Booklet 4 - Reactivity Of Metals Flashcards
What are the metals that react with water?
Potassium, sodium, lithium, calcium
Which metals reacts with acids?
Potassium, sodium, lithium, calcium, magnesium, zinc, iron, tin, lead
Which metals react with oxygen?
Potassium, sodium, lithium, calcium, magnesium, aluminium, zinc, iron, tin, lead, copper, mercury, silver
What does the reactivity of a metal depend on?
Depends on how easily it loses an electron to form a positive ion, it is called a cation
What is the word to descibe a metal that is more able to lose electrons and become a positive ion?
They are more reactive
What do metals that react with oxygen make?
What is the general equation for this?
Metal oxides
Metal + oxygen-> metal oxide
What is the equation for sodium and copper reacting with oxygen? What are they examples of?
Sodium + oxygen -> sodium oxide
4 Na + O2 -> 2NaO
Copper + oxygen -> copper oxide
2Cu + O2 -> 2CuO
Oxidation
Which metals react with dilute acids?
Anything more reactive than hydrogen
Which metals react with cold water?
Anything above magnesium
What is a displacement reaction?
It is when a more reactive metal will take the place (displace) a less reactive metal in a conpound.
Basically a battle between two metals to get rid of electrons
What type of metals are gold and silver and where are they found?
Unreactive metals
Found in the earth
What are most metals found as? What do they require to extract the metal?
Found as metal compounds, require chemical reactions to extract
What can metals less reactive than carbon be extracted by?
Extracted from their oxides by reduction with carbon
What is the equation for the reduction of iron ore by carbon?
What has happened?
Iron oxide + carbon -> iron + carbon dioxide
Fe2O3 + 3C -> 2Fe + 3
The carbon removes the oxygen from iron oxide, hence carbon has reduced the iron oxide
What is Oxidation?
A reaction where a substance gains oxygen or as a reaction where a substance loses electrons
What is reduction?
Loss of oxygen or gain of electrons
What is OILRIG?
Oxidation Is Loss, Reduction Is Gain
When can oxidation also occur? What does the metel need?
It can occur when there is no oxygen in the reaction, it only needs electrons to lose to undergo oxidation
What are redox reactions?
Where oxidation and reduction both occur
What happens to the ions of the less reactive metal?
They gain electrons and become REDUCED
What happens to the atoms of the more reactive metal?
They lose electrons and become OXIDISED
What does the pH scale do? What does it run from and to?
Shows how acidic or alkaline a solution is. Runs from 1-14
What does the Universal Indicator do? What colour is it in acid, alkali and neutral?
It shows the pHs of different substances.
Red in acid
Blue in alkali
Green when neutral
What can also give us a pH value?
A pH probe can give an electric value for pH often to 2 decimal places
What do acids produce?
Hydrogen ions, H+
What do aqueous solutions of alkalis contain?
Hydroxide ions, OH-
When neutralisation occurs write the equation for when the two ions combine to make water?
H+(aq) + OH-(aq) -> H2O(l)
What is a salt?
An ionic compound made from any metal and and non metal
The acid with metal hydroxides are neutralisation reactions. What reacts with what?
The H+ of the acid reacts with the OH- of the alkali.
H+ + OH- —> H2O
The acid with metal hydroxies or metal oxides are neutralisation reactions? What reacts with what?
The H+ of the acid reacts with the O2- of the base.
What happens when some metals are too UNreactive and some are too REACTIVE?
They will react with the water that the acid dissolved in as well the acid itself.
Why is it useful to know the reactivity of carbon even though its not in the reactivity series?
It is often used to displace metals that are lower than it in the series, from their metal oxides
Why is it useful to know the reactivity of hydrogen even though its not in the reactivity series?
It is low in the series, therefore it’s able to be displaced by metals hugher upnin the series
What is a Titration?
The volume of acid and alkali solutions that react with each other can be measured by titration using a suitable indicator
What is the titration technique?
1) . Wash and rinse a pipette with the alkali
2) . Use the pipetter to measure out a known and accurate volume of the alkali.
3) . Place the alkali in a clean dry conical flask and add a suitable indicator
4) . Place the acid in a burette that has been wahsed and rinsed in the acid. Take a reading of the volume of the acid ie the inital reading
5) . Add the acid until the indicator changes colour ie neutral point. This is the end point. Take the final reading
6) . Calculate the volume of acid added by subtracting the inital reading crom the final reading
7) . Repeat again
What happens to strong acids when dissolved in water?
They ionise to form H+ ions plus the negative ion
What is a weak acid? And give an example
they ionise in water partially more usually 2%
What makes weak acids like vinegar and citric acid much less acidic?
They ionise only 2% which means they produce fewer H+ ions when dissolved in solution.
What are the names of 3 strong acids?
HCl, HNO3, H2SO4
What are the names of the 3 weak acids?
CH3CO2H (ethanoic acid), citric acid, HaCO3 (carbonic acid)
What is a ‘strong’ acid?
A acid that’s completely ionised in aqueous solutions, all acid particles dissociate to release H+ ions
What is a ‘weak’ acid?
