Hardest Balancing Equation Ever - Who Knows? AP CHEM

Test Preparation AP Test Preparation
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<p>Our teacher told us this is the hardest AP Chem equation balance question he's ever come across. He gave our whole class an hour to do with no success. I have the answer now, but would like to test CollegeConfidential's intelligence =). Lets seeee.</p>

<p>Copper (I) sulfide plus hydrogen nitrate yields copper (II) nitrate plus copper (II) sulfate plus nitrogen dioxide plus water.</p>

<p>Very hard.</p>

<p>I guess whoever gets it right deserves major bragging rights. Good luck!</p>

2

<p>Use a matrix.</p>

<p>It will take 30 seconds.</p>

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<p>Edit: Oh wait, nvm xD</p>

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<p>@keemosabi...a matrix?</p>

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<p>Cu(NO3)2 plays no role in the reaction but anyways....</p>

<p>CuS + 8HNO3 => CuSO4 + 8NO2 + 4H2O</p>

<p>that is not including the copper(II) nitrate, which has a coefficient of zero</p>

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<p>@keemosabi</p>

<p>How do you do a matrix?</p>

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<p>@ the gov</p>

<p>Why would it play no role? there are still Cu 2+ ions. CuSO4 is soluble too.</p>

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<p>OK, so I did some search on this matrix thing keemosabi was talking about. Using the matrix, I did balanced the equation in 30 seconds. </p>

<p>Cu2S + 12HNO3 ==> Cu(NO3)2 + CuSO4 + 10NO2 + 6H2O</p>

<p>Why didn't my chem teacher teach this???</p>

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<p>Suprisingly, you did get it right manatee. Mind sharing what you did? This would be very helpful! thankss</p>

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<p>I learned the matrix method from this website: </p>

<p>Balancing</a> Chemical Equations with a TI calculator | My Chemistry Tutor | High School, AP and College Chemistry Help</p>

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<p>oh ****, that is nuts!</p>

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<p>I've never seen anything like that before...</p>

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<p>Wait...what? (I totally didn't understand the site.)</p>

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<p>^OK, so the matrix method, long story short because I can't type all that in here:</p>

<p>Make two matrixes(spelling?). The website shows you how to do this.
Take the det of matrix A, which is det([A]) on the calculator
Then take the [A] ^ -1 ** det([A])
The numbers are the coefficients of the balanced equation.</p>

15

<p>OMG thanks for this matrix trick. I’d need it since I’d just failed (literally) my balancing eqns test. </p>

<p>But besides using matrices, what other MANUAL ways are there to figure out this balancing without using calculator?</p>

<p>(And I do realize that this thread is 3 years ago, so you guys who once took AP chem might have graduated from high school already…)</p>

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<p>I can’t figure this out either. I tried balancing like you would a redox equation, but I’m at a loss as to how to balance the H+ -> H2O half equation or otherwise add it into the other two balanced half equations.</p>