Chem5 Run

Front 1

What is the enthalpy change?

Back 1

Heat energy change under constant pressure

Front 2

WHat is lattice enthalpy?

Back 2

Enthalpy change when 1 mole of a solid ionic lattice is separated into its gaseous ions under standard conditions

Front 3

What is bond dissociation enthalpy?

Back 3

Enthalpy change when all the bonds of the same type in 1 mole of gaseous molecules are broken

Front 4

What is enthalpy of atomisation of an element?

Back 4

Enthalpy change when 1 mole of gaseous atoms is formed from an elements in its standard state

Front 5

What is enthalpy of atomisation of a compound?

Back 5

ENthlapy change when 1 mole of a compound is converted into gaseous atoms

Front 6

What is the enthalpy chang eof solution?

Back 6

The enthalpy change when 1 mole of a solute is dissovled in suficent solvent such that no enthalpy change occurs on further dilution (the ions are fully separated and do not interact with one another)

Front 7

What is the purely ionic model?

Back 7

Ions are perfectly spherical point charges with charge evenly distributed around them

Front 8

Why is enthalpy of hydration exothermic?

Back 8

Water is polar as oxygen is electronegative;

positive ions form weak bonds with e=oxygen atom

Front 9

Why are mean bond enthalpies not accurate?

Back 9

Taken as a range over diff compoudns;

strength of bond varies between compounds;

not specific to particular compound;

experimental data better

Front 10

What is the issue with lattice enthalpy?

Back 10

Cant bea measured directly

Front 11

What is entropy?

Back 11

A measure of disorder, numebr f ways particles can be arranged/energy can be shared

Front 12

What are 3 ways of increasing entropy?

Back 12

Increase number of particles;

Gases move more randomly and quicker

dissolving a solid (particles can move freely and not held in one place

Front 13

What is a spontaneous reaction?

Back 13

One that occurs with no additional energy input

Front 14

Why does water evaporate?

Back 14

Increase in entropy although endothermic

Front 15

Why is sodium more reactive than magnesium

Back 15

Sodium only has to lose one eelctron, magnesium has to lose two

losing one requires less energy

Front 16

Why is sodium more reactive than magnesium

Back 16

More energy required to remove one electron

Front 17

How does sodium react wih water?

Back 17

Fizzes and forms a molten ball giving off hydrogen gas

Front 18

How does Magnesium react with cold water? How can you tell that a reaction has happened?

Back 18

Very slowly to produce hydroxide and oxygen;

weakly alkaline solution formed

Front 19

Why is magnesium only form a weakly alkaline solution?

Back 19

Only partly soluble

Front 20

Describe all reactions of period 3 elements with oxygen

Back 20

Sodium = yellow flame/vigorous

magnesium = brillinat white flame/vigorous

aluminium = N/A / slow

silicong = N/A / slow

phosphorous = brilliant white / spontaneous

sulphur = blue/steadily burns

Front 21

How do you produce SO3 ?

Back 21

Catalsyt and high temp

Front 22

Why is the melting point of aluminium oxide lower than magnesium oxide?

Back 22

Al3+ ion distrots/polarises electron cloud, bond partially covalent and weaker so less energy to separate ions

Front 23

Where do melting points of aluminium oxide and silicon dioxide lie relative to sodium oxide and magnesium

Back 23

Both above sodium below magnesium

silicon below aluminium

Front 24

Why dont silicon dioxide and aluminiun oxide react with water?

Back 24

They are insoluble

Front 25

What is the name given to H2SO3?

Back 25

sulfurous acid oro sulfuric(IV) acid

Front 26

How do you demonstrate that aluminium oxide is amphoteric?

Back 26

Al2O3 + 3H2O + 2NaOH -----> 2NaAl(OH)4;

Al2O3 + 6HCl ----> 2AlCl3 + 3H2O

Front 27

What do reducing agents and oxidising agents do?

Back 27

Reeducing agents donate electrons and oxidising agents accept electrons

Front 28

What is a salt bridge?

Back 28

A piece of filter paper soaked in aqueous KNO3 that completes the circuit and allows the movement of ions

Front 29

What is the standard electrode potential

Back 29

The voltage measured under standard conditions when the half cells si connected to a standard hydrogen electrode

Front 30

What factors affect the electrode potential of a half cell?

Back 30

Concentration, perssure, temp

Front 31

How do rechargebable cells work?

Back 31

Current supplied;

electrons forced opposite way around the circuit;

reactions are reversed;

none of the substances used up or escape

Front 32

Why cant you recharge a normal dry cell battery?

Back 32

Casing oxidised and wears away or a substance escapes

Front 33

What are the pros of rechargeable batteries?

Back 33

They are cheaper in the long run;

provide more power and can be used in high power devices;

less resources used making them and less landfill

Front 34

What are the cons of rechargeable batteries?

Back 34

More likely to contain heavy metals and toxic elements;

expensive to buy;

don't last as long before running out of charge

Front 35

What are the pros of non-rechargeable batteries?

Back 35

Cheaper to buy;

last longer before running out of charge;

less likely to contain heavy metals and toxic elements

Front 36

What are the cons of non-rechargeable batteries?

Back 36

Expensive in the long run;

more have to be made and more space in landfill;, boh

can't provide all that much power

Front 37

Describe a hydrogen-oxygen fuel cell?

Back 37

2 platinum electrodes (platinum coating over porous ceramic material);

separated by ion exchange membrane to allow movement of ions and not electrons;

and in acidic/alkaline electrolyte;

electrons forced to move around external circuit

Front 38

What are the advantages of fuel cells?

Back 38

Constant supply of electricity as long as constant supply of fuel;

onyl waste is water

Front 39

What are the disadvantages of fuel cell?

Back 39

Need constant supply of fuel;

hydrogen flammable;

produced throough electrolysis

Front 40

What is a transition metal?

Back 40

A metal that forms one or more stable ions with a partially filled d subshell

Front 41

Why are zinc and scandium not transition metals

Back 41

Zn only forms 2+ with full d subshel

Sc only forms 3+ with empty d subshell

Front 42

What are the physical properties of transition metals?

Back 42

High melting point/high boiling point

high density

similar ionic radii

Front 43

What are the chemical properties of transition metals/

Back 43

Variable oxidation states

form complex ions

form coloured ions

act as catalysts

Front 44

Why do transition metals have similar chemical proerties?

Back 44

Due to incomplete d subshell

Front 45

Why do transition metals have variable oxidation states?

Back 45

Energy levels of the 4s and 3d subshell are close together, different amounts of electrons can be lost or gaines using similar amounts of energy

Front 46

What colour is aqueous V2+?

Back 46

violet

Front 47

What colour is aqueous V3+?

Back 47

Green

Front 48

What colour is aqueous (VO)2+?

Back 48

Blue

Front 49

What colour is aqueous (VO2)+?

Back 49

Yellow

Front 50

What is a complex ion?

Back 50

Transition metal ion surrounded by coordinately bonded ligands

Front 51

What is a co-ordinate bond?

Back 51

A covalent bond in which both electrons come from the same atom

Front 52

What is a ligand?

Back 52

A species that donates a lone pair of electrons TO A CENTRAL METAL ION

Front 53

What is a unidentate ligand?

Back 53

A species that forms only one coordinate bond with a central metal ion

Front 54

What do dashed arrows represnt?

Back 54

Bonds sticking out behind the molecule

Front 55

What are the units of Plankcs constant and what is the value?

Back 55

Js

6.63*10^-34