Search found 50 matches

by soniatripathy
Fri Mar 16, 2018 4:36 am
Forum: General Rate Laws
Topic: 15.99
Replies: 1
Views: 98

15.99

Can someone please explain the reasoning behind the answers for e-h on this problem? im not sure why these graphs are/are not linear
by soniatripathy
Fri Mar 16, 2018 4:00 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: sketching reaction profiles
Replies: 2
Views: 123

sketching reaction profiles

i am confused on how to sketch a reaction profile (like in 15.89). are there certain steps and things to look for when sketching a reaction profile? what are they?
by soniatripathy
Fri Mar 16, 2018 3:34 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: drawing activated complexes
Replies: 1
Views: 105

drawing activated complexes

15.85 asks you to draw a proposed structure for the activated complex, is there a way to do that, i dont remember reading about it in the book? if there is a set process, what are the steps to drawing it?
by soniatripathy
Fri Mar 16, 2018 3:21 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: trend for temp and activation energy
Replies: 3
Views: 143

trend for temp and activation energy

is it a general trend that when the temp is higher, a higher activation energy can be overcome? (this question is in regards to the answer to 15.79 part a)
by soniatripathy
Fri Mar 16, 2018 2:34 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 15.67
Replies: 3
Views: 145

15.67

can someone explain the reasoning behind the calculations for 15.67? How do you get the ratio and then use that to solve for the factor?
by soniatripathy
Fri Mar 16, 2018 2:28 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 15.51
Replies: 1
Views: 77

Re: 15.51

yes, you are right! the rate determining step will be the slow one. This is because the slow step is the one that takes more time, but once that step is complete the fast steps can immediately complete the mechanism. Imagine a relay race, if there is a slow runner, that person is likely to play a ma...
by soniatripathy
Fri Mar 16, 2018 2:16 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 15.65 part b
Replies: 1
Views: 80

15.65 part b

how do you determine if a reaction is endothermic or exothermic for part b?
by soniatripathy
Fri Mar 16, 2018 2:10 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 15.49
Replies: 2
Views: 108

15.49

I am confused on how intermediates play a part in rate laws. I thought that intermediates cannot be included in rate laws? If so, why is HoBr included in the rate law for step 2 in part b of this question?
by soniatripathy
Wed Mar 14, 2018 3:51 pm
Forum: Balancing Redox Reactions
Topic: Oxidation state
Replies: 7
Views: 285

Re: Oxidation state

I found that this video is pretty comprehensive (and shorter than the other response) and gives you the most used rules of assigning oxidation numbers: https://www.youtube.com/watch?v=-a2ckxhfDjQ&t=61s
Hopefully this helps!
by soniatripathy
Wed Mar 14, 2018 3:45 pm
Forum: Balancing Redox Reactions
Topic: Test 2 Question 8
Replies: 2
Views: 142

Re: Test 2 Question 8

you will need to balance the half reactions and see the number of electrons exchanged. This is the number after you multiply both equations to have the same amount of electrons exchanged.
by soniatripathy
Wed Mar 14, 2018 3:31 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeters Isolated
Replies: 2
Views: 265

Re: Calorimeters Isolated

I thought that coffee cup calorimeters were closed because they allow heat exchange but not matter exchange?
by soniatripathy
Wed Mar 14, 2018 2:58 pm
Forum: Phase Changes & Related Calculations
Topic: 8.23
Replies: 5
Views: 380

Re: 8.23

will the heat capacity of a calorimeter always be q=C(deltaT) or are there cases which will require us to take mass into consideration and use the specific heat capacity?
by soniatripathy
Wed Mar 14, 2018 2:55 pm
Forum: Phase Changes & Related Calculations
Topic: When to use Kelvin or Celsius
Replies: 10
Views: 609

Re: When to use Kelvin or Celsius

The most important thing to consider in these cases are the units of the constants and given values. This will help you determine if you need to use K or C because you might need to get some of the units to cancel out. i think for things like deltaT either should be fine because they are both scaled...
by soniatripathy
Wed Mar 14, 2018 2:50 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Homework 14.25
Replies: 4
Views: 192

Re: Homework 14.25

I think that in terms if application for this class, they will only give us one value for easier comparison (i was worried about this for the test but the sheet they gave us seemed to be simplified and eliminated this confusion)
by soniatripathy
Wed Mar 14, 2018 2:45 pm
Forum: Balancing Redox Reactions
Topic: oxidation states
Replies: 4
Views: 162

