Reactivity series (Edexcel IGCSE Chemistry (Modular): Unit 1): Flashcards

False.

Sodium is higher in the reactivity series than zinc, so zinc cannot displace it. A displacement reaction only occurs when the added metal is more reactive than the metal in the compound.

In the thermite reaction, aluminium reacts with iron(III) oxide to produce iron and aluminium oxide.

A more reactive metal displaces a less reactive metal because it has a greater tendency to form positive ions, so it removes the less reactive metal from its compound and takes its place.

False.

When iron displaces copper, the blue copper(II) sulfate solution fades as iron(II) sulfate — a colourless solution — is formed, and copper deposits as a solid.

When a displacement reaction occurs in a metal salt solution, the added metal slowly disappears and the displaced metal deposits as a solid. A colour change in the solution is also often observed.

The reactivity series mnemonic is "Please send lions, cats, monkeys and cute zebras into hot countries signed Gordon" — each word's first letter matches a metal in order from most to least reactive.

Hydrogen is included in the reactivity series as a reference point. Only metals above hydrogen in the series react with dilute acids to produce hydrogen gas.

True.

Carbon sits between aluminium and zinc in the reactivity series. This position is important because carbon can be used to extract metals that are below it in the series from their oxides.

If a metal appears above hydrogen in the reactivity series, it will react with dilute acid to produce a salt and hydrogen gas. Metals below hydrogen do not react with dilute acids.

In the reactivity series mnemonic, the word "monkeys" stands for magnesium and "zebras" stands for zinc.

Rusting is the specific type of corrosion that affects iron, occurring when iron is exposed to both oxygen and water simultaneously.

For iron to rust, both oxygen (from air) and water must be present. If either is absent, rusting does not occur.

False.

Rust is porous and allows both air and water to reach the iron underneath. This means rusting continues, gradually weakening the structure.

Galvanising is a method of rust prevention in which zinc is applied to iron by electroplating or dipping into molten zinc.

Zinc is more reactive than iron, so it is oxidised preferentially. Even when scratched, the zinc acts as a sacrificial metal, corroding in place of the iron underneath.

Sacrificial protection is a method of preventing corrosion in which a more reactive metal is attached to a less reactive metal. The more reactive metal corrodes preferentially, protecting the less reactive metal.

True.

Paint, oil and grease all prevent rusting by forming a barrier that stops oxygen and water reaching the iron surface. If the barrier is scratched or removed, rusting can begin again.

In the rusting investigation, the nail in boiled water covered with oil does not rust because the oil prevents oxygen from reaching the water.

Corrosion is the general term for the degradation of metal surfaces. Rusting is the specific type of corrosion that occurs only in iron when it reacts with both oxygen and water.

Oxidation (in terms of oxygen) is any reaction in which a substance gains oxygen.

OIL RIG stands for Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons). It is a mnemonic to help remember the electron-transfer definitions of oxidation and reduction.

Reduction (in terms of oxygen) is any reaction in which a substance loses oxygen.

False.

Zinc is the reducing agent — it removes oxygen from copper(II) oxide. The copper(II) oxide is the oxidising agent because it supplies the oxygen.

In a redox reaction, oxidation and reduction always occur simultaneously. A substance that gains electrons is reduced and a substance that loses electrons is oxidised.

These reactions are called redox reactions because oxidation and reduction occur at the same time — one substance gains oxygen while another loses it. Neither can happen without the other.

An oxidising agent is a substance that oxidises another species in a reaction. It does this by supplying oxygen or by gaining electrons, and is itself reduced in the process.

In the ionic equation Mg (s) + Cu²⁺ (aq) → Mg²⁺ (aq) + Cu (s), magnesium is oxidised and Cu²⁺ is reduced.

Spectator ions appear unchanged on both sides of the equation and do not take part in the reaction. They are removed from ionic equations to show only the species that actually react.

True.

A reducing agent donates electrons to another species. Because it loses electrons, it is itself oxidised in the process.

The three metals investigated are:

1. Magnesium

2. Zinc

3. Iron

True.

Magnesium is the most reactive of the three metals, so it dissolves quickly, produces heat and gives off hydrogen gas rapidly. Zinc reacts more slowly and iron reacts most slowly.

The gas produced when metals react with dilute acid is tested using a lighted splint. A positive result is a pop sound.

Based on the practical results, the order of reactivity from most to least reactive is:

1. Magnesium

2. Zinc

3. Iron

Safety glasses must be worn because dilute acids are corrosive and can cause injury if they splash into the eyes. Hydrogen gas is also produced, which is flammable.

False.

The three metals react in the same way with both dilute sulfuric acid and dilute hydrochloric acid. The products in each case are a metal salt and hydrogen gas.