CHEMISTRY COMMUNITY

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Sorry, I wasn't sure where to put this question for chem 14b but for Ka and Kb will we be expected to know the general equations including HA and A?

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Why do you add lnA at the end of the Arrhenius equation? other than to make a linear plot, like other than for graphing purposes?

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when finding the rate law and after you solve for the intermediate do you always put the coefficient of the product?

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For the first order reaction cyclobutane (g)  2 ethylene(g) at 800K, the half-life
is 0.43 seconds. Calculate the time needed for the concentration of cyclobutane
to fall to 1/64 of its initial value.

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Calculate the time required for the concentration of N2O(g) to decrease from
0.75M to 0.33M. The rate constant for the reaction is k= 6.8 x 10-3 /s

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What is the most efficient way to determine the order of a reaction and what does that information tell you?

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I know chemical kinetics is used to analyze the speed or rate of a reaction but can it be used to analyze spontaneity?

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So I understand that both the Porous Disk and Salt Bridge are used to transfer ions but is one more efficient than the other? If so, why? Just curious

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In a concentration cell, why is the Ecell always 0?

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When making a cell diagram do you include gasses and liquids? Especially liquids like H2O, and the reactants are in aqueous form? Like isn't it implied that there is water on both sides on the reaction, so we shouldn't put it?

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Can someone explain why the charge is negative again? Also why is it the maximum work for this equation?

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Do standard oxidation potentials exist? If so, why don't we use them? Is it because of the equation? Would things become more complicated?

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Today Lavelle stated that when the standard reduction potential is positive that the reactant is favorable. Did I understand this wrong? Can someone explain please?

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Dr. Lavelle mentioned that when using the ln K2/K1 equation you must assume that entropy and enthalpy are both constant. If these assumptions are not true is there a different equation? or are they always true...?

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For the equation G=-RTlnK
when K<1 then G is positive which means R>P right? (non-spontaneous?)
and when K>1 then G is negative which means R<P right? (spontaneous?)

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Can someone please explain the G=G+RTlnQ equation please. Lavelle wrote Q is reaction quotient not K, is he just emphasizing that its not at equilibrium? I thought it was....?

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In a problem in which there is constant pressure, mols are given as well as the heat of the asks for the change in enthalpy, why would you divide the the heat by the mols?

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In lecture Lavelle did an example using four carbon monoxide molecules and mentioned that there is no translational/rotational movement and I was wondering what else must be stagnant for this system to have residual entropy?

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In lecture, Lavelle said that if the change in internal energy or the change in enthalpy were negative, we could ask if the reaction could be predicted to occur. He also mentioned that we could question if the reaction would be spontaneous and that it was likely to be. How would we know that/figure ...

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Will we ever have to do Hess's law problems in which we consider the changes in temperature?

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The literal definition for enthalpy of formation is that 1 mol of a compound is formed from pure elements in their stable form. My questions are does it always have to be 1 mol of the product, and are we meant to memorize the standard forms of all elements?

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So when calculating bond enthalpies the final answer will be an enthalpy of formation, correct? So I know that bond enthalpies are always positive, but the formation can be pos or neg based on if the number of reactants/products, right?

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Why is it reactants minus products when solving for the enthalpy of the reaction using bond enthalpies?

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Will the values for bond enthalpies between atoms always be positive?

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Can someone please explain how the reversr rxn for fusion is exothermic please.

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When are the concentration of hydronium and hydroxide equal? when in pure water?

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If a question asks how the system would be affected after adding a certain concentration (molarity) is that different from adding say grams? please explain difference abnd how you would answer.

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Is the pressure lower when there are less mols because they are less collisions? or why?

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Can someone please explain Charles’s law in depth.

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On page 151 of the 6th edition of our textbook there is an equation: P=dhg which solves for the pressure of a gas based on the height of a column of liquid and its density and gravity. I was wondering if we would need to know this calculation, if so can someone please explain it in depth because the...

