analysis

Question 1

what is analysis in chemistry

Answer 1

proving what we have

Question 2

what is a chemical test in analysis

Answer 2

reacting something with something else
e.g. react an alkene with bromine water and it changes from orange to colourless

Question 3

what are physical tests in analysis

Answer 3

melting points and boiling points tests

Question 4

what are the 3 ways to analyse substances

Answer 4

chemical, physical tests and spectroscopy

Question 5

what are the 2 types of spectroscopy’s and what are they used for

Answer 5

infrared - covalent bond movement
mass spectroscopy - breaking organic molecules into smaller pieces (fragments)

Question 6

how do mass spectrometers work

Answer 6

sample is vapourised in vaporiser
accelerated in ions beam
magnetic field changes their path and they are detected on the detector

Question 7

how is spectrometry used in the real world

Answer 7

police use it to find drugs looking for a single peak

Question 8

how is spectrometry used in organics

Answer 8

RFM of fragments of molecule will show peaks
helping being able to tell structural isomers apart

Question 9

what does the height of the peak mean in spectrometry

Answer 9

it doesn’t mean anything - just look where the peaks are

Question 10

are fragments negative or positive and how do you know this

Answer 10

positive
electrons bombard sample

Question 10

what is the name you assign the position at Mr

Answer 10

M+

Question 11

what do you do to peaks you cant assign

Answer 11

don’t worry - ignore them

Question 12

what direction do you work with the molecule when finding fragments

Answer 12

start with the whole molecule and work backwards - find breaks between C-C / C-N / C-O / O-H -

Question 13

where do you split fractions most often

Answer 13

functional groups

Question 14

describe the science behind infared

Answer 14

Bonds within molecules with dipoles absorb IR at certain frequencies leading to a spectrum.
Even if molecules do not have an overall dipole

Question 15

uses of infrared spectra

Answer 15

detectives use to identify paint

Question 15

how to determine if a compound is an aldehyde or a ketone

Answer 15

add potassium dichromate solution
aldehyde turns from orange to green

Question 16

what do inverted peaks on IR spectra mean

Answer 16

absorb radiation

Question 17

what does an OH on a carboxylic acid vs alcohol look like on IR spectra

Answer 17

carboxylic acid: sitting on top of the C-H absorption (300ish)
alcohol: sitting to left of C-H absorption - less broad

Question 17

what does C=O bond look like on IR spectra

Answer 17

1750ish

Question 18

what does data booklet mean by broad

Answer 18

bottom isnt pointy