Re: oxidation states

there are a few basic rules that you are supposed to memorize for assigning oxidation numbers. I found that this video is really helpful for learning them: https://www.youtube.com/watch?v=-a2ckxhfDjQ
Hopefully this video helps!
by soniatripathy
Wed Mar 14, 2018 2:40 pm
Forum: Balancing Redox Reactions
Topic: 14.15a
Replies: 3
Views: 218

Re: 14.15a

the best way to write half reactions is to first assign all the elements an oxidation number, then look at how it changes between the right and left side of the equation. Based on what is oxidized and what it reduced, you can write the half reactions and assign electrons to the correct side
by soniatripathy
Wed Mar 14, 2018 2:37 pm
Forum: Balancing Redox Reactions
Topic: Oxidizing Power
Replies: 2
Views: 126

Re: Oxidizing Power

also, if you look at the table, the values decrease as you go down. This means that as you go down, the stronger the reducing agent and the weaker the oxidizing agent
by soniatripathy
Wed Mar 14, 2018 2:32 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.49
Replies: 3
Views: 163

Re: 8.49

in the book, there are a couple of problems where they assume one mole of a substance. How do we know when to do that versus when we have to calculate the amount of moles (like the one problem on the midterm)?
by soniatripathy
Wed Feb 07, 2018 5:52 am
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Residual Entropy
Replies: 2
Views: 108

Re: Residual Entropy

0K is absolute zero at which there would be very little particle motion that contributes to heat. This also means that motion that contributes to thermal and positional disorder would be very low. the residual entropy is the amount of positional disorder that survives at such a low temperature. it i...
by soniatripathy
Wed Feb 07, 2018 5:41 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Calculating Degeneracy
Replies: 3
Views: 203

Re: Calculating Degeneracy

usually it is the number of combinations possible raise to the power of how many molecules or particles there are. example 9.8 in the book uses one mole of FClO3 as an example: W would be 4^(6.01 x 10^23) this is because there are 4 possible orientation for FClO3 because there are 4 different places...
by soniatripathy
Wed Feb 07, 2018 5:33 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Pressure and Volume
Replies: 3
Views: 93

Re: Pressure and Volume

as a word of caution I would say to double check with the units of the gas constant (R) that you are using just to make sure everything cancels out correctly
by soniatripathy
Wed Feb 07, 2018 5:29 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G
Replies: 3
Views: 132

Re: Delta G

∆G° is for fixed temperatures and does not depend on how the composition of the reaction changes as the reaction proceeds
∆G will depend on the composition of the reaction mixture and thus changes as the reaction proceeds
by soniatripathy
Mon Jan 22, 2018 5:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: adiabatic and diathermic?
Replies: 2
Views: 149

Re: adiabatic and diathermic?

It is probably helpful to know because it might show up in a question that asks you to identify is a system is closed, isolated, or open.
by soniatripathy
Mon Jan 22, 2018 5:53 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.25 Units
Replies: 1
Views: 90

Re: 8.25 Units

The questions already gives ∆T values (meaning the difference between initial and final temperatures) so you cannot add the conversion factor since that would be another temperature altogether.
by soniatripathy
Mon Jan 22, 2018 5:48 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hesss Law
Replies: 2
Views: 107

Re: Hesss Law

State properties are independent of how the substance was prepared. Another way of saying this is that the intermediate steps do not matter, but rather the end result. Because of this we can manipulate chemical equations and their accompanying ∆H values to get a desired chemical equations.
by soniatripathy
Mon Jan 22, 2018 5:39 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Enthalpy
Replies: 2
Views: 123

Re: Enthalpy

This depends on the units of your heat capacity. If you are using molar heat capacity then use moles but if you are using specific heat capacity use grams since grams are in the units. Overall, just make sure to check that your units cancel out in the final answer.
by soniatripathy
Mon Jan 22, 2018 5:38 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: HW #113
Replies: 1
Views: 88

Re: HW #113

In part A, they ask you to calculate ∆Hrxn using the standard enthalpies of formation. Doing so will give you 131.29 kJ of heat for the given reaction. Since this questions is asking about H2, look at the stoichiometric coefficient for H2. Since it is 1 that means that for 1 mole of H2 131.29kJ of h...
by soniatripathy
Mon Jan 22, 2018 5:15 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.99
Replies: 6
Views: 208

