Download E2 and E11 Acid Deposition Past Paper Questions

Chemistry 12 HL
Option E
E2 and E11 Acid Deposition
Past Paper Questions - ANSWERS
May 2008 TZ2
D2.
(a) H2SO3 / sulfurous acid / H2SO4 / sulfuric acid
(b) S + O2  SO2 / SO2 + ½ O2  SO3
SO2 + H2O  H2SO3 / SO3 + H2O  H2SO4
(c) any two of: alkaline scrubbing;
remove sulfur from coal;
using limestone-based fluidized beds;
November 2008
D2.
(a) carbonic acid is a weak acid / only partially dissociated / low solubility;
the pH must be lower than 5.6 for acid rain / OWTTE;
(b) H2SO3 / H2SO4 and burning coal / sulfur-containing fuels / smelting of sulfide ores;
HNO2 / HNO3 and reaction (between N2 and O2) in internal combustion/jet engine
(c) CO3
2–
+
+ 2H  CO2 + H2O / H2CO3
(d) plant growth is reduced;
2+
2+ +
nutrients (Ca Mg K ) are leached from the soil / OWTTE;
2+
reduction in Mg reduces chlorophyll (so affects photosynthesis);
leached from rocks damages roots (by preventing them from taking up water); [2 max]
Specimen Paper
E3
a)
b)
it contains dissolved carbon dioxide / carbonic acid;
+
1CO2(g) + H2O(l)  H2CO3(aq) OR CO2(g) + H2O(l)  2 H (aq) + HCO3 (aq)
coal contains sulfur (which burns to form SO2)
S(s) + O2(g)  SO2(g)
SO2(g) + H2O(l)  H2SO3(aq)
OR …
2SO2(g) + O2(g)  2SO3(g)
SO3(g) + H2O(l)  H2SO4 (aq )
Chemistry 12 HL
Option E
State symbols are NOT required for these equations.
c)
(i)
Any one of the following:
2+
2+
+
it leaches nutrients like Ca / Mg / K from the soil
2+
it lowers the concentration of Mg and thus reduces the amount of chlorophyll
/photosynthesis
it increase the concentration of Al
(ii)
3+
(from rocks) which damages roots
CaCO3 (s) + H2SO4 (aq)  CaSO4 (aq) + CO2 (g) + H2O (l)
OR:
+
CaCO3 (s) + 2 H (aq)  Ca
2+
(aq) + CO2 (g) + H2O (l)
(ionic form of the equation above)
State symbols not required.
d)
CaO is a basic oxide and neutralizes acids
+
CaO(s) + 2H (aq)  Ca
2+
(aq) + H2O(l)
OR CaO + H2SO4  CaSO4 + H2O
May 2009 TZ2
E3
(1) neutralization reaction produces an ammonium salt:
2 NH3 + H2SO4  (NH4)2SO4
OR 2 NH3 + H2SO3  (NH4)2SO3
OR 2 NH3 + HNO3  NH4NO3
+
(2) nitrification reaction converts ammonium (NH4 ) and oxygen gas to form an acid and water:
+
+
–
NH4 + 2 O2  2 H + NO3 + H2O
Plus any THREE of the following:
adding NH3 to soil makes it less acidic
salt particles formed are acidic/have pH lower than 7
salts are washed into the ground;
in earth they can be nitrified;
nitrification acidifies the soil
Chemistry 12 HL
Option E
May 2012 TZ1
E2
One major environmental problem that affects many countries is acid rain.
(a)
dissolved carbon dioxide / CO2(g) + H2O(l)  H2CO3(aq);
+
–
+
–
H2CO3(aq)  H (aq) + HCO3 (aq) / CO2(g) + H2O(l)  H (aq) + HCO3 (aq)
(b)
(i) internal combustion / high temperature engines;
N2(g) + O2(g)  2NO(g)
(ii) catalytic converters / exhaust recirculators;
2NO(g) + 2CO(g)  N2(g) + 2CO2(g)
(iii) nitric acid / HNO3 / nitrous acid / HNO2
May 2013 TZ1
E3
(a) leaches/removes nutrients from soil; Accept specific ions for nutrients.
plant leaves are damaged; Do not allow just damages plants.
increasing aluminium concentration in the soil;
root damage;
limestone buildings/rocks/statues react with acid;
lakes become acidic killing fish;
toxic metal ions leached/enter into water supplies; [3 max]
(b) redox / oxidation-reduction; Do not accept reduction or oxidation on their own.
2NO + 2CO  N2 + 2CO2
(c)
H2O + O3  2HO• + O2 / H2O + O•  2HO• ;
HO• + NO  HNO2 ;
2 HNO2 + O2  2 HNO3 ;
OR
2NO + O2  2NO2 ;
HO• + NO2  HNO3
Chemistry 12 HL
Option E
May 2013 TZ2
E1
(a) (i) acidic/acid-forming pollutants deposited on the Earth’s surface/leave the
atmosphere / rain/precipitation/deposition that is acidic/with a pH < 5.6; [1]
(ii) SO2/SO3/NO2 ; Allow names of oxides. Do not allow NOx.
SO2 + H2O  H2SO3 / SO3 + H2O  H2SO4 / 2SO2 + O2 + 2H2O  2H2SO4 /
2NO2 + H2O  HNO2 + HNO3 / 4NO2 + O2 + 2H2O  4HNO3
(iii) addition of lime / Ca(OH)2 / limestone / CaCO3
(b) For SO2/SO3:
remove S from fossil fuels;
alkaline scrubbing;
(limestone-based) fluidized bed combustion;
flue gas desulfurization in coal-burning power stations;
use oxide ores rather than sulphide ores;
For NO2:
control of fuel/air ratio;
recirculation of exhaust fumes;
catalytic converter;
thermal exhaust reactor;
[2 max]