## Search found 61 matches

Mon Mar 11, 2019 2:17 pm
Forum: First Order Reactions
Topic: Integration
Replies: 3
Views: 182

### Re: Integration

no we don't need to know how to actually integrate it (though it helps to understand how it works) just know the different orders and their respective equations that are given on the equation sheet
Mon Mar 11, 2019 2:15 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Verifying reaction mechanisms
Replies: 1
Views: 119

### Re: Verifying reaction mechanisms

i'm pretty sure it's always rate of decomposition of reactants but the unique rate should be the same for each of the species
Mon Mar 11, 2019 2:14 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre equilibrium approach
Replies: 3
Views: 171

### Re: Pre equilibrium approach

the fast steps will be at equilibrium
Mon Mar 11, 2019 2:14 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Intermediates
Replies: 8
Views: 265

### Re: Intermediates

the general rate law should only have reactants for the reaction as a whole. intermediates aren't found in the general reaction equation because they are created and then used up, so they wouldn't be in the rate law
Mon Mar 11, 2019 2:13 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: rate determining step
Replies: 2
Views: 134

### Re: rate determining step

the slow elementary step is the rate determining step. the other steps are fast so you assume those steps are at equilibrium so the fwd rate is the same as the rvs rate.
Mon Mar 11, 2019 2:10 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration cells
Replies: 2
Views: 123

### Re: Concentration cells

it's a type of electrolytic cell that has the same electrode on both sides. It relies on concentration gradients to run; so it's not as powerful as normal galvanic cells
Sun Mar 03, 2019 1:45 pm
Forum: First Order Reactions
Topic: Dividing Experiments to Find Order
Replies: 4
Views: 169

### Re: Dividing Experiments to Find Order

you can half fractional half reactions--> the rate law goes to a 1/2 power, etc
Sun Mar 03, 2019 1:33 pm
Forum: Second Order Reactions
Topic: Second order
Replies: 1
Views: 106

### Re: Second order

yes you can; the total rate order just has to be 2; so one or more of the concentrations should be to the 0th order. the units will still be 1/M/s
Sun Mar 03, 2019 1:32 pm
Forum: Zero Order Reactions
Topic: Units of K
Replies: 2
Views: 110

### Re: Units of K

M/s
Sat Feb 23, 2019 5:15 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Units
Replies: 4
Views: 100

### Re: Units

yeah you can figure it out by looking at g = h -ts; the units on the right side have to be the same as the left, so it's J, kJ or J/mol, kJ/mol
Sat Feb 23, 2019 5:12 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Finding K or Q with Nernst's Equation
Replies: 2
Views: 199

### Re: Finding K or Q with Nernst's Equation

you just rearrange the formula to find what Q is. and to find K, delta g is 0, so e is 0, and then continue to solve the equation.
Sat Feb 23, 2019 5:10 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Potential Calculation
Replies: 1
Views: 65

### Re: Cell Potential Calculation

so because the anode is the one being oxidized, the e standard reduction potential gives the reverse e standard. therefore, the e standard equation is like if you had the other method where you write the 2 half reactions out and you add the two values, but they built in the - sign into the equation ...
Sat Feb 23, 2019 5:07 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Quiz 3
Replies: 3
Views: 115

### Re: Quiz 3

i think it's just voltaic cells? he hasn't really gone over electrolytic cells in class?
Sat Feb 23, 2019 5:06 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic Cell Diagram
Replies: 6
Views: 189

### Re: Galvanic Cell Diagram

yes we need to know the order of the cell diagram and also how a salt bridge cell works overall
Sat Feb 23, 2019 5:05 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating standard cell potentials
Replies: 1
Views: 1417

### Re: Calculating standard cell potentials

bc youre doing the method of e standard = e (cathode) - e (anode). the negative sign is built into the equation.
Sun Feb 10, 2019 2:50 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: types of reversible processes
Replies: 1
Views: 1411

### types of reversible processes

what processes should we know for the midterm- isothermal reversible expansion? is there others that we have to know?
Sun Feb 10, 2019 2:48 pm
Forum: General Science Questions
Topic: Thermodynamics in the Work Field
Replies: 2
Views: 324

### Re: Thermodynamics in the Work Field

heat is released/absorbed in any rxn-- it matters more w gibbs free energy calcs bc delta g tells us if a rxn will be spontaneous or not. delta g= delta h - t delta s
this matters for things like atp hydrolysis.
Sun Feb 10, 2019 2:46 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 1
Views: 61

