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Electrolysis
GCSE chemistry and combined chemistry
Question | Answer |
---|---|
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 for the electrolysis of molten iron bromide? | Iron and bromine |
What will be the products for 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 for the electrolysis of sodium sulfate solution? | Hydrogen gas and Oxygen gas |
What will be the products for 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 for the electrolysis of copper chloride solution? | Copper and chlorine |
What will be the products for 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) |