CHEM ATP Flashcards
(c) Give two observations that are made as the silver chloride breaks down. electro
- yellow / green gas
- bubbles / effervescence
- shiny liquid / metal / solid / deposit / substance
why repeat
can spot anomalous results
OR
can find a mean/average
random- don’t forget excess hcl for acid and metal or carbonate
Explain why the bung must be replaced immediately after the sodium carbonate is added to the boiling tube.
(ii) Explain how the apparatus could be altered so that the bung does not have to be removed.
You may draw a diagram to explain your answer.
gas escapes before bung is replaced /so that gas does not escape
place one reagent in tube inside boiling tube / flask
* tip / shake tube to start reaction OR
* use a divided flask
* tip flask to start reaction- (The reaction can be started by tipping the flask
* do not have to replace / remove the bung
* so no gas escapes (while the bung is being removed / replaced )
hydrated copper(II) sulfate in a boiling tube and heated using a Bunsen burner.
- white fumes given off
- condensation at mouth of tube
- solid (changes from blue and) becomes white
temperature decrease
Explain why the temperature decrease becomes constant for high masses of sodium
hydrogencarbonate.
Suggest two changes that could be made to the apparatus that would improve the accurate results
all) acid used up / sodium hydrogen carbonate in excess- reaction over
use a pipette- more accurate than a measuring cylinder
use a polystyrene / styrofoam cup -insulator / reduces heat gain
ror gas- use a divided flask
safety precaution
safety glasses/goggles/gloves/lab coat
A few drops of liquid P were placed in a crucible. A lighted splint was applied to the surface of liquid P in the crucible- burned with an orange flame and lots of smoke;
soot was left around the top of the crucible
A few drops of liquid P were added to a test-tube containing 1cm3
of aqueous bromine.- colour changed from orange to colourless
flammable / fuel unsaturated / alkene / any named alkene organic / contains carbon / hydrocarbon
Describe what would happen if the apparatus is used before the error is corrected- conical flask and both tubes inside
liquid / drying-agent pushed out of flask
Explain why the graph line must pass through (0,0).
- bunsen burner adjust to give hot flame
there is no reaction (with no magnesium)
Open (air hole / collar)
Suggest a practical problem that using 50cm3
of solution C could cause. How could this
problem be solved?
Volume of potassium manganate solution added > 50 cm3
Use more than one burette / refill burette
suction pump
suck gases/ products formed. through apparatus
The student calculated that the total volume of gas collected in this reaction would be 85cm3
.
Suggest and explain why the actual volume of gas collected was different from 85cm3
volume of gas would be lower, gas dissolved in water
titration- what readings to take
initial burette reading and final burette reading
After the titration, the student discarded the contents of the conical flask and rinsed the conical flask with distilled water.
Suggest and explain what would be the effect, if any, on the titration values if the conical flask was not dried before repeating the titration.
values should be same moles / amount of sodium hydroxide added still same
ui not used in titration
too many colour changes no clear end point
determining concentration of acid which is highest
thermometric
* measure temperature (change)
* highest temperature (change) is most concentrated
* add (xs) hydrochloric acid
precipitation of metallic hydroxide
* measure mass / height of precipitate
* most precipitate is most concentrated
* add (xs aqueous) copper sulfate (for example)
gas produced
* measure volume of gas made
* largest volume is most concentrated
* add an ammonium salt or aluminium
evaporation
* mass of solid
* most mass is most concentrated
* evaporate solution
pH meter
* measure pH
* highest pH is most concentrated
* pH meter
dissolving
* measure time taken for solid to dissolve
* shortest time is most concentrated
* aluminium / aluminium oxide / zinc / zinc oxide
A lighted splint was used to touch about 1cm3
of liquid V.
liquid V set on fire and
burned with a smoky blue flame- pleasant smell-
(e) Draw one conclusion about liquid V.
fuel/ organic
chromatography place dot apparatus
teat pipette or dropper
Suggest what might have caused this result to be anomalous.- titration
overshot end point / more than 25 cm3 KOH in flask
cotton wool purpose
allow gas to escape Prevent loss of acid;
What conclusion can you draw about the identity of solid O from test 1?- white crystal
group 1 cation present
Suggest a practical problem that using 50 cm3 of solution C in this investigation would cause. Suggest a practical solution to the problem
volume of potassium manganate(VII) solution added would be greater than 50 cm3 solution: use more than one burette / refill burette
thermometer not in alcohol
to measure the temperature of vapour/ temperature of liquid would not be constant
