C5 - Chemical Changes Flashcards
The reactivity series (most reactive to least reactive)
Potassium, Sodium, (Lithium), Calcium, Magnesium, Aluminium, Carbon, Zinc, Iron, Tin, Lead, Hydrogen, Copper, Silver, Gold, Platinum
Mnemonic for Reactivity Series
Please Stop Calling Me A Careless Zebra, Instead Try Learning How Copper Saves Gold
Metals reaction with water
Metal + Water —> Metal Hydroxide + Hydrogen
Test for Hydrogen
Lit splint makes a squeaky pop
Metals reaction with Acid
Metal + Acid —> metal salt + hydrogen
Potassium, Sodium, Lithium, Calcium reaction with water
Fizzing, giving off hydrogen gas, leaving alkaline metal hydroxide solution
Potassium, Sodium, Lithium, Calcium reaction with (dilute) acid
Explosion
Magnesium, Aluminium, Zinc, Iron reaction with water
Very slow reaction
Magnesium, Aluminium, Zinc, Iron reaction with (dilute) acid
fizzing, giving off hydrogen gas, forming a salt
Tin and Lead reaction with water
Slight reaction with steam
Tin and Lead reaction with (dilute) acid
React slowly with warm acid
Copper, Silver, Gold reaction with water and acid
No reaction
Metals reaction with Oxygen
Metal + Oxygen —> Metal Oxide
What is metal’s reaction with oxygen called
Oxidation - gaining oxygen
What is a reduction reaction involving metal oxides
When metal oxides lose oxygen and return to their atomic form
What is the rule for displacement reactions
A more reactive metal will displace a less reactive metal from its salt / compound
What is an ionic equation
An equation which shows only the atoms and ions that change in a reaction
what is Oxidation
The gain of oxygen and loss of electrons
What is reduction
The loss of oxygen and the gain of electrons
What is the mnemonic for oxidation and reduction in terms of electrons
OILRIG - Oxidation Is Loss Reduction Is Gain
Why are displacement reactions called RedOx reactions
REDuction and OXidation happen at the same time
What is an Ore
A rock that contains enough metal to make it economical to extract the metal
When and How do you extract metals with carbon
You extract metals with carbon when the metal is less reactive than carbon. To extract with carbon you must heat the metal oxide with carbon and the carbon removed the metal from the metal oxide to form carbon dioxide
Equation for extracting metal with carbon
Metal oxide + Carbon —> Metal + Carbon dioxide
How are metals that are more reactive than carbon extracted
By electrolysis of the molten metal compound
What is a salt
A compound formed when the hydrogen in an acid is wholly or partially replaced by a metal or ammonium ions
Equation for formation of metal salts
Metal + Acid —> Metal salt + Hydrogen
Conditions for formation of metal salt
Metal must be above hydrogen in reactivity series.
Metal must not be high in reactivity series or reaction will be too vigorous
What kind of reaction is a metal and an acid
a REDOX reaction as both reduction and oxidation occurs
What happens during the reaction of metals and acids in terms of electrons
Metal atoms lose electrons and are oxidised. The hydrogen ions from the acid gain electrons and are reduced
What is a precipitate
An insoluble solid formed by a reaction taking place in a solution
What is an acid
A solution that contains hydrogen ions (H+)
What is a base
A substance that can neutralise an acid
What is an alkaline
A soluble base
Reaction of acid and a base
Acid + Base —> a Salt + Water
It is a neutralisation reaction.
What are types of bases
Metal oxides
What are salts made up of
Positive metal ions from a metal, base, or a carbonate
A negative ion from an acid
They have no overall charge as the sum of the charges of their ions equals zero
How to make a copper salt
- Add insoluble copper oxide to sulphuric acid and stir. Warm gently on a tripod and gauze (do not boil)
- The solution turns blue as the reaction occurs, showing that copper sulfate is being formed. Excess copper oxide can be seen.
- When the reaction is complete (no more dissolving or fizzing), filter the solution to remove the excess copper oxide.
- You can then evaporate the water so the crystals of copper sulfate start to form.
Reaction of an acid with an alkali
Acid + Alkali —> a salt + Water
This is a neutralisation reaction
What happens with ions in a neutralisation reaction of acid with alkali
H+ ions from acid react with OH- ions from alkali to form water molecules
What happens when acids react with metal carbonates
Acid + a Carbonate —> a salt + water + carbon dioxide
How to make a Salt from a Metal Carbonate
- Using a measuring cylinder, measure 20cm^3 of acid into beaker
- Add half a spatula of metal carbonate into acid and stir with a glass rod
- Continue adding metal carbonate in excess until no more dissolves and there is no more fizzing
- Set up a filter funnel in a conical flask and filter the mixture and discard the unreacted metal carbonate
- Pour the filtrate into a evaporating basin and either leave to evaporate at room temp or heat to evaporate water out of solution, leaving the salt
What happens to alkalises when added to water
They release OH- ions which make a solution alkaline when in excess
What happens to acids when added to water
They release H+ ions when added to water and these excess H+ ions make a solution acidic
What pH range is alkaline
8-14
what pH range is acidic
0-6
What colour does universal indicator turn in acidic solutions
Yellow-Orange-Red
What colour is universal indicator in neutral solutions
Green
What colour does universal indicator go in alkaline solutions
Blue - Purple
How is the pH of an acid related to the hydrogen ion concentration?
The greater the hydrogen ion concentration (as acids release H+ ions when dissolved in water), the lower the pH, the stronger the acid. If an acid is diluted by a factor of 10, the pH increases by one unit
Examples of strong acids
Hydrochloric acid
Sulphuric Acid
Nitric Acid
What happens to strong acids when dissolved in water
They completely dissociate - every molecule releases H+ ions which completely ionises the solution
What happens to weak acids when dissolved in water
They only partially dissociate - most of the molecules stay as they are and only a small number of molecules release H+ ions
Why is the reaction forming weak acids reversible
The molecules of the weak acid split to form H+ ions and negative ions, the ions recombine to form the original molecule again. A equilibrium is reached in which both whole molecules and their ions are present
