ONA: Half equations in electrolysis Flashcards
How does an aluminium atom form an aluminium ion?
Tip - Aluminium= G3
- Aluminium loses 3 electrons
How would an aluminium ion form an aluminium atom?
Tip - Aluminum = G3
- Aluminum ion gains 3 electrons to form neutral aluminium.
Go backwards
What is the rule for positive ions to form their neutral atoms?
- Positive ions must gain electrons to form their neutral atoms.
Opposite of what they did to become ion
What is the rule for negative ions to form their neutral atoms?
- Negative ions must lose electrons to form neutral ions.
- Opposite of what they did to become ion*
What is the “cathode”?
- The cathode is the negatively charged electrode.
What ions are attracted to the “cathode”?
- Positive ions are attracted to the cathode.
What is the “annode”?
- The annode is the positively charged electrode.
What ions are attracted to the “annode”?
- Negative ions are attracted to the annode.
What happens to positive ions once they reach the cathode?
- Positive ions gain electrons to form the neutral atom.
What happens to negative ions once they reach the annode?
- Negative ions lose electrons to form the neutral atom.
What are the 2 TopTips when writing half equations?
1.) Balance atoms/ charge
2.) Remember what existis as molecules.
How would you write a magnesium ion gaining 2 electrons at cathode?
Mg²⁺+2e⁻–> Mg
How would you write an oxygen ion losing 2 electrons at annode?
2O²⁻—>O₂+4e⁻
What are the steps of writing a half equation?
1.) Write what the ion becomes
2.) Add electons
3.) Balnace atoms/ charge
What do you need to make sure you write for a neutral atom that exists as a molecule?
- You must write a subscript 2.
Where does the electron symbol appear when electrons are lost?
- On the right hand side of the eqaution.
What is a neumonic to remember oxidation and reduction in terms of electrons?
Oxidation
Is
Loss
Reduction
Is
Gain
Would a calcium ion (Ca²⁺) be reduced or oxidised to form neutral Ca?
- Positive ions gain electrons
- Reduction is gain.
- Calcium ion is reduced.
Would a bromide ion (Br⁻) be reduced or oxidised to form neutral Br?
- Negative ions lose electrons.
- Oxidation is loss.
- Bromide ion is oxidised.
What reaction occurs at the cathode?
Gain of electrons
- Reduction occurs at cathode
What reaction occurs at the anode?
Loss of electrons
- Oxidation occurs at annode.
What is being reduced in this equation:
Al³⁺+3e⁻–> Al
- Al³⁺/ aluminium ion
What is being oxidised in this equation:
2Br⁻–> Br₂+2e⁻
- Br⁻/ bromide ion
What are the products of this reaction:
2Br⁻–> Br₂+2e⁻
Br₂+2e⁻
- Bromine
- 2 electrons lost
