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IB Chemistry: Option A
Higher & Standard Level
56
Chemistry
Not Applicable
03/31/2012

Additional Chemistry Flashcards

 


 

Cards

Term
Fragment of molecule/ ion with mass of 15
Definition
CH3
Term
Fragment of molecule/ ion with mass of 17
Definition
OH
Term
Fragment of molecule/ ion with mass of 29
Definition
C2H5
Term
Fragment of molecule/ ion with mass of 29
Definition
CHO
Term
Fragment of molecule/ ion with mass of 31
Definition
CH3O
Term
Fragment of molecule/ ion with mass of 45
Definition
COOH
Term
Factors that affect the colour of transition metal complexes
(4)
Definition
Identity of central ion
Oxidation no of central ion
Charge density of ligand
Geometry of complex ion
Term
State the reasons for using analytical techniques
Definition
Determine the structure, analysing different compositions of substances, and determining purity of substance
Term
Is info from one technique Sufficient to determine things?
Definition
No usually require multiple techniques.
Term
Describe atomic and molecular processes that occur in which absorption of energy occurs.
Definition
1. Em radiation is absorbed = used to move electrons from lower to higher energy level.
2. Vibrational energy of molecules are increased when infrared rad is absorbed as they move to a higher vibrational energy level.
Term
Describe how information from IR spectrum can be used to identify bonds?
Definition
Chemical bond has a natural frequency of vibration at which it vibrates.
Infrared red energy provides the correct amount of energy for only POLAR bonds to vibrate with greater amplitude.
Therefore polar bonds absorbs infrared radiation - and they are of specific frequencies.
By looking at a IR spectrum, which plots the transmittance (y) by the wavenumber (x) you can see which wavenumbers had the lowest transmittance and compare to bonds of a know wavenumber.
Term
What happens at a MOLECULAR level during absorption of IR?
Definition
ONLY POLAR BONDS WILL ABSORB IR RADIATION. vibrational energy of bonds = change in dipole moment = change in BOND polarity THEREFORE ABSORBANCE.
Term
Symmetrical stretch
Definition
Change in bond length
Term
Asymmetric stretch
Definition
Change in bond angle
Term
Bending
Definition
Change in bond angle
Term
IR spectroscopy: does it give an idea about functional groups?
Definition
No tells you bond ie O-H but does not inform whether that is from an alcohol or a carboxylic acid.
Term
Operating principles of double beam IR spectrometer?
Definition
Split a beam of monochromatic light into two beams of equal wavelength.
Pass one beam through a sample and the other through the reference.
Photomultiplier is used as the detector.
The TRANSMITTANCE is compared to the reference.
Reference takes into account absorption due to co2 and water vapour.
Then repeat with infrared radiation of a different wavelength.
Term
What is the integrated trace?
Definition
It indicates the relative no of hydrogen atoms in the environment.
Term
Effect of NMR spectroscopy due to environment surrounding hydrogen
Definition
If electrons surrounding = cut size of external mag field felt by hydrogen therefore need to increase external mag field.
If more electronegative atom attached then more exposed to magnetic field as electrons are further away and therefore need a lower magnetic field.
Term
Neighbouring carbon atoms on split
Definition
0 H = no split
1 H = doublet
2 H = triplet
3 H = quartet
Term
In fragmentation pattern are you measuring the mass:charge of individual atoms?
Definition
No one line will correspond to whole molecule.
Due to energetic collision between electron and molecule it can break up which would causes different fragments (obv with smaller mass).
Term
State the uses of atomic absorption spectroscopy.
Definition
Identification of metals in water, blood, soil and foods.
Term
Describe the principles of atomic absorption.
Definition
Obtain light made from element under investigation and pass through sample.
If element is present will absorb the light.
Degree of absorption relates to concentration of atoms present in sample irrespective of how they are bonded
Term
Determine use of fuel in AA spectrophotometer
Definition
Fuel forms a combustion mixture to produce heat
Term
Atomiser
Definition
To turn ions in the sample to atoms. To dehydrate sample
Term
Monochromatic light source
Definition
Used to produce light of specific frequency made from element under investigation. Wavelength of maximum absorbance is used generally
Term
Monochromatic detector in AA
spectrophotometer
Definition
Converts reference beam and beam that passes through sample into electrical signal by a photomultiplier.
Term
Effect of different ligands on the splitting of the d orbitals in transition ion complexes.
Compare NH3, H2O, Cl-
Definition
Cl- has lowest charge density
Water - higher charge density
Ammonia - highest charge density
Increased charge density means increased split in d orbitals therefore absorbs shorter wavelengths
Term
Factors that affect colour of transition metal ion complexes
Definition
Identity of metal ion
Oxidation number of metal ion
Identity of ligand.
Increase charge on metal ion =
Term
Organic molecules that contain a double bond absorb...why? And list 3 examples
Definition
UV radiation.
Arenes, alkenes and chlorophyll
Term
Conjugate systems means
Definition
Compound containing alternate double and single carbon bonds. System of connected p orbitals with delocalised electrons that increases stability therefore longer wavelength absorbed.
Term
A compound with conjugate bonds is more likely to absorb...
Definition
Visible light
Term
Beer lambert law - when is it used and what is the law ?
Definition
Used in uv-vis spectroscopy. Absorbance = data booklet
Term
State reasons for using chromatography
Definition
To separate and identify components in a mixture
Term
Explain that all chromatographic techniques involve adsorption on a stationary phase and partition between a stationary phase and a mobile phase.
Definition
Components in a mixture have different tendencies to adsorb on a stationary phase or dissolve in a solvent - this provides a means of separating the components of a mixture
Term
Outline use of paper chromatography
Definition
QUALITATIVE ANALYSIS:
Stationary phase = non volatile liquid - in paper 10% water
Mobile phase = liquid solvent
Water adsorbed by forming hydrogen bonds with OH groups in cellulose.
Moves up paper by capillary action
Spot of sample placed on paper at pencil mark
Lower part of paper below pencil line dipped into solvent.
Paper removed and dried.
Rf values calculated = distance moved by component / distance moved by solvent front.
Compared to known rf values.
Term
Outline use of thin paper later chromatography
Definition
Adsorption chromatography
Small spots of test solutions placed on baseline.
Stationary phase: thin layer of adsorbent particles of alumina or silica supported on a glass plate.
Mobile phase = liquid solvent
Term
Outline use of column chromatography
Definition
TLC on large scale
Column filled with adsorbent material (silica or alumina).
Tap is closed and column saturated with solvent.
Sample to be sep dissolve in min volume of solvent and added to top. Fresh solvent added to wash sample down - doesn't stagnate at top.
Different components separate as they pass through column at different rates- collected as sifferent fractions.
Term
Describe technique of gas-liquid chromatography
Definition
Used to separate and identify small samples of gases and volatile liquids.
Sample injected through self sealing cap into oven - gets vaporised. Vapour is carried through unreactive gas (mobile phase
Term
Describe technique for high performance liquid chromatography
Definition
For non volatile substances OR substance which decompose at temps near boiling points.
Column tightly packed with fine solid particles. High pressure forces mixture to separate components. Ultraviolet light used to detect different components.
Term
When to use GLC v. HPLC?
Definition
HPLC: identify temp sensitive compounds, analysis of oil, alcoholic bev, antioxidant, sugars and vits in foods, pharmaceuticals, polymers, biotech and biochemical research, quality control of insecticides and herbisicdes.

