Chemical Reactivity

level 2 chemistry: chemical reactivity external

colour, disappear, gas, mass, precipitation

rate of reaction can be measured by:

• time taken for a c______ change to be observed

• time taken for a x to d_______

• measuring g__ production over time

• measuring loss of m___ over time

• recording formation of a _______ over time

collisions, time

rate of reaction is determined by the number of successful ______ per unit of ______

orientation, energy

particles must collide with the correct ______ and sufficient ______ with which to overcome the E_A barrier

frequency

increasing the _____ of collisions increases the rate of reaction

energy, proportion

increasing the ______ of reactants increases the rate of reaction, by increasing the p_______ of particles with sufficient energy in order to overcome the E_A barrier

concentration, fixed

increasing what factor of rate of reaction increases the number of particles available to reaction in a ______ volume?

surface area, available

increasing what factor of rate of reaction increases the number of particles _______ to collide?

temperature

increasing what factor of rate of reaction increases the ______ energy of particles?

catalyst, lower

adding what increases the rate of reaction by providing an alternative reaction pathway with _______ E_A barrier?

faster, sufficient

increasing the temperature, and therefore kinetic energy, has two main effects:

• makes particles move ______, increasing frequency of collisions

• causes a greater proportion of particles to have _______ energy to overcome the E_A barrier

completion, products

in a / an _________ reaction, all reactants are used up, and only ______ remain

equilibrium, reactants, ratio

in a / an _________ reaction, both products and ______ are present at the end in the Kc ______

reverse, constant

equilibrium has two conditions:

1. rate of forwards reaction = rate of _______ reaction

2. the reactants and products are at ______ concentrations

concentrations, equilibrium

the magnitude of the Kc value gives the relative product and reactant ______ at _______

solids, liquids

_______, pure _____ and solvents are all not included in the Kc ratio, as their concentration stays the same throughout a reaction

temperature

what variable is Kc is affected by?

stoichiometric constants

in this formula, Kc = [C^c][D^d] / [A^a][B^b], what are the lowercase letters called?

quotient, equilibrium

the reaction _______, Q, represents the ratio of products to reactants at any point other than ________

products

a higher Kc value means a higher relative concentration of _______

reactants

a lower Kc value means a higher relative concentration of _______

forwards

if Q is lower than Kc, then the ______ reaction is favoured

reverse

if Q is higher than Kc, then the ______ reaction is favoured

oppose, minimise, equilibrium

le chatlier’s principle: if a change is made to a system at equilibrium, that system will adjust to o______ / m_______ that change, and re-establish ________

adjusts

equilibrium _______ by favouring the forwards or reverse reaction

concentration, pressure, temperature

the equilibrium position is affected by:

• c________

• p_______

• t__________

concentration, uses up

if the ________ of a reactant/product is increased, then the system adjusts to minimise that change in the direction that ______ ___ the added chemical to re-establish equilibrium

pressure, lowest

if the _______ of a system is increased, then the system adjust to minimise that change in the direction of the ______ number of gaseous molecules, to decrease the pressure and re-establish equilibrium

same

if there are the ______ number of moles on either side of the equation, there is no effect on the equilibrium position following a change in pressure

reacting

a non-_______ gas has no effect on the change in pressure of a system

temperature, endothermic, absorb, Kc

if the __________ of a system is increased, then the system adjusts to minimise that change by moving in the __________ direction, to _____ the added heat energy and re-establish equilibrium. since this changes [reactants] : [products], this will affect the ___ value

increase

if a system moves to favour its products resulting from a change in temperature, will Kc increase or decrease?

decrease

if a system moves to favour its reactants resulting from a change in temperature, will Kc increase or decrease?

acid

a / an _____ is a proton donor

base

a / an _____ is a proton acceptor

H

a “proton” is a __+ ion

conjugate

when an acid loses a proton, it becomes a _________ base

polar

H20 is a ______ molecule, meaning it can act as an acid or a base

pH

the __ of a substance depends on the relative concentrations of hydronium, H30+, and hydroxide, OH-

ionisation

the equilibrium expression for the ______ of water is: Kw = [H30+][OH-], where Kw = 1.00 × 10^-14mol/L

7

at pH __, [H30+] and [OH-] are both 1.00 × 10^-7mol/L

endothermic, absorb

the forwards reaction of the ionisation of water is _______, as Kw increases with an increase in temperature, to _____ the added heat energy.

H30+

[_____] = Kw / [OH-]

hydrogen

pH stands for potential ________

logarithmic

pH is a ________ scale, increasing by powers of 10

pH

____ can be calculated using the concentration of hydronium, or H30+, ions in solution: pH = -log[H30+]

H30+

the formula for calculating pH rearranges to become: [_____] = 10^-pH

strength

the ______ of an acid or base depends on its ability to ionise / dissociate

completely

a strong acid _______ ionises in water (→)

partially

a weak acid _______ ionises in water (⇋)

ionising

does ionising or dissociating require water as a reactant, to form new charged species?

ions

dissociation is the process by which a compound separates into its individual charged _____

completely

a strong base _______ dissociates in water (→)

partially

a weak base _______ ionises in water (⇋)

neutral

if a salt dissolves in water, and neither of the dissociated ions react with water, the resulting solution is _______

hydrolysis

what is the name of the process by which a salt dissolves in water, and one of the dissociated ions further reacts with water?

strong

are these acids strong or weak?

• HCl

• HNO3

• H2SO4

• H2CO3

• H3PO4

• HBr

weak

are these acids strong or weak?

• -COOH

• HF

• conjugates of weak bases

strong

are these bases strong or weak?

• metal hydroxides, -OH

• metal oxides, -O

weak

are these bases strong or weak?

• NH3 (ammonia)

• -NH2 (amines)

• conjugates of weak acids

conjugate, weak

only a c________ or w_____ acid or base ion will further dissociate in water during hydrolysis

higher

a strong acid produces a ______ (higher/lower) [H30+] than a weak acid of the same concentration

stronger

are stronger or weaker acids more reactive?

more, volume, higher

stronger acids produce _____ H30+ in the same ______, meaning a greater number of effective collisions and ______ rate of reaction

concentration

electrical conductivity depends on the ________ of ions in solution

mobile, ions

electrical conductivity requires ______ charged particles → in an ionic solution, these are _____

more, same, bettter

a strong acid produces _____ ions in solution than a weak acid of the _____ concentration, so is a _______ conductor

lower

a strong acid will produce a higher [H30+] than a weak acid of the same concentration, resulting in a ______ (lower/higher) pH