SASS Chem Reactions of Metals Ans Template

Page 1 ST ANDREW’S SECONDARY SCHOOL NAME TEACHING GROUP DATE DD MM YYYY CHEMISTRY Answering Templates : DESCRIBE [D] / EXPLAIN [E] Reactions of Metals Reactivity Series of Metals [D] Reaction with cold water (only for K, Na & Ca) For Group I metals: • Metal reacts explosively (K) / readily (Na) with cold water, where it ignites and darts around at high speeds on the surface of the water. • Effervescence is observed, producing a colourless gas that extinguishes a lighted splint with a ‘pop’ sound. For non-Group I metals: • Metal reacts very slowly (Ca) with cold water. • Effervescence is observed, producing a colourless gas that extinguishes a lighted splint with a ‘pop’ sound. [D] Reaction with steam (only for Ca, Mg, Al, Zn & Fe) • Metal reacts violently (Ca) / readily (Mg) / slowly (Zn / Fe) with steam. • A coloured solid (metal oxide) is formed. [D] Reaction with dilute acids (only for Ca, Mg, Al, Zn & Fe) • Metal reacts explosively (Ca) / violently (Mg) / readily (Zn) / quickly (Fe) with dilute acid. • Effervescence is observed, producing a colourless gas that extinguishes a lighted splint with a ‘pop’ sound. [E] Why aluminium, despite its high reactivity, does not react with steam or dilute acids? Þ Aluminium reacts readily with oxygen in air to form aluminium oxide that covers the metal surface. Þ This oxide layer prevents / protects aluminium from reacting with steam/ dilute acids. Displacement reactions In general, M (s) + m(NO3)2 (aq) ® M(NO3)2 (aq) + m (s) M > m Comparing reactivity [D] • A coloured solid (more reactive metal) is deposited. • Colour of the solution changes to another colour / decolourises. [E] Þ The (more reactive metal) is more reactive than (less reactive metal). Þ Thus, the (more reactive metal) displaces the (less reactive metal) from its (salt solution of less reactive metal). Key Terms in template Replace with Highlighted chemical name Italic colour observed

Page 2 Colours of selected metal compounds Metal ion Colour of salt solution Colour of oxide Cu2+ Blue Black Fe2+ Pale green Black Fe3+ Yellow Red-brown Zn2+ Colourless White Most metals are silver / grey in colour, except Cu (pink-brown) & Au (gold).