Search found 67 matches
- Thu Mar 14, 2019 10:33 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: catalyst vs intermediate
- Replies: 9
- Views: 871
Re: catalyst vs intermediate
to add to your question, how can you tell which substance is a catalyst versus an intermediate when given a series of steps?
- Thu Mar 14, 2019 10:31 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ice chart
- Replies: 2
- Views: 342
Re: ice chart
reactants are "-x" and products "+x" since the reactant is usually forming product. also you're usually given some reactant concentration and no product, so if you were to put "-x" under products you would get a negative concentration. hope this helps
- Thu Mar 14, 2019 10:29 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Water in cell diagram
- Replies: 1
- Views: 149
Re: Water in cell diagram
you don't include H2O since it's a solvent
- Thu Mar 14, 2019 10:28 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ice chart coefficients
- Replies: 1
- Views: 249
Re: Ice chart coefficients
you put coefficients if it's in the equation. so if you have 2H+ as a product, you'd write "-2x." hope this helps
- Thu Mar 14, 2019 10:25 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: C in a diatomic molecule
- Replies: 3
- Views: 548
Re: C in a diatomic molecule
to add to your question, when do we use Cp vs Cv?
- Tue Mar 12, 2019 10:34 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Sig Figs
- Replies: 9
- Views: 1129
Re: Sig Figs
i'm not 100% sure, but i think sig figs still count. but i was told that for the midterm they wouldn't count for thermo questions. don't know if that still applies
- Tue Mar 12, 2019 10:30 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: exercise 11.77 6th edition
- Replies: 2
- Views: 326
Re: exercise 11.77 6th edition
I found this answer on an older, similar post:
"Breaking a diatomic molecule X2(g) requires energy to become 2X(g), and therefore the reaction is endothermic. This is true for other halogens as well"
"Breaking a diatomic molecule X2(g) requires energy to become 2X(g), and therefore the reaction is endothermic. This is true for other halogens as well"
- Tue Mar 12, 2019 10:27 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: When to add H+ and H20 to the Cell Diagram
- Replies: 2
- Views: 1621
Re: When to add H+ and H20 to the Cell Diagram
H+ is aqueous so it's an active part of the reaction and is in the cell diagram but H2O is just a solvent so it doesn't get added into the cell diagram
- Mon Mar 11, 2019 10:20 pm
- Forum: First Order Reactions
- Topic: Integrated Rate Laws (7b.1/ 15.21)
- Replies: 3
- Views: 337
Re: Integrated Rate Laws (7b.1/ 15.21)
^to add on, you have to subtract the new [A] from the initial [A]. so when you use the molar ratio to get [A] when [B] = .034 mol/L, you should get [A] = .068 mol/L. then you have to subtract from the initial: .153 - .068 = .085 mol/L. this is the [A] you should use for your computation
- Mon Mar 11, 2019 10:13 pm
- Forum: First Order Reactions
- Topic: Doubling the Concentration
- Replies: 4
- Views: 472
Re: Doubling the Concentration
changing concentration wouldn't affect the reaction order. rate doubles because in a first order reaction, rate = k[A]. in a second order reaction, rate = k[A]^2, so if concentration were doubled the rate would increase exponentially, not double
- Mon Mar 11, 2019 10:10 pm
- Forum: General Rate Laws
- Topic: Rate definition
- Replies: 3
- Views: 370
Re: Rate definition
rate of a reaction depends on the rate constant (k) and some other variable (we've been working with concentration)
- Mon Mar 11, 2019 10:07 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Pre-Equilibrium Steps
- Replies: 2
- Views: 285
Re: Pre-Equilibrium Steps
we'd be given which steps are fast or slow, so we'd just have to know that the slow step is the rate-determining step
- Mon Mar 11, 2019 10:04 pm
- Forum: General Rate Laws
- Topic: Homogeneous vs Heterogeneous Reactions
- Replies: 2
- Views: 361
Re: Homogeneous vs Heterogeneous Reactions
homogeneous reactions have reactants and products that are all in the same phase (gas, liquid, solid, aqueous). heterogeneous reactions include more than one phase in the reaction
- Tue Feb 26, 2019 5:52 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 23116
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
for #4 on gibbs free energy, does it matter that the standard delta G is given in kJ instead of kJ/mol? i thought we'd have to divide by 2 to get the delta G per mole of NH3, but that didn't give me the right answer so i'm a little confused because plugging in the given value does give me the right ...
