Group 1+2

Question 1

Equation for decomposition of group 1 carbonates (except Li)

Answer 1

Oxide and CO2 produced
XCO3➡️ XO+CO2
E.g KCO3➡️ KO+CO2

Question 2

Equation for decomposition of Li carbonate (exception for group 1)

Answer 2

LiCO3➡️ LiO2+CO2

Question 3

Equation for decomposition of group 1 nitrates (except Li)

Answer 3

Form nitrite and oxygen

E.g. 2KNO3➡️ 2KNO2+O2

Question 4

How thermally stable are carbonates in group 1?

Answer 4

Very, decompose at high temps (won’t decompose under Bunsen)
E.g. When heating BaCO3 it gets so hot the test tube melts

Question 5

Why does thermal stability increase down groups 1 and 2?

Answer 5

Larger cations
Lower charge density (charge spread over larger area)
Less distortion (caused by positive ion)
More at stable

Question 6

What happens to the solubility of group 1+2 hydroxides down the group?

Answer 6

Solubility increases

Question 7

What happens to the solubility of group 1+2 sulphates as you go down the group?

Answer 7

Solubility decreases

Question 8

Why are group 2 compounds less thermally stable than group 1 compounds?

Answer 8

Greater charge on cation
Greater distortion
Less stable

Question 9

Equation for decomposition of group 2 carbonates

Answer 9

Oxide and CO2 produced
XCO3➡️ XO+CO2
E.g MgCO3➡️ MgO+CO2

Question 10

Equation for decomposition of group 2 nitrates

Answer 10

Oxide, nitrogen dioxide and oxygen produced

E.g 2Mg(NO3)2 ➡️ 2MgO+4NO2+O2

Question 11

What do you measure when testing for nitrate decomposition? (O2)

Answer 11

How long it takes for a certain amount of O2 to be produced

E.g. Enough to relight glowing splint

Question 12

What do you measure when testing for nitrate decomposition? (NO2)

Answer 12

How long it take for a certain amount of NO2- brown gas- is produced.
Toxic- done in fume cupboard

Question 13

What do you measure when testing for carbonate decomposition?

Answer 13

Time it takes for certain amount of CO2 to be produced.

E.g. Bubble through limewater, turns cloudy

Question 14

Flame colour of Li?

Answer 14

Red

Question 15

Flame colour of Na?

Answer 15

Orange/yellow

Question 16

Flame colour of k?

Answer 16

Lilac

Question 17

Flame colour of Rb?

Answer 17

Red

Question 18

Flame colour of Cs?

Answer 18

Blue

Question 19

Flame colour of Ca?

Answer 19

Brick red

Question 20

Flame colour of Sr?

Answer 20

Crimson

Question 21

Flame colour of Ba?

Answer 21

Green

Question 22

Equation for decomposition of Li nitrate

Answer 22

Produced oxide, nitrogen oxide and oxygen

4LiNO3➡️ 2Li2O+4NO2+O2

Question 23

How are flame colours produced?

Answer 23

Electrons excited by thermal energy (jump to higher energy levels)
Colour produced from energy emitted as they return (lower levels)

Question 24

How is a flame test done?

Answer 24

Mix small amount of compound with HCl
Heat platinum/nichrome wire in hot flame (Bunsen)
Dip wire into compound and put in flame

Question 25

Equations for group2+water reactions

Answer 25

Forms metal hydroxide and hydrogen

E.g. Mg+2H2O ➡️ Mg(OH)2+H2

Question 26

What happens to reactivity of (gr2+water) reaction down the group?

Answer 26

Reactivity increases
E.g. Mg- slow, little observations
Ba- fast, lots of bubbles

Question 27

Equations for gr2+oxygen reaction

Answer 27

Forms solid, white oxides

E.g. 2Mg+O2➡️ 2MgO

Question 28

Equations for gr2+chlorine reactions

Answer 28

Forms solid, white chlorides

E.g. Mg+Cl2➡️ MgCl2

Question 29

Gr2 oxides reaction with water- equation

Answer 29

MO(s)+H2O➡️M(OH)2 (aq)

Question 30

Gr2 oxides reaction with dilute acid- equation

Answer 30

MO(s)+HCl➡️MCl2(aq)+H2O

Question 31

Gr2 hydroxides reaction with water: equation

Answer 31

M(OH)2(s) +H2O➡️ M(OH)2(aq)

Question 32

Gr2 hydroxides reaction with dilute acid:equation

Answer 32

M(OH)2(aq) + 2HCl➡️ MCl2(aq) + 2H2O