Group 2

what are the uses of Barium Sulphate

• Barium meals - used in medicine, x rays shows soft tissues

• Insoluble

explain the reactions with water on Group 2 elements and Mg specifically

• form metal hydroxides

• reaction increases (no reaction with Be)

• Mg reacts slowly with cold water but rapidly with steam

• Mg + H2O → MgO + H2

whar is the trend of solubility when reacted with hydroxides

• solubility increases

• Mg limited/insoluble

• Barium very soluble

what is the trend of solubility when reacted with sulphates

• Decreased in solubility

• Mg very soluble

• Barium limited solubility

how do you test for sulphates

• add HCl to remove any carbonates as it can result in false results

• add Barium Chloride produces a white ppt

• BaCl2 + Na2SO4 → BaSO4 + 2NaCl

whats the trend for ionisation energy

• decreases

• extra electron shell added

• outer electron is further away from nucleus

explain the process of removing sulphur dioxide

• wet scrubbing can neutralise it - involves dissolving CaCO3 and spraying alkanes

• produces Calcuim Sulfite - plasterboards

explain the extraction of Titanium

name the use of Titanium

• Converted to TiCl4 by heating with C and Cl

• TiCl4 is passed through fractional distillation column

• purified version is reduced by Mg

• lightweight, used in planes

explain why the 3rd ionisation energy is much higher than 2nd ionisation energy of Be

• Electron removed from 1p not 2 s

• less shielding so electron is closer to the nucleus

• stronger attraction between nucleus and outer electron

explain why the melting point of Mg is higher than Na

• Mg2+ ions are smaller

• Stronger attraction to the sea of delocalised electrons

describe using 1 test-tube how to distinguish MgCl2 and AlCl3 with reagents

• NaOH (hydroxide)

• MgCl2 → white ppt formed

• AlCl3 → white ppt dissolved

suggest why a solution is kept until no more solid needs to be added

To make sure max amount of solid dissolves

give one medical use for MgOH

Indigestion relief or to neutralise stomach acid

state the trend in solubility with water in Group 2

decreases

give the equation for the reaction between TiCl4 and Mg

state the role of Mg

TiCl4 + 2Mg → Ti + 2MgCl2

Role - reducing agent