Experimental determination of structure

Question 1

Empirical formula definition

Answer 1

The simplest ratio of elements in the compound.

Question 2

Empirical formula mass of elements present

Answer 2

Divide mass of elements by RAM
Divide by the lowest number
Find ratio and the empirical formula.

Question 3

Empirical formula percentage by mass

Answer 3

Divide percentage by elements RAM
divide by lowest number
Find ratio and empirical formula.

Question 4

Empirical formula combustion products

Answer 4

Divide compounds by RAM
multiply by elements RAM
Divide by lowest number
Find empirical formula and ratio

Question 5

What can empirical formula be found from

Answer 5

Percentage by mass
Mass of elements present
Masses of combustion products

Question 6

Mass spectrometry uses

Answer 6

To find the accurate molar mass and structural features of a product

Question 7

Mass spectrometry procedure

Answer 7

A sample of the compound is bombarded with electrons
Removing electrons from the sample and producing a positively charged molecule.
The molecule breaks into smaller ion fragments.
A mass spectrum is them plotted using mass charge ratio and percentage abundance.

Question 8

Parent ion

Answer 8

The largest positively charged ion in a mass spectrometry

Question 8

Mass spectrometry definition

Answer 8

Where electrons bombard a sample to produce positively charged ions, allowing the mass to charge ratio and abundance to be determined.

Question 9

Infrared spectroscopy procedure

Answer 9

Infrared radiation will be passed through a sample.
A detector will measure the infrared radiation which is transmitted through the sample and determine the absorbance of the sample.

Question 10

Units for wave numbers

Answer 10

cm-1

Question 11

Wave numbers formula

Answer 11

1/ wavelength

Question 11

Where are wave-numbers found

Answer 11

P15 of the data booklet

Question 12

How does infrared spectroscopy work

Answer 12

Infrared radiation is directed at the sample
The infrared radiation will be absorbed causing the bonds within the molecule to bend and vibrate.
Meaning different wavelengths of infrared radiation are absorbed by different functional groups.

Question 13

Rule of infrared spectroscopy

Answer 13

Different wavelengths of light are absorbed by different functional groups.

Question 14

NMR procedure

Answer 14

Radio frequency waves are directed at a sample of a compound.
This causes the nuclei of the atoms to align with the field or against the field.
When radio frequency waves are absorbed the nuclei aligned with field (low energy) will flip to the high energy alignment.
When the high energy alignment nuclei relax back to the low energy alignment radio frequency is emitted producing a spectrum of lines.
This is the chemical shift of the spectrum.

Question 15

Chemical shift (NMR)

Answer 15

The spectrum of lines produced by the high energy alignment of the nuclei emitting radio waves.

Question 16

What is chemical shift affected by

Answer 16

the type hydrogen environments.

Question 17

What is the standard relative substance in NMR

Answer 17

tetramethylsilane
(Silicon with methyl groups around it).

Question 17

Chemical shift units

Answer 17

ppm - parts per million
Not the same as x10-6

Question 17

Information on high resolution NMR

Answer 17

chemical shift of environments
Number of hydrogen environments
Number of hydrogen atoms in each environment
Number of hydrogen atoms on adjacent carbon atoms.

Question 18

Information on low resolution NMR

Answer 18

Number of hydrogen environments
Number of hydrogen atoms in each environment
chemical shift of environment

Question 19

Number of different hydrogen environments

Answer 19

The number of different hydrogens in different positions on the molecule

Question 20

How do you find the ratio of hydrogen atoms in each environment

Answer 20

The area under the curve is the ratio of hydrogen atoms in each environment.

Question 21

Rule for hydrogen atoms on adjacent carbons

Answer 21

N+1 rule

Question 22

Singlet

Answer 22

0 adjacent hydrogens

Question 23

Doublet

Answer 23

1 adjacent hydrogens

Question 24

Triplet

Answer 24

2 adjacent hydrogens

Question 25

Quartet

Answer 25

3 adjacent hydrogens

Question 26

Drugs definition

Answer 26

Substances which alter biochemical processes in the body.

Question 27

How do drugs work

Answer 27

They bind to specific proteins

Question 28

Proteins that drugs bind to

Answer 28

Receptors and enzymes

Question 29

Agonists

Answer 29

Drugs which bind to receptors and mimic the action of the body’s natural active compounds.

Question 30

Antagonist

Answer 30

Drugs which bind to the receptors and block the action of the body’s natural active compounds.

Question 31

Inhibitors

Answer 31

Drugs which bind to the enzymes active site and prevent a substrate from binding to the active site, preventing the reaction normally catalysed.

Question 32

How do drugs bind to receptors

Answer 32

Van der waals and ionic bonding

Question 33

NMR low resolution production

Answer 33

1. X axis is chemical shift and Y axis is intensity.
2. The number of lines is the number of hydrogen environments.
   The intensity shows the ration of hydrogens in the different hydrogen environments