chem sac 5

how to test for molar mass

• state of matter

• result: IMB

how to test for solubility

• add h2o

• result based on polarity

how to test for pH

• add indicator

• result based on acid/base (colour)

what is bromine/iodine test used for

• finding degree of unsaturation

• determine if there is a c=c bond

what happens if bromine/iodine is added to alkene

• no reaction

• solution stays brown colour

what happens if bromine/iodine is added to alkene

• reaction occurs

• solution changes to colourless

how to test for hydroxyl group

• add oxidising agent - colour will change

• add carboxylic acid - distinct smell

how to test for carboxyl group

• add alcohol

• add carbonate

• both produce co2 + bubbles if present

IR spectroscopy datapoint terminology

• absorption band

• absorbance

IR spectroscopy general facts

• ignore <1500cm

• recognise other peaks with data book

alcohol

carboxylic acid

carbonyl

amino

mass spectrometry parent ion peak and base peak indicates

• parent ion: molar mass

• base: most common fragment

melting point determination - pure

• even crystal lattice structure

• stronger IMB

• overall melting point: same as pure substance

• mp range: <2°C

melting point determination - impure

• uneven crystal lattice structure

• weaker IMB

• lower melting point than pure substance

• mp range: >2°C

melting point definition

• a range from first signs of melting to last signs of melting

aliquot

sample

standard

a substance with precisely known concentration for use in quantitative analysis

equivalence point

• when reactants are added in correct stoichometric ratios

• theoretical

• use calculations to find

end point

• where the experiment ends

• practical

• indicated by colour change

overestimation of the equivalent point

titre

• found in burette

• found above

aliquot

• found in conical flask

• found below

what is burette rinsed with

substance it holds

what is conical flask rinsed with

distilled water

what is pipette rinsed with

substance it holds

what is volumetric flask rinsed with

distilled water

retention time

time take for compound to travel through chromatogram

adsorb and desorb meaning

• adsorb: stick

• desorb: unstick

if substance is strongly attracted to stationary phase

• it adsorbs strongly

• retention time: long

is a subtance is strongly attracted to mobile phase

• it desorbs strongly

• retention time: short

difference betweeen HPLC and column chromatography

high pressure

conditions for qualitative analysis

same column and conditions

longer column effect on retention time

longer

greater viscosity effect on retention time

longer

tightness of packing effect on retention time

longer

pressure effect on retention time

shorter

temperature effect on retention time

shorter