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by Meredith Steinberg 2E
Wed Mar 14, 2018 2:44 pm
Forum: *Alkanes
Topic: Naming compounds
Replies: 3
Views: 232

Re: Naming compounds

I do not believe we will have to draw the functional groups, I think we will just have to recognize one given a structure or chemical formula of a molecule.
by Meredith Steinberg 2E
Wed Mar 14, 2018 2:42 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Elementary reactions
Replies: 6
Views: 154

Re: Elementary reactions

Elementary reactions are the specifics of an overall reaction. They're elementary in that there may be species seen, such as intermediates and catalysts, that are not seen in the net reaction that takes place.
by Meredith Steinberg 2E
Wed Mar 14, 2018 2:41 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts vs Intermediates
Replies: 2
Views: 97

Re: Catalysts vs Intermediates

Intermediates are produced in one of the elementary steps, and consumed in another, thereby cancelling it out. Catalysts, however, are not produced in between and are at the beginning of the reaction and are at the end of the elementary steps to cancel out.
by Meredith Steinberg 2E
Sun Mar 11, 2018 6:05 pm
Forum: Second Order Reactions
Topic: the slope
Replies: 12
Views: 339

Re: the slope

If the slope were to be positive for the first order reaction, we would have to look at -ln(concentration) on the y axis, which doesn't conceptually make sense, so I don't think we would have to calculate a positive slope for equations that are given with a slope w a -k value.
by Meredith Steinberg 2E
Sun Mar 11, 2018 6:01 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.69
Replies: 2
Views: 91

Re: 15.69

In the equation, rate=K[reactants], K is directly related to the rate. Keep in mind, however, that K depends ONLY on the reaction and the temperature and will not change if the reactant concentrations change.
by Meredith Steinberg 2E
Sun Mar 11, 2018 5:58 pm
Forum: Second Order Reactions
Topic: Half life of second order reactions
Replies: 8
Views: 331

Re: Half life of second order reactions

I wouldn't worry too much about deriving the half life of a second order process. If we ever needed to use the equation, we would need 2 of the 3 unknowns: k, initial concentration, or the half life.
by Meredith Steinberg 2E
Wed Feb 28, 2018 9:45 pm
Forum: Zero Order Reactions
Topic: Negative order
Replies: 4
Views: 103

Re: Negative order

I wouldn't worry too much about it when you're studying, since we will only be tested on 1st, 2nd and zeroth order.
by Meredith Steinberg 2E
Wed Feb 28, 2018 9:44 pm
Forum: General Rate Laws
Topic: Half life
Replies: 3
Views: 76

Re: Half life

Today in class we derived that t1/2= 1/(k[A]sub0)
by Meredith Steinberg 2E
Wed Feb 28, 2018 9:42 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Units of Reaction Rate
Replies: 7
Views: 178

Re: Units of Reaction Rate

We will use gas constant, R, when we talk more about activation energy and its relationship to k and A.
by Meredith Steinberg 2E
Fri Feb 23, 2018 1:02 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: ln vs log [ENDORSED]
Replies: 5
Views: 126

Re: ln vs log [ENDORSED]

They are both just different ways to write the Nernst Equation, but they should yield the same answer
by Meredith Steinberg 2E
Fri Feb 23, 2018 1:01 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagram [ENDORSED]
Replies: 4
Views: 106

Re: Cell diagram [ENDORSED]

You only use commas when they are in the same phase, such as when they're both aqueous. All other times a single line should be used.
by Meredith Steinberg 2E
Fri Feb 23, 2018 1:00 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Spontaneous Directions [ENDORSED]
Replies: 7
Views: 149

Re: Spontaneous Directions [ENDORSED]

Redox reactions are spontaneous when standard potential is positive. This makes sense if you think about the equation G=-nFE. If E is positive, G will be negative, indicating a spontaneous process.
by Meredith Steinberg 2E
Fri Feb 16, 2018 5:41 pm
Forum: Balancing Redox Reactions
Topic: Salt Bridge Versus Pourous Disk
Replies: 6
Views: 141

