4 1 obtaining and using metals

The general equation for a metal reacting with an acid is: metal + acid → salt + hydrogen

True. Only metals above hydrogen in the reactivity series will react with dilute acids.

A salt is the ionic compound produced when a metal reacts with an acid.

The equation for the reaction of calcium with water is: Ca (s) + 2H2O (l) → Ca(OH)2 (aq) + H2 (g)

False. Copper is less reactive than hydrogen.

False. Magnesium reacts very slowly with cold water.

False. Potassium is more reactive than sodium.

If a metal-acid reaction is described as "vigorous", it means the reaction is rapid and intense

True. Potassium reacts violently with water and acid.

Displacement occurs when a more reactive substance takes the place of a less reactive substance.

False. Reactivity is determined by the tendency of the metal atoms to lose electrons.

True. Magnesium can displace copper from copper sulfate solution.

When a more reactive metal displaces a less reactive one, the less reactive metal coats the surface or falls out as a solid.

Observations made when copper sulfate solution reacts with magnesium:

Oxidation is the loss of electrons.

The balanced symbol equation is: Zn (s) + CuSO4 (aq) → ZnSO4 (aq) + Cu (s)

Reduction is the gain of electrons.

A redox reaction is one where oxidation and reduction occur simultaneously.

True. In the reaction, magnesium has been oxidised as it has lost electrons.

The species which has been reduced is copper as it has gained electrons.

The half equation for the oxidation of zinc atoms is: Zn ⟶ Zn2+ + 2e-

A half equation for the reduction of copper ions is: Cu + 2e- ⟶ Cu2+

The reactivity series orders metals from most reactive to least reactive.

Metals above carbon in the reactivity series are extracted by electrolysis.

False. The most reactive metals are at the top of the reactivity series.

The position of the metal on the reactivity series determines the extraction method.

Metals that must be extracted by electrolysis are higher up the reactivity series (above carbon) and include aluminum, sodium, potassium, calcium, lithium and magnesium.

False. Iron is extracted by reduction / in the blast furnace.

Metals below carbon in the reactivity series are extracted by heating / reduction with carbon.

False. Metals higher up are less resistant to oxidation than the metals placed lower down which are more resistant to oxidation.

When extracted by heating with carbon, the metal undergoes a reduction reaction.

Bioleaching is a technique that uses bacteria to extract metals from metal ores.

Phytomining is a process that uses plants to absorb metals from the soil.

The plants are harvested, dried, and burned to extract metals from their ash.

A leachate is an acidic solution containing significant quantities of metal ions.

Bioleaching produces toxic substances that need to be treated to avoid environmental contamination.

A low grade ore is an ore with a lower quantity of metal than a high grade ore.

Copper and nickel have ores that are becoming less available.

Two advantages of using bioleaching and phytomining to extract metals from ores are:

The four stages of phytomining are:

True. Bioleaching is often used to extract metals from sulfides (e.g. CuS or Fe2S).

Recycling metals provides employment and is economically beneficial, especially for costly metals like aluminium.

Mining and extraction can cause the destruction of habitats.

Two disadvantages of recycling metals include:

True. Recycling decreases the amount of waste produced and therefore space at landfill sites.

Sustainability is the ability to maintain ecological and resource balanced over time.

Iron can be recycled together with waste steel by adding both to a blast furnace.

Recycling reduces the use of fossil fuels.

True. It is much more energy efficient to recycle metals than it is to extract them as melting and re-moulding requires less energy.

The missing label is manufacture.

A life cycle assessment is an analysis of the overall environmental impact that a product may have throughout its lifetime.

The impact of obtaining raw materials on the environment is using up limited resources and damaging habitats.

The impact manufacturing process can have on the environment is using up land for factories and the use of fossil fuelled machines for production and transport.

A bicycle will have a less damaging impact on the environment.

The impact that the disposing of products can have on the environment is using up space in landfill sites.

False. Sometimes the costs and energy used in collecting, transporting and recycling metals can be more expensive than extracting new metals.

False. Iron ore is a finite source which requires a lot of energy to process.

Two disposal options for metals are recycling or storing in a landfill.

When metals are very scarce, they are all worthwhile to recycle.