Trends across Period 3
D-Block Elements
Standard Enthalpy Changes
Born-Haber Cycle
Entropy/Spontaneity
100
In terms of acid/base theory, what is a ligand and why?
It is a lewis base, since it donates a pair of electrons to the host proton.
100
Name two standard conditions implied in "Standard Enthalpy" :
Either 298 K (25 C), 101.3 Kpa
100
Is Lattice Enthalpy exothermic or endothermic? Why?
Exothermic. It is the formation of bonds.
100
If I punch John Paul, and his teeth scatter everywhere, is the change in Entropy positive or negative?
Positive. More disorder.
200
What makes a bigger impact on ionization energy: Distance from Nucleus (energy level) or No. of Protons?
Distance from Nucleus.
200
Name 3 characteristics of a D-Block element.
Variable oxidation states Coordinated ligand Complex ions Coloured compounds Magnetic properties Catalytic properties
200
What is this symbol: θ
It implies that the value given refers to standard conditions of Temperature and Pressure.
200
Define Lattice Enthalpy:
The enthalpy of creating 1 mol of a crystalline solid from its gaseous elements.
200
What does spontaneous reaction mean?
It means the reaction will proceed naturally; it will start occurring without external forces triggering it.
300
Why does melting point increase massively for Silicon?
Silicon has a giant network covalent structure.
300
How many H2O ligands would attach on to an Fe3+ ion, and what would be the net charge of the complex ion?
6; net charge of 3+. H20 is a neutral ligand.
300
What is the definition of ∆Hf, the standard enthalpy change of formation?
The enthalpy change when 1 mol of a substance is created from its constituent elements in their normal states under Standard Temp./Pressure.
300
What are two factors that influence lattice enthalpy?
Size of the ion; charge on the ions. higher charge density = higher lattice enthalpy.
300
State the equation for Gibb's Free Energy, and it's relation to spontaneity.
DeltaG = DeltaH -T*DeltaS
400
What happens when you add Cl2 to water?
dissociates into HOCl and HCl
400
Which of the following can be used as catalysts: Iron Vanadium Manganese Nickel
All of them.
400
What is the ∆Hf of Chlorine gas?
Zero; it is an element, and thus does not have CONSTITUENT elements.
400
What is the enthalpy of atomization?
The energy required to turn a solid into a gas. [break intermolecular bonds]
400
The reaction of Diamond with Oxygen is a spontaneous process, yet Diamond can go for long times without breaking down in open air. Explain.
Spontaneity makes no mention of kinetics; the rate of the reaction is very slow. This is because the activation energy of the reaction is so high that very few particles succeed in reacting.
500
Why do certain oxides have such low boiling points (as in 24 compared with 2000)? Hint: Bonding.
Covalent nature, as opposed to Ionic.
500
What gives rise to the energy differences within the d-block orbitals?
When regions of electron density are aimed at ligands, these constitute high energy states, and when regions of electron density are aimed away from ligands, it constitutes relatively low energy states. This is crystal field theory.
500
Why are Standard Enthalpies of combustion sometimes more accurate than average bond enthalpies in calculating enthalpy change? (1 reason) Either: 1. Products or reactants are in a state different to the truth since all elements in average bond enthalpy values are in gaseous state. 2. The enthalpy of breaking two of the same bonds is not always "twice" the enthalpy of breaking one of that bond. Example: breaking two C=O bonds is not the same as 2*(1 C=O bond).
Either: 1. Products or reactants are in a state different to the truth since all elements in average bond enthalpy values are in gaseous state. 2. The enthalpy of breaking two of the same bonds is not always "twice" the enthalpy of breaking one of that bond. Example: breaking two C=O bonds is not the same as 2*(1 C=O bond).
500
In the Born-Haber Cycle, the equation: Cl2 (g) ---> 2Cl (g) is re-expressed as : [1/2]Cl2 (g) ---> Cl (g). Why?
Because Lattice Enthalpies constitute formation of a solid from ONE MOL of the constituents.
500
What variable in the Gibb's Free Energy equation is a problem? (Leads to inaccuracy) and Why?
Temperature. Values of Entropy are ASSUMED to be constant at different temperatures, but this is not strictly true.
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