CHEMISTRY COMMUNITY

Katelyn Li 2J

This question asks to draw the lowest and second lowest energy conformation Newman diagrams for 3-chloro-4,4,4-trihydroxy-3-methylbutanenitrile looking down the C2-C3 bond axis. Can someone please explain the arrangements? I understand why it's staggered, but not where to put everything.

Katelyn Li 2J

Could someone please explain how the last two examples (E-3,7-dimethylocta-1,3,7-triene and Z-3,7-dimethylocta-1,3,7-friend) are E and Z? I understand the concept of E (opposite sides) and Z (same side) but I'm not sure how this is applied in this case.

Katelyn Li 2J

I understand that if the first step in a proposed reaction mechanism is fast and the second is slow, we use the pre-equilibrium approach. But if the first step is slow and the second is fast, is the rate law of the first step also that of the overall reaction? As in, no further work is needed?

Katelyn Li 2J

In addition to the pages in the course reader that Dr. Lavelle (and an earlier comment) specified, he also said that the concepts that will be quizzed are kinetics (Reaction profiles, Arrhenius equation and calculating activation energies), thermodynamics and kinetics of organic reactions, and hydro...

Katelyn Li 2J

Could someone please explain why raising the temperature increases the rate constant of reactions with higher activation barriers more than it does the rate constant of reactions with lower activation barriers?

Katelyn Li 2J

Did you hear oxygen went on a date with potassium? It went OK.

Katelyn Li 2J

A blacksmith tempers a 1.45kg katana made of carbon steel to 314.0 C and dunks it into a large vat of room temperature water (25.0 C). Assuming all the heat is transferred to the water such that the sword ends up at 25.0 C, and the steam does not eat past its measured boiling temperature (100.0 C), ...

Katelyn Li 2J

The question asks to determine the potential of the cells. I'm confused on part c, where the cell diagram is Pt (s) | Cl2 (g, 250 Torr) | HCl (aq, 1.0M) || HCl (aq, 0.85M) | H2 (g, 125 Torr) | Pt (s) In the solutions manual, the pressures are in the numerator and the concentrations are in the denomi...

Katelyn Li 2J

The questions asks: For each reaction that is spontaneous under standard conditions, write a cell diagram, determine the standard cell potential, and calculate G for the reaction. I'm confused about part c, which is the reaction (c) Cr2O72 (aq) + 14 H (aq) + 6 Pu3 (aq) ---> 6 Pu4 (aq) + 2 Cr3 (aq) +...

Katelyn Li 2J

To expand upon the previous reply, think of the diagram of the cell we've been looking at in class. On the anode side, Zn2+ ions are produced and on the cathode side, Cu2+ ions are used up. Without a salt bridge, the transfer of electrons from one reaction beaker to another would cause the charge to...

Katelyn Li 2J

How come for example 9.14 in the reading (not the actual question at the end of the chapter), subtracting the standard Gibbs free energy of the reactants from the products does not give the correct answer? The example asks to "Calculate the standard Gibbs free energy of formation of HI(g) at 25...

Katelyn Li 2J

I had Dr. Lavelle last quarter as well and I remember the scoring for questions usually had 1 point specifically for correct sig figs.

Katelyn Li 2J

When doing problems regarding the standard enthalpy of a substance, the reactants are in their pure elemental forms. So although the reaction you used may be a possibility, given the context of the question, you would not want to use CO because it is a compound.

Katelyn Li 2J

The law utilizes the fact that enthalpy is a state function, meaning that it is pathway-independent. Taking this into account, it allows us to bypass irrelevant values to only find the sum of all changes.

Katelyn Li 2J

The following plot shows how the partial pressures of reactant and products vary with time for the decomposition of compound A into compounds B and C. All three compounds are gases. Use this plot to do the following: (a) Write a balanced chemical equation for the reaction. (b) Calculate the equilibr...

