Extraction of metals Flashcards
Explain why calcium has a higher melting point than strontium.(2)
Calcium has a higher melting point than strontium, because1.Correct reference to size of cations/proximity of electrons(For Ca) delocalised electrons closer to cations / positive ions / atoms / nucleusOR cations / positive ions / atoms are smallerOR cation / positive ion / atom or it has fewer (electron) shells / levels2. Relative strength of metallic bonding (Ca) has stronger attraction between the cations / positive ions / atoms / nucleus and the delocalised electronsORstronger metallic bonding
Magnesium is used in fireworks. It reacts rapidly with oxygen, burning with a bright white light. Magnesium reacts slowly with cold water.Write an equation for the reaction of magnesium with oxygen. Write an equation for the reaction of magnesium with cold water.Give a medical use for the magnesium compound formed in the reaction of magnesium with cold water.
2Mg + O2 ——>2MgOM2 Mg + 2H2O Mg(OH)2 + H2Magnesium hydroxide is used as an antacid / relieve indigestion (heartburn) / neutralise (stomach) acidity / laxative
State why the value for the standard enthalpy of formation of Mn(s) is zero
Because it is an element / elemental
Titanium is extracted in industry from titanium(IV) oxide in a two-stage process.Write an equation for the first stage of this extraction in which titanium(IV) oxide is converted into titanium(IV) chloride.
TiO2 + 2Cl2 + 2C ———>TiCl4 + 2CO
Write an equation for the second stage of this extraction in which titanium(IV) chloride is converted into titanium.
TiCl4 + 4Na ————->Ti + 4NaCl
Chromium is extracted in industry from chromite (FeCr2O4).In the first stage of this extraction, the FeCr2O4 is converted into Na2CrO4 Balance the equation for this reaction……….. FeCr2O4 + ………. Na2CO3 + ………. O2 ———> ………. Na2CrO4 + 2Fe2O3 + 8CO2
4FeCr2O4 + 8Na2CO3 + 7O2 ———->8Na2CrO4 + 2Fe2O3 + 8CO2
In the final stage, chromium is extracted from Cr2O3 by reduction with aluminium. Write an equation for this reaction.
Cr2O3 + 2Al ——–>Al2O3 + 2Cr
Metals can be extracted by different methods.Give one reason why titanium cannot be extracted directly from titanium(IV) oxide using carbon.
Ti is not producedORTiC / carbide is produced OR titanium reacts with carbonORProduct is brittleORProduct is a poor engineering material
Titanium steel is an alloy of titanium and iron. Titanium steel is extracted from the mineral ilmenite (FeTiO3) in a two-stage process.Purified FeTiO3 is first converted into a mixture of two metal chlorides. These two metal chlorides are then reduced simultaneously using sodium.Write an equation for the reaction of FeTiO3 with chlorine and carbon to produce iron(III) chloride (FeCl3), titanium(IV) chloride and carbon monoxide.
FeTiO3 + 31⁄2Cl2 + 3C ——>FeCl3 + TiCl4 + 3CO
Write an equation for the simultaneous reduction of the mixture of iron(III) chloride and titanium(IV) chloride to iron and titanium using sodium.
FeCl3 +TiCl4 +7Na —————>7NaCl+Fe+Ti
Scrap iron is used to extract copper from dilute aqueous solutions containing copper(II) ions.Explain, in terms of redox, what happens to the copper(II) ions in this extraction.
The Cu2+ / copper(II) ions / they have gained (two) electronsOR Cu2+ + 2e– ——>CuOR oxidation state / number decreases (or specified from 2to 0)ANDThe Cu2+ / copper(II) ions / they have been reduced
Aluminium is an expensive metal because it is extracted from molten aluminium oxide using electrolysis.Write the half-equation for the reaction that occurs at the positive electrode during this extraction.
2O2– ————>O2 + 4e–
Iron is extracted from iron(III) oxide using carbon at a high temperature.State the type of reaction that iron(III) oxide undergoes in this extraction.
reduction
Write a half-equation for the reaction of the iron(III) ions in this extraction.
Fe3+ + 3e– ————-> Fe
At a high temperature, carbon undergoes combustion when it reacts with oxygen. Suggest why it is not possible to measure the enthalpy change directly for the followingcombustion reaction.C(s,graphite) + 1/2 O2(g) —–> CO(g)
CO is not the only product OR(Some) complete combustion (also)occurs ORCO2 is (also) formedFurther oxidation occurs
This question is about the extraction of titanium from titanium(IV) oxide by a two-stage process.The first stage in the process produces titanium(IV) chloride. In the second stage, titanium(IV) chloride is converted into titanium.The enthalpy change for the second stage can be determined using Hess’s Law.Give one reason why titanium is not extracted directly from titanium(IV) oxide using carbon.
One from 1 Ti is not produced TiC / carbide is produced (NOT TITANIUM CARBONATE) OR titanium reacts with carbon Product is brittle Product is a poor engineering material
Give the meaning of the term enthalpy change.
Heat (energy) change at constant pressure
Define the term standard enthalpy of formation.
The enthalpy change / heat change at constant pressure when 1 mol of a compound / substance / product is formed from its (constituent ) elementswith all reactants and products / all substances in standardstates i.e. 100 kPa / 1 bar and any specified T (usually 298 K)
Metals are usually extracted from oxides.Some of these oxides occur naturally. Other oxides are made by roasting sulfide ores in air, producing sulfur dioxide as a by-product.For the extraction of some metals, the oxide needs to be converted into a chloride.The ore molybdenite contains molybdenum disulfide (MoS2).The first stage in the extraction of molybdenum is to roast the ore in air to form molybdenum oxide (MoO3) and sulfur dioxide.Write an equation for the first stage in this extraction.
2MoS2 + 7O2———->2MoO3 + 4SO2
The release of sulfur dioxide into the atmosphere causes environmental problems and wastes a valuable resource. Identify one environmental problem and identify one use for the sulfur dioxide.
Acid rain (NOT GREENHOUSE GASES)SO2 could be used to make H2SO4 / sulfuric acidORTo make CaSO4 or plaster of Paris / plaster board
Pure molybdenum is formed in the second stage by the reduction of MoO3 using hydrogen.Write an equation for this reaction.
MoO3 + 3H2 ————–>Mo + 3H2O
State one risk in using hydrogen gas in metal extractions.
Explosive or easily ignited
Calcium is an expensive metal. It is extracted by the electrolysis of molten calcium chloride.State why calcium chloride must be molten for electrolysis to occur.
To allow ions to move (when molten) ORIons cannot move in the solid
Write an equation for the reaction that takes place at the negative electrode during this electrolysis.
Ca2+ + 2e- ———–>Ca