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Chemistry Question, Help please.

There are many methods of preparing salts; the one used today is the reaction between an insoluble metal carbonate and an acid:
EQUATION: CuCO3(s) + H2SO4(aq) CuSO4 (aq) + CO2(g) + H2O(l)
The copper sulphate crystals obtained have the formula CuSO4.5H2O

PROCEDURE AND QUESTIONS
Using a measuring cylinder measure out 25 cm3 of the 2 mol dm-3 solution of sulphuric acid provided and pour into a 100 cm3 beaker.

Q1. A measuring cylinder has an error of ± 0.5 cm3. Calculate the % error in this experiment by using a measuring cylinder.




Q2. What piece of apparatus would have reduced this % error ? _____________________________
Reply 1
To calculate % error do: (0.5x2/25) x 100
Reply 2
Original post by Meduser
To calculate % error do: (0.5x2/25) x 100


And what does it mean by what piece of apparatus would have reduced this % error?
Reply 3
Original post by AimXD
And what does it mean by what piece of apparatus would have reduced this % error?


Tbh I’m not entirely sure I was thinking along the lines of a pipette of sorts as you could measure more accurately. I’m only a student myself so I didn’t wanna give any info I don’t fully know 😂
Reply 4
Original post by Meduser
Tbh I’m not entirely sure I was thinking along the lines of a pipette of sorts as you could measure more accurately. I’m only a student myself so I didn’t wanna give any info I don’t fully know 😂


You still helped tho, Have you completed this Assignment (Unit 22.1 Preparing Substances)
Reply 5
Original post by AimXD
You still helped tho, Have you completed this Assignment (Unit 22.1 Preparing Substances)


Well I’m in year 2 doing OCR A so I’m not sure we have the same structure to our course
Reply 6
Also I’ve just re-read the Q and have seen you have only used the measuring cylinder for one measurement. Formula for % error is: (error x No. measurements taken divided by the measurement taken) x100. So it’s 0.5/25 x 100, sorry for that haha
Reply 7
Original post by Meduser
Also I’ve just re-read the Q and have seen you have only used the measuring cylinder for one measurement. Formula for % error is: (error x No. measurements taken divided by the measurement taken) x100. So it’s 0.5/25 x 100, sorry for that haha

Alright thanks a lot :biggrin: Might have different Questions later lol
Reply 8
Original post by AimXD
Alright thanks a lot :biggrin: Might have different Questions later lol


No problem! Ill be happy to help where I can haha
Ok well I do the IB and this question has some errors in it I feel, it should be saying uncertainty and not error. Assuming this was a mistake. To calculate percentage uncertainty you do the uncertainty divided by the amount measure * 100 so here it will be (0.5/25)*100 = +-2%. To reduce percentage uncertainty, you could either increase the amount of volume used (according to the % uncertainty equation) or use a measuring cylinder with a lower uncertainty. Once again, I am just a student so I may be wrong.
Reply 10
Original post by humayun.h
Ok well I do the IB and this question has some errors in it I feel, it should be saying uncertainty and not error. Assuming this was a mistake. To calculate percentage uncertainty you do the uncertainty divided by the amount measure * 100 so here it will be (0.5/25)*100 = +-2%. To reduce percentage uncertainty, you could either increase the amount of volume used (according to the % uncertainty equation) or use a measuring cylinder with a lower uncertainty. Once again, I am just a student so I may be wrong.


I do appreciate the Help thanks :smile:
Reply 11
Original post by Meduser
No problem! Ill be happy to help where I can haha


OK last thing i need help with and im Done with this Assignment the rest i have completed :smile:

Add a spatula measure of the copper(11) carbonate and stir with a glass rod

Q3. Note down your observations

a) ________________________________________________________________
b) ________________________________________________________________
c) ________________________________________________________________

Keep on adding more solid copper in small amounts with stirring until all the sulphuric acid has reacted

Q4 What observations did you make to decide that the reaction was complete
d) ________________________________________________________________
e) ________________________________________________________________

Using a fluted filter paper, filter the reaction mixture directly into a crystallising dish. Wash the beaker with a little water and rinse the solid with a little water, all washing collected in the crystallising dish.
It is normal to heat this solution to evaporate some of the water the heat is continued until the volume is reduced to about a half the original volume and then crystal are obtained on cooling.


Q5 Why is the solution not heated until all the water has evaporated? ___________________



We are simply going to leave the solution for a week to allow the water to evaporate and the crystals to form.
After a week pour of any excess solution in the evaporating dish and dry the crystals on absorbent paper and the weigh using a watch glass.

