Reactions Of Ions In Aqueous Solution Flashcards by Saleh Taha

What is the equation for pH

-log10[H+]

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When are metal aqua complexes formed

When we add a transition metal compound to water

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Draw the structure of (Cu(H2O)6)2+

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Draw the structure of (Fe(H2O)6)2+

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Draw the structure of (Fe(H2O)6)3+

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Draw the structure of (Al(H2O)6)3+

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What is the pH of metal-aqua ions

Below 7, they are acidic in solution

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What affects how acidic a metal aqua ion is in solution

The charge of the ion

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What is the equation for when (Fe(H2O)6)2+ reacts with water

(Fe(H2O)6)2+(aq) + H2O(l) ⇌ (Fe(H2O)5(OH))+(aq) + H3O+(aq)

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What is H3O+ ion called

Hydroxonium ion

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What is the term for using water to break a portion of a complex off using water

Hydrolysis

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What is the equation for when (Fe(H2O)6)3+ reacts with water
(initial hydrolysis)

(Fe(H2O)6)3+(aq) + H2O(l) ⇌ (Fe(H2O)5(OH))2+(aq) + H3O+(aq)

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Why do more positively charged ions form more acidic solutions

More positively charged ions have a greater charger density
and are more POLARISING
And so attract electrons in the O-H bond in water ligands more strongly, weakening the bond
Therefore more likely that H+ will be released

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What do we form from further hydrolysis of metal-aqua ions

Insoluble metal hydroxides

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What is the state of the neutral complex formed after repeated hydrolysis using OH- of metal aqua ions

Further hydrolysis leads to the formation of a neutral complex that is solid and forms precipitate in solution

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Write the equations for the 3 stages for the formation of a solid metal hydroxide precipitate from the hydrolysis of (M(H2O)6)3+(aq)
M = Al3+ and Fe3+

(M(H2O)6)3+(aq) + H2O(l) ⇌ (M(H2O)5(OH))2+(aq) + H3O+(aq)
(M(H2O)5(OH))2+(aq) + H2O(l) ⇌ (M(H2O)4(OH)2)+(aq) + H3O+(aq)
(M(H2O)4(OH)2)+(aq) + H2O(l) ⇌ M(H2O)3(OH)3(s) + H3O+(aq)

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Why are there only two steps to form an insoluble solid from metal aqua 2+ ions rather than 3 for metal aqua 3+ ions

Only two water ligands need to be deprotonated to form a neutral complex

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Write the equations for the 2 stages for the formation of a solid metal hydroxide precipitate from the hydrolysis of (M(H2O)6)2+(aq)
M = Cu2+ and Fe2+

(M(H2O)6)2+(aq) + H2O(l) ⇌ (M(H2O)5(OH))+(aq) + H3O+(aq)
(M(H2O)5(OH))+(aq) + H2O(l) ⇌ M(H2O)4(OH)2(s) + H3O+(aq)

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Which way does equilibrium shift when we add OH- ions to the reaction between a metal aqua ion and water

Equilibrium shifts right

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Metal hydroxides can act as an acid or base meaning they are….

Amphoteric

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What is a Bronsted lowry base

H+ acceptor

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What is a Bronsted lowry acid

H+ donor

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Give an example of an amphoteric metal hydroxide

Al(H2O)3(OH)3

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What is the equation for when aluminium hydroxide reacts with a excess base

Al(H2O)3(OH)3(s) + OH-(aq) —> (Al(H2O)2(OH)4)-(aq) + H2O(aq)

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How does aluminium hydroxide act when we add a base

Acts as a Bronsted lowry acid to react with the OH- and therefore it dissolves

How does aluminium hydroxide act when we add an acid

Acts as a Bronsted lowry base by accepting H+ ions to form H3O+ in solution and therefore it dissolves

What is the equation for when aluminium hydroxide reacts with an acid

Al(H2O)3(OH)3(s) + 3H3O+(aq) ---> (Al(H2O)6)3+(aq) + 3H2O(aq)

What do we form when we add small amounts of ammonia to metal aqua ions

Metal hydroxide precipitates

Write the equation showing the equilibrium as to how ammonia exists in solution

NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq)

What sometimes occurs when we add excess ammonia to metal aqua ions

A partial ligand substitution

What is the equation for when copper hydroxide reacts with excess ammonia

Cu(OH)2(H2O)4(aq) + 4NH3(aq) ---> (Cu(NH3)4(H2O)2)2+(aq) + 2OH-(aq) + 2H2O(l)

What do we form when we add sodium carbonate to 2+ metal aqua ions

Insoluble metal carbonate precipitates

What is the general equation for when we add a carbonate to 2+ metal aqua ions

(M(H2O)6)2+(aq) + CO32-(aq) ⇌ MCO3(s) + 6H2O(l)

Why do we not form a carbonate when we add sodium carbonate to 3+ metal aqua ions

3+ metal ions are more acidic than 2+ and there is more H3O+ ions in solution Carbonate ions react with the free H3O+ ions instead of displacing water ligands like 2+ ions

What is the general equation for when we add a carbonate to 3+ metal aqua ions

2(M(H2O)6)3+(aq) + 3CO2-(aq )⇌ 2M(OH)3(H2O)3(s) + 3CO2(g) + 3H2O(l)

What is observed when we add sodium carbonate to 3+ metal aqua ions

Fizzing (due to CO2 produced)