### Re: Bond Enthalpies

it's because bond enthalpies are written as positives, instead of negatives, so you do delta h of reactants - delta h products to get the rxn delta h
Sat Feb 02, 2019 6:19 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: are systems always measured at equilibrium?
Replies: 2
Views: 70

### Re: are systems always measured at equilibrium?

its usually at 25 celsius bc that's the temp that the scientists got all the standard value table measurements from. eg delta H standard (H2) at 25 degrees C
Sat Feb 02, 2019 6:17 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: The Relationship Between ΔH and ΔU
Replies: 2
Views: 132

### Re: The Relationship Between ΔH and ΔU

H=U + PV, so delta H = delta U + P delta V
So if so no change in delta V means that delta H = delta U.
and so if P is same and v is changing and no internal energy is changing then delta H = delta P * v
Sat Feb 02, 2019 6:12 pm
Forum: Phase Changes & Related Calculations
Topic: Chem equations vs. Physics equation for Phase change
Replies: 1
Views: 123

### Re: Chem equations vs. Physics equation for Phase change

they are the same equations? q=mc* delta T and q= mL talk about heat. and @ constant P q= delta H
Sat Jan 26, 2019 5:53 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy Units
Replies: 7
Views: 303

### Re: Enthalpy Units

enthalpy is in some kind of joules (J, kJ, etc). kJ/mol is just per mole what is the enthalpy
aka its not too significant
Sat Jan 26, 2019 5:51 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Signs in bond enthalpies
Replies: 4
Views: 147

### Re: Signs in bond enthalpies

yes to find the change in enthalpy: do bond energy (reactants) - bond energy (products)
Sat Jan 26, 2019 5:49 pm
Forum: Phase Changes & Related Calculations
Topic: Phase change enthalpy signs
Replies: 2
Views: 150

### Re: Phase change enthalpy signs

yes bc exothermic is - and endothermic is +.

freezing: exothermic: delta h is negative
melting: endothermic: delta h is positive
Mon Jan 21, 2019 11:02 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: listing strength of acids by their pKa/pKb values
Replies: 2
Views: 168

### Re: listing strength of acids by their pKa/pKb values

You can also always just switch it back to Ka/Kb then look at how large Ka/Kb is. Greater the Ka/Kb, the stronger it is, more it dissociates.
Mon Jan 21, 2019 10:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Stability
Replies: 3
Views: 94

### Re: Stability

The larger the equilibrium constant, the more a compound dissociates (look at the formula for K: [products]/[reactants])
Mon Jan 21, 2019 10:56 pm
Forum: Phase Changes & Related Calculations
Topic: How to tell acids and bases
Replies: 8
Views: 248

### Re: How to tell acids and bases

I'm pretty sure they'll always give you the formula? or like acids are called acids: eg acetic acid, hydrochloric acid; bases are hydroxides eg: barium hydroxide
Sun Jan 13, 2019 11:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Inert Gases
Replies: 2
Views: 92

### Re: Inert Gases

if the gas that is added is not involved in the reaction (aka isn't in the equation), then it is inert and won't affect equilibrium
Sun Jan 13, 2019 11:45 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Quotient Value
Replies: 5
Views: 113

### Re: Reaction Quotient Value

if q = k then the reaction is at equilibrium
Sun Jan 13, 2019 11:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pure Solids and Liquids
Replies: 2
Views: 67

### Re: Pure Solids and Liquids

in the chemical equation, they're given as for example Cl2(s) vs Cl2(g). So when its a solid, or a liquid (l) then it wouldn't go into the K/Q equations because their concentrations don't change.
Sun Dec 09, 2018 3:05 pm
Forum: DeBroglie Equation
Topic: momentum
Replies: 2
Views: 296

### Re: momentum

so momentum exists even if there's no mass--> E=pc :( i didn't know this either
Fri Dec 07, 2018 1:50 pm
Forum: Lewis Acids & Bases
Topic: Bronsted vs Lewis
Replies: 4
Views: 152

### Re: Bronsted vs Lewis

All Lewis Acid/bases are Bronsted Lowry acid/bases but not all Bronsted Lowry acid/bases are Lewis acid/bases. But B-L describes proton transfer while Lewis describes electron pair mvmt.
Fri Dec 07, 2018 1:48 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Neutral Ligands
Replies: 1
Views: 99

