Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
42 Cards in this Set
- Front
- Back
|
Explain what is meant by the term dynamic equilibrium. |
rate of forward reaction = rate of back reaction concentrations of reactants and products remain constant / closed system (1) ; |
|
|
The organic product forms as an impure liquid. Describe how the student could remove the acidic impurities from the liquid. |
(shaking with) sodium hydrogencarbonate (solution) (1) ; |
|
|
Name two ways of reducing the amount of carbon dioxide in the atmosphere, other than storing it under the ocean. |
burn less fossil fuel (1) ;named alternative power source (1) ;less deforestation / plant more trees (AW) / more photosynthesis (1) ;reacting the CO2 with lime/other suitable named solid (1) |
|
|
Use the mechanism shown in (ii) to explain why both these compounds are formed. |
)carbocation / intermediate 1 is attacked by nucleophiles / species carrying negative charge / both Br- and Cl– attack carbocation / intermediate 1 (1) attack by Br– gives compound A / Attack by Cl– gives compound B (1) |
|
|
Explain what is meant by the term electrophile and how the electrophile attacks the alkene |
(partially) positively charged/ electron deficient reagent (AW) (1) ;bonds by accepting a pair of electrons (1) ; |
|
|
Explain what is meant by the term radical |
(A particle) with one (or more) unpaired electron(s). |
|
|
IR 6 marker |
-Sun emits UV-Earth absorbs some of the energy (from the Sun)-Earth re-emits IR-CO2 absorbs IR radiation-Making bond vibrate (more)-Turned into kinetic energy that raises the temperature-Some CO2 molecules re-emit/radiate IR which warms Earth-More CO2 means a greater temperature increase/greater enhanced greenhouse effect |
|
|
Explain how chlorine causes ozone depletion in the stratosphere & suggest why bromomethane has a lower ozone depleting potential than chloromethane |
Chloromethane is not broken down in the troposphere/unreactive But is broken down/photodissociates in the stratosphere by high frequency UV radiation Breakdown of chloromethane produces chlorine free radicals which catalyzes the breakdown of ozone C-Br bond weaker than C-Cl so molecule reacts in the troposphere before reaching the stratosphere |
|
|
How do id-id bonds form? |
Electron movements create an uneven distribution of charge A dipole is induced in a neighbouring molecule leading to attraction |
|
|
Why are chlorine atoms more readily reduces than iodine atoms? |
Because chlorine atoms are smaller than iodine & so have a greater nuclear charge so the extra electron gained is more strongly attracted to the positive nucleus than with iodine |
|
|
Give an e.g. of a human activity that gives rise to oxides of nitrogen |
Burning fuel in vehicle engines/driving a vehicle |
|
|
Describe how the rate of reaction varies under temperature conditions |
Rate is greater when the temperature is higher At higher temperatures particles have more energy/move faster More frequent collisions Which thus leads to more successful collisions/more collisions have (total) energy of atleast the Activation energy |
|
|
Suggest why it still occurs slowly in the atmosphere even if it has a low activation energy/enthalpy |
Few collisions |
|
|
Suggest why this reaction has a low bond enthalpy |
No bond breaking |
|
|
Explain why a reaction is faster in the presence of a catalyst |
Catalyst's provide an alternative route with a lower activation energy |
|
|
Explain how the presence of ozone in the stratosphere benefits us |
Ozone stops/blocks out high frequency UV radiation which could otherwise damage DNA |
|
|
Pros & cons of (tropospheric) ozone |
Pro: Blocks out high frequency UV radiation which could otherwise damage DNA Con: Causes photochemical smog |
|
|
What is heating under refluex |
To boil a liquid in a container attached to a vertical/upright condenser |
|
|
Why heating under reflux is used/pros |
Increases rate of reaction Allows boiling for a long time Stops loss of reactants and or products/volatiles Stops liquids catching fire |
|
|
What is meant by ultraviolet dissociation of a molecule |
UV of high frequency causes the bonds in a molecule to break/causes photodissocation to form form free radicals Breaks homolytically...? |
|
|
Describe how ____ can be separated from an aq layer |
Put into a separating funnel Pipette of the top or the water layer |
|
|
Explain why _____ is classified as a nucleophile |
It is a negative ion with a lone pair & can be donated/available to form a bond |
|
|
Thermoplastic |
Soften/melts/deforms when warmed/heated |
|
|
Surface area effect (reaction rates) |
Finely divided powder (e.g.) = greater surface area of the catalsyt So more frequent collisions |
|
|
Explain why ____ is slightly soluble in water, but _____ is insoluble |
______ can form hydrogen bonds with water whereas ______ cannot form hydrogen bonds with water |
|
|
How do hydrogen bonds arise? |
Oxygen small & electronegative/lone pair on oxygen attracted to hydrogen with a partially positive charge/s+ charge *Note that O could also be N or F since hydrogen bonding only happens when H is bonded to either one of NOF* |
|
|
Describe the structure/bonding of diamond |
Giant network/giant lattice with every C bonded to four other Cs/ every C is tetrahedrally bonded Covalent |
|
|
Describe the evidence for the relationship between the increased concentration of greenhouse gases & global warming |
There is a relationship between models of gas & models of temperature |
|
|
Describe the theoretical work that led to the research of ozone depletion in the stratosphere & how the evidence was originally overlooked |
Prediction/discovery (in the lab) that Cl can damage the ozone layer Spectroscopic measurements showed ozone levels depleted/ lower than expected results initially overlooked as the values were too small & so they thought that it was an error |
|
|
Describe & explain why the ozone is important to humans & the natural processes by which ozone is formed in the stratosphere |
Blocks high frequency UV radiation which would other wise damage DNA, damages immune system, damages eyes, affects crops, cell mutations (any 3) UV radiation causes the photodissociation of oxygen molecules which forms oxygen radicals These radicals can then react with an oxygen molecule/O2 to form ozone |
|
|
Why ____ is only slightly soluble in water |
Hydrogen bonds between ____ are weaker than the water-water interactions |
|
|
Explain why ____ can exist as 2 E/Z isomers |
_____ has a C=C double bond with different groups on each carbon of the C=C |
|
|
What is the fingerprint region |
Region to the right of 1500cm^-1 Unique part of the spectrum for a molecule Can be used to identify the molecule |
|
|
How halogenoalkanes deplete ozone |
Halogenoalkanes break down in the presence of high frequency UV radiation to form radicals These radicals catalyze the breakdown of ozone *Low ozone concentrations were found in the arctic* = evidence for ozone depletion |
|
|
The molecule is polar because |
The charges do not balance e.g. CF3Cl + C-F bond is more polar than the C-Cl bond |
|
|
Type of EM radiation emitted from the Earth's surface |
Infrared radiation |
|
|
Propagation |
One radical is used up & is replaced by another |
|
|
Homolytic fission |
One electron from the bond goes to each atom |
|
|
Define initiation |
Movement of a single electron |
|
|
Define termination |
When 2 free radicals join together, they make a stable molecule |
|
|
Explain how infrared spectroscopy produces a spectrum for a compound & how the spectrum would confirm the presence of (e.g. carbon & hydrogen) in the product. |
Bonds absorb IR radiation Absorption of IR of a particular range of frequencies Causing vibration/bending/stretching Spectrum shows peaks where the absorption has occurred No peaks for bonds involving atoms other than C & H |
|
|
Explain why ____ have the partial charges you have shown in... |
E.g. This is because both fluorine & chlorine are more electronegative than carbon So therefore both fluorine & chlorine have a greater ability to attract the bonding electrons than does carbon |
