CHEMISTRY COMMUNITY

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Can neo- and tert- be used interchangeably? I know tert refers to when C is attached to 3 other carbons and neo has the formula C(CH3)3. It looks the same...

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What is the priority in naming/ numbering organic substances? Do we give the lowest numbers to bond first, then the functional groups, then the other substituents? What if there are double bonds, functional groups and other substituents (such as methyl and ethyl) in one molecule? Is different priori...

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When we number off the carbons for a cycloalkene or cycloalkyne do we give the lowest number to the functional group (for example if we see ether) before numbering the location of the double/triple bond?

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What's the difference between using the systematic, common, and IUPAC name? Does common naming involve only ISO-, Neo-, sec-, and tert-?

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Why Is the answer to 6A of final 2013 1,5,5,6 tetramethylcyclohex-1-ene and not 2,3,4,4 tetramethylcyclo-hex-ene? I thought that the double bond determines where 1 is and then we start counting based on what gives the 2nd substituent the smallest number.

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Why is it easier to make and manipulate 5 and 6 membered rings than it is to make larger rings directly?

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How do we know that we are cooling NO and NO2 to 298 K and not cooling NO2 for the first step?

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When drawing Lewis structures (#7-10 of chapter 4) how do we know where to place the negative charge? For example: 7) why is the negative charge on S in SCN^-? 8) S2O3^-2 why is there a negative charge on each of the single bonded oxygens? 10) N3^- why is there a positive charge on one of the nitrog...

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For 7B of the winter 2009 final, how do we know where on the molecule to place the DOUBLE bond?

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How do you know whether a reaction is more and less likely to occur at rm temp?

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When drawing reaction mechanisms, how do we know whether to draw the molecules in 3D (as done in the solution) or 2D? Does it matter?

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In what cases would we use the ending -ylium?

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How do we know whether we need to draw the 3D structures of molecules when drawing its reaction mechanism? And when to draw 2D when doing reaction mechanisms? Fall 2008 5C

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How do you know that chrome is the anode and copper is the cathode when the standard potentials are not given?

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Are we allowed to use the model kit on the exam?

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Why does NO have a higher residual entropy than BF3?

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Why is the heat capacity higher for ethane than ethene?

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Why does the cell voltage INCREASE when Na2S solution is added to the Pb2+ and PbS forms

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In general, how can we draw Newman projections without using model kits? For example, how would we approach problems such as 8A of the 2007 final? Question 8A on the 2007 final states: "Draw a Newman projection for the most stable conformation of 2, 3-dimethyl-pentane looking down the C2---C3 a...

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Question 6B on the Winter 2007 Final Exam states: "Draw a structure which clearly shows the most stable conformation for 1-ethyl-1-isopropylcyclohexane." Why is ethyl placed in the axial direction and isopropyl equatorial direction? Why can't ethyl be placed in the equatorial direction and...

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What is the difference between equatorial and axial? How can we demonstrate these two characteristics in a diagram?

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Does it matter where we place the hydrogens on each carbon atom of different conformations? In other words, do we have to place each hydrogen atom exactly as the book does for each conformation? (same angle and orientation)

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When we draw the newman projection for molecules such as 1-bromo-2-cholorethane, how do we know the placement of each atom on the tetrahedral?? for example for 3.6, when drawing the newman projection how do we know that the bromine atom will be on top with the two hydrogen atoms pointing downwards? ...

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Who do we go to if we think we found a grading mistake on the midterm?

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why is 1. 9C isopentane when the longest chain has only 4 carbons?

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How do we determine what the lowest combination of numbers we need to use when naming? For example: for 1.21: why is it 5-methylcyclopenta-1,3-diene and not 3-methylcyclopenta-1,4-diene? clearly 3 is less than 4. My question is in regards of naming all kinds of compounds, not just the cyclo-. Is the...

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What is the difference between the unique reaction rate of a reaction and a reaction rate? I thought that you divide by the stoichiometric coefficient only when we are asked for the UNIQUE reaction rate. How come for number 1 of quiz two, they divided by the coefficient even though it didn't ask for...

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Why will the amount of starting material decrease by a factor of 8 after 3 half-lives in a first order reaction? What equation am I looking at and how can I relate it to this problem?

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I understand that kinetics deals with the rate of a reaction and thermodynamics deals with whether the rxn is forward or backwards. However, what does it mean to be kinetically stable/unstable and thermodynamically stable/unstable?

