paper 1 mistakes

Question 1

% uncertainty formula

Answer 1

uncertainty/ measured value x100 xnumber of measuremnts

Question 2

what is a salt bridge soaked in

Answer 2

filter paper saturated with potassium nitrate KNO3

Question 3

aq copper (ii) ions with excess NH3

Answer 3

[Cu(H2O)6] 2+ + 4NH3 > [Cu(NH3)4(H20)2] 2+

Question 4

carbonate ion and charge

Answer 4

CO3 2-

Question 5

partial pressure=

Answer 5

total pressure x mole fraction

Question 6

mole fraction of A =

Answer 6

mols of A/ total number of mols of gas

Question 7

is the bond entlaphy of C-H exo or endo

Answer 7

endo

Question 8

is the second electron affinity for oxygen exo or endo

Answer 8

endo

Question 9

is the standard enthalpy change of formation of magnesium endo or exo

Answer 9

exo

Question 10

enthalpy of hydration definition

Answer 10

enthalpy change when 1 mole of gaseous ions forms 1 mole aq ions STP

Question 11

how do the enthalpy changes of hydration of F- and Cl- differ

Answer 11

F- smaller than Cl-
more exothermic enthalpy change of hydration
F is smaller, greater attraction to water

Question 12

average bond enthalpy

Answer 12

energy required to break 1 mole of bonds in gaseous molecules

Question 13

if temp is lowered and forward reaction is favoured, forward reaction is,

Answer 13

exo

Question 14

% dissociation =

Answer 14

(H+/HA) X 100

Question 15

what re lattice enthalpies always

Answer 15

exothermic

Question 16

what does the magnitude of lattice enthalpy indicate

Answer 16

ionic bond strength ( more exothermic= stronger ionic bond)

Question 17

can lattice enthalpies be measured directly

Answer 17

no (gaseous ion)

Question 18

downwards arrow on bon harbour cycle

Answer 18

exo

Question 19

upwards arrow on born harbur cycle

Answer 19

endo

Question 20

two factors that affect magnitude of LE

Answer 20

ionic radius
ionic charge
(charge density)

Question 21

how does ionic radius affect enthalpy change of hydration

Answer 21

becomes more exothermic with decreasing ionic radiu
(smaller ions, greater charge density, stronger ion-dipole attractions between water and ions, more energy released when they are hydrated

Question 22

how does ionic charge affect enthalpy of hydration

Answer 22

larger ionic charge, more exothermic
( greater charge density, stronger ion-dipole attractions, between water molecules and ions therefore more energy released when they are hydrated)

Question 23

what structure are the halogens
what does this mean

Answer 23

simple covalent
weak L forces between molecules

Question 24

H2O + Cl2

Answer 24

> HCl + HClO (Chloric acid )

Question 25

disadvantage of chlorinated of water

Answer 25

chlorine reacts with organic compounds in water to form halogenated organic molecules- carcinogenic

Question 26

Cl2 + 2NaOH

Answer 26

> NaClO + NaCl + H2O

Question 27

what is sodium chlorate (i)

Answer 27

bleach

Question 28

what must NaOH be to produced bleach

Answer 28

cold, aq

Question 29

if NaOH is hot and conc

Answer 29

3Cl2+ 6NaOH> 5NaCl + NaClO3 + 3H2O

Question 30

trend in oxidising power down group 7

Answer 30

decreases

Question 31

reactivity of halogens down group and why

Answer 31

decreases AR increases shielding increases less nuclear attraction to attract electron

Question 32

group 2 metal + water

Answer 32

M + 2H2O > M(OH)2 + H2

Question 33

what are metal hydroxides and trend

Answer 33

alkalis solubility of metal increases down group pH of alkali solution increases down group

Question 34

reactivity of group 2

Answer 34

increases down group AR increases shielding increases attraction between nucleus and outer electrons decrease outer e lost more easily

Question 35

metal oxide/ hydroxide + acid

Answer 35

> salt + water

Question 36

metal oxide + water

Answer 36

> metal hydroxide

Question 37

what do metal hydroxides do in water

Answer 37

dissolve / dissociate because they are alkalis (soluble bases )

Question 38

heat and group 2 carbonate

Answer 38

thermal decomposition CaCO3> CaO + CO2

Question 39

trend of thermal decomposition

Answer 39

more difficult to decompose down group

Question 40

how many mg is 0.301 g

Answer 40

301

Question 41

explain why a reaction has a negative enthalpy change

Answer 41

more energy released to make bonds than energy required to break the bonds