2- Salts And Electolysis Flashcards
What is an aqueous solution? (aq)
A substance dissolved in water
What are acids (how can you tell)?
They produce hydrogen ions when dissolved in water (H+)
What are alkalis (how can you tell)?
Bases (acid neutralisers) which dissolve in water to make alkaline solutions and produce hydroxide ions (OH-)
What happens when an acid reacts with a metal?
A salt and hydrogen gas are produced
Acid +,metal –> a salt + hydrogen
What will acid react with?
Metals above hydrogen in the reactivity series (but not too high or it is unsafe)
What happens when an acid reacts with a base?
Neutralisation reaction takes place and a salt and water are produced
How do you make an acidic aqueous solution if the acid is insoluble?
You add it a little at a time and then, once all the acid has reacted, filter the mixture to remove excess solid reactant
How do you make soluble salts from acids and alkali’s? (Equation)
Acid + alkali –> salt + water
How (using an equation) show a neutralisation reaction?
How can you tell the reaction has happened?
H+ + OH- –> H2O
You can’t tell by sight, you have to use a universal indicator
How can the solid salt be obtained from the solution?
Through crystallisation
What is produced when ammonia solution reacts with acids? What are they used for?
Ammonia salts, used as fertilisers
How can you make insoluble salts?
Mixing solutions of soluble salts that contain the ions needed
What is a precipitate?
An insoluble solid formed by a reaction taking place in solution
What is electrolysis?
The process that uses electricity to break down ionic compounds into elements called electrolyte
When does electrolysis take place?
When electricity passes through a molten ionic compound or a solution containing ions
How does electrolysis happen?
Two inert (not reactive) electrodes make contact with the electrolyte. positively charged ions in the electrolyte are attracted by the negative electrode where they form metals or hydrogen negatively charged ions are attracted to the positive electrode where they lose their charge and form non-metallic
What happens to 1)positively charged ions 2)negatively charged ions when they reach the electrode?
1) They gain electrons to become neutral atoms (a reduction)
2) They lose electrons to become neutral atoms (oxidation)
What happens if the ions in water are electrolysed?
Hydrogen may be produced at the negative electrode if the positive ions in the solution are a metal more reactive than hydrogen
How is oxygen usually produced in electrolysis?
From the positive electrode from an aqueous solution
Why must aluminium be extracted by electrolysis?
It is more reactive than carbon
How do you prepare aluminium for electrolysis?
Get aluminium oxide from the ore, purify it and then melt it
What are the products of aluminium when it has been through electrolysis?
Pure aluminium and oxygen
What is the overall reaction of aluminium in electrolysis? (Equation)
Aluminium oxide –> aluminium + oxygen
What happens at the negative electrode with aluminium oxide?
Aluminium ions are reduced to aluminium atoms by gaining electrons
