## Search found 67 matches

Thu Mar 14, 2019 6:25 pm
Forum: General Rate Laws
Topic: rate laws
Replies: 6
Views: 182

### Re: rate laws

no the only way to find the rate law is with experimental data, not the equation on its own
Thu Mar 14, 2019 6:20 pm
Forum: First Order Reactions
Topic: Doubling Concentrations
Replies: 3
Views: 133

### Re: Doubling Concentrations

You can only find orders based on experimental data so this depends on the reaction. If you double the concentration and nothing happens to the rate, this is a zero order reaction. If you double the concentration and the rate also doubles, this is a first order reaction. If you double the concentrat...
Thu Mar 14, 2019 6:18 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: OH-(aq) in cell diagram
Replies: 3
Views: 306

### Re: OH-(aq) in cell diagram

I believe you include H+ and OH- but exclude H2O
Tue Mar 12, 2019 9:45 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test #2 4b
Replies: 2
Views: 123

### Re: Test #2 4b

In cell diagrams it is standard to leave out water but put H+
Mon Mar 11, 2019 6:39 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Problem 7A17
Replies: 2
Views: 272

### Problem 7A17

I am confused in part c of this problem. When I solved for k i used the values from the first row of the table and got 2.85 however the answer is 2.85x10^12. I don't understand the solution for this and why everything is multiplied by .457 when that is nowhere in the problem. Is this because of units?
Mon Mar 11, 2019 2:36 pm
Forum: First Order Reactions
Topic: Integration
Replies: 3
Views: 176

### Re: Integration

we should probably be familiar with it but it would be very unlikely for him to ask you to do it
Mon Mar 11, 2019 2:35 pm
Forum: Zero Order Reactions
Topic: Zero Order Units
Replies: 3
Views: 133

### Re: Zero Order Units

it may be easier to understand where the units come from by solving for it rather than memorizing them
Mon Mar 11, 2019 2:33 pm
Forum: Zero Order Reactions
Topic: Graphs
Replies: 8
Views: 600

### Re: Graphs

all graphs are linear but the slopes and axis vary
Mon Mar 11, 2019 2:31 pm
Forum: General Rate Laws
Topic: Rate Laws
Replies: 8
Views: 254

### Re: Rate Laws

One Ta said that we should be familiar with the derivation but it would be very unlikely for it to be asked on the exam
Sun Feb 24, 2019 7:52 pm
Forum: Balancing Redox Reactions
Topic: Oxidation and Reduction?
Replies: 6
Views: 250

### Re: Oxidation and Reduction?

Reduction means gaining an electron
Sun Feb 24, 2019 7:51 pm
Forum: Balancing Redox Reactions
Topic: Oxidation and Reduction?
Replies: 6
Views: 250

### Re: Oxidation and Reduction?

.
Wed Feb 20, 2019 6:02 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Midterm Question
Replies: 5
Views: 402

### Midterm Question

One of the questions asks you to comment on the relative stability of reactants and products. How were you suppose to go about solving this problem?
Wed Feb 20, 2019 5:57 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Max Work
Replies: 5
Views: 189

### Re: Max Work

isothermal reversible reactions
Wed Feb 20, 2019 5:56 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G a state function?
Replies: 23
Views: 825

### Re: Delta G a state function?

yes it is a state function, and can be added like enthalpy and calculated in very similar ways
Wed Feb 20, 2019 5:55 pm
Forum: General Science Questions
Topic: Midterm
Replies: 5
Views: 463

### Re: Midterm

Ka2 is the second deprotonation, when an acid is polyprotic and can give away multiple hydrogens
Wed Feb 20, 2019 5:54 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Porous disc explanation?
Replies: 6
Views: 183

### Re: Porous disc explanation?

I believe that the porous disk serves the same function as the salt bridge
Wed Feb 13, 2019 4:07 pm
Forum: Administrative Questions and Class Announcements
Topic: midterm location
Replies: 3
Views: 130

### Re: midterm location

yes on his website under midterm information
Tue Feb 12, 2019 9:42 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy Equations
Replies: 2
Views: 152

### Re: Entropy Equations

Also generally when you use the boltzmann equation it will ask you for either residual or positional entropy rather than just entropy.
Tue Feb 12, 2019 9:40 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: entropy change
Replies: 2
Views: 96

### Re: entropy change

You can answer this question by looking at the equation delta s = q/T. If the temperature is higher than the delta s will go down, and vise versa
Tue Feb 12, 2019 9:39 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Delta S = nC In (T2/T1)
Replies: 2
Views: 144

### Re: Delta S = nC In (T2/T1)

You should use the equation that has the n in it. The other one is assuming that if you have an amount other than 1 mole you will account for this and multiply by that as well
Tue Feb 12, 2019 9:36 am
Forum: Calculating Work of Expansion
Topic: 0 work vs no work
Replies: 4
Views: 184