A acid that will only partially ionise in aqueous solutions, only a small proportion of acid particles dissociate to release H+ ions
What is the concentration of an acid?
Concentration measures how much acid there is in a certain volume of water, ie the total number of dissolved acid molecules
What is a ‘dilute’ acid?
Considered to be acids that are watered down versions of the real stuff ie more water and hardly any acid.
As pH decreases by 1 unit, what factor does the concentration of H+ ions increase by?
Factor of 10
What do metals that react with other substances what do they form?
the metal atoms from positive ions
What do some acids react with metals to produce?
Salts and hydrogen
How can soluble salts be made from by acids?
Reacting them with:
1). In soluble substance eg metals, hydroxides, metals oxides and carbonates
How can you produce solid salts?
By crystallising salt solutions
For a given concentration of aqueous solutions what does it mean for a stronger acid?
The lower the pH
What happens when an ionic compound is melted or dissolved?
The water ions are free to move about within a solution, these solutions are then able to conduct electricity
What is the liquid substance that is broken down called?
An electrolyte
What happens when you pass an electrical current through electrolytes?
It causes the ions to move to the electrodes. Positively charged ions move to the negative electrode the cathode, negatively charged ions move to the positive electrode the anode
What happens the ions at the electrodes?
They are discharged producing elements -> electrolysis
What happens when a simple ionic compound eg lead bromine is electrolysed?
Its electrolysed in molten state using inert electrodes, the metal (lead) is produced at the cathode and the non metal (bromine) at the anode
How can metals be extracted from molten compounds?
Using electrolysis
Why is electrolyis used to extract metals from metal compounds?
If the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon. Large amounts of energy are used in the extraction process to melt the compounds and to produce electrical current
What do the ions that are discharged in a aqueous solution during electrolysis depend on?
The releative reactivity of the elements involved
Why is oxygen only produced at the anode if no halide ions are made?
In the aqueous solution water molecules break down producing hydrogen ions and hydroxide ions that are discharged
What happens during electrolysis at the cathode?
Positively charged ions gain electrons and so the reactions are reductions
What happens during electrolysis at the anode?
Negatively charged ions lose electrons and so the reactions are oxidation
What reactions at electrodes be represented as?
1) . 2H+ + 2e- –> H2
2) . 4OH- –> O2 + 2H20 + 4e
What happens when a acid neutralises a base (vice versa)?
The products are neutral
What is the reaction between a acid and a base?
A neutralisation one
Acid + base -> salt + water
What do all metal oxides and metal hyrdoxides form?
Acid + metal oxide -> salt + water
Acid + metal hydroxide -> salt + water
What is the extraction of a metal?
reduction = loss of oxygen
what happens if H+ ions or metal ions are present at the cathode?
- if the elemental metal formed is more reactive, then hydrogen gas is made.
- if the elemental metal is less reactive than hydrogen a solid layer of the pure metal will be produced
what happens if OH- and halide ions are present at the anode?
- molecules of chlorine, bromine or iodine will be formed
- if none are present, then the OH- ions are discharged and oxygen will be formed
What is an alkali?
A base that dissolves in water to form a solution with a pH greater than 7, they form OH- ions is water.
describe the ionisation of a weak acid?
its a reversible reaction, which sets up an equilibrium between the undissociated and dissociated acid, since only a few of the acid particles release H+ ions, the position of equilibrium lies well to the left
what does it mean if the concentration of the H+ ions is higher?
the rate of the reaction will be faster, so strong acids will be more reactive than weak acids of the same concentration
what is the equation for acids and bases?
Acid + base -> salt + water
- its a neutralisation reaction
what is the equation for acid and metal carbonates?
Acid + metal carbonate -> salt + water + carbon dioxide
what does the salt produced in any reaction between an acid and a base or alkali depend on?
- the acid used eg hydrochloric acid produces chlorides, nitric acid produces nitrates and sulphuric acid produces sulfates
- the positive ions in the base, alkali or carbonate
what does it mean for the metal the higher up in the reactivity series it is?
the more easily they will form positive ions and the more easily it reacts with water or acid
what is the equation for a acid and metal?
Acid + metal -> salt + hydrogen
what the equation for a acid and water?
Metal + Water -> metal hydroxide + hydrogen
what happens to the metal ion and metal atom in a displacement reaction?
the metal ion gains electron and is reduced, the metal atom always loses electrons and is oxidised
what can and can’t be electrolysed in electrolysis?
an ionic solid can’t be electrolysed as the ions are in fixed positions while molten ionic compounds can be as their ions can move freely and conduct electricity
what happens when a simple ionic compound eg lead bromine is electrolysed in molten state?
its done using inert electrodes, the metal (lead) is produced at the cathode and the non metal (bromine) is made at the anode
why must the anode be replaced continually?
the anode is made of carbon and as it reacts with oxygen it produces CO2
how is aluminium manufactured?
by the electrolysis of a molten mixture of aluminium oxide and cryolite using carbon as the anode
- cryolite is used as it lowers the high melting point of Al, its a aluminium based compound
