Reactions of Group 2 Elements (Cambridge (CIE) A Level Chemistry): Revision Note
Exam code: 9701
Reactions of the Group 2 Elements
The Group 2 elements react with oxygen, water and dilute acids
Reaction of Group 2 elements table
Group 2 element | Reaction with oxygen | Reaction with water | Reaction with dilute HCl | Reaction with dilute H2SO4 |
|---|---|---|---|---|
Mg | Burns easily Bright white flame | Vigorous reaction with steam Very slow reaction with water | Reacts vigorously | Reacts vigorously |
Ca | Difficult to ignite Red flame | Reacts moderately Hydroxide formed | Reacts vigorously | Reaction is slowed by the formation of a sparingly soluble sulfate layer which coats the metal surface stopping hydrogen bubbles from rising |
Sr | Difficult to ignite Red flame | Reacts rapidly Hydroxide formed | Reacts vigorously | Reaction is quickly stopped by the formation of an insoluble sulfate layer on the metal surface |
Ba | Difficult to ignite Green flame | Reacts vigorously Hydroxide formed | Reacts vigorously | Reaction is quickly stopped by the formation of an insoluble sulfate layer on the metal surface |
Group 2 reactions with oxygen & water chemical equations
Group 2 element | Reaction with oxygen | Reaction with water |
|---|---|---|
Mg | 2Mg (s) + O2 (g) → 2MgO (s) | Mg (s) + 2H2O (l) → Mg(OH)2 (s) + H2 (g) * |
Ca | 2Ca (s) + O2 (g) → 2CaO (s) | Ca (s) + 2H2O (l) → Ca(OH)2 (s) + H2 (g) |
Sr | 2Sr (s) + O2 (g) → 2SrO (s) Sr (s) + O2 (g) → SrO2 (s) | Sr (s) + 2H2O (l) → Sr(OH)2 (aq) + H2 (g) |
Ba | 2Ba (s) + O2 (g) → 2BaO (s) Ba (s) + O2 (g) → BaO2 (s) | Ba (s) + 2H2O (l) → Ba(OH)2 (aq) + H2 (g) |
*Mg reacts with steam: Mg (s) + H2O (g) → MgO (s) + H2 (g)
Group 2 reactions with dilute hydrochloric acid & dilute sulfuric acid chemical equations
Group 2 element | Reaction with dilute HCl | Reaction with dilute H2SO4 |
|---|---|---|
Mg | Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g) | Mg (s) + H2SO4 (aq) → MgSO4 (aq) + H2 (g) |
Ca | Ca (s) + 2HCl (aq) → CaCl2 (aq) + H2 (g) | Ca (s) + H2SO4 (aq) → CaSO4 (s) + H2 (g) |
Sr | Sr (s) + 2HCl (aq) → SrCl2 (aq) + H2 (g) | Sr (s) + H2SO4 (aq) → SrSO4 (s) + H2 (g) |
Ba | Ba (s) + 2HCl (aq) → BaCl2 (aq) + H2 (g) | Ba (s) + H2SO4 (aq) → BaSO4 (s) + H2 (g) |
The reaction of all metals with oxygen follows the following general equation:
2M (s) + O2 (g) → 2MO (s)
Where M is any metal in Group 2
Remember that Sr and Ba also form MO2
The reaction of all metals with water follows the following general equation:
M (s) + 2H2O (l) → M(OH)2 (s) + H2 (g)
The exceptions to this general equation are:
Be which does not react with water
Mg which forms MgO (s) and H2 (g) when it reacts with steam (with cold water it forms Mg(OH)2 very slowly)
The reaction of all metals with dilute HCl follows the following general equation:
M (s) + 2HCl (aq) → MCl2 (aq) + H2 (g)
The reaction of all metals with dilute H2SO4 follows the following general equation:
M (s) + H2SO4 (aq) → MSO4 (aq) + H2 (g)
Remember that CaSO4 is sparingly soluble and that SrSO4 and BaSO4 are insoluble
Examiner Tips and Tricks
Learn the general equation for the reaction with oxygen, water and dilute HCl / H2SO4 and the exceptions instead of memorizing the entire table!
Unlock more, it's free!
Join the 100,000+ Students that ❤️ Save My Exams
the (exam) results speak for themselves:
Was this revision note helpful?
Build on this topic