- Tue Feb 26, 2019 5:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 23116
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
On #1 of the Gibbs to find the standard enthalpy and entropy of formation you have to do the sum of products minus the sum of the reactants using the numbers given right? For some reason I am not getting the same answer. the values are given per mole, are you multiplying them by the respective mole...
- Tue Feb 26, 2019 5:47 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 23116
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Madison Hurst wrote:In the Gibbs WS #4 how do you find T? or can you just assume its at 25 C?
yeah you just assume 25 C, so 298 K
- Mon Feb 25, 2019 7:38 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Difference in values
- Replies: 2
- Views: 268
Re: Difference in values
it's similar to delta H / delta H^o or delta S / delta S^o, the ^o always refers to a standard state
- Mon Feb 25, 2019 7:36 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams
- Replies: 2
- Views: 258
Re: Cell Diagrams
^to add on, within each half-reaction in a cell diagram, you'd typically write in the order of what's being reduced/oxidized. so if Ni2+ is reduced to Ni, the cell diagram for this cathode would be Ni2+(aq)|Ni(s)
- Mon Feb 25, 2019 7:33 pm
- Forum: Balancing Redox Reactions
- Topic: Test #2
- Replies: 9
- Views: 895
Re: Test #2
SydBenedict2H wrote:Will he ask us any acid base questions, or is he only asking Gibbs and electrochemistry?
acid base was covered in the midterm so it'll just be what's posted on his website
- Mon Feb 25, 2019 7:32 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Electrons
- Replies: 3
- Views: 339
Re: Balancing Electrons
^to add, if the half-reactions have different numbers of electrons, you just multiply the reactions by whatever factors will make the electrons cancel out
- Mon Feb 25, 2019 7:31 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst Equation
- Replies: 2
- Views: 304
Re: Nernst Equation
yes, it's the number that cancels out when you balance a redox reaction by writing out its oxidation/reduction half-reactions
- Mon Feb 25, 2019 7:29 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n value
- Replies: 11
- Views: 890
Re: n value
n is the number of electrons that cancel out when you write out oxidation/reduction half-reactions to get the balanced redox reaction
- Mon Feb 25, 2019 7:23 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Problem 6L.1
- Replies: 4
- Views: 798
Re: Problem 6L.1
You'd use n = 2 electrons because when you split up the half-reactions you get:
Oxid.: Ce4+ + e- --> Ce3+
Red.: 3I- --> I(3)- + 2e-
Multiply the oxidation half-reaction by 2 to balance out the electrons and cancel them out, leaving you with two electrons getting cancelled.
Oxid.: Ce4+ + e- --> Ce3+
Red.: 3I- --> I(3)- + 2e-
Multiply the oxidation half-reaction by 2 to balance out the electrons and cancel them out, leaving you with two electrons getting cancelled.
- Mon Feb 25, 2019 7:18 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 7th Edition 6L.5
- Replies: 1
- Views: 156
7th Edition 6L.5
This question asks for the cell diagrams of given skeletal equations. For (b) Ce4+ (aq) + I- (aq) --> I2 (s) + Ce3+ , I understand that the cell diagram would need a Pt (s) on the cathode end where Ce4+ reduces to Ce3+, so it'd be Ce4+(aq), Ce3+(aq) | Pt(s). But the answer key also has a Pt(s) on th...
- Tue Feb 12, 2019 5:32 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 23116
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Jordan Lo 2A wrote:Can someone explain #4? Is this because q=0 when delta T=0, and w=0 when -PdeltaV=0?
When delta T = 0, the internal energy delta U = 0. Since delta U = q + w, if delta U = 0 then w = -q, aka the work done on the system is equal to the heat absorbed.
- Tue Feb 12, 2019 5:29 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 23116
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Can someone explain how to solve 10 and 11? For 11, I used the mol(cv)(ln(t2/t1)) and am not getting the correct answer. Can someone please outline the steps to solve? For 10, use delta S = nRln(V2/V1) For 11, you need to add up two different delta S's, one for the volume change and one for the tem...
- Tue Feb 12, 2019 5:26 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 23116
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Hannah Yates 1K wrote:Can someone explain 5c?
You use work = -nRTln(V2/V1). Isolate ln(V2/V1) and then solve for V2/V1 by taking e of both sides
- Tue Feb 12, 2019 5:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 23116
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
can someone explain 6(d)? I tried using the additive equation for standard enthalpy of a reaction but I don't think I'm inputting the correct value for it or if that's even a possible way to get the answer
- Wed Jan 23, 2019 10:27 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kw - applies to solutions other than 100% water?
