CC10 Electrolysis Flashcards
Magnesium carbonate is insoluble. What do you need to do before it will conduct electricity?
Melt it
Sodium fluoride is soluble. Explain what the easiest way for it to conduct electricity is
Dissolve it in water because this does not require high temperatures
Which ions are in NaCl
Na⁺ and Cl⁻
Which ions are in CuCl₂
Cu²⁺ and two Cl⁻
Which ions are in Na₂SO₄
2 ions of Na⁺ and one SO₄²⁻
Is this process oxidation or reduction? Al → Al³⁺ + 3e⁻
Oxidation
Is this process oxidation or reduction? Na⁺ + e⁻ → Na
Reduction
Is this process oxidation or reduction? F₂ + 2e⁻ → 2F⁻
Reduction
Is this process oxidation or reduction? Fe²⁺ → Fe³⁺ + e⁻
Oxidation
In this reaction, what has been oxidised and what has been reduced? Mg²⁺ + 2Na → 2Na⁺ + Mg
Na has been oxidised, Mg²⁺ has been reduced
In this reaction, what has been oxidised and what has been reduced? 2Al + 3Ca²⁺ → 2Al³⁺ + 3Ca
Al has been oxidised, Ca²⁺ has been reduced
In this reaction, what has been oxidised and what has been reduced? K + Na⁺ → K⁺ + Na
K has been oxidized, Na⁺ has been reduced
What is electrolysis?
Using a dc electric current to decompose (break down) a substance
What is an electrolyte?
An ionic compound in the molten state or dissolved in water
What happens to an ionic substance when it is melted or dissolved in water?
The ions become free to move around
What is the name for the positive electrode?
The anode
What is the name for the negative electrode?
The cathode
Do positive ions move to the anode or the cathode?
Cathode
Do negative ions move to the anode or the cathode?
Anode
Where does reduction occur?
Cathode
Where does oxidation occur?
Anode
At which electrode would Zn²+(aq) turn into Zn(s)?
Cathode (needs to gain electrons)
At which electrode would Cl⁻(aq) turn into Cl₂(g)?
Anode (needs to lose electrons)
Balance the equation: Al³⁺ + e⁻ → Al
Al³⁺ + 3e⁻ → Al
Balance the equation: Cl⁻ → Cl₂ + e⁻
2Cl⁻ → Cl₂ + 2e⁻
Balance the equation: O²⁻ → O₂ + e⁻
2O²⁻ → O₂ + 4e⁻
What will be the products of the electrolysis of molten iron bromide?
Iron and bromine
What will be the products of the electrolysis of molten zinc oxide?
Zinc and oxygen
Define oxidation in terms of electrons
Oxidation is the loss of electrons
Define reduction in terms of electrons
Reduction is the gain of electrons
What will be the products of the electrolysis of sodium sulfate solution?
Hydrogen gas and Oxygen gas
What will be the products of the electrolysis of acidified water?
Hydrogen gas and Oxygen gas
What happens to the change in mass of the electrodes if you increase the current?
As current increases so does the change in mass.
When copper sulphate solution is electrolysed using copper electrodes. What happens to the mass of the electrodes?
The cathode mass increases. The anode mass decreases.
Why use propanone to dry the electrodes when reweighing them after the electrolysis.
It evaporates drying the electrodes, no need to physically dry them.
What will be the products of the electrolysis of copper chloride solution?
Copper and chlorine
What will be the products of the electrolysis of molten lead bromide?
lead and bromine
In the electrolysis of sodium chloride solution, what are the products?
Chlorine gas and hydrogen gas
Why is sodium not produced in the electrolysis of sodium chloride solution?
It is more reactive than hydrogen so hydrogen is produced instead.
What is produced at the anode in electrolysis of solutions?
Either a halogen or oxygen (when there is no halogen present)
What is produced at the cathode in electrolysis of solutions?
Which ever substance is the least reactive of the cations
