Electrolysis

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What is an electrolyte?
When ionic compounds are melted or dissolved in water, the ions (charged particles that have gained/lost electrons) are free to move around, and the liquid/solution will conduct electricity. Ionic compounds that dissolve in water to make a solution t
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What are the two electrodes?
Cathode and anode
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What happens when a voltage is applied across an electrolyte?
the charged ions are attracted to the electrode with the opposite charge to the ion.
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Where do positively charged ions move to?
The negative electrode (Cathode)
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Where do negatively charged ions move to?
The positive electrode (Anode)
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What is the positive electrode called?
Anode
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What is the negative electrode called?
Cathode
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What happens when an ion touches an electrode?
electrons can be transferred, producing elements.
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Explain the electrolysis apparatus
You fill a container halfway with an electrolyte and then you submerge a cathode and an anode in the water, both which must be connected to a power supply
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What happens when a voltage is applied across an electrolyte?
The charged ions are attracted to the oppositely charged electrons
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When simple ionic compounds are heated, what happens to it?
It melts
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What happens to the metal and non-metal ions within the molten ionic compound?
They are free to move, so the liquid can undergo electrolysis
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Are non-metal ions positive or negative?
They are negative
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T/F metal ions are negative
False
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What is the name of a positively charged ion?
Cation
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What is the name of a negatively charged ion?
Anion
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What is the name of a liquid or solution that conducts electricity?
Electrolyte
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What happens when we electrolyse molten copper oxide (CuO)?
Positively charged copper ions (Cu2+) move to the cathode. A pinkish coat of copper will appear on the cathode. Negatively charged oxygen ions (O2-) move to the anode. Oxygen atoms will form at the anode and combine to give O2 gas bubbles.
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What is electrolysis used for?
Electrolysis is used to extract reactive metals from molten ores (melted materials containing metals). It is used to extract metals such as aluminium, which are more reactive than carbon.
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What is the anode usually made out of?
Carbon
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Where is carbon dioxide made?
The anode
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Is aluminium formed at the cathode or the anode?
The cathod
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Name two disadvantages of electrolysis
Lots of energy is needed to: Melt the solid ionic compound to allow the ions to flow. To produce the electrical current. All this energy costs money, and a lot of it!
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T/F Electrolysis is frequently used to extract metals less reactive than carbon?
False. Its frequently used to extract metals more reactive than carbon, not less reactive
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In the electrolysis of aluminium, whats formed at the cathode and whats formed at the anode?
At the anode, carbon dioxide is formed, and at the cathode, aluminium is formed
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What is formed at the cathode is based on how reactive the metal is. If the metal is more reactive than hydrogen, what is produced?
Hydrogen
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What is formed at the cathode is based on how reactive the metal is. If the metal is less reactive than hydrogen, what is produced?
The metal is produced
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Why are the products of electrolysis in aqueous solutions difficult to predict?
the water molecules in the solution split up to form hydrogen (H+) and hydroxide (OH-) ions.
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What is formed at the anode depends on if halide ions are present. So what happens when the halide ion is or isn't present?
If halide ions are present, the respective halogen forms. If halide ions are absent, oxygen forms.
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n the electrolysis of aqueous solutions, what products can form at the cathode?
Hydrogen gas or a metal
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What is an aqueous solution?
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending to the relevant chemical formula. For example, a solution of table salt, or sodium chloride, in water
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At the anode does oxidation or reduction occur?
Oxidation reactions happen i.e. negatively charged ions lose electrons.
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What is the half equation for bromine in electrolysis?
2Br- → Br2 + 2e-
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At the cathode does oxidation or reduction occur?
Reduction reactions happen i.e. positively charged ions gain electrons.
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What is the half equation for lead in electrolysis?
Pb2+ + 2e- → Pb
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Why is the anode usually made of carbon?
It is a good conductor, and its cheap
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Where is aluminium formed?
The cathode
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Name the disadvantages of electrolysis.
Lots of energy is needed to: Melt the solid ionic compound to allow the ions to flow. To produce the electrical current. All this energy costs money, and a lot of it!
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What is a halide ion?
A halide ion is a halogen atom bearing a negative charge.
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What happens if a halide ion is present at the anode?
If halide ions are present, the respective halogen forms.
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What are some halide ions?
The halide anions are fluoride (F−), chloride (Cl−), bromide (Br−), iodide (I−) and astatide (At−).
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What happens if a halide ion is absent at the anode?
Oxygen is formed
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Card 2

Front

What are the two electrodes?

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Cathode and anode

Card 3

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What happens when a voltage is applied across an electrolyte?

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Card 4

Front

Where do positively charged ions move to?

Back

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Card 5

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Where do negatively charged ions move to?

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