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We discussed how liquids that were used as solvents were not to be included in solving the chemical equilibrium constant because at the beginning and end of the rxn there was an insignificant change to the volume, what about those liquids in rxn that are not solvents?

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In lecture we discussed how liquids and solids were not included in the chemical equilibrium equation because they were pure substances. Can someone please explain why gases are not pure substances.

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In the VSEPR formula, would you apply a radical as a "lone pair"

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When determining hybridization, do radicals count as regions of electron density?

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When dipole moments cancel that means that the molecule is nonpolar correct? Also, since dipole moments have the same magnitude (right?) the only way to cancel them is by direction, right? Is there any other way for them to cancel?

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Will we learn how to draw the sigma and pi bonds? Will this be on the test? Can someone explain how they intersect and what it means?

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This subject won't be on the test, correct? Also when will we learn molecular orbital theory?

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could you determine the geometry of a molecule (VSEPR) if given only its hybridization? if given its hybridization and another aspect? if so what aspect?

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why does hybridization exist?

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In hybridization, when combing the s, p and d block where does that hybridization fall in terms of energy compared to the regular electron configuration ?

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How does VSEPR work for the transition metals? Does it still apply?

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How does VSEPR work for isoelectric species? Does it still apply?

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When drawing the lewis structures on the test and using the wedges, if we "misplace" an axial or equatorial atom will that be a major mistake?

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This may be the wrong section to ask this question... However, in my discussion section, we were learning about Lewis acid and bases and my TA did an example with Al+3 and H20. He was saying that for the structure you would need 6H20 molecules and then he drew it and it was very confusing. If anyone...

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Can someone explain permanent dipole moments to me please? As well as their importance

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In discussion section, we went over how charge and volume are the factors that determine the "polarizing power" or a cation or the "polarizability" or an anion. In this list of ions, which would have the greater "polarizing power"? Please explain :)

Rb+, Sr+2, Be+2

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Just curious, but when Lavelle says that resonance is the average of the arrangement of atoms with different arrangements of electrons, how would this be shown? Is it only with the double-sided arrows? Or with line structures like he showed with Benzene?

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In class Lavelle referred to pi and sigma bonds when discussing resonance but never really went into much detail. Can anyone explain what each refers to?

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In class, Lavelle said that the most stable structure for a sulfate ion is with two double bonds because the formal charge matched the given charge of the ion. If this is so, why wasn't the first structure we created (with only single bonds) as stable? Is it because the FC values for the two double ...

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If you're comparing P^-3, Cl^-, S^-2, which would have the smallest ionic radius? Would you have to compare their protons at this point?

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In the D-block, when we write the 3d before the 4s, that means that electrons come from the 4s orbital when ions are formed right?

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Can someone explain to me again how to add up the electrons in a compound like Lavelle did in class with SO4^-2 please

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Does the superscript in configurations (2s^2) correlate to how many electrons can be in that orbital?

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How do you know which value (-1,0,1) corresponds to the axes px,py,pz? Will these be on the test: determining which axes.

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How does one determine whether or not values calculated for uncertainty of velocity or position are realistic? How does one know they are realistic?

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Also in an experiment, how would one alter the wavelength and frequency of light?

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In the photoelectric experiment shown to us in class the source of energy was light. Could another source of energy be used and produce the same or similar outcomes (a similar amount of electrons emitted)?

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Just to clarify, in the equation: E=hv
as well as in the photoelectric experiment, the energy of per photon is reliant solely on the frequency?

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In high school, for tests we were told to make sure that all our answers were in MKS (meters, kilograms and seconds) or just in SI units in general. For Lavelle’s exams are there specific units that he expects all answers to be converted to?

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In the equation: E= -hR/n^2 (solves for the energy of electrons as a function of n)
What are the variables and how do they contribute to finding the energy of the electron?

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When beginning to find the empirical formula, do you always start with the mass percentage composition if it is not given?

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