What is observed when we add NaOH to Fe2+ Cu2+ Al3+ and Fe3+

All react to form precipitates

State and explain what is observed when we add excess NaOH to an aluminium hydroxide precipitate

It dissolves as it is amphoteric White precipitate to a colourless solution

What is observed when we add NH3 to Fe2+ Cu2+ Al3+ and Fe3+

All react to form precipitates

When adding NaOH to Fe2+ Cu2+ Al3+ and Fe3+, a precipitate is formed. Which is the only precipitate that dissolves in excess NaOH

Aluminium hydroxide

When adding NH3to Fe2+ Cu2+ Al3+ and Fe3+, a precipitate is formed. Which is the only precipitate that dissolves in excess NH3

Copper Hydroxide

State and explain what is observed when we add excess NH3 to a Copper Hydroxide precipitate

Dissolves as there is a ligand substitution Colour goes from pale blue precipitate to dark blue solution (pale blue precipitate dissolves to form a dark blue solution)

What is observed when we add Na2CO3 to Fe2+ Cu2+ Al3+ and Fe3+

All react to form precipitates

What is observed when Al3+ and Fe3+ react with sodium carbonate

A precipitate and bubbles (CO2 formed)

Do we produce a gas when Cu2+ and Fe2+ react with sodium carbonate

No, only a precipitate is formed

Why must any Fe2+ solution being tested be made fresh

Fe2+ oxidises readily with air to form Fe3+

What colour is Cu2+(aq)

Blue

What colour is observed when we add small amounts of OH-(aq) or NH3(aq) to Cu2+(aq)

Pale blue precipitate

What colour is observed when we add excess OH-(aq) to the precipitate formed from adding small amounts of OH-(aq) to Cu2+(aq)

No change Insoluble in excess NaoH

What colour is observed when we add excess NH3(aq) to the precipitate formed from adding small amounts of NH3(aq) to Cu2+(aq)

Dark blue solution

What colour is observed when we add Na2CO3(aq) to Cu2+(aq)

Green - Blue precipitate

What colour is Fe2+(aq)

Pale green

What colour is observed when we add small amounts of OH-(aq) or NH3(aq) to Fe2+(aq)

Dirty green precipitate

What colour is observed when we add excess OH-(aq) to the precipitate formed from adding small amounts of OH-(aq) to Fe2+(aq)

No change Insoluble in excess NaoH

What colour is observed when we add excess NH3(aq) to the precipitate formed from adding small amounts of NH3(aq) to Fe2+(aq)

No change Insoluble in excess NH3

What colour is observed when we add Na2CO3(aq) to Fe2+(aq)

Green precipitate

What colour is Fe3+(aq)

Yellow

What colour is observed when we add small amounts of OH-(aq) or NH3(aq) to Fe3+(aq)

Orange precipitate

What colour is observed when we add excess OH-(aq) to the precipitate formed from adding small amounts of OH-(aq) to Fe3+(aq)

No change Insoluble in excess NaoH

What colour is observed when we add excess NH3(aq) to the precipitate formed from adding small amounts of NH3(aq) to Fe3+(aq)

No change Insoluble in excess NH3

What colour is observed when we add Na2CO3(aq) to Fe3+(aq)

Brown precipitate

What colour is Al3+(aq)

Colourless

What colour is observed when we add small amounts of OH-(aq) or NH3(aq) to Al3+(aq)

White precipitate

What colour is observed when we add excess OH-(aq) to the precipitate formed from adding small amounts of OH-(aq) to Al3+(aq)

Colourless solution

What colour is observed when we add excess NH3(aq) to the precipitate formed from adding small amounts of NH3(aq) to Al3+(aq)

No change

What colour is observed when we add Na2CO3(aq) to Al3+(aq)

White precipitate

Draw the table for colours of the ions Cu2+, Fe2+, Fe3+, Al3+

What is the the equation for adding drops (not excess) of OH- to (Al(H2O)6)3+

What ion does NH3 form

NH4+

Write the colour observed, final species and equation when (Cu(H2O)6)2+ reacts with concentrated HCl

Draw the routes for Fe

Draw the routes for Cu

Draw the routes for aluminium

How do we go from (Fe(H2O)6)3+ to (Fe(H2O)6)2+

XS Zn in acidic solution (HCl)

What is the formula and colour of the species produced when we add concentrated NH3 to (Fe(H2O)6)2+

Green Fe(H2O)4(OH)2

Write an equation for the reaction of (Al(H2O)6)3+ with excess OH-

[Al(H2O)6]3+ + 4 OH– ----> [Al(H2O)2(OH)4]– + 4 H2O

Explain why a compound called X yellow

Visible light absorbed and (d) electrons excited Only yellow light transmitted/reflected

What is the nest for NH4+

Addition of NaOH/OH– and warming gives gas that turns (damp) red litmus blue (ammonia turns damp red litmus paper blue) NH4+ + OH− → NH3 + H2O

What is the test for Al3+

Addition of NaOH/OH– until in excess gives white ppt that redissolves = Al3+ (Al(H2O)6)3+ + 3 OH− → Al(H2O)3(OH)3 + 3 H2O Al(H2O)3(OH)3 + OH− → (Al(H2O)2(OH)4)− + H2O OR addition of carbonate giving white ppt and effervescence 2(Al(H2O)6)3+ + 3CO32– → 2Al(H2O)3(OH)3 + 3CO2 + 3H2O