Essential Chemistry Flashcards
Give e.gs of H-bonds found in bio- systems
- base pairs in DNA
- alpha helix proteins
equation for volume-volume percent concentration? (% v/v)
%v/v= ( volume of solute(mL)/ volume of solute(mL)+volume of solvent(mL) ) x100
What is the equation for: Kb, association constant for weak bases?
what is the value of:
- pico
- femto
- pico = 10-12 m
- femto = 10-15 m
define secondary (20) standard
- prep. in lab for spec. analysis
- standardised against a 10 standard.
Define precision
the proximity of several measurements to: each other
Define: Amphiprotic molecule, giv an e.g
a molecule that both donates H+ (acid) and accepts H+(base)
e.g water
equation for mass-volume percent concentration? (% m/v)
%m/v = ( mass of solute (g) / volume of solvent (mL) ) x100
Give 3 examples of properties of
- chemical
- physical
- .b.p, density, m, v i.e. the whole of; density=m/v
- flammability, corrosiveness(i.e.rusting), reactivity w/H+ (acid),H2O, O2
what are the properries of 10 standards? (7 marks)
- v. pure
- stable
- no H2O’s of hydration
- high molecular weight
- low hygroscopicity (to min. weight changes due to humidity)
- high eq. weight (min. weighing errors)
- non-toxicity
what is the general rule between the strength of an acid and its conjug. base?
The stronger the Ac, the weaker the Conj. Base (vise versa)
equation for percentage concentration (mass/mass)
% mass/mass = ( mass of solute(g) / mass of solute(g) +mass of solvent(g) ) x100
define heterogeneous mixture? (opp for Homogeneous)
mixture with diff. composition, properties and appearance e.g salad with lettuce and cucumbers
What is MIC? (Minimum Inhibitory Concentration)
MIC: the lowest concentration of an antimicrobial that will inhibit the growth of an oragnism
define: combination reaction
2 or more subs react to form 1 product
which measuring equipment has the highest level of accuracy?
vol. flask
What is the rule for:
- pKa in acids and
- pKb in bases
- Smaller pKa = ^er Ka => ^er acid (smaller pH)
- Smaller pKb = ^er Kb => ^er base (bigger pH)
- Define weak electrolytes,
- give e.gs
- partially dissociates when dissolved in water.
- e.gs: PARTIALLY SOLUBLE IONIC SALTS, weak acids, weak bases.
what is the rule for pH, H+ ions and acidity
lower pH = higher no. H+ = more acidic
equation relating to pKw, pH and pOH?
pKw = pH + pOH = 14
what are the values of pico and femto?
pico = 1 x10^-12 m, femto = 1 x10^-15 m
Define strong electrolytes and give e.gs
compl. dissocates in water.
e. gs: SOLUBLE IONIC SALTS, strong acids, strong bases
give 2 e.g equations for strong electrolytes
acid: HCl → H+ + Cl-
base: NaOH → Na+ + OH-
give an e.g of a weak acid
Carbonic acid, H2CO3
equation for pOH?
pOH = -log[OH]
Define stock solution
concentrated solution that’ll be diluted to some lower concentration for actual use
equation for dilution of solution
C1 x V1 = C2 x V2
Describe function of:
- electrolyte (ionic comp.)
- non-electrolyte (non-ionic comp.)
- electrolyte: dissolves into cations and ions in a polar solvent e.g H20
- non-electrolyte: does not form ions when in solution. e.g glucose
name the 5 SI units, their physical quality and abbreviation
what is the gen. acid-base pair equation and give a gen. e.g
Give 3 e.gs of non-ionic but polar compounds.
sugar, proteins, DNA all dissolve in water.
3 possible units for molarity?
M, mol/L or molL-1
Define: Amphoteric , give an e.g
acts as both a base and an acid.
define: solution
homogeneous mix of 2 or more pure subs.
