group 2

Question 1

what happens to the atomic radius down group 2

Answer 1

• atomic radius increases
• shielding increases, making atom bigger

Question 2

what happens to the melting point down group 2?

Answer 2

• melting points decrease
• metallic bonding weakens as size of atom increases
• distance between positive ions and delocalised electrons increases, so strength of electrostatic forces weakens

Question 3

what happens to the 1st ionisation energy down group 2 ?

Answer 3

• ionisation energy decreases
• outermost electrons are successively further from the nucleus.

Question 4

what happens to the reactivity of group 2 metals down the group?

Answer 4

• reactivity increases

Question 5

give an equation and observation for magnesium reacting with steam

Answer 5

• Mg(s) + H20(g) > MgO(s) + H2(g)
• Mg burns with a bright white flame
• MgO appears as white powder

Question 6

give an equation for reaction of magnesium with water

Answer 6

Mg + 2H20 > Mg(OH)2 + H2

• much slower reaction, no flame

Question 7

what are observations for group 2 metals reacting with cold water ?

Answer 7

• fizzing ( more vigorous down group )
• metal dissolving ( faster down group )
• solution heating up ( more down group )
• with calcium a white precipitate appearing ( less forms down group )

Question 8

why is titanium a very useful metal?

Answer 8

• abundant
• low density
• corrosion resistant

Question 9

what are the steps in extracting titanium

Answer 9

• TiO2(s) is comverted to TiCl4(l) at 900C
• TiCl4 is purified by fractional distillation in an argon atmosphere
• Ti is extracted by Mg in an argon atmosphere

Question 10

explain why titanium cannot be extracted with carbon and via electrolysis

Answer 10

• titanium carbide ( TiC ) is formed rather than titanium
• cannot be extracted by electrolysis because it has to be very pure

Question 11

give equations for extraction of titanium from magnesium

Answer 11

TiO2 + 2Cl2 +2C > TiCl4 + 2CO
TiCl4 + 2Mg > Ti + 2MgCl2

Question 12

why is titanium expensive?

Answer 12

• expensive cost of the magnesium
• batch process, making it expensive
• process expensive due to the argon
• high temperatures required in both steps

Question 13

give equation for removal of waste gases from furnaces

Answer 13

• SO2 + CaO > CaSO3

Question 14

what happens to the solubility of hydroxides down group 2

Answer 14

they become more soluble

• all group 2 hydroxides appear as white precipitates, when not soluble

Question 15

why is magnesium hydroxide used in medicine ?

Answer 15

• it is used to neutralise excess acid in the stomach
• it is safe to use because it is so weakly alkaline

Question 16

why is barium meal safe to use ?

Answer 16

• barium sulfates low solubility means it is not absorbed into the blood

Question 17

how can i test for the presence of a sulfate ion?

Answer 17

• BaCl2 solution acidified with HCl is used as a reagent
• if BaCl2 is added to a solution that contains sulfate ions a WHITE PRECIPITATE of barium sulfate forms

Ba^2+(aq) + SO4^2-(aq) > BaSO4

Question 18

why is the hydrochloric acid needed

Answer 18

to react with carbonate impurities that are often found in salts which would form a white barium carbonate precipitate aka a false result

Question 19

how can we tell if a carbonate was present?

Answer 19

fizzing due to CO2 would be observed