Search found 65 matches
- Thu Mar 14, 2019 9:20 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Entropy for irreversible reaction
- Replies: 1
- Views: 448
Entropy for irreversible reaction
Why is the entropy of the surroundings equal to 0 for an irreversible equation?
- Wed Mar 13, 2019 10:35 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Units for K
- Replies: 4
- Views: 806
Units for K
Why do units change for k depending on the order of the reaction?
- Wed Mar 13, 2019 10:34 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Number 7.31 7th Edition
- Replies: 1
- Views: 183
Number 7.31 7th Edition
Can someone explain how to do 7.31 in the 7th edition? I'm confused as to how to rearrange the arrhenius equation.
- Tue Mar 12, 2019 5:42 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Units
- Replies: 3
- Views: 373
Units
What are the units for k in the different orders of reaction?
- Fri Mar 08, 2019 11:09 am
- Forum: Experimental Details
- Topic: Rate Laws
- Replies: 8
- Views: 1234
Rate Laws
How are rate laws determined?
- Fri Mar 08, 2019 11:07 am
- Forum: First Order Reactions
- Topic: Units
- Replies: 2
- Views: 268
Units
What are the different units for k for 0 order 1st order and 2nd order reactions?
- Tue Mar 05, 2019 5:41 pm
- Forum: Zero Order Reactions
- Topic: Half life
- Replies: 5
- Views: 539
Half life
Do we use half life for 0 order reactions or just 1st order?
- Tue Mar 05, 2019 5:40 pm
- Forum: Zero Order Reactions
- Topic: Zero Order reactions
- Replies: 2
- Views: 298
Zero Order reactions
What is the difference between 0th order and 1st order reactions conceptually? I'm still confused as what the "order" is actually describing.
- Tue Feb 26, 2019 9:16 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Question for Test 2
- Replies: 4
- Views: 421
Question for Test 2
Do we need to know delta G = -nFE for test 2?
- Tue Feb 26, 2019 4:58 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Entropy and Enthalpy
- Replies: 2
- Views: 291
Entropy and Enthalpy
How are entropy and enthalpy related?
- Thu Feb 21, 2019 9:04 am
- Forum: Balancing Redox Reactions
- Topic: Number 6k.5 7th edition
- Replies: 1
- Views: 179
Number 6k.5 7th edition
For number 6k.5 in the 7th edition, it asks to write the balanced redox reaction for o3+Br--> o2 + BrO3- and I'm confused as to how to separate it into two different equations since there are two parts with Os.
- Wed Feb 20, 2019 11:25 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation Numbers
- Replies: 2
- Views: 344
Oxidation Numbers
When asked what the initial and final oxidation numbers are is that just the charge of the ion?
- Fri Feb 08, 2019 8:33 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Internal Energy in a Reversible Isothermal expansion
- Replies: 1
- Views: 211
Internal Energy in a Reversible Isothermal expansion
Why is the internal energy of an ideal gas in a reversible isothermal expansion equal to 0??
- Fri Feb 08, 2019 9:55 am
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Enthalpy and Hheat
- Replies: 2
- Views: 319
Enthalpy and Hheat
When does delta H = q?
- Wed Feb 06, 2019 4:59 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Work and Internal Energy
- Replies: 1
- Views: 205
Work and Internal Energy
Why is it that when a gas is at constant volume, the work is equal to zero and the internal energy is equal to the amount of heat supplied?
- Wed Feb 06, 2019 4:38 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Question 4C.3 7th edition
- Replies: 1
- Views: 205
Question 4C.3 7th edition
For question 4C.3 when it asks to calculate the change in enthalpy when 765 J is transferred as heat to .820 mol Kr (g) at 298 K and 1.00 atm at constant pressure and constant volume, what equations would you use?
- Thu Jan 31, 2019 8:36 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Determining Internal Energy
- Replies: 3
- Views: 379
Determining Internal Energy
When determining the internal energy accompanying a reaction, why does the second step involve using the equation q=-Ccal*(change in temp) ? I'm just confused as to why there's a negative sign.
- Wed Jan 30, 2019 10:33 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Work Question
- Replies: 4
- Views: 451
Work Question
Does anyone understand what exactly "work" is? I'm confused as to what the difference is between work and energy. Are they the same?
- Thu Jan 24, 2019 10:18 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Acid/ Base
- Replies: 1
- Views: 187
Acid/ Base
How do we know if a molecule is an acid or base if we are given a Ka, how do we know if the molecule is a base so we'd have to find the Kb?
- Thu Jan 24, 2019 10:17 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ka and Kb
- Replies: 1
- Views: 226
Ka and Kb
How are Ka and Kb related?
- Thu Jan 24, 2019 10:16 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ka meaning
- Replies: 1
- Views: 296
Ka meaning
When Ka is small, that means that the reaction favors the formation of products right? (and that there are more reactants?)