### Re: Neutral Ligands

aqua: OH2
Ammine: NH3
carbonyl: CO
nitronyl: NO
ethylenediamine (en): Nh2Ch2Ch2Nh2
diethylenetriamine (dien): Nh2Ch2Ch2NhCh2Ch2Nh2
Thu Dec 06, 2018 11:32 pm
Forum: Naming
Topic: 6th edition: 17.31d
Replies: 1
Views: 82

### 6th edition: 17.31d

why for sodium bisoxalato (diaqua) ferrate (iii) is oh2 written before c2o4

My answer was: Na [Fe (C2O4)2 (OH2)2]

but apparently its: Na [Fe (Oh2)2 (C2O4)2 ]
Thu Nov 29, 2018 1:45 pm
Forum: Sigma & Pi Bonds
Topic: Sigma/Pi bonds and Hybrid Orbitals
Replies: 1
Views: 90

### Sigma/Pi bonds and Hybrid Orbitals

Can hybrid orbitals make both sigma and pi bonds, or only sigma bonds?
Thu Nov 29, 2018 12:30 am
Forum: Bond Lengths & Energies
Topic: 6th edition: 3.87-- bond length vs electronegativity/polarity
Replies: 1
Views: 291

### 6th edition: 3.87-- bond length vs electronegativity/polarity

For this question, why does the bond length matter more than electronegativity & polarity for determining bond strength?

CF4 bond strength > CCl4 bs > CBr4 bs
Sun Nov 25, 2018 1:57 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Atomic Placement of CH2F2
Replies: 1
Views: 53

### Atomic Placement of CH2F2

How can we determine which atoms go where in CH2F2. I looked it up to find that F takes the spot above the central molecule C. Is there a specific reason why or is it just how we generally write it (and we could easily flip the atomic placement)?
Sat Nov 24, 2018 4:40 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Intermolecular Forces
Replies: 1
Views: 89

### Re: Intermolecular Forces

First, determine whether a molecule has a dipole or is capable of making a hydrogen bond (N, O, F is bonded to H). Then see if the dipoles cancel out (using molecular shape). If btwn 2 molecules there are dipoles that aren't being cancelled out, it would be dipole-dipole. For 1 dipole, and 1 nonpola...
Sat Nov 24, 2018 4:36 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Distortion and London Dispersion Forces
Replies: 2
Views: 130

### Re: Distortion and London Dispersion Forces

seeing that london dispersion forces are induced dipole-induced dipole attractions, more distortion means that its more likely for these intermolecular attractions to happen. P much all london dispersion forces are super weak; however, the amount of ldf add up which is why they are very important in...
Thu Nov 22, 2018 3:30 am
Forum: Determining Molecular Shape (VSEPR)
Topic: molecular vs electron geometry
Replies: 2
Views: 43

### molecular vs electron geometry

What is the difference between molecular and electron geometry? eg: how can you tell which one (like tetrahedral) is which, and are they mutually exclusive?
Fri Nov 16, 2018 2:54 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: H-Bonding
Replies: 8
Views: 303

### Re: H-Bonding

no h-bonding is only for polar molecules, more specifically for H-F, H-O, H-N bonds
Fri Nov 16, 2018 2:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: tetrahedral vs trigonal planar
Replies: 9
Views: 487

### Re: tetrahedral vs trigonal planar

tetrahedral has 4 bonding regions, while trigonal planar has only 3. When you look at the lewis structure of the central atom, look at how many bonding regions it has.
Fri Nov 16, 2018 2:49 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bond Strength
Replies: 3
Views: 172

### Re: Covalent Bond Strength

I'm pretty sure it does decrease with increased length. Refer to Coulomb's law: as radius increases force of attraction decreases
Fri Nov 09, 2018 3:15 pm
Forum: Dipole Moments
Topic: Dipole induced-dipole
Replies: 2
Views: 112

### Re: Dipole induced-dipole

these are also instantaneous attractions bc the induced dipole comes from a momentary fluctuation in an atom's electron cloud.
Fri Nov 09, 2018 3:12 pm
Forum: Bond Lengths & Energies
Topic: bond angles
Replies: 3
Views: 172

### Re: bond angles

lone pairs take up more space/ repel bonds more so it will change the measured bond angles.
Fri Nov 09, 2018 3:10 pm
Forum: Dipole Moments
Topic: Melting points
Replies: 5
Views: 221

