Chemistry Exam (I may need to remember)

How does NMR work?

Uses radio waves

• change spin states of protons and neutrons

How does IR spec work?

Absorbs infrared radiation

• changes vibrational energy states of covalent bonds in molecules

How does mass spec work?

• molecule is vaporised (gaseous 

• Bombarded with electrons to ionise it

How does HPLC work?

Equation for mass spec?

Upfield/downfield is which way?

What does it show?

What is shielding?

• Upfield is more shielded (closer to TMS/0/right)

• connected or closer to electronegative atom (PULLS electrons to itself)

Can galvanic cells have porous electrodes?

YES! Fuel cells and galvanic cells can both have porous electrodes.

• they increase the surface area for the reaction

What is the purpose of a electrolyte in a fuel cell?

What is the purpose of a porous electrode in a fuel cell?

Primary structure of a protein?

The specific sequence of amino acids in the protein chain.

• simplest level of a protein structure

• shows peptide links only

Secondary structure of a protein?

Chains coiling or pleating due to the formation of H-bonds between peptide links

• hydrogen bonds, polar interactions are shown

Tertiary structure of a protein?

• Overall 3D shape

• Stabilised by hydrogen bonds, dipole-dipole, dispersion, ionic interactions, covalent crosslinks (disulphide links S-S)

Quaternary structure of a protein?

2 or more polypeptide links (10 or more amino acids)

• hydrophilic and hydrophobic interactions

What does denaturation do?

changes the active site (shape) of the enzyme

• can alter the secondary, tertiary and quaternary (if possible) 

• is irreversible 

Optical isomers?

OR enantimers

• same molecular formula

• same semi-structural formula

• different spatial arrangement

Chiral

• can’t be superimposed

—> left foot can’t fit in right shoe

Achiral

• can be superimposed

—> water bottle

in a scientific poster, which section would explain the reason for undertaking an investigation?

intro

Hydrogen bonging takes place during the formation of__

secondary, tertiary and quaternary structures only. NO PRIMARY

Cellular respiration

is an EXOthermic reaction (negative delta H)

Glucose is oxidised and loses electrons

petrodiesel and biodiesel

• both derived from plant and animals 

Biodisel —> crops and whatnot

petroldiesel —> formed over millions of years from plants and animals and a ton of pressure and heat

• biodiesel is more hygroscopic (attracted to water, likes it) bc of the ester functional group

• biodiesel forms crystals at a higher temperature

around the same temp that it boils at is where it’ll form crystals

stronger bonds = boiling point higher but also comes together much easier

Independent variable

The thing we change

• on the x-axis

Dependent variable

The thing we measure (according to the aim) (e.g temp change of the water but, we’re trying to find out the delta H)

• on the y-axis

Accuracy

How close a result is to the true value (The value that would be found if the quantity could be measured perfectly)

Precision

How close repeated results are to each other

Resolution

How small of a unit of measurement it has

• If a syringe has more lines indicating the amount of liquid, then it has a higher resolution

Repeatability

• repeated by the same student

• similar results and under the same conditions

Reproduceability

• performed by different people 

• produces similar results, under similar conditions

Validity

How well does the experiment address the aim of the experiment

Personal errors

Miscalculations and mistakes (e.g forgetting to do something, reading it wrong, measuring the wrong thing)

Random errors

it’s a random error (e.g needle fluctuates unpredictably between two heights, so don’t know)

Systematic errors

Usually biases one direction (higher or lower)

Cause readings to differ from the true value in a systematic manner so that when a particular value is measured repeatedly, the error is the same.

unit of measurement for concentration

mol/L also known as M

Glycerol formula

C3H8O3

IR Spec

1) hydroxyl

2) carboxyl

3) primary amine

4) secondary amine/alkyne

1) smooth, clean, broad-ish tongue

2) broad, hairy beard

3) vampire fangs

4) single fang

coal seam gas vs coal

coal seam gas releases more energy per gram than coal.

• coal seam gas’ major component is CH4

hydrophobic

repels water, doesn’t like it

hydrophillic

likes water, can be dissolved in it