Dr McKeever Lectures

Question 1

What are the two forms of energy?

Answer 1

Potential and kinetic

Question 2

What makes up a system?

Answer 2

The system itself, the boundary and it’s surroundings

Question 3

What are the three different types of systems?

Answer 3

Open system - Mass and heat (energy) can move freely in and out
Closed - Heat (energy) can move freely in and out, mass cannot
Isolated - mass and heat cannot exit or enter the system

Question 4

What’s the zeroth law of thermodynamics

Answer 4

If two systems are at equilibrium with a third, then the two systems are at equilibrium with each other

Question 5

What is the first law I of thermodynamics?

Answer 5

Energy can only be transformed from one to another

Question 6

What is the first law of thermodynamics equation ?

Answer 6

(Delta) U = Q - W

Change in internal energy =

heat added to system - work done by system

Question 7

In U = Q- W, if Q is positive what does this tell us?

Answer 7

Heat is being added to the system so the reaction is endothermic

Question 8

In U = Q - W , if Q is negative what does this tell us?

Answer 8

The system is losing heat and the process is exothermic

Question 9

What happens if the system is isovolumetric

Answer 9

U = Q

There is no work done by the system

Question 10

What happens if the system is isothermal?

Answer 10

Q = W
No change in internal energy

Question 11

What does absolute zero mean?

Answer 11

The temperature of -273C or 0K, where all vibration and atomic movements stop

Question 12

What is the equation for Gibbs free energy?

Answer 12

G = H - TS
KJ/mol = kJ/mol - K x J

Question 13

What does it mean if G is negative in Gibbs

Answer 13

The reaction goes in the forward direction and is spontaneous

Question 14

What does it mean if Gibbs is 0?

Answer 14

The reaction will be in equilibrium and can proceed either direction (products or reactants)

Question 15

What does it mean is G is positive in Gibbs?

Answer 15

The reaction will not proceed

Question 16

What is another equation used to find G?

Answer 16

G(products) - G(reactants)

Question 17

What factors effect the basic it’s of amines

Answer 17

Hybridisation - Sp2
Resonance stabilisation - lone pair shared with ring reduces basicity
Inductive stabilisation - alkyl groups donate electron density, more basic

Question 18

What is ortho, para and meta

Answer 18

Para is opposite the functional group
Ortho is beside the functional group
Meta is two away from the functional groupo

Question 19

What does Infrared spectroscopy measure?

Answer 19

The vibration of bonds, each bond has a different type of vibration

Question 20

What does Mass Spectrometry do?

Answer 20

Splits the molecule into fragments and measure the molecular weight of the fragments to give information to the structure and functional group

Question 21

Stronger bonds are more rigid so they vibrate faster

Question 22

Vibrational mode equation is 3n-6, where n=no. Of atoms

Question 23

Stronger bonds absorb higher frequencies. Triple>double>single

Question 24

OH broad around 3000, deep trough on IR graph

Question 25

OH in carboxylic acid has a longer, broad stretch as well as a C=O stretch

Question 26

Nitriles and Carbenes range around the 2200 area in IR

Question 27

Limitations of IR would be that it doesn’t tell you the actual structure just what’s present in the molecule

Question 28

Chromophores and Auxochromes are…

Answer 28

Chromophores - absorb specific wavelengths
Auxochromes - unable to absorb but cause a shift in wavelength absorption

Question 29

In NMR the magnet is used to…

Answer 29

Make the nuclei spin in a parallel fashion, either with or against the field

Question 30

Low field and high fields are area in an NMR graph, what does each represent?

Answer 30

Low field is where there is more deshielding of atoms and high field is where there is more shielding of atoms

Question 31

A chemical shift (in ppm) of a given proton is the same regardless of the operating field and frequency of the spectrometer being used

Answer 31

Chemical shift = Shift downfield from TMS (Hz)/spectrometer frequency (MHz)

Question 32

As electronegativity increases, there is more deshielding of the neighbouring molecule

Answer 32

As you add more electronegative groups to a compound it has a stronger deshielding effect

Question 33

Proton peaks are relative in NMR, if you know the number of protons in one peak you can work out the other peak by seeing if it is 2x or 3x it’s height

Question 34

2n+1 is the splitting pattern of hydrogens

Answer 34

In 1-dichloro-2chloro-ethane, the H on the dichloro is next to 2 H’s so using the equation above the splitting patter would be (2+2H+1=3) so the graph will show three splits