### Re: 0 work vs no work

I believe no work and 0 work are interchangeable
Mon Feb 04, 2019 5:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Midterm
Replies: 12
Views: 386

### Re: Midterm

I also like to redo the tests we have done before the midterm to test myself again and make sure I've learned from my mistakes
Mon Feb 04, 2019 5:36 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Cup of Tea
Replies: 17
Views: 734

### Re: Cup of Tea

you can both change the matter within it (the tea) and transfer energy by holding it and making it warmer or cooler
Mon Feb 04, 2019 5:33 pm
Forum: Calculating Work of Expansion
Topic: Units for Work
Replies: 2
Views: 126

### Re: Units for Work

I think those are the only units for Joules that you should know about
Sun Feb 03, 2019 4:46 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: When to use Quadratic equation
Replies: 10
Views: 1176

### Re: When to use Quadratic equation

you need to use the quadratic equation when you can not estimate the x in the denominator and must solve it fully by hand
Sun Feb 03, 2019 4:43 pm
Forum: Phase Changes & Related Calculations
Topic: Drawing a heating curve
Replies: 6
Views: 284

### Re: Drawing a heating curve

I dont think it matters in terms of units, however it could matter in relativity to other transitions
Sun Feb 03, 2019 4:41 pm
Forum: Calculating Work of Expansion
Topic: What is Work?
Replies: 5
Views: 164

### Re: What is Work?

work is the process of achieving motion against an opposing force
Sun Feb 03, 2019 4:40 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: open system
Replies: 8
Views: 312

### Re: open system

This is the same idea as adding a drop of water into the ocean. A drop of water compared to the volume of the ocean is so small that it will not affect it just like how the whole universe is tiny compared to the beaker
Wed Jan 23, 2019 9:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5% Rule
Replies: 5
Views: 237

### Re: 5% Rule

the 5 percent rule can be used in any calculation of K
Wed Jan 23, 2019 9:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW Problem 6D. 15
Replies: 1
Views: 86

### Re: HW Problem 6D. 15

In the homework problems they sometimes do not put the Ka value in the question but they instead expect you to refer to a chart in the reading that lists many of the Ka values.
Wed Jan 23, 2019 9:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE boxes
Replies: 5
Views: 186

### Re: ICE boxes

yes, ice boxes work with pressures, molarity, and moles
Tue Jan 15, 2019 6:24 pm
Forum: Ideal Gases
Topic: Homework for week 2 [ENDORSED]
Replies: 10
Views: 2364

### Re: Homework for week 2[ENDORSED]

you can always do homework from any relevant section, or whichever section you think will help you the most to practice at the level you are at
Tue Jan 15, 2019 6:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE table
Replies: 4
Views: 187

### Re: ICE table

Whenever you are dealing with equilibrium and have unknown values, setting up an ice table can be helpful in order to know which parts you are missing as well as how to solve for them
Tue Jan 15, 2019 6:19 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic vs. Endothermic Reaction
Replies: 9
Views: 955

### Re: Exothermic vs. Endothermic Reaction

Yes you should be given delta h in order to determine whether the action is endo( taking in heat) or exo(giving off heat)thermic
Mon Jan 14, 2019 4:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids and Liquids in K
Replies: 4
Views: 150

### Solids and Liquids in K

I understand that solids and liquids should not be included in the calculation of K values, but could someone explain why this is? Why are they insignificant?
Mon Jan 14, 2019 3:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K changing with temperature [ENDORSED]
Replies: 3
Views: 129

### K changing with temperature[ENDORSED]

Could someone please explain why Kp changes when temperature is changed but not when the pressure is changed. Thanks
Mon Jan 14, 2019 3:55 pm
Forum: Ideal Gases
Topic: Using Kc or Kp
Replies: 13
Views: 418

### Re: Using Kc or Kp

both of them always work, you just have to see which information you are given to work with. If you are given moles and liters molarity can be found so Kc can be used but if pressures are given use Kp. Kp is also most commonly with gases
Fri Dec 07, 2018 10:50 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: molarity and acid base calcs
Replies: 1
Views: 90

### molarity and acid base calcs

#6B3 in the textbook edition seven asks about calculating the difference between 200 ml of 0.025M HCL solution and accidentally using a 250 ml flask to make this solution. I know that HCl completely dissociates so calculations with ph can be calculated with the 0.025M. However, i dont understand the...
Thu Dec 06, 2018 9:20 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Ka&Final
Replies: 1
Views: 142

### Re: Ka&Final

It was mentioned in the lectures briefly and it is also in the assigned reading so I think it would be best to know how to calculate it and what it represents, however in one of the review sessions a TA said he didn't think we would be tested on that so im not sure.
Thu Dec 06, 2018 9:13 pm
Forum: Lewis Acids & Bases
Topic: Strong Acids
Replies: 6
Views: 241