Re: 8.99

Keep in mind that the question specifies that chloride ions are produced meaning that the products could not be ZnCl2 but rather Zn^2+ and 2Cl^-. This way you can use the information given in appendix 2 to calculate ∆Hrxn
by soniatripathy
Tue Jan 16, 2018 1:36 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: HW Ch.8 #59 and 63
Replies: 7
Views: 308

Re: HW Ch.8 #59 and 63

kJ/mol and kJ just denote whether the enthalpy given applies to one mole or reactant or multiple. Usually kJ is more all the moles of reactants while kJ/mole specifies for one mole. In those problems I think it is just referring to the same concept.
by soniatripathy
Tue Jan 16, 2018 1:29 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: HW Question 8.9
Replies: 5
Views: 513

Re: HW Question 8.9

The following are the gas constants given on the equations and constants sheet: R = 8.314 J·K-1·mol-1 = 8.206 × 10-2 L·atm·K-1·mol-1 =8.314 x 10-2 L·bar·K-1·mol-1 = 62.364 L·Torr·K-1·mol-1 This is the energy per temperature increment per mole. It is very important to note the units when using this i...
by soniatripathy
Tue Dec 05, 2017 3:15 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Problem 11.81
Replies: 3
Views: 253

Re: Problem 11.81

One way to easily see whether products or reactants will be favored is to use the following rules: K < 1 favors reactants K = 1 pretty much the same favorability for reactants and products K > 1 favors products (an easy way to remember this is that the inequality sign favors the side of the reaction...
by soniatripathy
Tue Dec 05, 2017 3:06 am
Forum: Naming
Topic: Suffixes
Replies: 4
Views: 300

Re: Suffixes

You should also know the suffixes for polyatomic ions. For example ions at end in -ate, like sulfate, the ending in the coordination compound should be -ato. sulfate --> sulfato. For ions ending in -ite, like nitrite, the ending will be changed to -ito. nitrite --> nitrito. Another one you should kn...
by soniatripathy
Mon Dec 04, 2017 11:38 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Ionic Equation
Replies: 3
Views: 648

Re: Ionic Equation

The question is not super clear but if you are referring to writing net ionic equations then you know which species dissociates based on solubility rules and strong acids and bases. There are 3 basic steps to writing net ionic equations: (1) write a balanced equation with the states of matter includ...
by soniatripathy
Mon Dec 04, 2017 1:15 am
Forum: Resonance Structures
Topic: Naming coordination compounds [ENDORSED]
Replies: 3
Views: 292

Re: Naming coordination compounds [ENDORSED]

Even though both are acceptable, make sure to stick with one convention if there are multiple ligands in the coordination compound.
by soniatripathy
Mon Dec 04, 2017 12:53 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Are moleculary geometry and shape different? [ENDORSED]
Replies: 3
Views: 250

Re: Are moleculary geometry and shape different? [ENDORSED]

Molecular shape (also known as electron arrangement) considers the arrangement of bonds ignoring the lone pairs. It is simply based on the number or region of electron density. So an all central atoms with sp3 hybridization will have the same molecular shape of tetrahedral and all central atoms with...
by soniatripathy
Mon Dec 04, 2017 12:45 am
Forum: Naming
Topic: (H2O) or (OH2)? [ENDORSED]
Replies: 3
Views: 247

Re: (H2O) or (OH2)? [ENDORSED]

usually it is written and OH2 because the oxygen is the one that is bonding to the central atom. one reason is because hydrogen only has one electron and if it was bonded to the central atom there would be no room for the other hydrogen or oxygen in water to bond. The notation is similar to how cert...
by soniatripathy
Mon Dec 04, 2017 12:27 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Exceptions to the Octet Rule
Replies: 4
Views: 271

Re: Exceptions to the Octet Rule

the first element in the periodic table to have an expanded octet is phosphorus. There are definitely others like boron that are satisfied with 6 electrons. Two really good exceptions to the octet to know are phosphorous with 10 and sulfur with 12. Those are ones that come up a lot esp with compound...
by soniatripathy
Fri Nov 10, 2017 6:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Drawing lewis structures
Replies: 5
Views: 272

Re: Drawing lewis structures

I think that generally if you follow a couple of basic rules then the structure should come out right. For example, using the element with the lowest ionization energy in the center and arranging the atoms as symmetrically as possible and having the correct number of e-. Sometimes the angles may not...
by soniatripathy
Thu Nov 09, 2017 8:51 pm
Forum: Resonance Structures
Topic: 3.57 Resonance structures?
Replies: 2
Views: 215

Re: 3.57 Resonance structures?