Q6 Describe the crystals you have obtained ______________________________________________
Original post by AimXD
OK last thing i need help with and im Done with this Assignment the rest i have completed :smile:

Add a spatula measure of the copper(11) carbonate and stir with a glass rod

Q3. Note down your observations

a) ________________________________________________________________
b) ________________________________________________________________
c) ________________________________________________________________

Keep on adding more solid copper in small amounts with stirring until all the sulphuric acid has reacted

Q4 What observations did you make to decide that the reaction was complete
d) ________________________________________________________________
e) ________________________________________________________________

Using a fluted filter paper, filter the reaction mixture directly into a crystallising dish. Wash the beaker with a little water and rinse the solid with a little water, all washing collected in the crystallising dish.
It is normal to heat this solution to evaporate some of the water the heat is continued until the volume is reduced to about a half the original volume and then crystal are obtained on cooling.


Q5 Why is the solution not heated until all the water has evaporated? ___________________



We are simply going to leave the solution for a week to allow the water to evaporate and the crystals to form.
After a week pour of any excess solution in the evaporating dish and dry the crystals on absorbent paper and the weigh using a watch glass.

Q6 Describe the crystals you have obtained ______________________________________________


Umm are you not meant to acc do the exp & then note down your observations?😂
Reply 13
Original post by Meduser
Umm are you not meant to acc do the exp & then note down your observations?😂

I know but I wasn’t in when they conducted the experiment .... 😂
Original post by AimXD
I know but I wasn’t in when they conducted the experiment .... 😂

Do you have any ppl in ur class you can ask aha?
Ok well for Q4 it’d be that effervescence stops and the solid stops dissolving. And I know that for Q6 the crystals should be blue as Cu2+ forms blue coloured compounds :smile:
Reply 15
Original post by Meduser
Do you have any ppl in ur class you can ask aha?
Ok well for Q4 it’d be that effervescence stops and the solid stops dissolving. And I know that for Q6 the crystals should be blue as Cu2+ forms blue coloured compounds :smile:

Alright I’ll see for the results, you’ve helped a lot thanks a lot
Original post by AimXD
Alright I’ll see for the results, you’ve helped a lot thanks a lot


No problem! I’ve been thinking about Q5 and I literally think it’s j so the max amt of crystals can be obtained & so that large ones form
Add a spatula measure of the copper(11) carbonate and stir with a glass rod

Q3. Note down your observations

Should have a green powder (CuCO3) reacting with H2SO4 to turn solution from colourless to blue because CuSO4 is formed and that is blue. Should've seen a gas being let off through bubbles (CO2) and fizzing i suppose.(All guesses from equation you gave). Beaker gets hotter because it is exothermic?

Keep on adding more solid copper in small amounts with stirring until all the sulphuric acid has reacted

Q4 What observations did you make to decide that the reaction was complete
No more bubbling, no more fizzing? Temperature began to decrease? Something to do with green powder (CuCO3) just sinking or not reacting idk.

Using a fluted filter paper, filter the reaction mixture directly into a crystallising dish. Wash the beaker with a little water and rinse the solid with a little water, all washing collected in the crystallising dish.
It is normal to heat this solution to evaporate some of the water the heat is continued until the volume is reduced to about a half the original volume and then crystal are obtained on cooling.


Q5 Why is the solution not heated until all the water has evaporated? No clue


We are simply going to leave the solution for a week to allow the water to evaporate and the crystals to form.
After a week pour of any excess solution in the evaporating dish and dry the crystals on absorbent paper and the weigh using a watch glass.

Q6 Describe the crystals you have obtained blue solid? lol
Reply 18
Original post by humayun.h
Add a spatula measure of the copper(11) carbonate and stir with a glass rod

Q3. Note down your observations

Should have a green powder (CuCO3) reacting with H2SO4 to turn solution from colourless to blue because CuSO4 is formed and that is blue. Should've seen a gas being let off through bubbles (CO2) and fizzing i suppose.(All guesses from equation you gave). Beaker gets hotter because it is exothermic?

Keep on adding more solid copper in small amounts with stirring until all the sulphuric acid has reacted

Q4 What observations did you make to decide that the reaction was complete
No more bubbling, no more fizzing? Temperature began to decrease? Something to do with green powder (CuCO3) just sinking or not reacting idk.

Using a fluted filter paper, filter the reaction mixture directly into a crystallising dish. Wash the beaker with a little water and rinse the solid with a little water, all washing collected in the crystallising dish.
It is normal to heat this solution to evaporate some of the water the heat is continued until the volume is reduced to about a half the original volume and then crystal are obtained on cooling.


Q5 Why is the solution not heated until all the water has evaporated? No clue


We are simply going to leave the solution for a week to allow the water to evaporate and the crystals to form.
After a week pour of any excess solution in the evaporating dish and dry the crystals on absorbent paper and the weigh using a watch glass.

Q6 Describe the crystals you have obtained blue solid? lol

Lol thanks for help I’ll see what my class mates got and try and round them up with the info you gave me thanks again 😂

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