Group 2 Alkaline Earth Metals And Redox

Question 1

Describe the trends in atomic radius down group 2

Answer 1

It increases as extra electron shells are added as u go down the group

Question 2

Why does first ionisation energy decrease down group 2

Answer 2

The outer electron is in a higher energy level and there’s an increase in shielding .
Outer electrons are further from the nucleus reducing the nucleus attraction

Question 3

How does reactivity increase down group 2

Answer 3

Reactivity increases down group 2 because it’s easier to lose electrons

Question 4

Why does melting point decrease
Why’s there a dip at mg

Answer 4

as the metal ions get larger the distance between the bonding electrons (outer e-) and the positive nucleus gets larger and reduces the overall attraction between the two.

The crystal changes

Question 5

As you react group 2 elements with hydroxides down the group..
Sulfate

Answer 5

It goes from least to most soluble
Most to least

Question 6

Test for identifying sulfate ions in solution

Answer 6

Add dilute hcl and then barium chloride solution to a solution containing sukfate ions a white precipitatie forms (barium sulfate ) bc barium is insoluble

Question 7

Use of barium metal

Answer 7

I, used in barium meals to diagnose stomach problems.
Barium sulfate is insoluble so jt forms a suspension rather than a solution

Question 8

Mg is used as…

Answer 8

Part of the process of extracting titanium from its ore

Question 9

Removal of sulfur dioxide from flue gases

Answer 9

It can be removed from flue gases by reacting with an alkali

Question 10

Describe the trends in boiling points of group 7 down the group

Answer 10

Increases, as vanderwalls forces increase in strength as size of molecule increases

Question 11

Describe the trends in electronegativity of group 7 elements down the group

Answer 11

Decreases down the group , outer electrons r getting further from the nucleus as they are more shielded

Question 12

Why does group 7 get less reactive down the group

Answer 12

Atoms become larger and the outer shell is further from nucleus

Question 13

What happens when u add chlorine to a solution containing bromide ions ?

Answer 13

Chlorine displaces the bromide ions . Colourless to orange

Question 14

What happens when u add chlorine to potassium iodide ions

Answer 14

Chlorine displaces the iodide ions . Colour change from colourless to brown

Question 15

If u add bromine to a solution of potassium iodide

Answer 15

Bromine displaces the iodide ions , colourless to brown

Question 16

The reducing power of halides..

Answer 16

Increase down the group as it’s easier to loose the outer electron because the electrons are held less strongly by nucleus

Question 17

Test for halide ions
How to test further

Answer 17

Add nitric acid to remove any ions interfering w experiment , add silver nitrate solution , chloride = white pptp. Bromide = cream pptp . Iodide = yellow ptp

Add ammonia. Silver chloride pptp dissolves in dilute NH3 . Silver bromide ptp dissolves in conc NH3
.silver iodide ptp is insoluble in conc NH3

Question 18

describe how to carry out a flame test:
test for froup 2 ions

Answer 18

1 dip wired loop into conc hcl to clean, dip into unknown compound, hold loop in blue part of bunsen flame

calcium ion = brick red.
strontium = red
barium = pale green

Question 19

how to identify group 2 ions using NaOH

Answer 19

add naoh to test tube containing solution and observe ptp then keep adding excess naoh
mg = slight white pptp excess = white pptp
calcium = slight white pptp
strontium = slight white pptp
barium = no change

Question 20

test for ammonium ions

Answer 20

hold damp red litmus paper over substance being tested , damp paper will turn blue if there are ammonium ions

another method - add NaOH solution to solution being tested , heat , damp red litmus paper turns blue due to ammonia gas given off

Question 21

how to test for carbonate ions?

Answer 21

add dilute HCL, if solution containing carb ions will fizz this is C02 gas
to test this c02 further bubble it thru limwater, itll turn cloudy. confirming there is carb ions

Question 22

The use of Mg(OH)2
Ca(OH)2 in
group 2

Answer 22

medicine
agriculture.

Question 23

the reaction between chlorine gas and cold NaOH solution

Answer 23

produces sodium chlorate (NaCLO) solution
-this is bleach which kills bacteria , used in water treatment
-in this reaction chlorine is ox and red which is disproportionation

Question 24

chlorine gas and water makes

Answer 24

chloride and chlorate ions

Question 25

uses of chlorine

Answer 25

kills bacteria
its toxic and harmful if breathed in. its still used tho because the cancer risk is small compared to the risks of drinking untreated water

Question 26

Conditions for the electophillic substitution reaction between hydrogen halides and alkenes

Answer 26

Ethene gas is passed thru conc HBR

Question 27

How are alkenes identified ?

Answer 27

If an alkene is present the bromine water solution turns from orange to colourless

Question 28

What is an electrophile and give 3 examples

Answer 28

• an electron acceptor attracted to areas of high electron density (the double bond )
• HBr, Br2 and H2S04

Question 29

Conditions for h2so4 electrophillic addition

Answer 29

Ethene gas is passed thru cold conc h2so4

Question 30

hydration of ethene adv and disadv

Answer 30

A Forms pure product, better atom economy
D- uses lots of energy and fossil fue,s , non renewable,

Question 31

Fermentation of glucose adv and disasv

Answer 31

a - uses less energy , lower equipment cost
D - slower reaction , land for crops needed

Question 32

Properties of polymers

Answer 32

• saturated, main carbon chain is non polar so t makes them unreactivw

Question 33

1. How are addition polymers produced ?

Answer 33

From alkenes where the double bond is broken to form a repeating unit

Question 34

2. how can reaction conditions affect the polymers produced ?

Answer 34

High pressures and temps produce branched chain polymers with weak im forces . Lower temps and pressures produces straight chain polymers with strong im forces

Question 35

4. what is PVC?

Answer 35

An addition polymer with water proof properties , it gains these properties by the addition of plasticisers during the reaction