Zusammenfassung der Ressource
metals
- properties
- physical
- shiny
- dense
- malleable and ductile
- generally high m.p and b.p
- excellent conductors of heat and electricity
- chemical
- form positive ions(cations
- metal oxides tend to be basic
- react with acid to form hydrogen gas +
a salt
- metals reactions
- with acid
- If a metal reacts with dilute hydrochloric acid then
hydrogen gas and the metal chloride are produced
- Metal+HCl(aq) -----> metal chloride+ H2(g)
- example
- magnesium+hydrochloric acid ------> magnesium chloride+hydrogen
- Mg(s)+2HCl(aq)------>MgCl2(aq)+H2(g)
- If a similar reactions are carried out using other metals with acid, an order of reactivity can be
produced by measuring the rate of evolution of hydrogen. This is known as a reactivity series.
- The most reactive metal is the one that has the highest tendency to lose outer electrons to from a
positive metal.
- The higher evolution rate, the more reactive metal.
- with water/steam
- Reactive metals react with cold water to
produce the metal hydroxide and hyrogen gas
Anmerkungen:
- 1. 2K(s)+ 2H2O(l) --->2 KOH(aq)+H2(g)
2. 2Na(s)+ 2H2O(l) ---> 2NaOH(aq)+H2(g)
3. Ca(s)+H2O(l) ----> Ca(OH)2(aq)+H2(g)
Rate of evolution of hydrogen; 1>2>3
- Moderately reactive metals react slowly with cold water
. However; react rapidly with steam to produce the
metal oxide and hydrogen gas.
Anmerkungen:
- 1. Mg(s)+H2O(g) ----> MgO(s)+H2(g)
2. Zn(s)+H2O(g) -----> ZnO(s)+H2(g)
3. 2Fe(s)+3H2O(g) --> Fe2O3(s)+3H2
Rate of evolution of hydrogen; 1>2>3
- less reactive(unreactive)
metals;
- Pb Cu Ag Au Pt ---> do not react with
- Mg is one of the metals
used in construction of the
Airbus A380
- with air/oxygen
- Many metals react directly with oxygen to form oxides.
Anmerkungen:
- for example;
- magnesium burns brightly in oxygen to form the white powder magnesium oxide
- magnesium+oxygen ---> magnesium oxide
- 2Mg(s)+O2(g)----> 2MgO(s)
- Ag ,Au and Pt do not react with
oxygen
- decomposition of
- metal nitrates
- When nitrates of reactive metals (K,Na) they decompose
to produce the metal nitrite and oxygen gas
- sodium nitrate ---heat---> sodium nitrite + oxygen
- 2NaNO3(s) ---heat---> 2NaNO2(s)+O2
- Nitrates of moderately reactive metals (Ca, Mg, Al, Zn, Fe, Pb,
Cu) produce brown fumes of nitrogen dioxide gas when
heated, as well as the metal oxides and oxygen gas
- magnesium nitrate ---heat---> magnesium oxide + nitrogen dioxide + oxygen
- 2Mg(NO3)2(s) ---heat---> 2MgO(s) + 4NO2(g) + O2(g)
- Unreactive metal nitrates(Ag, Pt, Au) produce the metal, nitrogen dioxide and oxygen.
- 2AgNO3(s) ---heat---> 2Ag(s) + 2NO2(g) + O2(g)
- metal carbonates
- The carbonates of most reactive metals(K and Na ) thermally
stable and require very high temperature to decompose.
- Na2CO3(s) ---heat---> no reaction
- The carbonates of moderately reactive metals decompose to metal oxide and
carbondioxide. Less reactive metal carbonates are too unstable to exist.
- CaCO3(s) ---heat---> CaO(s) + CO2(g)
- Ag2CO3(s) ---heat---> no reaction
- metal hydroxides
- Hydroxide of reactive metals show no
decomposition when they are heated. The
hydroxide of moderately rractive metals do
decompose to produce the metal oxide and
water.
- Ca(OH)2(s) ---heat---> CaO(s) + H2O(g)
Anmerkungen:
- Ca(OH)2(s) : slaked lime
CaO(s) : lime
- metal oxides
- It is too difficult to decompose the oxides of reactive and moderately
reactive metals. It is possible to thermally decompose some oxides of less
reactive metals.
- Na2O(s) ---heat---> no reaction
- Al2O3(s) ---heat---> no reaction
- 2Ag2O(s) ---heat---> 4Ag(s) + O2(g)
- uses
- unreactive
- car bodies , coins, pots and pans
- uses of aluminium metal
- aluminium forms a relatively thick oxide layer on
the surface of the metal which prevents further
reaction
- handles cooking foil
- reactive
- competition reactions
- In solid state
- A more reactive metal has a greater tendency to form a metal ion by
losing electrons than a less reactive metal does. If a more reactive
metal is heated with the oxide of less reactive metal, then it will remve
the oxygen from it.
- example:
- Iron(ııı) oxide is mixed with aluminium and the mixture heated by using
magnesium fuse, a very violent reaction occurs as the competititon between the
aluminium and the iron for the oxygen take place
- Fe2O3(s) + 2Al(s)---heat---> Al2O3(s) + 2Fe(s)
- 2Fe^3+(s) + 2Al(s) 2Al^3+(s) + 2Fe(s)
- This reaction is exothermic and redox
reaction. This particular reaction is
known as the Thermit reaction.
- Since large amounts of heat are given out and the iron is
formed in molten state, this reaction is used to weld together
damaged railway lines.
- Chromium and titanium are prepared from their oxides using
this type of competition reaction.
- Carbon, non-metal, is able to reduce metal oxides below it in
the series.
- Fe2O3 (s) + 3CO(g)---heat---> 3CO2(g) + 2Fe(s)
- PbO(s) + CO(g) ---heat---> CO2(g) + Pb(s)
- or
- in aqueous solution
- A more reactive metal will displace less reactive metal
from a solution of its salt. This type of reaction is known
as a displacement reaction.
- example
- When a piece of zinc metal
is left to stand in a solution
of copper(ıı) sulphate. The
copper(ıı) sulphate slowly
loses its blue colour as the
zinc continiues to displace
the copper from the
solution and eventually
becomes colourless zinc
sulphate.
- Zn(s) + Cu(NO3)2(aq) ---heat---> Zn(NO3)2(aq) + Cu(s)