Electrochemistry Flashcards
(30 cards)
What happens when an electric current is passed through a molten ionic compound?
The compound decomposes or breaks down.
Can aqueous solutions of ionic compounds conduct electricity?
Yes, the process also occurs for aqueous solutions of ionic compounds.
Can covalent compounds conduct electricity?
No, covalent compounds cannot conduct electricity and do not undergo electrolysis.
Can ionic compounds in solid state conduct electricity?
No, they cannot conduct electricity as they have no free ions that can move and carry the charge.
What is the method for electrolysis of molten lead(II) bromide?
Add lead(II) bromide into a beaker and heat it to turn molten. Add two graphite rods as electrodes and connect to a power pack or battery. Turn on the power pack or battery.
What happens to negative bromide ions during electrolysis of molten lead(II) bromide?
They move to the positive electrode (anode) and lose one electron to form bromine molecules, producing bubbling as brown bromine gas is given off.
What happens to positive lead ions during electrolysis of molten lead(II) bromide?
They move to the negative electrode (cathode) and gain electrons to form grey lead metal, which deposits on the surface of the electrode.
What is brine?
Brine is a concentrated solution of aqueous sodium chloride.
What electrodes can be used for electrolysis of brine?
Inert electrodes made from platinum or carbon/graphite can be used.
What ions are present in brine?
Na+ and Cl– ions from the brine, and H+ and OH– ions from the water.
What are the products of electrolysis of brine?
Chlorine and hydrogen gases are produced, and sodium hydroxide solution remains in the electrolysis chamber.
What are the industrial uses of the products from electrolysis of brine?
Chlorine is used to make bleach, hydrogen is used to make margarine, and sodium hydroxide is used to make soap and detergents.
What is produced at the negative electrode during electrolysis of brine?
H+ ions are discharged at the cathode, gaining electrons to form hydrogen gas.
What is produced at the positive electrode during electrolysis of brine?
Cl– ions are discharged at the anode, losing electrons to form chlorine gas.
What happens to Na+ and OH– ions during electrolysis of brine?
They remain behind and form the NaOH solution.
Conductivity of ionic compounds
Reactivity Series
What is electroplating?
Electroplating is a process where the surface of one metal is coated with a layer of a different metal.
What is the purpose of electroplating?
Electroplating is done to make metals more resistant to corrosion or damage.
Examples include chromium and nickel plating, and galvanising (zinc plating) typically done to iron and steel.
How does electroplating improve the appearance of metals?
Electroplating is also done to improve the appearance of metals.
An example is coating cutlery and jewellery with silver.
What is a fuel?
A fuel is a substance which releases energy when burned.
What is hydrogen used for?
Hydrogen is used as a fuel in rocket engines and in fuel cells to power some cars.
What is a fuel cell?
A fuel cell is an electrochemical cell in which a fuel donates electrons at one electrode and oxygen gains electrons at the other electrode.
What is the reaction for hydrogen in a fuel cell?
H2 → 2H+ + 2e–