- Fri Jan 18, 2019 3:43 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Question 6D.13 7th edition
- Replies: 1
- Views: 334
Question 6D.13 7th edition
For this question, it asks to rank the following solutions in order of increasing pH: (a) 1.0 * 10^-5 M HCl(aq); (b) 0.20 M CH3NH3Cl(aq); (c) 0.20 M CH3COOH(aq); (d) 0.20 M C6H5NH2(aq). Justify your ranking. How would I solve this ??
- Wed Jan 16, 2019 9:52 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 7th edition 6A.23
- Replies: 1
- Views: 200
7th edition 6A.23
For this question, it asks to calculate the h3O and OH concentrations, but I found that the H3O concentration is 2*10^-13 Does that mean that the solution is neutral? The question asking if it is, but is it??
- Wed Jan 16, 2019 9:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6th edition 11.69
- Replies: 1
- Views: 115
Re: 6th edition 11.69
Because the reaction is responding to minimize the effect of increasing pressure, the more pressure you add to the products the more reactants will be made.
- Wed Jan 16, 2019 9:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Endothermic Reaction
- Replies: 4
- Views: 331
Endothermic Reaction
If a reaction is endothermic and you added heat, would the Kw be bigger or smaller and why? I'm a bit confused.
- Sun Jan 13, 2019 3:49 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Number 5I.33 7th edition
- Replies: 1
- Views: 151
Number 5I.33 7th edition
A sample of ammonium carbamate, NH4(NH2CO2), of mass 25.0 g was placed in an evacuated flask of volume 0.250 L and kept at 25 8C. At equilibrium, 17.4 mg of CO2 was present. What is the value of Kc for the decomposition of ammonium carbamate into ammonia and carbon dioxide? The reaction is NH4(NH2CO...
- Sat Jan 12, 2019 10:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: number 5I.25 7th edition
- Replies: 1
- Views: 162
number 5I.25 7th edition
A reaction mixture is prepared by mixing 0.100 mol SO2, 0.200 mol NO2, 0.100 mol NO, and 0.150 mol SO3 in a reaction vessel of volume 5.00 L. The reaction SO2(g)+ NO2(g) -> NO(g) + SO3(g) is allowed to reach equilibrium at 460 C, when Kc = 85.0. What is the equilibrium concentration of each substanc...
- Sat Jan 12, 2019 9:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Understanding Q
- Replies: 3
- Views: 294
Understanding Q
When solving for Q and comparing it to K, why is it that if Q < K it means that more products are formed and if Q > K it means more reactants are formed? I'm confused trying to figure this out conceptually.
- Wed Jan 09, 2019 8:55 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Section 5H.2 Composite Equations
- Replies: 1
- Views: 52
Section 5H.2 Composite Equations
When calculating composite equations, why does the second reaction have to be squared? For example, in the book it gives the example 2P(g)+3Cl2(g)-> 2PCL3 PCl3(g) +Cl2 (g) -> PCl5 (g) and 2P(g)+ 5CL2 (g) -> 2PCl5(g) and states that K for the third reaction is equal to K1*K2^2. Why does the K value f...
- Wed Jan 09, 2019 8:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5H.1 part B
- Replies: 2
- Views: 176
5H.1 part B
For the reaction N2(g) + 3H2(g) -> 2 NH3(g) at 400. K, K = 41. Find the value of K for each of the following reactions at the same temperature: (a) 2 NH3(g) -> N2(g)+3 H2(g) (b) 1/2 N2(g) + 3/2 H2(g) ->NH3(g) (c) 2 N2(g)+6 H2(g) -> 4 NH3(g). I understand that for part a you just put 1/41 to solve fo...
- Wed Jan 09, 2019 8:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Number 5G.9 Question
- Replies: 1
- Views: 212
Number 5G.9 Question
Number 5G.9 asks: "A sample of ozone, O3, amounting to 0.10 mol, is placed in a sealed container of volume 1.0 L and the reaction 2 O3(g) S 3 O2(g) is allowed to reach equilibrium. Then 0.50 mol O3 is placed in a second container of volume 1.0 L at the same temperature and allowed to reach equi...
- Tue Jan 08, 2019 5:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Number 5G.5 question
- Replies: 1
- Views: 115
Number 5G.5 question
For 5G.5, the question asks to calculate the value of K for the decomposition assuming that the initial pressure of X2 was at .10 bar. I'm just confused as to how you would go about calculating this?
- Mon Dec 03, 2018 11:35 pm
- Forum: Naming
- Topic: Coming up with formula from name
- Replies: 3
- Views: 281
Coming up with formula from name
When coming up with the formula for a compund from its name, how do you know where to place the elements? For example, in exercise 3b in 9C of the 7th edition, the name of the compound is pentaamminesulfatocobalt (III) chloride. How do we know that means [Co(NH3)5(SO4)]Cl and not (NH3)5(SO4)CoCl ?
