chemical reactivity

Question 1

what is a conjugate pair

Answer 1

base formed when an acid donates a proton (H+) and an acid formed when a base accepts a proton (H+)

Question 2

strong acids

Answer 2

HCl, H2SO4, HNO3

Question 3

weak acids

Answer 3

CH3COOH, NH4+, HF

Question 4

Strong bases

Answer 4

carbonates, hydroxides, metal oxides, hydrogen carbonates, NaOH, KOH

Question 5

weak bases

Answer 5

NH3

Question 6

amphiprotic

Answer 6

can accept or donate H+ (act as acid or base depending on the other substance)

Question 7

strong acid qualities

Answer 7

completely dissociates to form high conc. of H3O+
low ph as pH depends on conc. of H+ as H3O+
only forward reaction
high conduction of electricity due to lots of H3O+ ions
no strong acid left

Question 8

weak acid qualities

Answer 8

partially dissociates in water so only some H+ ions break away from molecule
lower pH than strong acid
conducts electricity but weakly as there are still H3O+ ions being produced
reversible reaction - dynamic equilibrium
most weak acid left

Question 9

strong base qualities

Answer 9

fully dissociate in water to produce lots of OH- ions and greater proportion of the reactant readily accepts proton
conducts electricity well due to large OH- being produced
one way forward reaction
High ph due to lots of OH- ions present therefore only a few H3O+ ions due to water self ionizing
no strong base left

Question 10

weak base

Answer 10

partially dissociate and smaller proportion of reactants convert to products by only some accepting protons
produces less OH- ions but still mainly OH- therefore pH is high but lower than strong bases
dynamic equilibrium
conducts electricity still but weaker due to less OH- charged particles freely moving
most weak base left

Question 11

acid + base —->

Answer 11

salt + water

Question 12

ionic salt reaction

Answer 12

split salt to the two different ions
then weak acid or base forms and react with water = dynamic equilibrium and the left over ion from salt becomes spectator
state the pH and why and whether it can conduct electricity
can conduct because although few H3O+ ions or OH- ions are being produced there is still a high conc of ions from the initial ionic salt split

Question 13

collision theory

Answer 13

particles must collide - and with correct orientation and with sufficient activation energy

Question 14

way of writing collision theory

Answer 14

state the change
how this affects collision theory
increase ROR or decrease

for temp - two things = kinetic energy and less or greater proportion
catalyst added = alternative pathway with less activation energy so greater proportion overcome activation energy barrier for successful collisions per second
conc = per unit volume
surface area = more or less particles exposed

Question 15

draw exo and endo graphs

Question 16

Kc =

Answer 16

[products]/[reactants]. only gas
if Kc greater than 1 = reaction favours products
Kc less than 1 = reaction favours reactants
Kc = 1 then neither reactants or products favoured as both are in equal ratio
Kc is equilibrium constant

Question 17

Q

Answer 17

any concentration of reactant and products at any time to compare with Kc and see if system is at equilibrium

Question 18

le chatellier

Answer 18

system will be at equilibrium unless a change is made, then the system will do the opposite of the change made to minimise this change and reestablish equilibrium

Question 19

write dynamic equilibrium

Answer 19

state change, how will equilibrium respond, what direction favoured and why (remember to explain this)

Question 20

colour

Answer 20

observation straight after change not compared to beginning

Question 21

increase pressure

Answer 21

only gases
more particles hitting sides of container to minimise this less moles direction favoured so pressure decreases as less particles hit container so product conc increases or decreases depending on this

Question 22

decrease pressure

Answer 22

less particles hitting container so more moles direction favoured so more hit container and increase pressure

Question 23

same moles

Answer 23

pressure doesn’t affect as there are equal mole ratio

Question 24

writing pressure

Answer 24

state change - how is this minimised - which direction - why - what does this produce more of

Question 25

endo

Answer 25

absorb heat
surrounding temp decreases
favour exo to increase heat

Question 26

exo

Answer 26

releases heat and surrounding temp increases so favour endo to decrease heat

Question 27

rH

Answer 27

forward reaction

Question 28

change in temp = change in Kc value

Answer 28

temperature affects K because changes in temperature shift the reaction toward a certain side. Think of temp. as a reactant or product in the reaction. If endothermic, it would look something like this:
Reactants + Temperature -> Products
If you increase the temperature, the reaction will shift toward the products in equilibrium, and hence Kc would be have to be changed.
because a certain direction is exo or endo to produce products and is in closed system so temp cant escape

Question 29

catalyst

Answer 29

increases the rate of forward and reverse reaction at the same time so equilibrium does not change but catalyst makes a system reach equilibrium faster

Question 30

formula for OH- conc

Answer 30

[OH-] = 10^-(14-pH)