Posted: 3/8/2011 8:15:05 PM EDT
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Hey, I need some help with my chem 1 quiz. I don't think we even covered this in lecture yet but I have about 3.75 hours left to complete this one problem.
question: Acid spills are often neutralized with sodium carbonate. For neutralization of acetic acid the equation is: 2 CH3COOH(l) + Na2CO3(s) ––> 2CH3COONa(aq) + CO2(g) + H2O(l) Calculate the DHrxn for this reaction. I honestly don't know where to begin with this question. |
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Quoted: Find deltaH of formation of all of the molecules used. Then its products - reactants. Reaction is also performing work on the atmosphere because a gas is created and liberated. Assume all the CO2 enters the atmosphere even though some will remain in solution. |
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Find deltaH of formation of all of the molecules used. Then its products - reactants. Reaction is also performing work on the atmosphere because a gas is created and liberated. Assume all the CO2 enters the atmosphere even though some will remain in solution. Kj, just how much schooling do you have and what in because I swear to god you are a genius! |
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Quoted: Quoted: Find deltaH of formation of all of the molecules used. Then its products - reactants. Reaction is also performing work on the atmosphere because a gas is created and liberated. Assume all the CO2 enters the atmosphere even though some will remain in solution. I'm fairly sure that would be included in the value of delta H formation of CO2 gas. Assuming the system is at 298K and 1atm. Or else the question would be asking about work performed by the system. I am assuming that this is for a chem 1 or chem 2 class. |
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Quoted: The chart in my textbook doesn't list CH3COONa but it does have Na+ (deltaH= -240.1) and CH3COO- (deltaH= -486). So am I correct with delta H being -726.1? I'm looking through notes now.. my book lists C2H4O2 (L) as -484.3 kJ/mol so you should use -486kJ/mol for your acetic acid ETA: OOPS just realized you were looking for CH3COONa and not CH3COOH |
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I think we should start by recognizing that we are trying to calculate the Change in Enthalpy for the chemical reaction.
another e.g.: http://www.chem.tamu.edu/class/majors/tutorialnotefiles/enthalpy.htm You'z gotz 'ta git yurself some tables a standard enthalpy data, like the CRC Handbuk er somp'in like dat der. Try to solve it like almost all problems are resolved today. Figure out the problem or at least the symptoms. keep Google-ing it until you you see enough similar examples to figure it out. 
and don't forget the enthalpy of "phase change" |
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Quoted: Quoted: Quoted: Find deltaH of formation of all of the molecules used. Then its products - reactants. Reaction is also performing work on the atmosphere because a gas is created and liberated. Assume all the CO2 enters the atmosphere even though some will remain in solution. Kj, just how much schooling do you have and what in because I swear to god you are a genius! He has schooling in 100% pure awesomeness. |
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Quoted: Ok let's see... 2CH3COONa + CO2 + H2O - 2CH3COOH - Na2CO3 2(-726.1) + (-393.5) + (-285.8) - 2(-485.8) -(-1130.7) -1452.2 - 393.5 -285.8 + 971.6 + 1130.7 = -2290.6 Sound about right?? Since Na2CO3 is also a reactant But I'm not sure if the value for CH3COONa is correct, it been a while since i had to figure those out. |
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Ok let's see... 2CH3COONa + CO2 + H2O - 2CH3COOH + Na2CO3 2(-726.1) + (-393.5) + (-285.8) - 2(-485.8) + (-1130.7) -1452.2 - 393.5 -285.8 + 971.6 - 1130.7 = -2290.6 Sound about right?? You are correct, I got -2292 but I was lazy in that I didn't include the decimals. |
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Find deltaH of formation of all of the molecules used. Then its products - reactants. Reaction is also performing work on the atmosphere because a gas is created and liberated. Assume all the CO2 enters the atmosphere even though some will remain in solution. Kj, just how much schooling do you have and what in because I swear to god you are a genius! He has schooling in 100% pure awesomeness. I'm really thinking he has schooling in bad ass mother fucker, stealing you women, and making mere mortals his bitches!  Out of all the ARFCOMMERs I would love to meet KJ I bet any question I had he could answer it.
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Sweet, thanks a ton guys this forum is the best. For the record, I got 0 out of 5 on the quiz but we use smartwork so no telling what caused it to be incorrect. Professor usually has to go through everyones again to fix grades anyways. That sounds fucked. What happened to in class quizzes? Thats all I get here at Oregon State.. |
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Quoted: Quoted: Quoted: Quoted: Quoted: Find deltaH of formation of all of the molecules used. Then its products - reactants. Reaction is also performing work on the atmosphere because a gas is created and liberated. Assume all the CO2 enters the atmosphere even though some will remain in solution. Kj, just how much schooling do you have and what in because I swear to god you are a genius! He has schooling in 100% pure awesomeness. I'm really thinking he has schooling in bad ass mother fucker, stealing you women, and making mere mortals his bitches! Out of all the ARFCOMMERs I would love to meet KJ I bet any question I had he could answer it.I'd want to meet him just to see if he rides a bike everywhere... even inside houses.
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Find deltaH of formation of all of the molecules used. Then its products - reactants. Reaction is also performing work on the atmosphere because a gas is created and liberated. Assume all the CO2 enters the atmosphere even though some will remain in solution. hahaha so there is something you're not an expert on! Thermodynamic identities! Enthalpy (H) includes the work creating a system. |