- Sun Dec 02, 2018 1:57 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Homework week 10
- Replies: 3
- Views: 404
Homework week 10
Do we still have homework due this week?
- Fri Nov 30, 2018 10:15 am
- Forum: Bronsted Acids & Bases
- Topic: Bronsted Acid
- Replies: 2
- Views: 206
Bronsted Acid
For Bronsted acids, is what makes the molecule an acid it separating in an aqueous solution?
- Tue Nov 27, 2018 6:10 pm
- Forum: Hybridization
- Topic: Hybridization of Central Atom
- Replies: 3
- Views: 360
Hybridization of Central Atom
Can someone explain to me how to know if the hybridization of an atom is either in 1s or 2s? For example in number 2.45 in the 7th edition, the book asks to Identify the composition of the bonds and the hybridization of each lone pair—for example, by writing s (H1s,C2sp 2). How do you know that the ...
- Thu Nov 22, 2018 3:52 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 3 Question
- Replies: 4
- Views: 491
Test 3 Question
Is test 3 just going to be on vsepr and hybridization?
- Fri Nov 16, 2018 10:42 am
- Forum: Dipole Moments
- Topic: Polar vs. Nonpolar
- Replies: 5
- Views: 445
Polar vs. Nonpolar
I'm still confused how to tell if a molecule is polar or nonpolar/ how to know which atom has the delta negative or delta positive charge. Is there a way you can tell which atom has the positive or negative charge by looking at the periodic table or something?
- Fri Nov 16, 2018 10:30 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Octahedral Shape
- Replies: 4
- Views: 836
Octahedral Shape
Why is the shape of a molecule,such as XeF4 octahedral when there are 6 parts of electron density?
- Tue Nov 13, 2018 10:29 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Hybridization of Central Atom
- Replies: 1
- Views: 200
Hybridization of Central Atom
Do we need to know how to figure out the hybridization of a central atom? and if so, how do we?
- Tue Nov 13, 2018 10:20 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar vs. NonPolar
- Replies: 5
- Views: 577
Polar vs. NonPolar
How can you tell if a molecule is nonpolar or polar by just looking at the periodic table rather than looking up electronegativity?
- Fri Nov 09, 2018 10:45 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Tetrahedral molecules
- Replies: 4
- Views: 393
Tetrahedral molecules
Do all tetrahedral molecules have a 109.5 degree angle in between the atoms?
- Tue Nov 06, 2018 12:46 pm
- Forum: Ionic & Covalent Bonds
- Topic: Greater Ionic Character? [ENDORSED]
- Replies: 3
- Views: 588
Greater Ionic Character? [ENDORSED]
How do you know which compound has a greater ionic character or not? For example on the homework 2d.5, it's asking which has a greater ionic character HCl or HI but I'm not sure how to tell.
- Sun Nov 04, 2018 6:59 pm
- Forum: Lewis Structures
- Topic: Lewis Acids vs Bases
- Replies: 2
- Views: 277
Lewis Acids vs Bases
Could someone please explain the differences between Lewis acids and bases? I know that the acids don't fill an octet and bases do or have a lone pair of electrons in the center, but what exactly does that mean? Thanks!
- Sat Nov 03, 2018 9:42 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Negative Energy
- Replies: 1
- Views: 215
Negative Energy
Why is it that when an electron transitions from a higher to a lower energy level the energy of the photon emitted is negative?
- Fri Nov 02, 2018 5:20 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodal planes
- Replies: 6
- Views: 1285
Nodal planes
How do you know how many nodal planes exist for an orbital?
- Fri Nov 02, 2018 4:54 pm
- Forum: Photoelectric Effect
- Topic: Question on kinetic energy
- Replies: 5
- Views: 687
Question on kinetic energy
For the photoelectric effect equation, is the kinetic energy always equal to 1/2mv^2 or can that be used for any part of the equation like the energy of the photon?
- Mon Oct 29, 2018 12:44 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Finding Formal Charge
- Replies: 3
- Views: 235
Finding Formal Charge
Hi I'm just confused about why we have to find the formal charges of each atom/ what purpose it serves??
- Mon Oct 29, 2018 12:38 pm
- Forum: Resonance Structures
- Topic: Bond lengths
- Replies: 6
- Views: 401
Bond lengths
I'm confused as to how to find/ if we have to know how to find the bond length of experimentally observed structures. For example, in lecture Professor Lavelle went over how Benzene has double and single bonds, with the double bonds being 1.34A and the single bonds being 1.54A, but the experimentall...
