past paper 2022

Question 1

when answering a question on how easily an electron can be removed what do you mention?

Answer 1

• distance of electron from the nucleus
• nuclear charge
• shielding from inner shells/ subshells

Question 2

which subshells is filled and emptied first 4s or 3d?

Answer 2

4s is filled and emptied first.
- when 4s is empty it has a lower energy
- when 4s is full it has a higher energy

Question 3

why is ice less dense than water?

Answer 3

• in ice water molecules form a rigid lattice meaning molecules are further appart
• in liquid water, molecules are closer as molecules fill the spaces

Question 4

what are the assumptions of enthalpy?

Answer 4

• constant temperature and pressure

Question 5

what are the neccessary requirements for a buffer solution?

Answer 5

• large resovoir of an acid and its conjugate base
• meaning that small additions will allow the ratio of acid and conjugate base to remain relitively constant

Question 6

why can transition metals have variable oxidation states?

Answer 6

there is only a gradual increase in successive ionisation energies

Question 7

what are the steps to an ionic equasion?

Answer 7

• balance oxygens
• balance hydrogens
• balance charges

Question 8

how does a buffer solution work?

Answer 8

• large resovoir of acid and conjugate base
• H+ reacts with base to form acid
• OH- reacts with acid to form water and base
• the ratio of acid and conjugate base remains essentially constant

Question 9

what are the colours of a universal indicator?

Answer 9

• alkaline is purple/ blue
• acid is red/ organe
• nuetral is green

Question 10

why does the pink phenophaline colour fade?

Answer 10

• CO2 absorbed into the water leading to the water causing carbonic acid to form

OR

• the equillibrium shifts left as the acid is neutralised meaning its concentration falls

Question 11

explain how the buffer solution in blood works.

Answer 11

• CO2 dissolves in blood to form carbonic acid
• equillibrium shifts right to form more H+ and HCO3-
• the large resovoir of conjugate base combine with H+ to control the PH

Question 12

what is starch a test for and what is the colour change?

Answer 12

• a test for I2
• starch reacts with iodine
• a positive test is a colour change from yellow to blue/ black

Question 13

what does a zero order curve look like for time against concentration?

Answer 13

linear slope

Question 14

what does a first order curve look like for rate against time?

Answer 14

linear- positive relationship between concentration and rate

Question 15

what does a second order curve look like for rate against time?

Answer 15

upward sloping curve

Question 16

what is an important factor when considering what hetrogenous catalyst to use?

Answer 16

strength of adsorbtion
- if adsorbtion is too weak, the reactants will struggle to adsorb
- if adsorbtion is too strong, products will struggle to desorb

Question 17

what is the charge of any chlorate ion?

Answer 17

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