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How do you determine which is the slop step in a multistep reaction? 14.91

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What is kinetic data? How do we determine the conditions under which to use kinetic data? (14.89)

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How do you know that a reaction might be radical chain initiating? (14.77) What exactly does it mean to be radical chain initiating

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Yes, delta H sub c does stand or enthalpy of combustion

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delta G

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1) what if I'm dealing with delta S= (CdeltaT)/T and delta S = Cln (T2/T1)? (notice both equations don't have n). Which equation do I use then to calculate entropy when temperature is changing? 2) Again: For question 4 of midterm 2007, the second equation was used, however, for the past chem quiz (w...

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when can we use delta S=(nCdeltaT)/ T and delta S=Cln (T2/T1)? For question 4 of midterm 2007, the second equation was used, however, for the past chem quiz (which had the same question just different numbers) the first equation was used. I tried using the first equation for 4 of midterm 2007 but go...

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why would raising the temperature favor the formation of reactants when the equilibrium constant is smaller in comparison to another equilibrium constant? isn't K = products over reactants? if K is smaller then there would be more reactants. Therefore, shouldn't there be an increase in products?

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Is delta U = to delta H only when the number of moles of gases do not change, the volume does not change, and pressure is constant?
If the number of moles do change, but the volume is still constant we need to use: delta U = delta H - delta n R T right?

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Is the internal energy zero for an irreversible path too? When exactly is delta U zero?

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Is the internal energy of an ideal gas expanding reversibly zero?

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How do we recognize when a substance is in its standard state? (aka in its purest form?) Is there a particular chemical equation?

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What is the difference between Q and K. How come sometimes we solve G using Q and other times K?

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How do you determine the microstates a molecule has without having to draw all the different configurations of it? why is W (degeneracy) = 2^N? why is there a 2??? is there more than one way to figure out W?

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Why does reduction take place at the electrode with higher concentration? (13.99)

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How do you know whether the products or the reactants will be favored in terms of E (knot), G(knot), and any other way we can determine which side is favored? When we say the product is favored does it mean the reaction prefers a forward reaction to produce more products or that there are more produ...

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Why can't we assume the reaction is under constant pressure? The question states that the volume is changing...

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Midterm 2012 number 5. A system undergoes a two step process. In step one it absorbs 50 J of heat at constant volume. so internal energy is 50J. in step 2 it releases 5 J of heat at 1 atm and it is returned to its ORIGINAL internal energy. The internal energy for step 2 is -50J. Why is it negative?

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What is the difference between E(knot) and E? Is E zero in a concentration cell or E(knot)?

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Why does the internal energy change signs when the process returns to its original internal energy?

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What equation can we use to calculate the K value given only the Eknot value and n? (Midterm 2011 7&8 C)

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Do we use C=3/2R only when there is constant volume? If so, why is that 3/2R was used to calculate entropy when the volume of nitrogen gas at 3 L is compressed suddenly (and irreversibly) to .500 L by driving in a piston? This is occurring in an internal combustion engine and the temperature of the ...

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How do we know that when finding the Q value for a concentration cell (using the Nernst eq) we need to divide the concentration of the anode by the concentration of the cathode? How did they come up with that ratio? the cell is Ag(s)l Ag+(aq)llAg+(aq)l Ag(s).

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How do you determine the oxidation number for Mn and NO on the product side for the following?
1) MnO4^- +8H^+ + 5e---> Mn^2+ +4H2O
2) NO3^- + 4H^+ 3e ---> NO + 2H2O

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What is happening in a voltaic cell? Why would the cell potential increase with the addition of ions? Why would a forward reaction increase cell potential? (winter 2007 midterm question 5B)

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Question in midterm: In a neuron the concentration of K+ ions inside the cell is about 20-30 times greater than the outside. What potential difference between the inside and the outside of the cell would you expect to measure if the difference is due only to the imbalance of potassium ions? My quest...

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Why is the standard cell potential 0 in a concentration cell? And what is happening in a concentration cell?

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What is the concept behind internal energy? What exactly are we solving for and how does it affect the system when there are changes in volume, temperature, and pressure?

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When do we add an inert metal (ex: Pt) to a cell diagram? Why do we add it?

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My TA said that professor Lavelle posted a chart on how to name coordination compounds. Where can we find that chart?

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