Not all the resonance structures are favorable because the formal charges change based on the number of lone pairs and shared pairs. Resonance structures usually just change double/triple bond placement because the hybrid spread bond character over the molecule.
by soniatripathy
Thu Nov 09, 2017 8:35 pm
Forum: Resonance Structures
Topic: SO2 resonance
Replies: 2
Views: 231

Re: SO2 resonance

It should have only two resonance structures (i just checked too). One of the reasons might be because of the expanded octet so it can have multiple bonds and electron placements. some might not be the most electronically favorable but they might still be valid
by soniatripathy
Thu Nov 09, 2017 8:28 pm
Forum: Lewis Structures
Topic: Lewis Structure [ENDORSED]
Replies: 4
Views: 232

Re: Lewis Structure [ENDORSED]

I talked to one of the LAs and she said that only when it is stated to write the lowest one then it is needed. Otherwise (at this level) a valid lewis structure is okay. Obviously it is better to get the most stable one but sometimes that takes a bunch of trial and error.
by soniatripathy
Thu Nov 09, 2017 12:57 pm
Forum: Dipole Moments
Topic: Polarity
Replies: 5
Views: 482

Re: Polarity

I know that LDMS help a lot especially because polar molecules are not symmetric
by soniatripathy
Tue Oct 24, 2017 4:23 am
Forum: Quantum Numbers and The H-Atom
Topic: Magnetic Quantum Numbers & Orbital Orientation
Replies: 1
Views: 215

Re: Magnetic Quantum Numbers & Orbital Orientation

principle quantum number (n): This tells you the energy level and corresponds to the period in the periodic table azimuthal quantum number (l): This tells you the subshell and has possibilities of up to n-1. Here s=0, p=1, d=2, and f=3. magnetic quantum number (ml): This tells you which part of the ...
by soniatripathy
Tue Oct 24, 2017 4:07 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 3d and 4s
Replies: 5
Views: 330

Re: 3d and 4s

The 2 exceptions to e- config. that you need to know for this class are Chromium and Copper. The 3d will "rob" one electron for the previous subshell to make it less reactive. This occurs because a half filled subshell is the second most stable e- orientation (after a filled subshell).
by soniatripathy
Fri Oct 20, 2017 10:19 am
Forum: DeBroglie Equation
Topic: Conversions
Replies: 3
Views: 222

Re: Conversions

I use the abbreviation (KHDBDCM) method because it reduces the possibility of error when doing calculations and I dont need to memorize a bunch of unit converstions. Also, sometimes questions will ask you to convert to picometers, nanometers, or other metric units. To do this just come up with a pne...
by soniatripathy
Fri Oct 20, 2017 10:06 am
Forum: Photoelectric Effect
Topic: Problem in post assessment
Replies: 2
Views: 150

Re: Problem in post assessment

The kinetic energy can be used to figure out the velocity (since the mass of en e- is known) and then you can use deBroglies to find the wavelength
by soniatripathy
Wed Oct 11, 2017 8:27 pm
Forum: Properties of Light
Topic: Planck Constant [ENDORSED]
Replies: 8
Views: 440

Re: Planck Constant [ENDORSED]

just remember that you use the sig figs in the values given (including given constants) for the final answer so just take that into consideration with writing your final answer
by soniatripathy
Wed Oct 11, 2017 8:24 pm
Forum: Photoelectric Effect
Topic: Units Cancelling Out
Replies: 3
Views: 234

Re: Units Cancelling Out

For E=hv the units for h are (J*s) and the units for v are s^-1. When you multiply (J*s)x(s^-1) the seconds cancel out and you hare left with J, which is the unit used to measure energy.
by soniatripathy
Fri Oct 06, 2017 2:26 am
Forum: Limiting Reactant Calculations
Topic: Determining Limiting Reactant
Replies: 6
Views: 542

Re: Determining Limiting Reactant

I find that it is easier to calculate the limiting reactant by dividing the moles of each reactant by its stoichiometric coefficient. This makes is easier to see that the smaller quotient is the limiting reactant.
by soniatripathy
Fri Oct 06, 2017 2:21 am
Forum: Limiting Reactant Calculations
Topic: M19
Replies: 3
Views: 264

Re: M19

When caffeine is burned, the carbon in CO2, the hydrogen in water, and the nitrogen in nitrogen gas come directly from caffeine. This means that the first step is to calculate the moles of C, H, and N from the given masses. You would then need to convert the moles of each element to grams. The sum o...

Go to advanced search