Please post any questions related to the 2011 & 2011B exams as comments below. Scoring guidelines are on the documents page of your website.
6 comments:
Anonymous
said...
For Exam 1, Part A, #3a, would the standard enthalpy change be the same as the molar enthalpy of formation? I thought that "standard" means for one mol of the product, just like the molar enthalpy of formation. I also thought that we would need the heats of formation of everything in the reaction to find the standard enthalpy change, but that's not given to us...so would the answer be the same as the given molar enthalpy of formation?
For Exam 1, Part A, #1, do you include H20 in the Ka and Kb expressions? I know you would not normally, but in this case the H20 cannot be ignored because you absolutely need it as a reactant to form OH- or H30+. So do you include it in the denominator of the expression? If so...I'm confused as to how to find the initial concentration of the water.
... p. 495 in AP chem textbk which you said was better than the red one Chem 1 used last year AGREED:D " Dalton's law of partial pressures requires the total pressure and either the partial pressures of the other gases or their mole fractions." No using mol ratios (what I use to call stoichiometry) at equilibrium because of Kp right?
6 comments:
For Exam 1, Part A, #3a, would the standard enthalpy change be the same as the molar enthalpy of formation? I thought that "standard" means for one mol of the product, just like the molar enthalpy of formation. I also thought that we would need the heats of formation of everything in the reaction to find the standard enthalpy change, but that's not given to us...so would the answer be the same as the given molar enthalpy of formation?
For Exam 1, Part A, #1, do you include H20 in the Ka and Kb expressions? I know you would not normally, but in this case the H20 cannot be ignored because you absolutely need it as a reactant to form OH- or H30+. So do you include it in the denominator of the expression? If so...I'm confused as to how to find the initial concentration of the water.
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... p. 495 in AP chem textbk which you said was better than the red one Chem 1 used last year AGREED:D " Dalton's law of partial pressures requires the total pressure and either the partial pressures of the other gases or their mole fractions." No using mol ratios (what I use to call stoichiometry) at equilibrium because of Kp right?
Last attempt 5 hr to go if V and T is same so P is proportional to n something like that? Whatever!!
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