Module 5 Flashcards
Define stereoisomerism
When molecules have the same structural formula but with a different arrangement in space
What limitations are there to predicting feasibility?
Rate may be very slow
Activation energy may be very high
In a (hydrogen) fuel cell, fuel and oxygen move into the cell and water moves out, what are the differences between an alkali hydrogen fuel cell and an acid one?
In an alkali fuel cell, the water leaves on the same end that the hydrogen comes in (the anode) and hydroxide ions diffuse across to it from the cathode. In an acid one, the water leaves at the cathode (where the oxygen comes in) and hydrogen ions diffuse across to it.
Define enthalpy change of hydration
The enthalpy change that accompanies the dissolving of gaseous ions into water to form one mole of aqueous ions
Define first electron affinity
The enthalpy change when one mole of electrons is added to one mole of atoms forming one mole of gaseous (1-) ions
Why might a weak acid + strong base pH titration curve look different to others?
Becuase, when the base is initially added a buffer, will be set up, trying to oppose the change in pH and therefore putting a ‘kink’ in the curve
In an operating cell, what happens to the electrode with the more reactive metal (negative electrode)?
It loses electrons (is oxidised)
How would a... - 0 order reaction - 1 order reaction - 2 order reaction ...look on a concentration-time graph?
- 0th would be a descending straight line
- 1st would be a downwards curve, with a constant half-life
- 2nd would be a steeper downwards curve, with a changing half-life
What is the Gibbs’ free energy equation?
ΔG = ΔH - TΔS (for T in Kelvin)
What happens when ammonia is added to pale blue hexa-aqua-copper ions?
First a pale blue precipitate forms but then it dissolves again in excess ammonia to form a dark blue solution of [Cu(NH3)4(H20)2]
What would be the sign of ΔS in a reaction where the liquid reactants become gaseous products?
positive (+) since the system is becoming more disordered
What are the differences between primary and secondary cells?
Primary cells aren’t rechargeable and are alkaline based, secondary cells are rechargeable and are acid based
Define enthalpy change of solution
The enthalpy change that takes place when one mole of a solute dissolves in a solvent
Which compounds form tetrahedral complex ions?
Cobalt and Copper
How would a... - 0 order reaction - 1 order reaction - 2 order reaction ...look on a rate-concentration graph, and how could you calculate k from it?
- 0th would be a horizontal straight line where k=r
- 1st would be a diagonal straight line (line y=x) where k=gradient
- 2nd would be a steep upwards curve where k would equal the gradient of the rate against concentration squared
What is a ligand?
Molecule or ion that can donate a pair of electrons to a central metal ion to form a coordinate bond
Which factors affect lattice enthalpy, and how?
As ionic radius increases lattice enthalpy becomes less negative
As ionic charge increases lattice enthalpy becomes more negative
What is a complex ion’s coordination number?
The number of coordinate bonds attached to the central metal ion
What happens when chloride ions are added to pale blue hexa-aqua-copper ions?
A yellow solution forms of [CuCl4] notice how it is only 4, to replace 6 H20 molecules - this is because chlorine is ‘bigger’!
How can you calculate the rate constant, k, from a 1st order concentration-time graph?
ln(2) divided by (half-life)
