5- inorganic chem

what is the rate equation?

rate= k (A)^m (B)^n

what equation to calcualte activation energy from a graph

gradient x 8.314/1000

suggest two reasons why it is unlikely that a multi step mechansism reaction could happen in one step

• the overall equation dosent match the rate equation

• collision are unlikely with more then two species

what is the overall order of reaction

m+n

why would you use an excess of ____ ensure that the order with respect to ____ is effectively zero

becuase the change in concentration is small itll have effectively zero effect on the rate of reaction

what does order 0 mean

the rate is unaffected by the concentration

what does order 1 mean

the rate is direclty proportional to the concentration, when it doubles so does the rate

what does order 2 mean

rate is proportional to the concentration squared, if you double the concentration the rate will increase by a factor of 2²

what does half life mean

the time take for the concentration of a reactant to decrease by half

what is the equation for finding k when using half life of a first order reaction, concentration time graphs

k= ln 2/ half life

whats the equation that links rate, change in concnetration and change in time

rate = change in conc/ change in time

how to find k with order 0 using graphs 

concentration time graph: gradient = k 

rate concentration graph: y intercept = k 

how to find k with order 1 using graphs 

concentration time graph: k= l2/ h.lL 

rate concentration graph: gradient = k 

initial rate

the instantaneous rate of a chemical reaction at t=0

what are pros and cons of continous monitoring

pros: more accurate

cons: more work to monitor several reactions over some time. Takes longer to process results

what are pros and cons of the clock method

pros: quick and simple to carry out easy to process 1/t

cons: only gives an approximation of the initial rate, need to choose quantities carefully

What is the shape of an order 0 graph showing time concentration

What would a graph look like for order 0 showing concentration and rate of reaction

What would a graph showing order 1 for conenctration and time

Order 1: concentration/ rate of reaction

Order 2: concentration/ time

Order 2 : concentration/ rate of reaction

lattice enthalpy

the energy change that accompanies the formation of one mole of ionic compound from gaseous ions under standard condidtions

standard enthalpy change of formation

the enthakpy change that happens when one mole of an element is formed from its constituent elements under standard conditions

enthalpy change of atomisation

the enthalpy change that takes place when one mole of gaseous atoms forms from the element in its standard states

firs ionisation energy

the energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions

electron affinity

the enthalpy change that takes place when one electron is added to each atom in one mole of gaseous atoms to form on mole of gaseous 1- ions

standard enthalpy change of solution

the enthalpy change that takes place when one mole of compound is completely dissolved in water under standard conditions

standard enthalpy change of hydration

the enthalpy change that takes place when one mole of isolated gaseous ions is dissolved in water forming one mole of aqueous ions under standard conditions

entropy

a measure of the dispersal of energy in a system, the more disordered a system , the greater the entropy

symbol: S

units: J K-1 mol -1

• the number of wats a system can be arranged , higher entropy= more ways it can be arranged 

entropy calculation

△S = ∑S products - ∑S reactants

gibs free energy calc 

△G = △H - (T x △S )

• temp is in kelvin 

• JK mol-1

how do we know if a reactioin is feasible

△G negative = feasible

∆G>0

-△S on a graph

gradient

temp becomes feasible on a graph 

when line goes through x 

△H on a graph

y intercept

dynamic equilibrium

• can be only set up in a closed system

• the rate of the forward reaction = rate of the reverse reaction

• the amount of reactants and product appear to stay the same

le chateliers principle 

states that when a system in dynamic equilibrium is subjeted to a change, the reaction will shift to minimise the change 

temperature effect on equilibrium

increase: shift in endo direction

decrease: shift in exo direction

pressure effect on the equilibrium

increase: shift side with least moles of gas

decrease: shift side with most moles of gas

concentration effect on equilibrium

increase (x): shifts to the side without x

decrease (x): shift to side with X

kc 

standard equilirbium constant 

kc equation

𝐾𝑐=[𝐶]^𝑐[𝐷^]𝑑////[𝐴]^𝑎[𝐵]^𝑏

kc effect on equilibrium 

if kc is small it will shift to the left 

if kc is big it will shift to the right 

K_p

used for gaseous equilbria when we know the partial pressure of the gases in the system

partial pressure

the contribution made by a gas towards the total pressure in a system

Kp equation

p(C)^c p(D)^d `/// (A)<sup>a</sup> p(B)<sup>b</sup> `

partial pressure equation 

partial pressure = mole fraction x total pressure P

mole fraction equation

moles (A)/ total moles in mixture

what happens to the Kp value when the temp is increase ( -ve)

• forward reaction is exothermic 

• this means that the equilitbim will shift to the left 

• this means that the denominator will increase and the numerator will decrease 

• Kp will therefore decrease