- Replies: 3
- Views: 322
Re: Kw - applies to solutions other than 100% water?
Kw implies that the solution is water since the expression represents the autoprotolysis of water
- Wed Jan 23, 2019 10:18 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Volume and Le Chatelier's Principle
- Replies: 5
- Views: 438
Re: Volume and Le Chatelier's Principle
Minimizing the effect of changing volume is dependent on what side has more moles, so if both sides are the same then there's no shift that will minimize the effect. Aka it doesn't shift left or right
- Wed Jan 23, 2019 9:59 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ACIDS AND BASES: What to do with very dilute acid
- Replies: 2
- Views: 173
Re: ACIDS AND BASES: What to do with very dilute acid
To add on, I don't think Dr. Lavelle would give us a borderline problem like that. If he did however, I'm pretty sure you still consider it negligible and add it.
- Wed Jan 23, 2019 9:56 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Increase in Volume Effect on Equilibrium
- Replies: 6
- Views: 1496
Re: Increase in Volume Effect on Equilibrium
The reaction responds in such a way that minimizes the effect of a pressure change, so increasing volume (decreasing pressure) in a system with more moles on one side will favor that same side.
- Wed Jan 23, 2019 9:38 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Writing equations for weak acids/bases
- Replies: 3
- Views: 586
Re: Writing equations for weak acids/bases
We can disregard spectator ions when writing out equations with salts, but I think you should write out the entire equation for other scenarios to make sure you're noting the correct Kb / Ka values that correspond
- Wed Jan 23, 2019 9:36 pm
- Forum: Phase Changes & Related Calculations
- Topic: ∆Hsub=∆Hfus+∆Hvap
- Replies: 3
- Views: 533
Re: ∆Hsub=∆Hfus+∆Hvap
∆Hfus = Hliquid- Hsolid ∆Hvap = Hvapor - Hliquid ∆Hsub = Hvapor - Hsolid Since sublimation goes straight from a solid to a vapor state, it'll have the same total change as the individual changes in fusion and vaporization put together. Therefore, you can combine them all to get ∆Hsub=∆Hfus+∆Hvap Hop...
- Sun Jan 13, 2019 9:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium constant
- Replies: 6
- Views: 531
Re: Equilibrium constant
Technically, it affects both since pressure and concentration are related by PV=nRT --> P=(concentration)RT <--> concentration=P/RT
But yes Kp is pressure and Kc is concentration
But yes Kp is pressure and Kc is concentration
- Sun Jan 13, 2019 9:47 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Effect of increased concentration on equilibrium
- Replies: 9
- Views: 1463
Re: Effect of increased concentration on equilibrium
In addition to more products getting produced, the concentration of any other reactants in the reaction would decrease.
- Sun Jan 13, 2019 9:45 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Determining Which side is favored
- Replies: 5
- Views: 669
Re: Determining Which side is favored
Yes, since Q and K are the same ratio ([products]/[reactants]) that means the [products] would have to decrease, or the [reactants] would have to increase, in order for Q to be less than K. Therefore, there will be more reactants yielding products so that the forward reaction is favored.
- Thu Dec 06, 2018 10:26 pm
- Forum: Lewis Acids & Bases
- Topic: Strong Acids
- Replies: 6
- Views: 616
Re: Strong Acids
One reason that HF is a weaker acid than HI is because of the stronger bond - it is less likely to donate a proton
- Thu Dec 06, 2018 10:20 pm
- Forum: Bronsted Acids & Bases
- Topic: Glucose as an acid
- Replies: 3
- Views: 288
Re: Glucose as an acid
I don't think it's either actually, it's a neutral organic compound
- Thu Dec 06, 2018 10:12 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizing Power: Size vs. Charge
- Replies: 4
- Views: 710
Re: Polarizing Power: Size vs. Charge
First look at charge (greater charge corresponds to higher polarizing power) and then size (smaller atoms have higher polarizing power)
- Tue Nov 27, 2018 11:42 pm
- Forum: Ionic & Covalent Bonds
- Topic: Covalent vs. Ionic
- Replies: 2
- Views: 262
Re: Covalent vs. Ionic
During one lecture Dr. Lavelle said any questions on ionic/covalent character would be pretty straightforward if we aren't given an electronegativity chart. So we can just figure it out based on how close/far apart the atoms in a molecule are on the periodic table.