### Re: Melting points

hydrogen bonds have a stronger attraction than other intermolecular attractions; thus, it takes more energy to change phase, so the melting/boiling points will be higher
Thu Nov 01, 2018 10:57 pm
Forum: Ionic & Covalent Bonds
Topic: Copper Ions
Replies: 3
Views: 117

### Re: Copper Ions

Copper(I) is Cu+ and Copper(II) is Cu2+
Thu Nov 01, 2018 10:56 pm
Forum: Lewis Acids & Bases
Topic: Lewis Acids and Bases on Midterm
Replies: 4
Views: 251

### Re: Lewis Acids and Bases on Midterm

i feel like we should probably know basics (eg electron pair is shared)

and pretty much when you draw the molecule's Lewis structure where you would need one species to share an electron pair w the other--> thats a lewis acid/base pair
Thu Nov 01, 2018 10:47 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Homework 2.43e
Replies: 3
Views: 197

### Re: Homework 2.43e

does this rule not apply to seaborgium and roentgenium (which are under the same group as Cr/Cu but 1 period down)?
Thu Oct 25, 2018 11:34 pm
Forum: Administrative Questions and Class Announcements
Topic: Exam
Replies: 2
Views: 137

### Re: Exam

we don't need to know how to use schrodinger's eqn tho we have to know where it comes from & what it does
Thu Oct 25, 2018 8:38 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: quiz 2: 5-s orbital
Replies: 3
Views: 128

### Re: quiz 2: 5-s orbital

N has no impact on the number of electrons directly; however it determines what l can be. So when l=0 (s orbital shell) there can only be 1 orbital which fits 2 electrons
Thu Oct 25, 2018 8:32 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2 Material?
Replies: 2
Views: 227

### Re: Test 2 Material?

We should probably know that the equation is solved by the 3 quantum numbers n, l, and m.
Fri Oct 19, 2018 2:58 pm
Forum: *Shrodinger Equation
Topic: Shrodinger Equation on Test
Replies: 5
Views: 227

### Re: Shrodinger Equation on Test

I thought that we wouldn't need to use wave function equations nor use any calculus.
Fri Oct 19, 2018 2:55 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Lecture Question
Replies: 4
Views: 200

### Re: Lecture Question

there are higher energy orbitals that theoretically exist--> g would be the next one which would require 121 protons
Fri Oct 19, 2018 2:53 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: M quantum number
Replies: 1
Views: 35

### M quantum number

In lecture, Prof. Lavelle mentioned that Ml values could be named like x, y, and z. I was wondering for bigger orbitals like d, or f, what alpha letters would be used to represent the different Ml values.
Thu Oct 11, 2018 9:31 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: H-Atom Emperical Equation
Replies: 2
Views: 97

### Re: H-Atom Emperical Equation

i thought other equations have similar like formats with much more complex values (even for atoms with only 1 electron, not to mention the ones with multiple electrons), but in general we don't have to know that for this class.
Thu Oct 11, 2018 9:16 pm
Forum: Properties of Light
Topic: speed of light
Replies: 8
Views: 345

### speed of light

When we do hw, should we use 3.0x10^8 m/s for the speed of light, or a more accurate value?
Thu Oct 11, 2018 7:28 pm
Forum: Empirical & Molecular Formulas
Topic: Rounding for limiting reactants
Replies: 5
Views: 292

### Re: Rounding for limiting reactants

When I do limiting reactant/empirical formula problems I usually find the ratios then instead of multiplying to a whole number, I first look to see if it converts to some nice fraction-- eg 4.33 = 13/3 or 4.63-4.68 = 14/3, then solve from there. :)
Fri Oct 05, 2018 9:28 pm
Forum: Limiting Reactant Calculations
Topic: Total Mass
Replies: 2
Views: 88

### Re: Total Mass

Yes your way works: the number might not be exactly the same if you rounded each step--> general rule: keep all the sig figs until the end
Fri Oct 05, 2018 2:49 pm
Forum: Properties of Light
Topic: Formulas We Need to Know [ENDORSED]
Replies: 1
Views: 55

### Formulas We Need to Know[ENDORSED]

For exams, will we need to memorize all the formulas that we discussed in class?
Thu Oct 04, 2018 10:27 pm
Forum: SI Units, Unit Conversions
Topic: Scientific Notation
Replies: 11
Views: 498

### Re: Scientific Notation

Yes use whatever sig figs is the least accurate in the given: aka if you have 3, 4, 5 sig figs given to you in the question: respond with 3 sig figs.

Go to advanced search