Chemistry: Reactivity Series, Extraction of Metals, and Dynamic Equilibria

Comprehensive vocabulary flashcards covering the reactivity series, methods of metal extraction (carbon reduction, electrolysis, bioleaching, phytoextraction), recycling, life cycle assessments, dynamic equilibria, and Le Chatelier's principle.

Oxidation (in terms of oxygen)

A chemical reaction in which a substance gains oxygen.

Reduction (in terms of oxygen)

A chemical reaction in which a substance loses oxygen.

Reactivity series

A list of metals ordered from most reactive to least reactive, showing how easily each metal is oxidised.

Carbon (in the reactivity series)

An element included in the reactivity series to show how metals compare to it, which helps decide whether a metal can be extracted from its ore by reduction with carbon.

Hydrogen (in the reactivity series)

An element included in the reactivity series to determine whether metals will react with dilute acids; metals below hydrogen will not react.

Oxidation (in terms of electrons)

The loss of electrons during a chemical reaction.

Reduction (in terms of electrons)

The gain of electrons during a chemical reaction.

Displacement reaction

A redox reaction where a more reactive metal displaces a less reactive metal from its compound; the more reactive metal is oxidised and the less reactive metal is reduced.

Metal ore

A rock found in the Earth's crust that contains enough metal compound to make extraction worthwhile and worth the cost.

Bauxite

The natural ore consisting of aluminium oxide ($Al_2O_3$) from which aluminium is extracted.

Reduction with carbon

The extraction method used for metals below carbon in the reactivity series, in which oxygen is removed by heating the metal oxide with carbon.

Cryolite

A molten compound used to dissolve aluminium oxide ($Al_2O_3$) during electrolysis in order to lower its melting point and reduce energy costs.

Bioleaching

A biological extraction method using bacteria to break bonds in low-grade ores and separate metals, producing a solution of metal ions.

Leachate

The solution containing metal ions produced by bacteria during the process of bioleaching.

Phytoextraction

A biological extraction method in which plants absorb metal compounds from soil, are harvested and burned, leaving metal-rich ash from which metals can be extracted.

Life Cycle Assessment (LCA)

An evaluation of the total environmental cost of a product across four stages: getting raw materials, manufacture, product use, and disposal.

Reversible reaction

A chemical reaction in which the products can react together to reform the original reactants, indicated by the symbol $\rightleftharpoons$.

Dynamic equilibrium

A condition in a closed system where the forward and backward reactions proceed at the exact same rate, keeping the concentrations of reactants and products constant.

Haber process

The reversible reaction between nitrogen and hydrogen to make ammonia ($N_2 + 3H_2 \rightleftharpoons 2NH_3$), carried out at $450\text{ }^\top C$, $200\text{ atmospheres}$, and using an iron catalyst.

Closed system

An isolated reaction environment from which no reactants or products can escape, required for reversible reactions to reach dynamic equilibrium.

Le Chatelier's principle

The principle stating that if a change in concentration, pressure, or temperature is imposed on a reversible reaction at equilibrium, the position of equilibrium will shift to undo or minimise that change.

Effect of temperature increase on equilibrium

Shifts the equilibrium position in the endothermic direction to absorb the added heat.

Effect of pressure increase on equilibrium

Shifts the equilibrium position towards the side with fewer gas molecules to reduce overall pressure.

Effect of increasing reactant concentration on equilibrium

Shifts the equilibrium position to the right to consume the extra reactants and produce more products.