### Re: Strong Acids

HF is weaker than HI because Iodine is a larger atom and thus it is going to have a weaker bond with hydrogen. Because of this it can give away the hydrogen very easily making it a stronger acid.
Tue Nov 27, 2018 3:28 pm
Forum: Lewis Structures
Topic: Complicated Lewis Structures
Replies: 3
Views: 60

### Complicated Lewis Structures

I'm having a hard time knowing where to put each element with more complicated Lewis structures. For example, in question 2E19. in the seventh edition it asks for the shape and bond angles of (CH3)2Be. I drew the Lewis structure and it seemed correct. I drew it as H-C-C-Be with two more hydrogens on...
Mon Nov 26, 2018 7:48 pm
Forum: Hybridization
Topic: s-character and bond angle, question 2F15 7th edition
Replies: 1
Views: 89

### Re: s-character and bond angle, question 2F15 7th edition

This question also states that the bond angle for sp3 is 109.5 and bond angle for sp2 is 120. You can think of it as sp3 being 25 percent s characteristics and 75 percent p characteristics (1:3 ratio), and for sp2 this would be 33.3 percent s characteristic and 66.6 percent p characteristic (1:2 rat...
Mon Nov 26, 2018 7:41 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: London Forces
Replies: 2
Views: 109

### Re: London Forces

London dispersion forces are present between all molecules, including polar molecules
Mon Nov 26, 2018 7:15 pm
Forum: Administrative Questions and Class Announcements
Topic: Dipole Moment
Replies: 3
Views: 188

### Re: Dipole Moment

I believe the arrow should point towards the more electronegative element or you can write the greek letter (not sure what its called) with the positive and negative signifying that it is partially negative or partially positive on each element in the molecule
Mon Nov 26, 2018 7:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Location of Lone Pairs
Replies: 2
Views: 83

### Re: Location of Lone Pairs

Someone asked this question in my lecture, and Dr. Lavelle showed that because octahedral is completely symmetrical no matter where you put a lone pair is is exactly the same. There is no "top" or "bottom." It was easier to visualize when he showed us with his 3D props, but octah...
Mon Nov 26, 2018 7:08 pm
Forum: Hybridization
Topic: Electron Density and Hybridization
Replies: 1
Views: 110

### Electron Density and Hybridization

Do the regions of electron density surrounding the atom always match up with the hybridization state? So far I have been doing this and it has been working ex: if there are two regions of electron density it is sp hybridization,3 is sp2 and so on. However in the solution manual for 2F13. (seventh ed...
Fri Nov 16, 2018 6:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: dash and wedge diagram
Replies: 3
Views: 75

### Re: dash and wedge diagram

the dash shows that the atom is farther away from you and the wedge shows that the atom is coming towards you. We do not need to draw the Lewis structures this way it is just helpful to visualize the 3d nature of molecules on a 2d surface. However, if you were to draw them this way, where the dashes...
Fri Nov 16, 2018 6:01 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Bromine Electron Configuration
Replies: 2
Views: 2163

### Re: Bromine Electron Configuration

I believe the reason you would have received half credit for this answer is because it asked for the full electron configuration. You gave the short hand noble gas version. Your configuration was correct it just should have started at 1s2 etc.
Fri Nov 16, 2018 5:59 pm
Forum: Resonance Structures
Topic: Bond Lengths
Replies: 2
Views: 111

### Re: Bond Lengths

yes, in this question you were suppose to take the average of the bond lengths. This is because of resonance and how electrons are delocalized and double and single bonds are just used as visual representations for Lewis structures.
Thu Nov 01, 2018 10:56 pm
Forum: Lewis Structures
Topic: central atoms
Replies: 8
Views: 276

### Re: central atoms

ionization energy and electronegativity do follow the same trends so technically you could use either. Using electronegativity makes more sense to me because if something was extremely electronegative it is not likely to want to share a lot of electrons therefore will not be in the middle
Mon Oct 29, 2018 10:35 pm
Forum: Lewis Structures
Topic: D block valence electrons
Replies: 2
Views: 55

### D block valence electrons

How do you count valence electrons when an element is in the d block? Do you only count the s block or the d block as well up until that element? If you don't include the d block why is this?
Mon Oct 29, 2018 10:29 pm
Forum: Resonance Structures
Topic: Bond lengths
Replies: 6
Views: 133

### Re: Bond lengths

you will not need to calculate bond lengths. Professor Lavelle just included this in order to show that Lewis structures have a limitation, and this is why we need to show resonance
Mon Oct 29, 2018 10:27 pm
Forum: Lewis Structures
Topic: Number of Electrons
Replies: 2
Views: 49

