Group 2 And 7 Flashcards

1
Q

What happens to melting point down group 2

A

Melting point generally decreases except with mg
Because metallic bonding gets weaker (size if metal ion increases)

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2
Q

What do group 2 metals form when reacting with water

A

Metal hydroxide and hydrogen gas

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3
Q

What is the reaction of magnesium with water vs steam

A

Reacts very slowly with cold water to form magnesium hydroxide

Readily reacts with steam to form magnesium oxide

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4
Q

How do the rest do group 2 metals react with water as you go down?

A

All react with cold water to from hydroxides

Vigorous reaction increases down the group

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5
Q

Why does reactivity of group 2 metals increase down the group

A

It is successively easier to remove electrons to form the 2+ ion
(Atomic radius increases)

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6
Q

What is the trend in solubility do group 2 metal hydroxides down the group

What does this results in

A

Increases

So higher ph cos more hydroxide ions

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7
Q

How do you test for mg ions and ca ions

A

They are sparingly soluble so react magnesium chloride or calcium chloride with sodium hydorxide to form a white precipitate

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8
Q

What type of reaction is it when group 2 metal hydroxides react with acids

A

Neutralisation

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9
Q

What is a use of magnesium hydroxide

A

Relieve acid indigestion
Laxative

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10
Q

What is a use of calcium hydroxide
What’s another name for it

A

Raise the ph of soils in agriculture

Slaked lime

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11
Q

How do you test for ammonia gas
What is reaction between ammonium ions and oh minus ions

A

Form ammonia gas and water

Damp red litmus paper turns blue

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12
Q

What is the trend in solubility of group 2 metal sulfates

A

Solubility decreases down the group

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13
Q

What is the chemical test for SO4 2- ions

A

Colourless solution of sodium sulfate, add barium chloride to form barium sulfate (white precipitate)

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14
Q

Why does barium chloride need to be acidified first

A

To remove any other ions that could cause a false positive

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15
Q

How is Barium Sulfate used in medicine

A

Barium meal

To examine a patients digestive system, the mixture containing barium sulfate coats the inner lining of intestines

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16
Q

Why is is safe to have a barium meal i if barium ions are so toxic

A

Barium sulfate has a very low solubility so hardly any barium ions present in the solution and can’t dissolve into blood etc

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17
Q

How is titanium extracted

A

Reacting titanium chloride with magnesium

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18
Q

What are the 2 most useful properties of titanium

A

Corrosion resistant

High strength to weight ratio

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19
Q

What are uses of calcium carbonate and calcium oxide

A

Neutralise sulfur dioxide present in flue gas

Flue gas desulfurisation

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20
Q

What is the trend in electro negativity of group 7 elements down the group

A

Electronegativity decreases

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21
Q

What is the trend in boiling points down group 7

A

Boiling point increases
More electrons so stronger van der waals forces

22
Q

What happens when halogens act as oxidising agents

A

They gain electrons to become halide ions

23
Q

What is the trend in oxidising abilities as you go down group 7
And why

A

The halogens decrease in oxidising ability

The ability to gain electrons reduces down the group

24
Q

What type do reactions are halogen displacement reactions

A

They are redox reactions

25
Q

What is the role of the halogen in halogen halide displacement reactions

A

Oxidising agent

26
Q

What are 2 disproportionation reactions that chlorine can do

A

React with water
React with cold sodium hydroxide

27
Q

Define disproportionation reaction

A

A reaction in which the same element is simultaneously oxidised and reduces

28
Q

How is chlorine used in water supplies

A

Used to purify water supplies as it is toxic to bacteria
Added to swimming pools too

29
Q

What are 2 risk of using chlorine in water supplies
What is the compromise of this

A

Chlorine is toxic to humans so risk associated with chlorination leaks

Risk of forming chlorinated hydrocarbons

Sufficient chlorine added to kill bacteria but not enough to harm humans

30
Q

What is another reaction of chlorine

A

Chlorine reacts with in direct sunlight to produce hydrogen chlorine and oxygen

31
Q

What is formed when chlorine reacts with cold aqueous sodium hydroxide

A

Sodium chlorate
(NaOCl)

Household bleach

Sodium chloride and water are 2 other products

32
Q

What is the trend in reducing ability of halide ions down the group
And why

A

Reducing ability increases
Ability of halide ion to lose electron increases

33
Q

What are the stages of a halide ion reacting with concentrated sulfuric acid

A

Stage 1 is displacement
The halide ions reacts with sulfuric acid (which act as a proton donor)

Stage 2 is redox
With bromides and iodides a redox reaction occurs between concentrated sulfuric acid and halide ion
Chloride and fluoride aren’t good enough reducing agents to react

34
Q

What do bromide ions reduce sulfuric acid to

A

Sulfur dioxide

35
Q

What do iodide ions reduce sulfuric acid to

A

They reduce sulfuric acid to sulfur dioxide, sulfur and hydrogen sulfur

36
Q

What is the test for identifying halide ions
What is the exception of this

A

React them with acidified silver nitrate solution to produce a silver halide precipitate

Silver fluoride (it is soluble so won’t form a precipitate)

37
Q

Why do you add nitric acid before adding silver nitrate solution

A

To get rid of any soluble impurities like carbonate and hydroxide ions.

They’d give a false positive

38
Q

What is the colour of fluorine

A

Pale yellow gas

39
Q

What is the colour of chlorine

A

Green gas

40
Q

What is the colour of bromine

A

Red / brown liquid

41
Q

What is the colour of iodine

A

Grey solid

42
Q

Define oxidising ability

A

The power to take electrons

43
Q

What is an oxidising agent

A

Electron acceptor

44
Q

What colour solution forms when chlorine dispatches bromine ions and iodide ions

A

Bromine- orange / yellow solution
Iodide - brown solution

45
Q

What is the colour of precipitates when AgCl, AgBr and AgI are formed

A

Cl - white
Br - cream
I - yellow

46
Q

How do you test if the precipitate is cream or white

A

Add dilute ammonia solution to the AgCl, AgBr and AgI

With cl it dissolves
With br it won’t
With with Ai it won’t

It = precipitate

47
Q

How do you further test the precipitates

A

Add concentrated ammonia solution

AgBr - should dissolve

AgI - won’t dissolve

48
Q

What is reducing power

A

Ability to donate electrons

49
Q

What happens when sodium halides react with concentrated sulfuric acid

A

Misty white fumes produced
(NaHSO4)

50
Q

What colour is solid sulfur

A

Yellow

51
Q

How do you detect hydrogen sulfide
(H2S)

A

Bad egg smell