- Tue Nov 27, 2018 11:34 pm
- Forum: Hybridization
- Topic: sigma and pi bonds
- Replies: 5
- Views: 483
sigma and pi bonds
what makes sigma bonds weaker than pi bonds?
- Tue Nov 27, 2018 11:25 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 3
- Replies: 38
- Views: 2540
Re: Test 3
Ashley P 4I wrote:Does anyone have a trick to memorizing all these things?
I made a big chart to study off of, you can find one online if you just search up VSEPR geometries
- Tue Nov 27, 2018 11:21 pm
- Forum: Hybridization
- Topic: S- Character
- Replies: 1
- Views: 211
Re: S- Character
s-character is how much of a hybrid orbital is made up of the s orbital (ie sp = 50%, sp2 = 33%, sp3= 25%, etc.)
increasing s-character is basically decreasing the number of bonds, which allows for more space between bonds, therefore increasing bond angles.
increasing s-character is basically decreasing the number of bonds, which allows for more space between bonds, therefore increasing bond angles.
- Tue Nov 27, 2018 11:13 pm
- Forum: Resonance Structures
- Topic: Bond lengths & number of resonance structures
- Replies: 3
- Views: 638
Re: Bond lengths & number of resonance structures
A molecule's structure is an average of all resonance structures so the bond lengths would be an average
- Tue Nov 27, 2018 11:08 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Seesaw Shape Bond Angles
- Replies: 8
- Views: 739
Re: Seesaw Shape Bond Angles
The VSEPR formula for seesaw is AX4E, so the 4 bonding groups and single lone pair result in <120 equatorial <90 axial
- Wed Nov 14, 2018 3:56 pm
- Forum: Properties of Electrons
- Topic: Polar vs Non polar
- Replies: 15
- Views: 4639
Re: Polar vs Non polar
This is what my high school chem teacher taught us: "A molecule with a uniform distribution of electron density is nonpolar; and one with an asymmetrical distribution is polar. A molecule is nonpolar only if it has no lone pair electrons about the central atom and all groups attached to the cen...
- Wed Nov 14, 2018 3:54 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Grades
- Replies: 5
- Views: 475
Grades
Does anyone know how the grading scale works for Dr. Lavelle's class? Is it on a curve or does each letter grade correspond to a specific and fixed percentage range?
- Wed Nov 14, 2018 3:46 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Question 4.5 (Determining shape from Lewis structure)
- Replies: 2
- Views: 319
Re: Question 4.5 (Determining shape from Lewis structure)
When you draw the Lewis structure, you can determine the number of bonding pair and lone pair electrons. You can then create a VSEPR formula which corresponds to a particular shape. For example, a formula of AX3 corresponds to a trigonal planar shape.
- Thu Nov 08, 2018 6:31 pm
- Forum: Electronegativity
- Topic: Electronegativity Calculation
- Replies: 5
- Views: 578
Re: Electronegativity Calculation
In the book the equation for electronegativity is given as the average of ionization energy and electron affinity. But in lecture Dr. Lavelle said we'd just be given the table of values if we need to use them on a test so we probably don't need the equation
- Thu Nov 08, 2018 6:28 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic vs Covalent Bonds
- Replies: 18
- Views: 1763
Re: Ionic vs Covalent Bonds
The book states that most bonds are somewhere in between purely covalent and purely ionic. When depicting these bonds, how does one know when to depict a bond as ionic or covalent when it is in this in between state? The book uses a rough guideline in which a difference in electronegativity greater...
- Thu Nov 08, 2018 6:22 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability
- Replies: 3
- Views: 149
Polarizability
Can someone explain the relationship between number of electrons and polarizability?
- Wed Oct 31, 2018 7:16 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Spin Magnetic Quantum Number
- Replies: 6
- Views: 924
Re: Spin Magnetic Quantum Number
I think as the electrons fill an orbital they take a +1/2 spin, then as the become paired they take -1/2 spin.
- Wed Oct 31, 2018 7:09 pm
- Forum: Octet Exceptions
- Topic: Expanded Valence Shells
- Replies: 2
- Views: 830
Re: Expanded Valence Shells
You are right about any atom with n=3 or higher being able to have an expanded valence shell. Dr. Lavelle mentioned that this applies to atoms in periods 3 and higher.
- Wed Oct 31, 2018 7:06 pm
- Forum: Trends in The Periodic Table
- Topic: Electron affinity
- Replies: 5
- Views: 319
Re: Electron affinity
Electron affinity is the energy released when an electron is added to a gas-phase atom. You can think of it as how much an atom attracts an electron. On the periodic table, it is highest on the upper right (with the exception of noble gases since they have full valence shells).
