oxidised

Iron oxide + aluminium  → aluminium oxide + iron
The iron in iron oxide has lost oxygen and has been ____________
The aluminium has gained oxygen and has been _____________  

Other Answer Choices:

oxidised

reduced

To summarise
Oxidation is _________ of oxygen or _________ of electrons.
Reduction is _________of oxygen or _________  of electrons.
Positive metal ions _________ electrons and are ____________ to form neutral metal atoms.
e.g. Al3+ 3e- →Al (reduction)
Neutral non-metal atoms _________electrons and are ____________ to form negative non-metal ions.
Br₂ + 2e-→ 2Br⁻

Other Answer Choices:

gain

reduced

loss