Chemical Changes Flashcards
(21 cards)
What is an acid?
Something which forms H+ ions in water.
What is a base?
A substance with a pH above 7.
What is an alkali?
A base which forms OH- ions in water.
What is the neutralisation reaction?
acid + base = salt + water
What is the difference between strong and weak acids?
Strong acids fully ionise in water, while weak acids don’t. Ionising a weak acid is a reversible reaction.
What additional product is gained from a metal carbonate reacting with an acid?
Carbon Dioxide.
What is the reactivity series?
- Potassium
- Sodium
- Lithium
- Calcium
- Magnesium
- Carbon
- Zinc
- Iron
- Tin
- Lead
- Hydrogen
- Copper
- Silver
- Gold
- Platinum
What is the reaction of a metal and an acid?
Acid + Metal = Salt + Hydrogen
What is the reaction of a metal and water?
Metal + Water = Metal Hydroxide + Hydrogen
What type of reaction is separating a metal from its oxide?
A reduction reaction.
In displacement reactions, which parts are reduced and oxidised?
The metal ion is reduced.
The metal atom is oxidised.
What happens during electrolysis?
The positive cations move to the negative cathode to be reduced.
The negative anions move to the positive anode to be oxidised.
What must the electrodes be?
Inert so they do not react with the electrolyte.
What is the problem with extracting metals by electrolysis?
It is very expensive as it takes a lot of energy to melt the ore and provide the current.
What is aluminium extracted from?
Bauxite.
What is aluminium oxide mixed with to lower its boiling point?
Cryolite.
What happens at the cathode during electrolysis of an aqueous solution?
If the metal is more reactive than hydrogen, hydrogen is produced.
Otherwise, the metal is produced.
What happens at the anode during electrolysis of an aqueous solution?
If there are halide ions present, they are discharged.
Otherwise, the OH- ions are discharged, producing oxygen gas.
How do you test for chlorine?
It bleaches damp litmus paper, turning it white.
How do you test for hydrogen?
It makes a squeaky pop with a lit splint.
How do you test for oxygen?
It relights a glowing splint.
