What factors would cause the percent yield to be HIGH? Select all that apply.
a. The recovered copper containing copper oxide from exposure to the air
b. Recovered copper being wet
c. The recovered copper containing unreacted zinc
d. Using too much nitric acid to react with the copper wire
e. Adding too much zinc to the copper(II) sulfate
2007-01-28 06:29:44 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
My classes do a lab similar to this one. They have found that these things are the most common errors:
a) Sometimes they wait too long to get their final mass, and the copper has time to oxidize. If they try to warm the product to evaporate the water they can actually cause the copper to oxidize more.
b) If the copper is not dried completely it will contain water which adds to the mass.
c) This is the most common problem for my students. They do not dissolve all of the Zn, so it adds to the final mass.
D) This is a problem if they are not careful to make sure the reaction has proceeded to completion. However, this tends to give them a lower %.
2007-01-28 06:42:04 · answer #1 · answered by physandchemteach 7 · 0⤊ 0⤋
I'm assuming you mean the copper cycle experiment, where you dissolve copper by reacting it with nitric acid, taking it through a series of compounds, then going back to copper metal.
a, b, c, and e can all lead to percent yields that are too high, though e can usually be eliminated if you add enough non-oxidizing acid to react any unreacted zinc. d won't make a difference.
2007-01-28 06:42:36 · answer #2 · answered by TheOnlyBeldin 7 · 0⤊ 0⤋
A I think I'm not sure I don't remember Chemistry class that well.
2007-01-28 06:39:49 · answer #3 · answered by Anonymous · 0⤊ 0⤋
ABC Just submitted and it is correct!
2015-02-17 08:33:46 · answer #4 · answered by ? 1 · 0⤊ 0⤋
not enough info, sorry
2007-01-28 06:34:25 · answer #5 · answered by Ken M 2 · 0⤊ 0⤋