2018 and 2019 past paper

Question 1

why are solids not included in Kc?

Answer 1

• the concentration of solids remain constant

Question 1

which is more soluble, group 1 or group 2 hydroxides?

Answer 1

group 1

Question 2

what are the assumptions you make in Ka calculations?

Answer 2

• the initial concentration of HA is the same as the final concentration (there is negligable dissociation)
• the concentration of A- and H+ is equal
• the dissociation of H+ from water is negligable

Question 3

what is the equasion linking gibbs free energy and the rate constant?

Answer 3

G= -RT Ln(K)

Question 4

what is the equasion linking gibbs free energy and E cell?

Answer 4

G= -nFEcell
- n= the number of transfered electrons

Question 5

what is formed when group 1 nitrates decompose?

Answer 5

MNO2 + O2

Question 6

what is formed when group 2 nitrates decompose?

Answer 6

MO+ NO2 + O2

Question 7

what ion turns a damp litmus paper blue?

Answer 7

ammonium

Question 8

what gas turns a damp litmus paper white?

Answer 8

CO2

Question 9

what does a group 2 carbonate decompose to?

Answer 9

MO + CO2

Question 10

explain how flame colours are produced.

Answer 10

• promotion of an electron
• electron drops back down as it is unstable at the higher energy level
• resuls in energy being released

Question 11

what is the similarity between flame tests and complex colour formation?

Answer 11

both depend on the differences in energy level

Question 12

what is the anode in an alkaline hydrogen fuel cell?

Answer 12

O2 + H2O+ 2e- = 4OH-

Question 13

what is the cathode in an alkaline hydrogen fuel cell?

Answer 13

H2 + 2OH- = 2H2O

Question 14

what is the anode in an acidic hydrogen fuel cell?

Answer 14

O2 + 2H+ + 4e- = 2H2O

Question 15

what is the cathode in an acidic hydrogen fuel cell?

Answer 15

H2 = 2H+ + 2e-

Question 16

what is the overall reaction for a hydrogen fuel cell?

Answer 16

O2 + 2H2 = 2H20