paper 2 past paper questions Flashcards
test for aldehydes and ketones and results
tollens reagent
- aldehyde: silver mirror
-ketone: no observation
or fehlings solution
aldehyde: orange/red precipitate
ketone: no observation
whats the meaning of fractions in fractional distillation
a mixture of compounds with similar boiling points
whats the catalyst used for catalytic cracking
zeolites
test for alkenes and alkanes and results
bromine water
-alkene: turns colourless
-alkanes: no observation
why does carbon dioxide absorb infrared radiation
the C=O bond vibrates at the frequency of IR radiation
what environmental problem does NO cause
acids rain
why may experimental and theoretical enthalpies differ
the value measured may not be accurate due to heat loss or incomplete combustion
What’s is a reflux reaction
heating the chemical reaction while continually cooling the vapour produced back into liquid form, using a condenser
How are oxides of nitrogen formed in engines
High temperatures in engines drive reactions between nitrogen compounds from the fuel and the oxygen
State the meaning of the term heterogeneous catalyst.
A catalyst that is in a different phase to the reaction
what happens in benzene
the p orbitals overlap
electrons are delocalised
why does using a conical flask instead of a beaker give more accurate results in some experiments
it reduces loss of liquid droplets and makes sure all the solution flows back into the bottom of the flask
why is chloroethanoic acid stronger acid than ethanoic acid
the chlorine atom polarises the O-H bond which weakens it making it a better proton donator
what reaction is responsible for the formation of nitro benzene from benzene
electrophilic substitution
reagents and conditions for prop-2-ene nitrile to 3-bromopropanenitrile
- KCN
- ethanolic
