Group 2 (alkaline earth metals) Flashcards
What happens to atomic radius down group 2?
Increases due to extra electron shells
What happens to first ionisation energy down group 2?
Decreases due to increased atomic radius and shielding
What happens to melting point down group 2?
Decreases due to weaker metallic bonding. Mg doesn’t fit the pattern (lower than all other group 2 metals)
How is magnesium used to extract titanium?
Titanium dioxide is heated with carbon and chlorine, forming titanium chloride and CO. Titanium chloride then reduced by Mg
What acts as the reducing agent in the extraction of titanium?
Magnesium
What are the formulas for extracting titanium using magnesium?
TiO2 + 2Cl2 + 2C –> TiCl4 + 2CO
then
TiCl4 + 2Mg –> Ti + 2MgCl2
Why is using magnesium to extract titanium less efficient?
Happens in two stages
Why can’t titanium be extracted using carbon?
Produces a carbide that is too brittle
TiO2 + C –> TiC + O2
Equation for the reaction of oxygen and sulfur dioxide?
2SO2 + O2 –> 2SO3
Equation for the reaction of sulfur trioxide and water which ultimately produces acid rain?
SO3 + H2O –> H2SO4
What is quicklime?
CaO
Equation for the use of CaO to prevent acid rain?
CaO + SO2 –> CaSO3 (calcium sulfite)
What is limestone?
Calcium Carbonate (CaCO3)
Equation for the use of CaCO3 to prevent acid rain?
CaCO3 + SO2 –> CaSO3 + CO2
Equation for the reaction with group 2 metals with water (apart from beryllium which is unreactive)?
Ca + 2H2O –> Ca(OH)2 + H2
Equation for the reaction with Mg and and steam (vigorous reaction)?
Mg + H2O (g) –> MgO + H2
What happens to the solubility of hydroxides in water down group 2?
Increases (except magnesium hydroxide which is sparingly soluble, so is a white ppt)
What is used to cure heartburn and why?
Mg(OH)2 because it’s a base just strong enough to neutralise the pH of the stomach, and is sparingly soluble so not strong enough to damage the body
How is soil pH neutralised?
Ca(OH)2 (slaked lime)
Ca(OH)2 + 2HCl –> CaCl2 + 2H2O
What happens to the solubility of sulfates down group 2?
Decreases (barium sulfate almost insoluble)
How and why is barium sulfate used to make tissues visible on x-rays?
Dense enough to absorb x-rays and insoluble enough so not toxic
How is barium chloride used to test for sulfate ions?
Will react with sulfate ions to form barium sulfate (white ppt)
What if instead of sulfate ions the solution contained carbonate ions?
Would form barium carbonate which is also a white ppt.
So add acid which reacts with carbonate to form CO2 (removes carbonate ions)
