Search found 24 matches

by Shreya Banerjee 2F
Tue Mar 08, 2016 3:54 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Cis vs. Trans
Replies: 1
Views: 312

Re: Cis vs. Trans

Yes, if it is a trans conformation where both substituents are in the equatorial position. If they are both in the equatorial position, it makes the conformation more stable than the cis conformation, where one substituent is in the equatorial position and the other is in the axial position. On the ...
by Shreya Banerjee 2F
Tue Mar 01, 2016 11:36 am
Forum: *Organic Reaction Mechanisms in General
Topic: Organic 4.28
Replies: 1
Views: 362

Re: Organic 4.28

The first step involves breaking the double bond in the propene, breaking the bond in the hydrogen bromide, and bonding the hydrogen to a carbon. That is why the first transition state has dotted line between the hydrogen and carbon, bromine and carbon, and a dotted line on the double bond (because ...
by Shreya Banerjee 2F
Mon Feb 29, 2016 5:23 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Drawing Reaction Profile based on only the mechanism
Replies: 1
Views: 359

Drawing Reaction Profile based on only the mechanism

How can we look at the reaction and determine how to draw the reaction profile? For example, how can we determine whether the reactants or products have higher free energy by only looking at the reaction mechanism? And if it is a multistep reaction mechanism, how do we know which transition state ha...
by Shreya Banerjee 2F
Sun Feb 28, 2016 11:09 am
Forum: Second Order Reactions
Topic: given half life, calculate time needed
Replies: 3
Views: 871

Re: given half life, calculate time needed

I think the solution manual calculated k because you need to use it eventually (for part c) and it was just easier. You can calculate it the way you said, though, I think the manual just chose to do it that way because you need k to calculate the time it takes to get one fifth of the concentration.
by Shreya Banerjee 2F
Sat Feb 20, 2016 11:07 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Pre-Equilibrium
Replies: 1
Views: 316

Re: Pre-Equilibrium

You should use it any time your slow step has an intermediate that is not present in the overall equation. Your rate law comes from the slow step of your reaction, but if it doesn't match with the overall reaction, you need to use the value of K to "cancel" it out.
by Shreya Banerjee 2F
Sun Feb 14, 2016 4:57 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Spontaneous
Replies: 1
Views: 310

Re: Spontaneous

It depends on what the graph looks like. In a graph that plots the free energy of the products versus the free energy of the reactants, you can tell whether the reaction is spontaneous based on whether the free energy of the reactants is higher or lower than the free energy of the products. If the f...
by Shreya Banerjee 2F
Sat Feb 06, 2016 6:06 pm
Forum: Balancing Redox Reactions
Topic: Oxidizing and Reducing Agents vs. Half Reactions
Replies: 1
Views: 273

Re: Oxidizing and Reducing Agents vs. Half Reactions

It's a bit confusing, but the reducing agent is the one that loses the electrons (causing the other species to be reduced) while the oxidizing agent is the one that gains electrons (causing the other species to be oxidized). So the oxidizing agent is the compound that is reduced and the reducing age...
by Shreya Banerjee 2F
Tue Jan 26, 2016 2:14 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Practice Quiz #1 Question
Replies: 1
Views: 293

Re: Practice Quiz #1 Question

We change the sign because we want the system to return to its original internal energy, meaning we want \Delta U to be equal to 0 overall. Because we already calculated that 158 J were lost from the system (therefore it is negative), we have to put an equal amount back into the system (so we make t...
by Shreya Banerjee 2F
Sat Jan 23, 2016 6:48 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: How to find enthalpy of rxn using enthalpies of formation?
Replies: 2
Views: 345

Re: How to find enthalpy of rxn using enthalpies of formatio

It does include all the reactants and products, but the rest of them are elements. The molar enthalpy of an element is 0, so it doesn't have to be included in the calculation. The book solution omitted nitrogen and oxygen because their enthalpy is 0 and wouldn't contribute anything to the answer.
by Shreya Banerjee 2F
Sun Jan 17, 2016 3:03 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Question 8.25, what is this even asking?
Replies: 2
Views: 401

Re: Question 8.25, what is this even asking?

