organic Flashcards
explain why crude oil can be separated by fractional distillation
alkanes have different chain lengths; so different boiling points
explain the trend in reactivity of primary halogenoalkanes
C-X bond becomes weaker down group 7; so reactivity increases
explain why ethanol has a higher boiling point than ethene
ethene uses london forces; ethanol uses hydrogen bonds; more energy needed to break hydrogen bonds
describe the stages of a reaction in a catalytic converter
gas adsorbed onto catalytic surface; bonds break and reaction occurs; products released from surface
some polyesters break down naturally; explain why this is an advantage
does not accumulate in the environment
explain why a benzene ring is more reactive with an OH group attached
lone pair on O from OH adds electron density to delocalised ring; so more reactive to electrophiles
give the steps for using 2,4-DNP to distinguish between an aldehyde and a ketone
react to form orange precipitate; filter and recrystallise product; compare its melting point to a database
how can you tell a solution contains a single optical isomer rather than a racemic mixture
it rotates the plane of polarised light
buildings made of limestone can be damaged due to SO2 and NO2 in the atmosphere; describe how these gases come to be present in the atmosphere and explain how they can damage limestone
they form when fuel is burnt; they react with water to form acid rain; which then reacts with the limestone
what is structural isomerism
molecules have same molecular formula but different structural formula
what are the steps of free radical substitution
initiation, propagation, termination
what happens in the initiation step of free radical substitution
homolytic fission of halogen caused by UV light, forming two radicals
what is homolytic fission
breaking of a covalent bond where both species get one electron; this forms two radicals
what is heterolytic fission
breaking of a covalent bond where both electrons go to one species; this forms two ions
what is cracking
thermal decomposition of long chain hydrocarbons to form (more useful and in demand) shorter chained ones
