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Balancing given redox reaction and calculating percent yield

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#2. Balance the redox equation for the reaction of Cu and HNO3 giving NO2 directly.

#3. Copper dissolves in nitric acid, producing copper (ll) nitrate.

After reaction with sodium hydroxide and heating, copper nitrate changes to copper (ll) oxide.

Calculate the percent yield of this process if 1.235 g of copper produced 1.235 g of copper oxide. Show your calculations.

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#2. Balance the redox equation for the reaction of Cu and HNO3 giving
NO2 directly.
At anode,
Cu ---> Cu2+ + 2e-
at cathode,
2e- + 4H+ + 2NO3- -----> 2H2O + 2NO2

now, add both the half reactions together

Cu + 4H+ + ...

Solution Summary

Balancing given redox reactions and calculating percent yield is presented in the solution.

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See Also This Related BrainMass Solution

Chemical Reactions

Writing Reactions,Write balanced molecular equations for the two reactions you performed and the five reactions in the video (http://www.youtube.com/v/i-HHvx1VC_8&hl=en). Keep the following in mind:
- select the type of reaction.
- include all state symbols like (s), (l), (g), or (aq).
- Type NONE if there is no total or net ionic equation for the reaction.

(A) CuSO4(aq) + Al(s) --> ?
reaction type
• Molecular =
• total ionic =
• net ionic =

(B) CuSO4(aq) + CaCl2(aq) --> ?
reaction type
• Molecular =
• total ionic =
• net ionic =

(C) Watch the video (http://www.youtube.com/v/i-HHvx1VC_8&hl=en). Pause it as necessary. Write the appropriate reactions as you did for A and B. Type NONE if there is no total or net ionic equation.
i) Cu(s) + S(g) --> ?
reaction type
• Molecular =
• total ionic =
• net ionic =

ii) Ca(OH)2(s) --> ?
reaction type
• Molecular =
• total ionic =
• net ionic =

iii) Fe2O3(s) + Al(s) --> ?
TIP: What state is indicated by 'molten'?
reaction type
• Molecular =
• total ionic =
• net ionic =

iv) KI(aq) + Hg2(NO3)2(aq) --> ?
TIP: Mercury(I) actually forms a dimer and is typically found as Hg2+2. Treat it like a polyatomic ion.
reaction type
• Molecular =
• total ionic =
• net ionic =

v) CH4(g) + O2(g) --> ?
reaction type
• Molecular =
• total ionic =
• net ionic =

Results

For the following calculations, please note that you are starting with the hydrates of copper(II) sulfate (CuSO4.5H2O) and calcium chloride (CaCl2.2H2O). The waters will not affect the reactions, but they do affect the molar mass of the substance and therefore the moles of substance.

Reaction A
Calculate the theoretical mass of copper for Reaction A. (**Keep 2 significant figures here so that we can avoid rounding issues...Previously, I stated "round this mass to one decimal place since that is all the digital balance can measure" but that is not working.)

Calculate the percent yield of copper for Reaction A to two significant figures.

Reaction B
Calculate the theoretical mass of precipitate for Reaction B. (**Keep 2 significant figuress here so that we can avoid rounding issues...Previously, I stated "round this mass to one decimal place since that is all the digital balance can measure" but that is not working.)

Calculate the percent yield of precipitate for Reaction B to two significant figures.

List at least three errors that may have affected the percent yield.

Video Reactions - Observations
Describe each reaction. (What were the ways that you could tell a reaction was taking place? List the evidence for each reaction.
i) Cu(s) + S(s) --> ?
ii) Ca(OH)2(s) --> ?
iii) Fe2O3(s) + Al(s) --> ?
iv) KI(aq) + Hg2(NO3)2(aq) --> ?
v) CH4(g) + O2(g) --> ?

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