2.4 GROUP 2

Question 1

solubility of G2 hydroxides

Answer 1

solubility trend: increases

Mg( OH )2 insoluble
Ca( OH )2 slightly soluble
*the above have ionic eq

Sr(OH)2 soluble
Ba(OH)2 soluble

Question 2

solubility of G2 sulfates

Answer 2

solubility trend: decreases

MgSO4 soluble

CaSO4 slightly soluble
SrSO4 insoluble
BaSO4 insoluble
*the above have ionic eq

Question 3

solubility trend of G1 hydroxides and sulfates

Answer 3

no trends

because all soluble

Question 4

why group 1 and 2 metals are called as s block elements?

Answer 4

as the highest occupied energy level is the s-orbital

Question 5

trend in first ionization energy of G2

Answer 5

trend: decreases

explanation:
down the group, the proton increases but the shielding effect of inner shells electrons increases too.
however, the outer shell electron is further away from nucleus.
which weakens the force of attraction and less energy is needed to remove an electron

Question 6

trends down G2

melting point
electrical conductivity
reducing power
reactivity

Answer 6

melting point: decreases, weaker metallic bond

electrical conductivity: increases, easier to form delocalised electrons

reducing power: increases , ionisation energy decreases easier to lose electron and from cation

reactivity : increases , easier to form cation

Question 7

group 2 + oxygen

Answer 7

form oxides

refer note

Question 8

group 2 + water

Answer 8

form hydroxides

refer note

Question 9

group 2 + chlorine

Answer 9

form chlorides

refer note

Question 10

state the acid-base nature of G2 oxides

Answer 10

basic oxides
except BeO is amphoteric

non metal oxides are acidic like CO2, NO2

Question 11

unlike magnesium why barium is kept immersed under paraffin oil or in vacuum sealed ampoules

Answer 11

barium is very reactive
readily react with O2 and moisture in air
turns into liquid when exposed to air

Question 12

lithium chloride can be made by burning lithium in chlorine. why rubidium chloride is not prepared like that

Answer 12

rubidium is more reactive

is vigorous and therefore dangerous

Question 13

bonding present in BeCl2

Answer 13

covalent

Question 14

bonding present in BaCl2

Answer 14

ionic

Question 15

why the type of bonding is different for BeCl2 and BaCl2

Answer 15

BeCl2
Be 2+ is small and highly polarising and therefore greater distortion of electron clouds on chlorides
hence, shows greater covalent character

BaCl2
large electronegativity difference between Ba and Cl2
hence shows greater ionic character

Question 16

compare the reaction of g2 hydroxides and and oxides

Answer 16

see notes pg4

Question 17

how to make metal hydroxides give three ways

Answer 17

g2 plus water
g2 oxides except Beo plus water
g2 salt plus base like NaOH

Question 18

which g2 sulfates is least soluble

Answer 18

BaO4

Question 19

state the use of insolubility of sulfates in medical field and lab test

Answer 19

refer to notes pg5

Question 20

why strontium stops reacting with dilute sulphuric acid after a few seconds even though they react initially

Answer 20

strontium and sulphuric acid forms insoluble strontium sulphate. forms a layer around the Sr metal prevent further reaction with acid

Question 21

barium with cold water

Answer 21

barium hydroxide (aq) plus hydrogen

Question 22

aqueous solution of barium hydroxides to a pure sample of barium sulphate

Answer 22

barium hydroxides react with excess sulphuric acid to ensure all barium hydroxide convert completely to BaSO4