- Wed Oct 24, 2018 9:00 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: electron configurations
- Replies: 1
- Views: 196
Re: electron configurations
I believe it's because the f block starts right after the s block at period 6, so it doesn't include the d block until after the lanthanide series ends.
- Wed Oct 24, 2018 8:52 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Electron Configuration Order
- Replies: 2
- Views: 122
Re: Electron Configuration Order
The 3d orbital actually comes before 4s because it has lower energy, and the electron configuration is written from lowest to highest energy. For example, scandium's electron configuration is [Ar]3d(1)4s(2), not [Ar]4s(2)3d(1).
- Wed Oct 24, 2018 8:48 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Electron Spin
- Replies: 3
- Views: 247
Re: Electron Spin
I believe for the ground state electron configuration of an atom, the convention is to fill orbitals with +1/2 spin and then go back to pair electrons with a -1/2 spin.
- Wed Oct 17, 2018 4:31 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodal Planes
- Replies: 3
- Views: 281
Re: Nodal Planes
Remember that electron density is the probability of an electron being present in that region. So since nodal planes approach 0, there is no chance of an electron being found there (aka the electron density = 0).
Also, the number of nodal planes increases per orbital (s = 0, p = 1, d = 2, f = 3).
Also, the number of nodal planes increases per orbital (s = 0, p = 1, d = 2, f = 3).
- Wed Oct 17, 2018 4:25 pm
- Forum: Properties of Light
- Topic: Homework Problem
- Replies: 2
- Views: 247
Re: Homework Problem
You have to know that the UV spectrum includes the Lyman series, in which n1 = 1. Using the given wavelength, you can find frequency. Then you isolate n2 in Rydberg's formula and plug in all your values to find the final energy level.
- Wed Oct 17, 2018 4:20 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Differentiating Orbitals
- Replies: 2
- Views: 114
Re: Differentiating Orbitals
Where the orbitals lie also depend on their lobe orientation. For example the d-orbital can have lobes either on xy- yz- zx- planes, the x & y axes, or the xy-plane. So it varies within each orbital
- Thu Oct 11, 2018 8:33 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Homework Week 2
- Replies: 5
- Views: 483
Re: Homework Week 2
Yeah that's fine, since we haven't finished covering the quantum world
- Thu Oct 11, 2018 8:28 pm
- Forum: Empirical & Molecular Formulas
- Topic: Is it possible for the Empirical and Molecular formula to be the same? [ENDORSED]
- Replies: 8
- Views: 1220
Re: Is it possible for the Empirical and Molecular formula to be the same? [ENDORSED]
It is possible! Take H2O for example. The formula can't get any simpler, so it is both the molecular and empirical formula of water.
- Thu Oct 11, 2018 8:12 pm
- Forum: Properties of Electrons
- Topic: Emission vs Absorption
- Replies: 4
- Views: 387
Re: Emission vs Absorption
When an atom absorbs a photon, the energy from the photon sends the electron to a higher energy level. The electron emits energy in the form of light when it returns to its ground state.
- Wed Oct 03, 2018 4:07 pm
- Forum: Significant Figures
- Topic: sig fig for avogadros number
- Replies: 3
- Views: 2066
Re: sig fig for avogadros number
Since the textbook uses 6.022*10^23, it would probably be better to use that value so your answers can be more precise and line up with the textbook answers. In addition, it is a constant value so its sig figs are not dependent on other components of the problem.
- Wed Oct 03, 2018 3:59 pm
- Forum: General Science Questions
- Topic: Finding Molecular Formula, Mass Percentage
- Replies: 2
- Views: 360
Re: Finding Molecular Formula, Mass Percentage
Mass percentage is not necessary in this problem because you are already given the amount of each reactant with respect to the sample. You can use this information to set up ratios of mass of element per mass of sample (leaving you with grams), then divide by molar mass (leaving you with moles) in o...
- Wed Oct 03, 2018 3:46 pm
- Forum: Balancing Chemical Reactions
- Topic: Combustion Reactions.
- Replies: 8
- Views: 2976
Re: Combustion Reactions.
In response to the most recent comment: no, it does not matter which order products or reactants are written in, as long as they are on their respective sides of the chemical equation (reactants on left, products on right)
So the equation can be written as C6H6 + O2-> H2O + CO2
So the equation can be written as C6H6 + O2-> H2O + CO2