Reactivity series

Q: What is the full order of the reactivity series including hydrogen?

A: Potassium (K), Sodium (Na), Calcium (Ca), Magnesium (Mg), Aluminium (Al), Zinc (Zn), Iron (Fe), Hydrogen (H), Copper (Cu), Silver (Ag), Gold (Au).

Q: Give a mnemonic to remember the reactivity series including hydrogen.

A: King Nathan’s Cat Maggie Always Zooms Fast. Henry Clutches Angry Angus.

Q: Define the reactivity series.

A: The reactivity series is a list of metals arranged in order of decreasing reactivity, showing their ability to lose electrons and form positive ions.

Q: Why is hydrogen included in the reactivity series?

A: Hydrogen is included as a reference point to compare metals’ ability to react with acids and water, since it can be displaced from acids by metals more reactive than itself.

Q: Predict whether potassium reacts with water and write the balanced equation.

A: Potassium reacts vigorously with cold water, producing potassium hydroxide and hydrogen gas.

Equation: 2K (s) + 2H₂O (l) → 2KOH (aq) + H₂ (g)

Q: Which metals react with cold water and what do they produce?

A: Potassium, sodium, and calcium react with cold water to produce metal hydroxides and hydrogen gas.

Q: Write the equation for magnesium reacting with steam.

A: Mg (s) + H₂O (g) → MgO (s) + H₂ (g)

Q: Explain why aluminium does not react with water easily despite being high in the reactivity series.

A: Aluminium forms a strong, protective oxide layer on its surface that prevents further reaction with water or air.

Q: Which metals react with dilute acids to produce hydrogen gas?

A: Metals above hydrogen in the reactivity series such as magnesium, zinc, and iron react with dilute acids to produce hydrogen gas and metal salts.

Q: Write the equation for zinc reacting with dilute hydrochloric acid.

A: Zn (s) + 2HCl (aq) → ZnCl₂ (aq) + H₂ (g)

Q: Why do metals below hydrogen not react with acids to produce hydrogen?

A: They are less reactive than hydrogen and cannot displace hydrogen from acids.

Q: Describe and explain a displacement reaction using the reactivity series.

A: A more reactive metal displaces a less reactive metal from its compound in solution. For example, zinc displaces copper from copper sulfate.

Equation: Zn (s) + CuSO₄ (aq) → ZnSO₄ (aq) + Cu (s)

Q: Write the ionic equation for zinc displacing copper from copper sulfate.

A: Zn (s) + Cu²⁺ (aq) → Zn²⁺ (aq) + Cu (s)

Q: Explain how the reactivity series determines metal extraction methods.

A: Highly reactive metals (K, Na, Ca, Mg, Al) require electrolysis of molten compounds for extraction; less reactive metals (Zn, Fe, Pb) can be extracted by reduction with carbon; metals less reactive than hydrogen (Cu, Ag, Au) are found native or extracted by simple methods.

Q: Explain why gold is found as a native metal.

A: Gold is very unreactive and does not easily form compounds; it remains in elemental form in the earth.

Q: How does the reactivity series predict metal corrosion?

A: Metals high in the series corrode easily because they oxidize quickly, forming oxides or hydroxides.

Q: Give an example of a metal reacting with oxygen and write the equation.

A: Magnesium burns in oxygen to produce magnesium oxide.

Equation: 2Mg (s) + O₂ (g) → 2MgO (s)

Q: Write a balanced equation for iron reacting with dilute sulfuric acid.

A: Fe (s) + H₂SO₄ (aq) → FeSO₄ (aq) + H₂ (g)

Q: Explain what happens when a metal reacts with water and acid in terms of electron transfer.

A: Metal atoms lose electrons (oxidation) to form positive ions; electrons reduce H⁺ ions to hydrogen gas.

Q: Why does magnesium react faster with acid than iron?

A: Magnesium is more reactive and loses electrons more readily, so it reacts faster with H⁺ ions.

Q: How can the reactivity series be experimentally determined?

A: By testing metals with acid or water and observing hydrogen gas evolution or displacement reactions.

Q: Write the general reaction for a metal displacing hydrogen from an acid.

A: Metal (M) + 2H⁺ (aq) → M²⁺ (aq) + H₂ (g)

Q: What is the role of carbon in metal extraction?

A: Carbon acts as a reducing agent removing oxygen from metal oxides, forming CO or CO₂.

Q: Give an example and equation of metal extraction using carbon.

A: Extraction of iron from iron oxide using carbon monoxide.

Equation: Fe₂O₃ (s) + 3CO (g) → 2Fe (s) + 3CO₂ (g)

Q: Why do metals high in the reactivity series not get extracted by carbon reduction?

A: Their oxides are too stable for carbon to reduce; electrolysis is used instead.

Q: How does the reactivity series explain why zinc can displace copper from copper sulfate solution?

A: Zinc is more reactive, loses electrons, forming Zn²⁺ ions; copper ions gain electrons and deposit as copper metal.

Q: What safety precautions should be taken when testing metal reactivity with acids?

A: Wear goggles, use dilute acid, work in a ventilated area, and handle reactive metals carefully.

Q: Explain why aluminium does not react with dilute acid as readily as magnesium despite being above hydrogen.

A: Aluminium’s oxide layer protects the metal from acid attack.

Q: What is the ionic equation for magnesium reacting with hydrochloric acid?

A: Mg (s) + 2H⁺ (aq) → Mg²⁺ (aq) + H₂ (g)

Q: What observations indicate a metal is reacting with acid?

A: Bubbling due to hydrogen gas, metal dissolving, and temperature rise.

Q: What is a displacement reaction?

A: A reaction where a more reactive metal displaces a less reactive metal from its compound.

Q: Why does copper not react with dilute hydrochloric acid?

A: Copper is less reactive than hydrogen and cannot displace hydrogen ions.

Q: How is the reactivity series useful in predicting the products of redox reactions involving metals?

A: It predicts which metals will oxidize (lose electrons) or reduce (gain electrons) in reactions.

Q: How does the reactivity series relate to the electrochemical series?

A: Both rank metals by their tendency to lose electrons; electrochemical series uses standard electrode potentials.