Re: Salt Bridge Versus Pourous Disk

There isn't an overall difference, because both maintain neutrality in the solutions
by Meredith Steinberg 2E
Fri Feb 16, 2018 5:39 pm
Forum: Balancing Redox Reactions
Topic: Salt Bridges
Replies: 14
Views: 191

Re: Salt Bridges

Salt bridges keep both solutions neutral as reduction and oxidation are occurring
by Meredith Steinberg 2E
Fri Feb 16, 2018 5:38 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode/ Cathode
Replies: 6
Views: 123

Re: Anode/ Cathode

Usually the anode is on the left and the cathode is on the right, and we see the electrons flow from left to right. If this isn't the case, though, just remember that oxidation (loss of elections) occurs at the anode and reduction (gain of electrons) occurs at the cathode.
by Meredith Steinberg 2E
Sun Feb 11, 2018 12:29 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Sig Figs in 11.19
Replies: 2
Views: 98

Re: Sig Figs in 11.19

It should be two sig figs, but I wouldn't worry too much about it since we won't be penalized for improper sig figs on tests.
by Meredith Steinberg 2E
Sun Feb 11, 2018 12:25 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Non-spontaneous
Replies: 4
Views: 100

Re: Non-spontaneous

The forward reaction is favored when there doesn't need to be an outside source, such as increasing temperature, to catalyze the reaction. If the forward reaction is favored, then the reverse reaction is not favored (and vice versa).
by Meredith Steinberg 2E
Sun Feb 11, 2018 12:22 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 913
Replies: 2
Views: 93

Re: 913

Ideal gas behavior assumes that the ideal gas has a quantity of 1 mol.
by Meredith Steinberg 2E
Wed Jan 31, 2018 11:26 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.3
Replies: 5
Views: 131

Re: 9.3

When heat is leaving a system, it's energy sign is negative. When it is entering a system, its energy sign is positive. This can also be applied when you're doing problem 9.5 when heat is being transferred from one reservoir to another.
by Meredith Steinberg 2E
Wed Jan 31, 2018 11:24 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Question 9.5
Replies: 3
Views: 105

Re: Question 9.5

Heat is being given off in the 800K reservoir, which makes the energy sign negative, and it's being absorbed in the 200K reservoir, which makes its energy sign positive.
by Meredith Steinberg 2E
Wed Jan 31, 2018 11:22 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.5
Replies: 5
Views: 105

Re: 9.5

Heat is leaving the large reservoir at 800K, which explains why the entropy is negative.
by Meredith Steinberg 2E
Wed Jan 24, 2018 4:57 pm
Forum: Phase Changes & Related Calculations
Topic: Combustion of liquids
Replies: 4
Views: 140

Re: Combustion of liquids

In combustion reactions, the products normally come in the form of gaseous CO2 and liquid H20, unless otherwise specified.
by Meredith Steinberg 2E
Wed Jan 24, 2018 4:55 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Positive and Negative Signs 8.21
Replies: 3
Views: 103

Re: Positive and Negative Signs 8.21

It ends up not mattering which side gets the negative. What's important to know (as seen in the solutions manual) is that
heat lost=-(heat gained).
by Meredith Steinberg 2E
Wed Jan 24, 2018 4:52 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm
Replies: 2
Views: 160

Re: Midterm

I think it depends on how far we get into the Second & Third Laws and if we move on to Electrochemistry before the midterm. We'll probably learn more about it as the midterm gets closer.
by Meredith Steinberg 2E
Thu Jan 18, 2018 12:00 pm
Forum: Phase Changes & Related Calculations
Topic: Question about Problem 8.41
Replies: 5
Views: 177

Re: Question about Problem 8.41

Yes because there is a transfer of heat from the water to the ice
by Meredith Steinberg 2E
Thu Jan 18, 2018 11:59 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.29 heat capacity
Replies: 3
Views: 94

