Chem: Metals

What general products are formed when a metal reacts with an acid?

A salt and hydrogen gas.

How can the reaction between metals and dilute acids be used to compare their reactivity?

The rate at which hydrogen bubbles are produced indicates reactivity; faster bubbling means a more reactive metal.

What test is used to confirm the presence of hydrogen gas?

The burning splint test, which produces a squeaky pop sound.

What products are formed when reactive metals react with cold water versus steam?

Cold water reacts with metals to form a metal hydroxide and hydrogen; steam reacts with less reactive metals to form a metal oxide and hydrogen.

How does copper react with cold water, steam, or dilute acid?

Copper does not react at all with cold water, steam, or dilute acids.

List the metals in the reactivity series from most reactive to least reactive.

Potassium, Sodium, Lithium, Calcium, Magnesium, Aluminium, Zinc, Iron, Copper, Silver, Gold.

What happens during a metal displacement reaction?

A more reactive metal displaces (pushes out) a less reactive metal from its oxide or salt solution.

Why are metal displacement reactions classified as redox reactions?

The more reactive metal is oxidised (loses electrons), while the displaced metal ion is reduced (gains electrons).

What two chemical conditions are required for iron to rust?

Contact with both oxygen (from air) and water.

What is the chemical name and formula for rust?

Hydrated iron(III) oxide (Fe2O3·xH2O).

How do barrier methods prevent iron from rusting?

They coat the iron to physically block water and oxygen from reaching it (e.g., painting, coating with plastic, oiling, or greasing).

How does sacrificial protection (and galvanising) prevent rusting?

A more reactive metal (such as zinc) is placed on or attached to the iron; the sacrificial metal is oxidised instead of the iron.

How are oxidation and reduction defined in terms of oxygen transfer?

Oxidation is the gain/addition of oxygen; reduction is the loss/removal of oxygen.

What are an oxidising agent and a reducing agent in terms of oxygen transfer?

An oxidising agent oxidises the metal (and is reduced); a reducing agent reduces the metal (and is oxidised).

How are unreactive metals like gold found in the Earth's crust?

Unreactive metals are found uncombined as pure elements.

How is carbon used to extract metals from their ores?

Carbon acts as a reducing agent to remove oxygen from metal oxides that are less reactive than carbon.

What method must be used to extract metals that are more reactive than carbon from their ores?

Electrolysis must be used to separate the metal from its compound.

Why does aluminium not corrode easily like iron?

Aluminium reacts quickly with oxygen to form a protective layer of aluminium oxide that sticks firmly to the metal surface and prevents further reaction.

Why is copper used for electrical wiring and underfloor heating systems?

It is an excellent conductor of electricity (low resistance) and heat, allowing efficient energy transfer.

Why are pure metals generally softer than alloys?

Pure metals have regular layers of identical atoms that slide over each other easily; alloys contain different sized atoms that distort the layers.

What are the main components, properties, and uses of low carbon, high carbon, and stainless steel?

Low carbon steel (0.1–0.3% C) is easily shaped for car bodies; high carbon steel (0.22–2.5% C) is strong and brittle for bridges; stainless steel (+ chromium/nickel) is corrosion-resistant and hard for cutlery.

What transition metals make up the alloys brass and bronze?

Brass is an alloy of copper and zinc; bronze is an alloy of copper and tin.