Katelyn Li 2J

With all the stress about finals coming up, I think it's important that we all think like a proton and stay positive! :)

Katelyn Li 2J

For part (d), it asks to write the formula for sodium bisoxalato(diaqua)ferrate(III). I wrote it in the order it was written in the name, that is, Na[Fe(C204)2(OH2)2], but in the solutions manual, it puts (OH2)2 before the (C2O4)2. Is there a reason for this or does it not matter too much?

Katelyn Li 2J

I hate when people reply to my texts with "K." Who wants to talk about potassium?

Katelyn Li 2J

For part 4Aii, it asks to draw and name the shape of XeF2 and give a bond angle. I drew the correct Lewis structure, but I'm confused as to why the shape is linear. I thought the side of Xe with two pairs of electrons would create more repulsive forces than the side with just one pair and result in ...

Katelyn Li 2J

The prefix Mega- for SI units indicates that it is 10^6, so 1 MeV = 10^6 eV. The mass of the neutron is given as 1.00866 g/mol, so you can first convert it to SI units, which would be 0.00100866 kg/mol. Then, divide by Avogadro's number to find the mass of a single neutron rather than an entire mole...

Katelyn Li 2J

For the last part of this question, it asks to draw the Lewis structure for H2C(NH2)COOH. How do you know what order to draw the structure in? I thought that for compounds like this, it was usually drawn in the same order it was written in, but the solutions manual puts NH2 on the far left. Also, ho...

Katelyn Li 2J

For question 2.39, it asks to determine whether the given electron configuration denotes an atom in its ground state or an excited state. I am fairly confident in determining the answers, but I am curious as to whether those configurations are actually possible, particularly in part (b). How can an ...

Katelyn Li 2J

When asked to write a balanced equation, are we required to specify the states of matter? For example, question 7 of the Fall 2015 quiz prep says to write a balanced equation for the combustion of CH3OH. I understand how to do the actual problem, but how can you tell what state of matter CH3OH is? I...

Katelyn Li 2J

I think in this case it should be 1.10 because that's the whole range of the potential speed.

For example, some object with a speed of 9 m/s and an uncertainty of plus or minus 1 m/s means it could be 8 m/s or 10 m/s. Therefore, the uncertainty would be 2 m/s.

Katelyn Li 2J

Just a clarifying question: Normally, if given the radius of an atom, we'd double it to find the diameter, which would then be used as the uncertainty of the position. In this case, because the question specifies that the uncertainty is 1% of the radius, it doesn't require us to double it. Is that c...

Katelyn Li 2J

I have another question about this problem, specifically part b. I worked it through and thought it required 4 sig figs, but when I checked the solutions manual, it was rounded to 3. Can someone explain why the answer is given with 3 sig figs?

Katelyn Li 2J

A photon walks into a hotel. The man at the front desk asks if he needs help with any luggage. The photon says, "No thanks, I'm traveling light."

CHEMISTRY COMMUNITY

Search found 27 matches

Winter 2014 Q6E/F

Example on Page 17 (Organic Textbook)

Fast/Slow Steps in Reaction Mechanisms

Re: Quiz 3 [ENDORSED]

Effects of Temperature on Rate Constant

Re: Post All Chemistry Jokes Here

Midterm 2013 Question 3A

Question on 14.37

14.23

Re: Salt Bridge?

Methods of Calculating Gibbs Free Energy

Re: Importance of Sig Figs

Re: HW 8.67 b) [ENDORSED]

Re: Hess's Law

Question on 11.89

Re: Post All Chemistry Jokes Here

Question on 17.31

Re: Post All Chemistry Jokes Here

Fall 2015 Midterm Question 4

Re: Fall 2013 Midterm Q4

Question on 3.41

Question about 2.39

Determining States of Matter in Reactions

Re: Quiz 1 Fall 2015 #3 [ENDORSED]

Re: Heisenberg Uncertainty Problem in A-V Module

Re: Fundamentals E.21: Amount in moles vs Number of molecules vs Formula units

Re: Chemistry Jokes