Define accuracy
the proximity of a measurement to: the true value of a quantity
define: intramolecular H-bond
deine: intermolecular H-bond
- H-bond w/in molecule. (e.g. protein tertiary structure)
- H-bond between molecules. (e.g. DNA double helix)
describe: doubling dilutions (3marks)
- Good for accurate coverage of a narrow scale.
- Used in many serological assays
- 2-fold descrease of conc. 400 micrograms per ml → 200, →100 and so on.
equation for molarity?
M= n/v, Molarity(M)= Moles(mol) / Volume (Litres, L)
define
- Mobile phase
The liquid or gas that flows through a chromatography system, moving the materials to be separated at different rates over the stationary phase
define stationary phase
Matrix (solid or liquid): examples include the silica layer in thin layer chromatography TLC
give the general formula for alkanes, alkenes and alkynes
alkane = CnH2n+2
alkene = CnH2n
alkyne = CnH2n-2
how do i know which substance is most polar on a TLC plate
most polar, the one that stayed closest to the bottom (the one that moved the least)
expl: mobile phase - non-polar and travels to top, thus, if one doesn’t travel that much, it is less non-polar and therefore, more polar because like attracts like, so the non-polar substance will move with the non-polar mobile phase.
state if the following are polar or non-polar
- mobile phase
- stationary phase
- mobile phase = non-polar
- stationary phase = polar
define chromatography
Physical method of separation that distributes components to separate between two phases, one stationary (stationary phase), the other (the mobile phase) moving in a definite direction.
define retardation factor, Rf
Distance migrated by sample on a TLC plate under set conditions
define retention time, Rt
Characteristic time it takes for a particular analyte to pass through the system (from the column inlet to the detector) under set conditions
define : normal phase
The stationary phase is polar and the mobile phase is relatively non-polar. Order of elution: least polar first, most polar last
define reverse phase
The stationary phase is non-polar and the mobile phase relatively polar.
define: eluate
Mobile phase leaving the column.
define: eluent
Mobile phase leaving the column.
what do all macromolecules contain
asymmetrical carbon AKA chiral centre
what does it mean if all macromolecules containn a chiral centre .
they show stereoisomerim
define stereoisomerim in macromolecules
molecules that show the same structure but different biological properties
give 3 types of biological macromolecules and examples following them and wehat they are made of
- proteins - e.g enzymes, receptors, - aas
- DNA - N/A - nucelic acids
- carbs - N/A - sugar
explain the chirality and biological significance
carbon atoms are attached to same groups thus, they have sae molecular weight as eachother but differ in 3D spacial arrangements of atoms
what does it mean if spacial arrangement is different?
diff spacial arrangement leads to failure of binding to a certain receptor active site
explain relationship with chirality in drug molecule
chirality in drug molecule creates different enantiomers, thus only one can bind to receptor active site. this is due to spacial arrangement of functional groups being diff.
explain the 4 points of configuration isomers that differ to confirmation
- 3D spacial arrangement of atoms or groups w/in a molecule.
- changing the config of mol. means that bonds are broken or reformed
- diff configs means diff molecules
- High E process
Define and describe Conformation & Torsional angle (3marks)
- Rotatation of single bonds
- Low Energy Process
- 3600 confirmations
describe the diff. btwn bond vs torsional angle
- bond angle: angle btwn 3 atoms
- torsional angle - angle btwn 4 atoms
what does total number of confirmations depend on?
it depends on number of rotatable bonds and torsional angle
give equation relating to total no of confirmations
Total no of confirmations = (360/T)R
T - tosional angle
R - number of rotatable bonds i.e. <u><em>C-C or C-N</em></u>
describe the trend if the no of rotational bonds increase?
increase of no of rotational bonds = higher value = increase of total no of confirmations = lower chance for molecules to bind to active site of receptor
what happens if there are less confirmations
the less confirmations = more effective the drug = more active site binding
what can confirmational restriction lead to
higher activity
what happens if confirmational restriction increases
loss of compound activity, thus active confirmations no longer form
