Chemistry Pract Assessment (1 Viewer)

[mohppp07]

Hi,
I have to design a practical to calculate the chemical composition of Zinc in a mixture of ZnCO3, Sand, and soluble salts.
I know I need to dissolve it in HCl but idk how much, can someone helpme plz.

 

[wizzkids]

Well, there are lots of possible approaches to determine the percentage by mass of zinc in such a mixture. I presume that is what you are being asked to do. Are you actually going to do this, or are you just designing the method?
Easiest Method.
ZnCO₃ is almost insoluble in pH 7 water at room temperature.
SiO₂ is also insoluble.
Does that hint give you a clue?

 

[Eagle Mum]

Can you assume that the only zinc present is as ZnCO3 (ie. there’s no zinc in the unknown soluble salts)?

 

[wizzkids]

Can you assume that the only zinc present is as ZnCO3 (ie. there’s no zinc in the unknown soluble salts)?

That's a good question. There is insufficient information to rule that out. The student probably shouldn't assume there is no Zn in the soluble salts. They are probably doing Year 11 Chemistry, and they are probably up to Module 2, "calculate percentage composition'. I would expect the teacher to map the task to the Year 11 syllabus, but who knows?

 

[Eagle Mum]

OP, if not already stated in the task description, state that the designed practical is "to find the chemical composition of zinc in ZnCO3 of the given mixture". Any thing else would be unreasonably difficult.