- Mon Oct 29, 2018 12:35 pm
- Forum: Ionic & Covalent Bonds
- Topic: Formal Charges
- Replies: 3
- Views: 357
Re: Formal Charges
yes I believe so
- Mon Oct 29, 2018 12:34 pm
- Forum: Octet Exceptions
- Topic: Sulfate Ion structure
- Replies: 2
- Views: 189
Sulfate Ion structure
I'm a bit confused as to why when we draw the Lewis Structure for the sulfate ion how it's okay for the sulfur to take in more than 8 electrons..Is there a limit of how many electrons it can take? How do we know how many electrons can fit into a atom?
- Sun Oct 28, 2018 10:13 pm
- Forum: Lewis Structures
- Topic: Dots in Lewis Stucture
- Replies: 14
- Views: 1170
Re: Dots in Lewis Stucture
In lecture on Friday Professor Lavelle said that it doesn't matter :)
- Tue Oct 23, 2018 8:35 pm
- Forum: Properties of Electrons
- Topic: 1E.7 for the HW
- Replies: 2
- Views: 570
1E.7 for the HW
For number 1E.7 on the homework, it asks to determine whether each of the following electron configurations represent the ground or excited state of an electron and I'm confused as to how you would determine that? please help
- Mon Oct 22, 2018 9:42 am
- Forum: Trends in The Periodic Table
- Topic: s, p, d, f
- Replies: 16
- Views: 4272
Re: s, p, d, f
For test 2, do we need to know how to find the quantum numbers of an electron? How do you do that?
- Mon Oct 22, 2018 9:36 am
- Forum: *Particle in a Box
- Topic: Test 2
- Replies: 9
- Views: 1318
Test 2
Will test 2 cover material about orbitals?
- Thu Oct 18, 2018 12:05 am
- Forum: Photoelectric Effect
- Topic: Equation units
- Replies: 4
- Views: 408
Equation units
For the photoelectric effect equation, do we need to use kg or g? In most examples I've only seen kg but could you also use grams for determing the energy?
- Tue Oct 16, 2018 10:02 pm
- Forum: DeBroglie Equation
- Topic: Homework Problem 1b.15
- Replies: 2
- Views: 313
Homework Problem 1b.15
For homework problem 1B.15, they ask: The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 3 103 km?s 21. (a) What is the wavelength of the ejected electron? (b) No electrons are emitted from the surface of the metal until the frequency of the radiation reaches 2.50...
- Tue Oct 16, 2018 9:09 pm
- Forum: Photoelectric Effect
- Topic: HW Question 1b.5
- Replies: 1
- Views: 266
HW Question 1b.5
For question 1B.5, the book asks to calculate the wavelength of an atom with 140.511 keV of energy. I know how you would calculate this if the energy were in joules, but how do you convert this to joules?
- Tue Oct 09, 2018 9:30 pm
- Forum: Properties of Light
- Topic: Homework Problem 1A.9
- Replies: 2
- Views: 169
Homework Problem 1A.9
When trying to determine the wavelength and energy of photon for when the wave has a frequency of 300MHz, how would you do it? I'm confused how to apply the equations to the problem.
- Tue Oct 09, 2018 7:32 pm
- Forum: Balancing Chemical Reactions
- Topic: Percent Yield
- Replies: 5
- Views: 480
Percent Yield
Do we need to know how to calculate the percent yield for test 1?
- Mon Oct 08, 2018 11:03 pm
- Forum: Limiting Reactant Calculations
- Topic: Test 1 Question
- Replies: 5
- Views: 651
Test 1 Question
Are there any more practice problems that we could do to study for the test this week besides the ones in the homework? Also does anyone know what the format of the test is going to be?
- Mon Oct 08, 2018 10:14 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Number of questions on test one [ENDORSED]
- Replies: 39
- Views: 21502
Re: Number of questions on test one [ENDORSED]
How many points will the test be out of?
- Thu Oct 04, 2018 3:55 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Problem G5
- Replies: 8
- Views: 707
Re: Problem G5
I'm still confused as to how the MinitialVinitial=mfinalvfinal formula applies to this problem, which values correspond to each part exactly?
- Wed Oct 03, 2018 11:10 pm
- Forum: Balancing Chemical Reactions
- Topic: Short cuts/methods for balancing equations
- Replies: 15
- Views: 1632
Re: Short cuts/methods for balancing equations
When balancing equations, I see that a lot of people say they start with the element that occurs the least. Does that mean the element with the least number of atoms on the reactant side, product side, or both? Or does it even really matter what order you balance an equation?
- Wed Oct 03, 2018 11:04 pm
- Forum: Significant Figures
- Topic: All students read this sig fig post [ENDORSED]
- Replies: 170
- Views: 33591
Re: All students read this sig fig post [ENDORSED]
Do we have to be aware of sig figs for every single calculation we carry out? I'm confused as to whether we don't have to worry about them or not when calculating something like molar mass.