Reactivity, displacement and corrosion

Which word equation represents the rusting of iron?

iron + water + oxygen → hydrated iron(III) oxide Rusting requires both water and oxygen to form hydrated iron(III) oxide. Hydrogen is not involved.

Which of the following metals does NOT react with dilute hydrochloric acid?

Copper Copper is below hydrogen in the reactivity series and does not react with dilute hydrochloric acid.

What is the chemical name for rust?

Hydrated iron(III) oxide Rust is hydrated iron(III) oxide, a reddish-brown compound formed when iron reacts with water and oxygen.

Which of the following is a correct statement about the reactivity series?

Potassium reacts more vigorously with cold water than calcium. Potassium is above calcium in the reactivity series and reacts more violently with cold water. Copper does not react with steam, carbon is less reactive than zinc, and gold does not react with dilute acid.

In the context of rust prevention, what is galvanising?

Coating iron with a layer of zinc. Galvanising involves coating iron with zinc, which provides both a barrier and sacrificial protection.

The following section of the reactivity series shows a newly discovered element, Y. The only oxide of Y has the formula YO. Ca Mg Fe Y H Cu Which of the equations shows a reaction which would take place?

Y(s) + 2HCl(aq) → YCl₂(aq) + H₂(g) Y is below iron but above hydrogen in the reactivity series, so it will displace hydrogen from dilute acid, forming YCl₂ and H₂. Y is above copper so it can displace copper, but the oxide formula YO suggests Y²⁺, so the first equation has incorrect charges. The second equation would require Y to be above iron, but it is below. The fourth would require Cu above Y, but Cu is below.

In an experiment to investigate the composition of air, a student left iron nails in a test tube inverted over water. After one week, the water level inside the test tube rose. Which statement explains why the water level rose?

Iron oxide was produced. Iron reacts with oxygen in the air to form iron oxide (rust). This removes oxygen from the air inside the tube, reducing the volume of gas and causing the water level to rise.

A student adds zinc to copper(II) sulfate solution. Which observations are correct for this reaction?

Solution turns paler blue; orange/brown residue on the metal. Zinc displaces copper from copper(II) sulfate, forming colourless zinc sulfate and copper metal. The blue colour fades as copper(II) ions are removed, and a pinkish-brown (orange/brown) copper deposit forms.

Four metals W, X, Y, Z are tested with dilute hydrochloric acid. Observations: W - slow reaction, X - violent reaction, Y - very slow reaction, Z - no reaction. Which row correctly identifies the metals?

W=aluminium, X=potassium, Y=iron, Z=silver Potassium reacts violently with acid. Aluminium reacts slowly due to oxide layer. Iron reacts slowly. Silver does not react. Thus X=K, W=Al, Y=Fe, Z=Ag.

Four metals P, Q, R, S are added to solutions of their ions. Results (✓ = reaction, ✗ = no reaction): |Metal|P²⁺|Q²⁺|R²⁺|S²⁺| |---|---|---|---|---| |P|✗|✗|✓|✓| |Q|✓|✗|✓|✓| |R|✗|✗|✗|✗| |S|✗|✗|✓|✗| What is the order of reactivity from most to least reactive?

Q, P, S, R A metal displaces ions of less reactive metals. Q displaces P, R, S; so Q is most reactive. P displaces R and S; so P is next. S displaces only R; so S is next. R displaces none; so R is least. Order: Q > P > S > R.

Small blocks of zinc are attached to steel ship hulls to prevent rusting. Which statement explains this process?

Zinc is higher in the reactivity series than iron, so it has a higher tendency to become oxidised. Zinc is more reactive than iron, so it loses electrons (oxidised) more easily. It corrodes sacrificially, protecting the iron from oxidation.

Which of the following metals reacts with cold water to form a metal hydroxide and hydrogen gas?

Calcium Potassium, sodium, and calcium react with cold water. Iron and zinc react only with steam. Copper does not react with water.

A student measures the temperature rise when 0.1 g of each metal is added to excess dilute hydrochloric acid. Results: Mg: +12°C, Zn: +6°C, Fe: +3°C, Cu: 0°C. Which metal is most reactive?

Mg Greater temperature change indicates a more vigorous reaction and higher reactivity. Magnesium shows the largest temperature rise.

Which of the following displacement reactions will occur?

Zinc + iron(II) chloride → A more reactive metal displaces a less reactive one. Zinc is above iron in the reactivity series, so zinc displaces iron from iron(II) chloride.

The table shows the volume of hydrogen gas produced after one minute when five metals (P, Q, R, S, T) react with dilute hydrochloric acid. |Metal|Volume of H₂ (cm³)| |---|---| |P|15| |Q|5| |R|40| |S|10| |T|0| What is the order of reactivity from most to least reactive?

R, P, S, Q, T The volume of hydrogen produced in a fixed time indicates reaction rate; more reactive metals produce more hydrogen. R produces most, then P, S, Q, T produces none (T is below hydrogen).

Which of the following is a correct method to prevent rusting by sacrificial protection?

Attaching a block of magnesium to an iron pipe Sacrificial protection uses a more reactive metal (like magnesium or zinc) attached to iron. The more reactive metal corrodes instead. Painting, oil, and tin are barrier methods.

How would you design the inquiry for reactivity, displacement and corrosion?

Compare teacher-prepared iron samples stored with different access to water and oxygen. Compare access to water and oxygen; record the amount of visible rust after a fixed time; use iron samples with the same exposed surface area.

What limitation matters when applying reactivity, displacement and corrosion?

A damaged barrier coating may expose iron, whereas sacrificial protection depends on a more reactive metal remaining electrically connected.