Incorrect Answers - Materials

Question 1

What factors can diminish the battery capacity over time at high C-rates?

Answer 1

Moisture (water) and oxygen impurities are introduced typically during the battery fabrication process

Cathode degradation (high-energy Coulombic repulsive interactions have a destabilising effect)

This effect is more apparent when the C-rate begins to exceed the kinetics if these electrochemical processes

Question 2

How can we calculate the theoretical capacity?

Answer 2

Discharge capacity / capacity retention

Question 3

How can we quantify how much gelator has been assembled?

Answer 3

By using an internal standard in the NMR

Question 4

What is the equation for order?

Answer 4

S = (1/2) x <3cos² theta - 1>

where theta is the angle of the long axis with respect to the director and the triangular brackets indicate that this is averaged out over a large number of molecules

Question 5

How does the anisotropy of a system change when the order parameter increases?

Answer 5

The anisotropy increases due to fewer molecules deviating from the director

This increases the values for dielectric anisotropy and birefringence

Question 6

How do we increase the carbon chain length by 1 for a chiral nematic?

Answer 6

1) HBr, sulfuric acid (brominate)

2) Mg, carbon dioxide, HCl (Grignard to form carboxylic acid)

3) Lithium Aluminium Hydride, then HCl (reduction to alcohol)

4) HBr, sulfuric acid (brominate)

Question 7

How do we increase the carbon chain length by 2 for a chiral nematic?

Answer 7

1) TsCl, Py (add tosylate leaving group)

2) NaOEt, DEM (enolate chemistry)

3) KOH, heat, HCl (single carboxylic acid formed)

4) Lithium Aluminium Hydride, then HCl (reduction to alcohol)

5) HBr, sulfuric acid (brominate)