filter the solution using filter paper

soild obtain is pure barium sulphate

wash

pat dry do not heat cause g2 decompose under heat

Question 23

Mg(Cl)2 + excess NaOH

all aq

Answer 23

percipitation
ionic eq form

white percipitate is form
insoluble in excess NaOH
not amphoteric

Question 24

Ba(Cl)2 + excess NaOH

all aq

Answer 24

no ionic eq
no percipitate
remains clear

Question 25

``` flame test Li+ Na+ K+ Rb+ Ca+ Sr+ Ba+ ```

Answer 25

Li+ deep red Na+ golden yellow K+ lilac Rb+ bluish red Ca+ brick red Sr+ crimson red Ba+ green

Question 26

flame test method

Answer 26

refer notes

Question 27

explanation for flame colour

Answer 27

refer notes

Question 28

why platinum or nichrome wire is used in flame test

Answer 28

unreactive with conc HCL it is dipped in | will not give a flame colour of its own

Question 29

why conc HCL is used not H2SO4 and HNO3

Answer 29

reacts with salt and forms metal chlorides | chlorides are much mire volatile than sulfates or nitrate

Question 30

why is it necessary to clean the wire by repeatedly dipping in conc HCL and heat prior testing

Answer 30

to ensure no traces of metal ions remain | that would produce a flame colour which lead to false observation

Question 31

why is it impossible to identify K+ ions in a sample contaminated with small amounts of Na +

Answer 31

the intense yellow flame will mask the pale lilac flame

Question 32

thermal decomposition meaning

Answer 32

use of heat to break down a single reactant into 2 or more simpler products the higher the thermal stability, the higher the temp needed to decompose it

Question 33

g1 carbonates effect of heat general eq trend in thermal stability

Answer 33

effect of heat: do not decompose general eq: no trend in thermal stability: very stable

Question 34

g2 carbonates effect of heat general eq trend in thermal stability

Answer 34

effect of heat: decompose to give metal oxide and co2 general eq: refer notes trend in thermal stability: increases

Question 35

does g1 hydrogencarbonates decomposes under heat?

Answer 35

yes | eq refer notes

Question 36

experiment diagram to investigate thermal stability

Answer 36

refer notes pg 8

Question 37

how experiment for thermal stability helps to explain thermal stability

Answer 37

time taken foe lime water to turn cloudy

Question 38

experiment diagram to investigate thermal stability how you would control the factors in the experiment so diff carbonates can be compare

Answer 38

1. constant bunsen flame 2.fixed height of test tube above flame 3. fixed moles or mass of carbonates 4. fixed volume of limewater same cloudiness of limewater

Question 39

experiment diagram to investigate thermal stability this experiment gives only approximate results suggest an alternative improvement to increase the reliability

Answer 39

collect and measure the volume of co2 using a syringe for a fixed Heating time weigh the solid before and after heating to determine the change in mass or a fixed amount of heating time

Question 40

g1 nitates effect of heat general eq trend in thermal stability experimental evidence

Answer 40

effect of heat: decompose to give metal nitrate and o2 general eq : refer notes pg 9 trend in thermal stability: increases experimental evidence: time taken for the solid to melt

Question 41

g2 nitates effect of heat general eq trend in thermal stability experimental evidence

Answer 41

effect of heat: decompose to give metal oxide, nitrogen dioxide amd o2 general eq: refer notes trend in thermal stability: increases experimental evidence: time taken for appearance of brown gas and time taken for solid to melt

Question 42

the thermal stability of ionic compounds depends on

Answer 42

ionic charge of cation ionic radius of cation

Question 43

down g2 carbonates and nitrate increases because

Answer 43

cation radius increases but charge remains the same polarising power of cation decreases difficult to distort electron cloud on anion / more energy is needed to weaken the bond

Question 44

why MgO2 cannot be further decomposed to Mg and O2?

Answer 44

O2- is small and high charge | there fore O2- cannot be easily polarised

Question 45

why G1 carbonates are more stable than G2 carbonates

Answer 45

g1 metal ion is less polarising than g2 metal ion less distortion of electron cloud on CO3 2- more energy is needed to break the bond in g1 carbonates

Question 46

calcium plus water

Answer 46

calcium hydroxide and hydrogen

Question 47

state the trend in solubilty of g2 hydroxides

Answer 47

increases

Question 48

why MgCl2 does not produce a flame colour

Answer 48

the radiation is not in the visible light range

Question 49

polarising power meaning

Answer 49

the ability of cation to distort the electron cloud of cation

Question 50

radium hydroxide soluble in water?

Answer 50

yes

Question 51

radium sulphate soluble in water?

Answer 51

no