Chem 15- Chromatography, Mass Spec, NMR

what is the simple purpose of chromatography, mass spec or NMR

chromatgraphy: seperating mixture compounds

mass spec: gives info about mass/ molecular fragments

NMR: tells u about different chemical envrionments of atoms in molecules

what are the two phases of a chromatography

stationary (paper) and mobile (solvent)

what decides the speed at which components in a mixture in a chromatography

• stronger attraction to stationary phase → moves slower

• greater solubility in mobile phase → moves faster

What is the purpose of the Rf value and the formula

purpose: helps identifies substances

Formula: Distance travelled by substance/ distance travelled by solvent front

how does gas chromatography work

a sample is vaporised and carried by an inert carrier gas through a column and comes out based on how the substance interacts with the stationary phase

what is retention time

the time taken for a substance to come out of a gas column based on its interaction with the stationary phase

whats the relationship between attraction to stationary phase and retention time

stronger attraction to stationary phase = longer retention time

what is HPLC and the difference of it between paper chromatography

it is high performance liquid chromatography which involves pumping a tightly packed column at high pressure

the stationary phase is material packed in the column

detector records when substances exit the column and graph onto a chromtogram with peaks

what do the peaks represent in a chromatogram

different components in a mixture

what is the basic explanation of how NMR works

• Nucleons have a spin that aligns (low energy) or goes against (high energy) a magnetic field, creating an energy gap between aligned and against

• NMR sends radio radiation that excites proteins different amounts based on energy gap

• This is only possible in sample with odd number of total nucleons

what does no. of signals (peaks) and split of peak of a NMR H spec suggest

number of hydrogen environments

N+1 of hydrogen attached to adjacent carbons

in a H NMR spec how do you know which peak is associated to which environment

this is based on the ratio of the number of hydrogen atoms in each environment