A sequence of chemicals Flashcards
Copper Cycle
how was the sample of copper initially weighed
1) weigh and tar the 250 mL beaker
2) add the cu(s) to the beaker to find the mass
how much nitric acid was added to a 100 mL graduated cylinder
10 mL
what are a safety note about nitric acid
causes severe burns
vapours irritate respiratory system, eyes and skin
how was part A of the experiment completed
add the 10 mL of nitric acid to the weighed copper and record the observations
- the solution colour is from Cu(NO3)2
- fumes are nitrogen dioxide
what can the reaction from part a be described as
oxidation dissolution as the copper is being oxidized in the process
how was part b of the solution done
a few mL of RO water is added to the solution which results in the solution changing colour
why does the part B step change colour
due to hydrated CU(II) ions
Cu(H2O)6 +2
how was the NaOH required for step C prepared
6 g of the solid NaOH was weighed and added to 25 mL of RO water
- this preparation is done in an ice bath because it is a VERY exothermic reaction
how was step C completed
the created 6 M NaOH solution was carefully added to the Cu(OH2)6 solution while stirring slowly
what was the expected product of step C
Copper (II) hydroxide
Cu(OH)2
what does a teal-coloured thin suspension after step C mean
you had to add more 6 M NaOH to the copper solution for the correct product
how was Step d completed in this experiment
- 100 mL of RO water was added to the copper solution
- stirring constantly the copper solution was brought to a gentle boil for a good 10 mins or so
- use a Buchner funnel to filter the copper solution through
- wash the copper on the filter paper TWICE with 30 mL of RO water
- after discarding of the waste water, wash the copper on the filter paper ONCE with 25 mL acetone
where does the acetone used to rinse the CuO on the filter paper go after use
down the non-halogenated organic waste container
how was step E completed
- 25mL of 3 M H2SO4 to the CuO while stirring so all the copper becomes CuSO4
how was the 3 M H2SO4 prepared for step E of the experiment
add 6 mL of the acid to 30 mL of water to form 36 mL of the diluted acid
how much zinc was added during step F and how many times
up to 3 times of 0.5 grams of zinc was added to the CuSO4 solution
how was excess zinc removed from the beaker during step F and WHY
add 10 mL of RO water and 5 mL of 3 M H2SO4 to the beaker and mix with a stir rod
the zinc will react with the aqueous strong acid to produce H2 gas while the 3 M H2SO4 will NOT attack the copper metal but it WILL dissolve the zinc metal
how was the resulting copper from step F extracted from the solution
set up a Buchner funnel
- wash copper twice with 25 mL RO water
- wash copper twice with 25 mL acetone
how long was the copper placed in the oven for
about 15 mins
how was the recovered percent of copper done
- once the copper has been washed the required times in the Buchner funnel, it was added to a PRE-WEIGHED beaker and placed in the oven for 15 mins
- after the beaker has cooled, weight it again WITH the copper in it and determine the mass of the copper
- divide the INITIAL mass of the copper by the RECOVERED mass ( and multiply by 100) to determine percent copper recovered
what happened when the solid copper was mixed with the HNO3 in step A
the copper turned from brown to dark green AND a brown gas was seen emerging off of the solution surface
what happened when a few mL of RO water was added to the solution from part A (with the CU(NO3)2)
the solution turned from dark green to teal before ENDING in a dark blue
what happened when the Cu(OH2)6 solution reacted with NaOH in step C
reaction took place in the ice bath and the copper solution turned from blue to BLACK
what was noticed as the black copper (ii) hydroxide was heated
a solid precipitate was formed within the solution
what was produced during the heating stage of part D
CuO(s) and water
what happened when the CuO reacted with H2SO4
all the black solid was dissolved and the colour changed from black back to BLUE
what happened when the zinc was added to the CuSO4
the reaction was immediate and the colour changed to a copper-brownw
what was the copper solid appearance like after heating
was less saturated and more a reddish brown colour
what is the balanced chemical reaction for Step A
Cu(s) + 4 HNO3(aq) ——-> Cu(NO3)2 (aq) + 2 NO2(g) + 2 H2O (l)
what is the balanced chemical reaction for Step B
Cu(NO3)2 (aq) + 6H2O (l) ——-> Cu(OH2)6 ^2+ (aq) + 2NO3-(aq)
what is the balanced chemical reaction for Step C
Cu(OH2)6 (aq) + 2NaOH (aq) ——>Cu(OH)2 (s) + 6 H2O (l) + 2Na+ (aq)
what is the balanced chemical reaction for Step D
Cu(OH)2 (s) + heat —–> CuO(s) + H2O(l)
what is the balanced chemical reaction for Step E
CuO(s) + H2SO4 (aq) ——>CuSO4 (aq) + H2O (l)
what is the balanced chemical reaction for Step F
CuSO4(aq) + Zn(s) ——-> ZnSO4 (aq) + Cu(s)