GLC: compounds that vaporise without decomp, analysis of urine samples from athletes for drugs, underground mine gases and blood alcohol levels
Term
When is column chromatography proffered
Definition
Using large amounts of sample.
Term
Discuss calibration of GLC
Definition
Sub of known concentration (that you are testing lets say ethanol in blood) passed through column. Ratios directly proportional to relative concentration - predict concentration by comparing to known.
Term
Detection of components in GLC and HPLC
Definition
GLC: Detected using flame ionisation. Gas is ionised as it pass├ęs through hydrogen flame. Resulting current = measure of component present.
Or using mass spectrometer.
HPLC: same but with uv light.
Term
Possible stationary and mobile phase for HPLC
Definition
Stat: silica / silicon dioxide/ long chain hydrocarbon.
Mobile: hexane, water, alcohol, solvent.
Term
Possible mob and stat phase for GLC
Definition
Stat: long chain hydrocarbon/ alkanes.
Mob: nitrogen gas/ helium gas/ argon gas
Term
Greenhouse gases name five
Definition
Co2, ch4, h20, o3, N20,
Term
Describe how Greenhouse gases cause greenhouse effect
Definition
1. Greenhouse gases do not absorb uv light therefore uv light from sun is allowed heats up planet surface.
2. When radiation is re radiated from earth = infrared radiation.
3. Greenhouse gases absorb IR radiation.
4. Part of absorbed radiation reemitted to earth = increase temp
Term
Region of em
Spectrum used in HNMR
Definition
Radio waves
Term
Why is TMS used as reference standard. Tetremethylsilane.
Definition
Si surrounded by four methyl groups.
Strong single peak - 12
Protons in identical chemical environment.
Low boiling point.
Volatile.
Non toxic.
Unreactive.
Does not interfere with sample.
Term
Which nuclei can be used in NMR and why?
Definition
Odd number of proton in nucleus. Odd no of proton therefore Proton behaves as tiny bar magnet. ( higher understanding - do not need to know).
Term
Why do molecules absorb IR radiation ?
Definition
Vibration / stretching of molecules produces change in dipole moment - allows absorption of IR.
Term
Source of SO3/SO2 in atmosphere
Definition
Combustion of COAL containing sulphur - fossil fuels will not be accepted
Term
Aerobic decay of C, N, S, P
Definition
CO2, SO42-, NO3-, PO43-
Term
Anaerobic decay of C, N, S, P
Definition
CH4, NH3, H2S, PH3
Term
Methods for reducing CO : name 3
Definition
1. Thermal exhaust reactor
2. Lean burn engines
3. Catalytic convertor
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