C9 metals Flashcards
general physical properties of metals
- electrical conductor
- thermal conductor
- high melting/boiling point
observations of reaction of metal with dilute acids
- metal gradually disappears (soluble salt formed)
- effervescence
metal + acid –>
salt + hydrogen
metal + water –>
metal hydroxide + hydrogen
describe reaction between metal and cold water
- slow to begin
- exothermic, so reaction speeds
metal + steam –>
metal oxide + hydrogen
use of aluminium and why
- aircraft: low density
- overhead electrical cables: low density, good electrical conductivity
- food containers: resistance to corrosion
use of copper and why
- electrical wiring: good electrical conductivity
define alloy
mixtures of a metal with other elements
what is brass composed of
mixture of copper and zinc
what is stainless steel composed of
mixture of iron and other elements, eg
- chromium
- nickel
- carbon
why are alloys more useful than pure metals
can be harder and stronger than pure metals
use of stainless steel and why
- cutlery
- hardness and resistance to corrosion
why are alloys stronger and harder than pure metals
- diff sized atoms
- mean layers can no longer slide over each other
order of reactivity series
Please Stop Calling Me A Cunty Zebra, I Have Called SalGado
potassium
sodium
calcium
magnesium
aluminium
carbon
zinc
iron
hydrogen
copper
silver
gold
reaction of K, Na, Ca with cold water
- react vigorously
- strongly alkaline solutions formed
reaction of potassium with cold water (equation and observations)
2K + 2H2O –> 2KOH + H2
- floats on surface of water
- effervescence pushes metal around on surface
- strongly exothermic
- hydrogen ignites with lilac flame
- potassium quickly disappears, eventually explodes with pop
reaction of sodium with cold water (equations and observations)
2Na + 2H2O –> 2NaOH + H2
- moves around on surface of water
- very exothermic, metal melts to form silvery ball, steadily disappears as reaction continues
- if sodium trapped, hydrogen may ignite with yellow flamerea
reaction of calcium with cold water (equation and observations)
Ca + 2H2O –> Ca(OH)2 + H2
- metal sinks
- reaction slow to begin with, speeds as reaction is exothermic
- eventually cause rapid bubbling
- white suspension of calcium hydroxide forms
reaction of magnesium with steam (equation and observation)
Mg + H2O –> MgO + H2
- reacts vigorously
- gives off very bright white flame
- powdery white MgO forms
reaction of magnesium cold dilute acid
rapid bubbling
reaction of magnesium in warm dilute acid
often not done as it may be unsafe
reaction of zinc in cold dilute acid
slow bubbling
reaction of zinc in warm dilute acid
rapid bubbling
reaction of iron in cold dilute acid
very slow bubbling
reaction of iron in warm dilute acid
slow bubbling
reaction of copper in dilute acid
do not react
reaction of silver in dilute acid
do not react
reaction of gold in dilute acid
do not react
describe what is meant by a displacement reaction
more reactive element replaces less reactive element in a compound
conditions required for rusting of iron
presence of oxygen and water
common barrier methods against rusting
- painting
- greasing
- coating with plastic
how do the common barrier methods prevent corrosion
excludes oxygen and water
metal + oxygen –> (also known as)
metal oxide (corrosion)
equation for rusting
iron + water + oxygen –> rust (iron(III) oxide)
explain sacrificial protectoin
- more reactive metal placed in contact with less reactive metal
- more reactive metal loses electrons more easily
- presence of these electrons prevents oxidation
how does ease in obtaining metals from ore relate to its position in the reactivity series
more reactive = harder to obtain
how is iron from hematite extracted (simple)
reduction of iron(III) oxide in blast furnace
describe the extraction of iron from hematite
- burn carbon (coke) to provide heat and produce CO2 (C + O2 –> CO2)
- reduce CO2 to CO (C + CO2 –> 2CO)
- reduce iron(III) oxide by CO (Fe2O3 + 3CO –> @Fe + 3CO2)
- thermal decomposition of calcium carbonate/limestone to produce calcium oxide (CaCO3 –> CaO + CO2
- formation of slag (CaO + SiO2 –> CaSiO3)
what is the main ore of aluminium and how is it extracted
- bauxite
- by electrolysis
