quantitative analysis Flashcards
when is a gas evolved in a reaction?
effervescence, colour/odour of gas is detected, when a solid substance is heated
what is the effect of oxygen on moist litmus paper?
no effect, oxygen gas is neutral
what are colourless and odourless gases that can be tested for?
oxygen, hydrogen, carbon dioxide
what is the effect of hydrogen gas on moist litmus paper?
no effect, hydrogen gas is neutral
what is the effect of carbon dioxide on moist litmus paper?
gas will turn moist blue litmus paper red, gas is acidic
what is the test for oxygen?
by inserting a glowing splint into the test tube, if the glowing splint is relit, oxygen is present
what is the test for hydrogen?
if a lighted splint is extinguished with a ‘pop’ sound, hydrogen is present
why does oxygen gas rekindle a lighted splint?
oxygen gas supports combustion
what is the test for carbon dioxide?
if bubbled gas in limewater forms a white precipitate, carbon dioxide is present
describe ammonia gas
colourless gas with a pungent smell
what is the test for ammonia gas?
if moist red litmus paper turns blue, ammonia gas is present (alkaline)
describe chlorine gas
greenish-yellow gas with a pungent smell
what is the reaction of chlorine gas with moist litmus paper and what is the conclusion?
will turn moist blue litmus paper to red and then bleached, gas is acidic
describe sulfur dioxide
colourless gas witha pungent smell
how does sulfur dioxide react with moist litmus paper?
turns moist blue litmus paper red (acidic)
how does Ca2+ react with aqueous sodium hydroxide?
white preciptate is formed which is insoluble in excess NaOH
what is the ionic equation of calcium + aqueous sodium hydroxide?
Ca2+ (aq) + 2OH- (aq) -> Ca(OH)2 (s)
how does Al3+ react with aqueous sodium hydroxide?
white precipitate is formed which dissolves in excess NaOH to give a colourless solutioin
how does Pb2+ react in aqueous sodium hydroxide
white precipitate is formed which dissolves in excess NaOH to give colourless solution
how does Fe2+ react in aqueous sodium hydroxide?
dirty green precipitate is formed which is insoluble in excess NaOH which turns reddish brown on standing
how does Fe3+ react in aqueous sodium hydroxide?
reddish-brown precipitate is fo0rmed which is insoluble in excess NaOH
how does Cu2+ react in aqueous sodium hydroxide?
light blue precipitate is formed which is insoluble in excess NaOH
how does NH4+ react in aqueous sodium hydroxide?
no precipitate is formed, on heating a gas evolved turns moist red litmus paper rblue
how does Ca2+ react with aqueous ammonia?
no precipitate is observed
how does Al3+ react with aqueous ammonia?
white precipitate is formed which is insoluble in excess aqueous ammonia
how does Pb2+ react with aqueous ammonia?
white precipitate is formed which in insoluble in excess aqueous ammonia
how does Zn2+ react with aqueous ammonia?
white precipitate is formed which dissolves in excess aqueous ammonia to give a colourless solution
how does Fe2+ react with aqueous ammonia?
dirty green precipiate is formed which is insoluble in excess aqueous ammonia and turns reddish brown on standing
how does Fe3+ react with aqueous ammonia?
reddish-brown precipiate is formed which is insoluble in excess aqueous ammonia
how does Cu2+ react with aqueous ammonia
?
light blue precipitate is formed and is soluble in excess aqueous ammonia
how do you differentiate Al3+ and Pb2+ ions?
add aqueous Hcl/NaCl, if Pb2+: white precipitate, Al3+: white precipitate :
how do you test for CO3^2-?
addin dilute HCl and pass the gas given off into limewater
what is the observation for carbonate test?
effervescence is observed and gas given off forms a white precipiate with limewater and carbon dioxide gas is given off
how do you test for NO3^-?
add dilute sodium hydroxide followed by aluminium and warm gently
what is the observation for nitrate ion?
a colourless gas with a pungent smell is evolved on warning, it turns moist red litmus paper blue and ammonia gas is given off
how do you test for Cl-?
add dilute nitric acid followed by aqueous silver nitrate/add dilute nitric acid follows by aqueous lead (ii) nitrate
what is the observation for chloride ion?
white precipitate is observed
how do you test for I- ion?
add dilute nbitric acid followed by aqueous silver nitrate/add dilute nitric acid follows by aqueous lead (ii) nitrate
what is the observation for iodide ion?
yellow precipitate is observed
how do you test for So4^2-?
add dilute nitric acid/follows by aqueous barium nitrate/add dilute hydrochloric acid followed by aqueous barium chloride