Chemistry Question (1 Viewer)

[Entity]

What mass of Zinc is formed when 0.2 mole zinc oxide reacts with excess carbon?

Ive tried working it out so many ways, and never get the answer that is in the back of the book. BoB says its 65.4 ...

Help me out here?

 

[ibbi00]

Can you write the question word for word?

 

[Entity]

What mass of Zinc is formed when 0.2 mole zinc oxide reacts with excess carbon?

Thats the exact question word for word.

 

[ibbi00]

ZnO + C → Zn + CO

1:1 mole ratio
Therefore, n(ZnO) = n(Zn) = 0.2 mole (as per the question)


n = m/M
m = n X M
m = 0.2 X 65.41
m = 13.082 g

Huh?

 

[riya03]

^Thats what i worked out too!

 

[Entity]

Thats what i worked out too. Thanks guys.

 

[silence--]

looks like they just put the molar mass of zinc as the answer. correct answer(s) are above

 

[mcromancer]

In the new version of conq. chem. the answer is 13.082.
Mustve been a error in the older book.

 

[Entity]

Just so i dont have to create a new thread,

Copper is extracted froma common orse, chalcocite (Copper(I) Sulfide) by roasting in the ore in air. When 15.3g chalcocite was so treated, 11.3g copper was obtained. What is the percentage yield of the process?

I have no idea how to do this, I tried just about everything I could think of. Im probably overthinking it, but how do you do it?

 

[mcromancer]

Cu2S + O2 -> 2Cu + SO2

n(Cu2S) = m/M
= 15.3g/(2x63.55+32.07)
= 0.096mol

2 mole of copper is produced from 1 mole of chalcocite.

Copper = 2 x 0.096 x 63.55
= 12.2016g

% yield = 11.3g/12.2016 x 100
= 92.6%

 

[Entity]

How very logical. Thank you very much.