The problem wants you to calculate the change in internal energy when you mix those substances together (HBr and KOH). It gives you the change in temperature at the beginning of the problem because it wants you to factor in the heat absorbed by the calorimeter when you do the calculation.
by Shreya Banerjee 2F
Sun Jan 10, 2016 10:34 am
Forum: Phase Changes & Related Calculations
Topic: change in enthalpy value
Replies: 3
Views: 364

Re: change in enthalpy value

You change the sign of the enthalpy value whenever you reverse the equation.
by Shreya Banerjee 2F
Thu Dec 03, 2015 11:14 am
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Henderson-Hasselbach equation
Replies: 1
Views: 417

Re: Henderson-Hasselbach equation

You can only use the Henderson-Hasselbach equation when you have an weak acid and its conjugate base, or a weak base and its conjugate acid. Usually, that means a buffer, but you can use it any time you have those conditions. When you have anything else, it's usually easier to just use the ICE table...
by Shreya Banerjee 2F
Sun Nov 29, 2015 10:25 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Strong acids
Replies: 1
Views: 339

Strong acids

In the course reader, there are six strong acids listed. However, in the textbook, chloric acid is listed as a stronger acid than nitric acid (which is on the list in the course reader). Are we supposed to consider chloric acid a strong acid?
by Shreya Banerjee 2F
Thu Nov 26, 2015 6:43 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Sig Figs for calculating pOH and pH
Replies: 1
Views: 631

Re: Sig Figs for calculating pOH and pH

You do consider sig figs in calculations, but there are some different rules when you have calculations that include logarithms and exponents. The number of sig figs in your answer will be the number of decimal places in your exponent or logarithm. For example, if you have 10 -4.364 , your answer sh...
by Shreya Banerjee 2F
Tue Nov 17, 2015 1:43 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure
Replies: 2
Views: 517

Re: Pressure

Yes, the system would move to favor the side with fewer moles of gas. In your example, the concentration of both the reactants would increase and the concentration of both the products would decrease. If there are multiple compounds on the favored side, all of the compounds will increase in concentr...
by Shreya Banerjee 2F
Sat Nov 14, 2015 2:58 pm
Forum: Naming
Topic: Order when writing compounds
Replies: 2
Views: 277

Re: Order when writing compounds

When you write the the formula of a compound, the ligands should also be in alphabetical order, just like when you write the names. So, for the example you gave, CN would come first because alphabetically C comes before H.
by Shreya Banerjee 2F
Sat Nov 07, 2015 10:19 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Difference between Q and K
Replies: 3
Views: 511

Re: Difference between Q and K

K is the ratio of those concentrations at equilibrium. Q is when you do the same calculations, but the equation is not at equilibrium. No matter what, K does not change for a certain reaction at a certain temperature (meaning that some reaction at 300 K will always have the same K value no matter wh...
by Shreya Banerjee 2F
Fri Nov 06, 2015 7:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium and limiting reactant
Replies: 1
Views: 2480

Re: Equilibrium and limiting reactant

When you find the limiting reactant, it is generally only for reactions in which the forward reaction goes to completion. Meaning, equations for which the equilibrium very strongly favors the products and pretty much all of the reactant is used up. So saying that a reaction "ends" really h...
by Shreya Banerjee 2F
Tue Nov 03, 2015 8:35 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Rules on Cell Phones
Replies: 1
Views: 473

Midterm Rules on Cell Phones

Are we strictly prohibited from having cell phones during the midterm, even if they are turned off? Is there any way that we can bring them and have them secured by the proctor while we take the exam, so we can have access to them after we are done?
by Shreya Banerjee 2F
Fri Oct 30, 2015 9:35 pm
Forum: Ionic & Covalent Bonds
Topic: Which is more ionic?
Replies: 1
Views: 320

Re: Which is more ionic?

LiH is more ionic because the ions in it have lower polarizability. The larger Cl- molecule has a higher polarizability, making the compound HCl more covalent in character and thus less ionic.
by Shreya Banerjee 2F
Sat Oct 24, 2015 11:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs and polarity
Replies: 1
Views: 214

Lone pairs and polarity

What (if any) impact do lone pairs of electrons have on the polarity of a molecule?
by Shreya Banerjee 2F
Sat Oct 17, 2015 10:04 pm
Forum: Lewis Structures
Topic: empty D orbitals
Replies: 1
Views: 1104

Re: empty D orbitals

You should consider any element that has the ability to have d orbitals to be able to hold electrons in those empty d orbitals. This means that any element from the p-block of period 3 onward (because this is the first energy level where the d orbitals can be present) has empty d orbitals that can b...
by Shreya Banerjee 2F
Sat Oct 10, 2015 12:33 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: What does l mean?/ Subshells vs. Orbitals
Replies: 2
Views: 2049

Re: What does l mean?/ Subshells vs. Orbitals

L gives us the shape of the orbital because it tells us the energy level of the subshell, and thus whether it contains s, p, d, or f orbitals. l = 0 gives the lowest energy subshell, corresponding to s, and so on. Subshells represent a set of the same type of orbitals at the same energy level (so th...
by Shreya Banerjee 2F
Fri Oct 02, 2015 9:58 pm
Forum: Properties of Electrons
Topic: Balmer, Lyman, and other series
Replies: 1
Views: 370

Balmer, Lyman, and other series

I am a bit confused on the differences between the Balmer, Lyman, and other series for the excitation of electrons. I know that these all relate to what energy levels the electron moves between, but I'm not entirely sure on how to determine which series to use. What are the differences between any o...

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