### Re: Number of Electrons

to find the number of valence electrons you count across the period the s and p elements including the element you are looking at. You cant only look at the column numbers because for example carbon is in the 14th column but only has 4 valence electrons
Sun Oct 28, 2018 11:12 pm
Forum: Ionic & Covalent Bonds
Topic: Roman numerals next to element
Replies: 8
Views: 2005

### Roman numerals next to element

What do roman numerals next to an elements name mean? Ex: in 2A.23 indium(III) sulfide
Sun Oct 28, 2018 9:36 pm
Forum: Electronegativity
Topic: Electronegativity vs Electron Affinity
Replies: 4
Views: 16510

### Electronegativity vs Electron Affinity

Could someone please explain what the difference is between electronegativity and electron affinity. In lecture they seemed like the same thing and they seem to have the same trends on the periodic table. Can these terms be used interchangeably?
Sun Oct 28, 2018 9:34 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Equation
Replies: 2
Views: 154

### Re: Equation

Whatever is given in the prompt is what should be used because it is about uncertainty, not the same exact measurement each time. It will depend on the situation
Sun Oct 28, 2018 9:30 pm
Forum: Lewis Structures
Topic: Dot's in the Lewis Structure
Replies: 10
Views: 381

### Re: Dot's in the Lewis Structure

Just make sure each side has one before pairing them. This applies to hund's rule from quantum mechanics. Same spin electrons should be put in different orbitals before pairing them.
Sun Oct 21, 2018 2:10 pm
Forum: Trends in The Periodic Table
Topic: Homework
Replies: 10
Views: 332

### Re: Homework

I think this is individual to the person. As long as you do 7 problems you should get full credit, however it may be more helpful to work on the sections you need the most help with
Sun Oct 21, 2018 2:08 pm
Forum: *Shrodinger Equation
Topic: Application of Equation on test
Replies: 5
Views: 510

### Re: Application of Equation on test

I think having an understanding of the equation and what it is used for will be helpful on the test, rather than knowing how to actually compute it
Sun Oct 14, 2018 5:42 pm
Forum: Properties of Electrons
Topic: Energy emitted by electrons
Replies: 6
Views: 218

### Re: Energy emitted by electrons

The energy is released as positive electromagnetic radiation (photons)
Sun Oct 14, 2018 5:39 pm
Forum: SI Units, Unit Conversions
Topic: Unit Conversions
Replies: 3
Views: 265

### Re: Unit Conversions

Personally I just have the very common units memorized such as kilo and milli. You generally memorize these just through using them so much. I would just memorize the units as they come up in the different topics of chem, because there are likely some that won't come up. However if you are intent on...
Wed Oct 10, 2018 6:11 pm
Forum: Significant Figures
Topic: Repeating Decimal
Replies: 3
Views: 765

### Re: Repeating Decimal

Using the fraction is a good idea, or just keeping as many decimals as possible until the end result when you can round to the proper number of sig figs. As long as you keep a reasonable amount of decimal places, the end result shouldn't change
Wed Oct 10, 2018 5:57 pm
Topic: Black Body
Replies: 10
Views: 676

### Re: Black Body

Professor Lavelle said a black body is a hypothetical material that can absorb all frequencies of light (it's not real).
Mon Oct 08, 2018 11:33 pm
Forum: Limiting Reactant Calculations
Topic: How to find the limiting reactant easily and quickly
Replies: 5
Views: 1145

### Re: How to find the limiting reactant easily and quickly

I've always found that the easiest way to find the LR(but maybe not the fastest) is converting both reactants into one product. You do this by taking the mass given to you of both products and using molar mass and molar ratios to convert into product. You can convert to either moles of grams, both w...
Thu Oct 04, 2018 8:52 pm
Forum: Limiting Reactant Calculations
Topic: Actual yield [ENDORSED]
Replies: 4
Views: 266

### Re: Actual yield[ENDORSED]

The actual yield is the amount that is produced within a lab setting. The theoretical yield is the amount produced assuming there are no errors, outside reactions etc. The actual yield will typically be given to you in a problem where you must find the percent yield. Here you would divide the actual...
Thu Oct 04, 2018 8:45 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant vs. Reagent??? [ENDORSED]
Replies: 6
Views: 302

### Re: Limiting Reactant vs. Reagent???[ENDORSED]

In lecture, Dr. Lavelle said that reactant is used in the hypothetical sense when doing calculations but reagent is when you are referring to a lab setting and actually doing the experiment. For the purposes of the class, because there is no lab component they can be interpreted as the same thing.
Thu Oct 04, 2018 8:44 pm
Forum: Significant Figures
Topic: Significant figures for molar mass
Replies: 7
Views: 2081

### Re: Significant figures for molar mass

Both molar masses would be adequate and likely get you the same result because the difference is so small. In general the more accurate one would be preferable. You should keep as many sig figs as possible until the very end of the calculation when you have your answer