A 200g bar of Zn is reacted with 1200 mL of a 1.5M solution of Cu(NO3)2.?

Question

The reaction occurs in this form:
Zn(s) + Cu(NO3)2(aq) --> Zn(NO3)2(aq) + Cu(s)

-What is the net ionic equation?
-Calculate the # of moles of Cu(NO3)2 present.
-What is the mass of Cu(s) produced by this setup?
-If this reaction is repeated, this time with a large quantity of Cu(NO3)2 solution, how much Cu(s) will be produced?

Thanks! I was stumped by this question...

Answer 1

Wow it's been a while. Let me give this a shot.
a) Look for the changes in "charge", or "oxidation state", and include those.
Only the oxidation states for Zn and Cu change here. Both sides of the equation also have equal charge, so don't need to do anything else complicated to the ionic equation like adding electrons.
Zn(s) + Cu2+(aq) --> Zn+2(aq) + Cu(s)

b) 1.5 X 1.2 = 1.8 moles

c) Trick question.
First find number of moles of Zn.
200 / 65 = 3.08 moles.

Since from the equation, 1 mole of Zn reacts with 1 mole of Cu, and there are more moles of Zn (3.08) than Cu (1.8), then only 1.8 moles of Cu will be produced.

1.8 moles of Cu weigh: 1.8 X 63.5 = 114.3 g

d) If you use a large quantity of Cu(NO3)2, then you will have more moles of Cu(NO3)2 than Zn. So the Cu you can get is at most 3.08 moles, since that's the max you can get, provided all the Zn you have (3.08 moles) react.

Cu(s) produced = 3.08 X 63.5 = 195.58 g

Hope I didn't make any mistakes - it's been years. Good luck!

Answer 2

Zn + Cu++ +2NO3-... ----> ...Zn++ + 2NO3- + Cu

1.5 M * 1.2 L = 1.8 moles of Cu(NO3)2

The limiting reagent is Cu(NO3)2, since one mole of Zn will react with one mole of Cu(NO3)2 and will produce one mole of Cu, and 1.8 moles of Cu(NO3)2 will produce 1.8 moles of Cu. The atomic mass of Cu is 63.55, then 1.8 moles is 114.39 grams (1.8*63.55).

If the quantity of Cu(NO3)2 is large enough so that the Zn is the limiting reagent, and the atomic mass of Zn is 65.38, so 200g is 3.06 moles. Thus 3.06 moles of Cu will be produced which will have a mass of 3.06*63.55 = 194.5 grams of Cu