Practical Flashcards
what are the 5 things to consider when observing reactions?
- colour from start to end (maybe middle)
- state
- temperature
- smell
- speed of reaction
define effervescence
bubbles in a liquid
define solution
solute dissolved in solvent
define precipitation
substance in solid form from solution
define immiscible
incapable of being mixed
define gelatinous
jelly like consistency
what is an acid/base reaction ?
H+ ions are transferred
what is a decomposition reaction?
breakdown of a substance to form more than one product
what is a precipitation reaction ?
formation of a solid when two solutions react
when would you use distillation over reflux ?
when desired product may react further
outline the process of recrystallisation
- add hot solvent to impure sample
- leave to cool - crystals will begin to form
- filtrate crystals under reduced pressure
- wash w/ cold solvent and dry
what must the solvent be for recrystallisation ?
product is soluble in hot solvent product is (nearly) insoluble in cold solvent
how does filtering by reduced pressure work ?
- mixture poured into Buchner funnel w/ filter paper
- flask connected to vacuum line, so under reduced pressure
- liquid is sucked into flask
state the way to measure melting point
- put small amount of solid in capillary tube
- put into beaker of oil w/ sensitive thermometer
- slowly heat and stir
- record temp that the solid melts
independent variable -
variable you change