C1 2019

Question 1

The enthalpy of lattice formation for caesium iodide in table 1 is a value obtained by experiment (-585kJ)
The value obtained by calculation using the perfect ionic model is -582kJ

Answer 1

Perfectly ionic

Question 2

Equation for electrospray ionisation for P

Answer 2

P + H+ -> PH+

Question 3

State the meaning of the term periodicity

Answer 3

Repeating pattern/trend across a periodic table

Question 4

Name the property of arsenic oxide that describes its ability to react in these two ways

Answer 4

Amphoteric

Question 5

Give formula of L and equation for reaction 2
[Fe(H2O)6]3+ + HCl -> L

Answer 5

L = [FeCl4]-
[Fe(H2O)6]3+ + 4Cl- -> [FeCl4]- + 6H2O

Question 6

Suggest a reagent for reaction 3
[Fe(H2O)6]3+ -> [Fe(H2O)6]2+

Answer 6

Zn

Question 7

Solid sodium chloride reacts with concentrated sulfuric acid
Give an equation for this and state role of sulfuric acid

Answer 7

NaCl + H2SO4 -> NaHSO4 + HCl
Proton donor

Question 8

Fumes of sulfur dioxide are formed when sodium bromide reacts with conc sulfuric acid
Give an equation
Observations
Role of H2SO4

Answer 8

2NaBr + 2H2SO4 -> Na2SO4 + SO2 + Br2 + 2H2O
Brown gas
Oxidising agent

Question 9

Ionic equation to form Ag2CO3

Answer 9

2Ag+ + CO32- -> Ag2CO3

Question 10

AgBr -> Ag(NH3)4+

Answer 10

AgBr + 2NH3 -> Ag(NH3)2+ + Br

Question 11

Suggest two ways that the student could reduce the percentage uncertainty in the measurement of the volume of sodium thiosulfate solution, using the same apparatus as this experiment

Answer 11

Use lower conc of Na2S2O3
Use more of alloy