paper 1 2024

Question 1

soluion Q turns brown when bromine added.
identify halide ion present

Answer 1

iodide

Question 2

give the ionic equation that occurs when bromine water is added to Q

Answer 2

Br2+2I- >I2 +2Br-

Question 3

explain in terms of oxidising ability, why observations from this reaction do not allow the student to identify the halide present in P and R

Answer 3

bromine water is not a strong enough oxidising agent to displace Cl2 and Br2 as they are a more reactive halogen

Question 4

describe the chemical test of identifying halides using silver nitrate

Answer 4

dissolve P and R in dilute nitric acid and add 2cm3 of silver nitrate. Cl- forms a white ppt. Br- forms a cream ppt (I- is yellow ppt)

Question 5

explain why the third ionisation energy of berylium is much higher than the second

Answer 5

outer electron is being removed from an orbital that is lower in energy,1s instead of 2s, so requires more energy due to less shielding between outer e- and positive nucleus

Question 6

magnesium reacts slowly with cold water but rapidly with steam.
give one similarity and one difference

Answer 6

similarity: gas/produces H2
difference: steam produces MgO water produces Mg(OH)2

Question 7

reaction of calcium with water is a redox reaction. explain why

Answer 7

Calcium (0) is being is bing oxidised into Ca(OH)2 (+2).
hydrogen (+1) is eing reduced (0)

Question 8

define electronegativity

Answer 8

ability for an atom to attract a pair of electrons to itself in a covalent bond

Question 9

explain why C-Cl bond is polar

Answer 9

theres a difference in electronegativity so Cl becomes delta minus and C becomes delta positive

Question 10

CCl4 is not a polar molecule explain why

Answer 10

its a symmetrical molecule so dipoles cancel out

Question 11

explain how VDW arise

Answer 11

electron clouds repel causing one molecule to have a temporary dipole. this induces a dipole in another molecule. two temporary dipoles are attracted to each other which causes VDW

Question 12

write full electron configuration for Br

Answer 12

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5

Question 13

give first ionisation energy for bromine

Answer 13

Br2 (g) > Br2+(g) + e-

Question 14

define enthalpy of formation

Answer 14

enthalpy change when one mole of a substance is formed from its constituent elements in standard states under standard conditions