Topic 7

Question 1

What is the molecular ion peak, where would you find it?

Answer 1

The species formed from the molecule by the loss of one electron, it has the greatest m/z value and so is the tallest peak

Question 2

What is the M+1peak

Answer 2

A smaller peak occurring directly to the right, it occurs due to the naturally occurring isotope of C13 instead of C12

Question 3

What causes the other peaks on a mass spectrometry

Answer 3

Fragments of the organic compound

Question 4

What is a fragment

Answer 4

They occur when the molecular ion breaks into smaller pieces

Question 5

What is the test and result for the functional group of O-H alcohols

Answer 5

PCl5 causes white fumes

Question 6

Write the equation for the complete reaction between sodium and ethane -1,2-diol

Answer 6

CH2OHCH2OH + Na –>
CH2O(-)Na(+)CH2O(-)Na(+) + H2

Question 7

When creating a distillate, how would you change the apparatus to achieve the conditions needed for the oxidation of ethanol, ethanol requires a stronger oxidising conditions

Answer 7

• Remove thermometer
• Leave the top of the condenser open

Question 8

Why is PCl5 not a suitable reagent to be used to distinguish between ethane-1,2, diol and ethanedioic acid

Answer 8

as they both have OH they would both produce white fumes

Question 9

What is the reason why there is no molecular ion peak in the mass spectrum of 2-methylpropan-2-ol

Answer 9

The molecular ion is unstable

Question 10

Why may the data book value for the enthalpy change of combustion be different than our calculated one

Answer 10

The data book bond energies refer to gaseous state, water in combustion is a liquid at 298K