reactions of group 2 metals with water

What element of group 2 doesn’t react with water

Beryllium

What happens when magnesium reacts with water

Magnesium hydroxide and hydrogen gas

Why is magnesium oxide formed rather than magnesium hydroxide when magnesium reacts with steam

Hydroxide is not stable at higher temperatures and so thermally decomposes into magnesium oxide and water

What happens when calcium reacts with water cold

Releases bubbles of hydrogen in an exothermic reaction

What happens when calcium hydroxide forms

White precipice of calcium hydroxide is formed and the remaining solution. Is slightly alkaline because calcium hydroxide is slightly soluble in water

What is found when barium reacts with water

White predicate of barium hydroxide is formed but its a thin precipitate because as you go down group 2 the solubility of the hydroxides increases so the amount of precipate reduces

How can the relative solubility of group 2 hydroxides be found

By adding a solution of sodium hydroxide to solutions of the group 2 ions and observing the precipitate

Why is magnesium hydroxide said to sparingly soluble

Solution is slightly alkaline indicating that some hydroxide ions are dissolved in the water

Suggest how you could determine the solubility of barium hydroxide in g/100cm3 water at 20 degreees c. GIVE FULL PRACTICAL DETAILS

Measure 100cm3 of water in a beaker

Place in a water bath set at 20 degrees c

Measure a known solid of barium and add 20cm3 of water at a time and stir until it dissolves no more

Weigh the solid nd determine how much has been dissolved

That is solubility in g/100cm3

What happpens when group2. Metals react with sulfate

Group 2 sulfates become less soluble down the group so the white precipate becomes more as down group

What group 2 sulfate is said to be sparingly soluble

Calcium sulfate

What group 2 sulfate is insoluble

Barium sulfate so their is a thick white precipate

Describe a method on how to test if a solution has sulfate ions

To 1cm 3 of unknown solution add 1cm3 of dilute HCL and ad 1cm3 of aqueous barium chloride solution

If thick white precipate is formed then sulfate one’s are present

Why is HCL added

Removes any other ions such as carbonate ions which may affect the test