Paper 1- 2021 Flashcards
Born haber cycle: calcium chloride
-Can only change one thing per line.
Ca2+(g)+2e-+2Cl(g) Ca2+(g)+e-+Cl2(g) Ca2+(g)+2Cl-(g) Ca+(g)+e-+Cl2(g) Ca(g)+Cl2(g) Ca(s)+Cl2(g)
Cacl2(s)
Percentage abundance
47.8=(46X2x)+ (47X2x)+ 48(100-5x)+ 49x/100
-The one not include in ratio(2:2:1) do that abundance bracket 100-abundance of other isotopes.
Period 3 oxide that is insoluble in water
-Al2O3
-Al2O3+3H2SO4 –>Al2(SO4)3+3H2O
Affecting efficiency of catalyst
Increase surface area by using powdered Fe instead of solid Fe.
How Iron acts as a heterogeneous catalyst?
-Hydrogen and Nitrogen absorb onto surface/active site of the iron
-Bonds weaken /reaction takes place
-New bonds form between reactants held closely on surface of catalyst
-In turn weakens bonds between P and catalyst and P leaves(desorbs)
-Products desorbs from surface of iron
Why is reaction slow before catalyst added?
Two -ve ions repel therefore activation energy is too high
Fe2+ ions catalyse between perpxodisulfare and iodide ions
S2O82-+2Fe2+ —>2S2O42-+ 2Fe3+
2I-+2Fe2+ —>I2+ 2Fe3+
Why doesn’t Zn2+ catalyse reaction
Zn2+ is the only ion, can’t form variable oxidation states.
Fe3+ lower Ph than Fe2+
-Fe3+ has greater charge density than Fe2+ therefore greater polarising power.
-Fe3+ greater attraction to water molecule and O-H bond allowing it to release H+ ions more easily
-Fe3+ releases more H+ ions therefore lower Ph and more acidic.
Decreasing pressure for:
2SO2+O2 —>2SO3
Effect: decreases yield
Explain: to counteract decreases eq. shifts to LHS(more moles) to increase pressure.
Why does kw increase as temp increases
Dissociation of water= endothermic
Increasing temp shift eq. to RHS which increases no. of H+ ions which decrease Ph value.
Why can all three indicators be used
Ph ranges within entire steep part of curve
Delta H and Delta S
P-R
Joules to KJ
1J=0.001KJ
E0=
R - L
+ve - -ve
Red - Ox
Ox. Agent-Red. Agents
(+ve on L) (-ve on R)
Why will [Co(H2O)6] 3+ undergo redox with Fe(H2O)6 2+?
E0 of Co3+> Fe3+
Why do do Co complex ions have different electrode potentials?
Different ligands
Why is aq. electrolyte not used for Li cell?
E0 for Li+ more -ve than water
Why is EMF value different to previous answer?
Non- standard conditions used
-ve LiCoO2 electrode
Li+(aq)+ e- —>Li(s)
+ve electrode for LiCoO2
Li+ +CoO2 +e- —>LiCoO2
Why can enthalpy change not be determined directly by calorimeter for hydration reaction?
Not possible to prevent some dissolving
Why is enthalpy based on perfect ionic model smaller than calculated value?
Value calculated displays covalent character
Bond ms holding lattice together are stronger
Why enthalpy of hydration less exothermic down group?
Enthalpy of hydration becomes less exothermic as:
Smaller ion
Down group ionic radius increases which decreases attraction between ion and O-ve of water.