Re: 8.29 heat capacity

The solutions manual explains that as more atoms are present in the molecule, there are more possible bond vibrations that can absorb added energy
by Meredith Steinberg 2E
Wed Jan 17, 2018 11:08 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: R value in equation
Replies: 4
Views: 126

Re: R value in equation

The R value depends on the units you're working with
by Meredith Steinberg 2E
Fri Jan 12, 2018 11:26 am
Forum: Phase Changes & Related Calculations
Topic: Ideal Gas
Replies: 5
Views: 181

Re: Ideal Gas

An ideal gas means the gas follows the properties of gases "ideally." For example, an ideal gas contains random particle motion, and each particle collision is completely elastic (no energy is lost during the collision). An ideal gas follows the ideal gas law PV=nRT.
by Meredith Steinberg 2E
Fri Jan 12, 2018 9:56 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpies of Formation of Diatomic Molecules
Replies: 6
Views: 605

Re: Standard Enthalpies of Formation of Diatomic Molecules

O2 is the most stable form of oxygen and therefore has an enthalpy equal to zero. This is the same for other diatomic elements, such as nitrogen (N2), chlorine (Cl2), etc.
by Meredith Steinberg 2E
Fri Jan 12, 2018 9:42 am
Forum: Phase Changes & Related Calculations
Topic: Constant Temperature
Replies: 4
Views: 165

Re: Constant Temperature

Because heat is needed for a phase change, the temperature of the sample will remain the same even though heat is being supplied because the heat is being used to break bonds.
by Meredith Steinberg 2E
Tue Dec 05, 2017 11:24 am
Forum: Bronsted Acids & Bases
Topic: Proton Transfer Equilbria
Replies: 2
Views: 139

Re: Proton Transfer Equilbria

In an acid-base equilibrium reaction, a proton is transferred (bronsted), or another way to thing about it is that an electron is donated (Lewis).
by Meredith Steinberg 2E
Tue Dec 05, 2017 11:20 am
Forum: Lewis Acids & Bases
Topic: Memorizing Acids and Bases
Replies: 7
Views: 270

Re: Memorizing Acids and Bases

I think it's important just to know the trends on the periodic table, which will help you determine which acids/bases are strong. For example, group 1 and group 2 hydroxides are generally strong bases. In addition, we learned that as the atomic radius increases (weaker bonds), it's easier for acids ...
by Meredith Steinberg 2E
Thu Nov 30, 2017 10:58 am
Forum: Naming
Topic: Cobalt-cobaltate
Replies: 2
Views: 105

Re: Cobalt-cobaltate

-ate is added when the overall complex has a negative charge. Remember for iron instead of it becoming ironate it becomes ferrate.
by Meredith Steinberg 2E
Thu Nov 30, 2017 10:55 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: TM cations in solutions
Replies: 1
Views: 98

Re: TM cations in solutions

TM cations in solution form complexes with H2O. Some ligands, however, bind more easily than others. Adding NH3 or KCN (electron rich species) will replace H20 ligands because it's an easier way to make coordination compounds.
by Meredith Steinberg 2E
Wed Nov 29, 2017 3:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T Shape or Trigonal Pyramidal
Replies: 3
Views: 148

Re: T Shape or Trigonal Pyramidal

T shape structures have the VSEPR formula AX3E2, which means there are 2 lone pairs on the central atom. Trigonal pyramidal structures have the VSEPR formula AX3E, which means there's one lone pair on the central atom.
by Meredith Steinberg 2E
Wed Nov 29, 2017 2:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular v Electron Arrangement
Replies: 2
Views: 135

Re: Molecular v Electron Arrangement

Yes, the electron arrangement takes into account the lone pairs (same as looking at the amount of regions of electron density). For example, NH3 has 4 regions of electron density (tetrahedral arrangement), but has a molecular shape of trigonal pyramid.
by Meredith Steinberg 2E
Tue Nov 21, 2017 10:26 am
Forum: Hybridization
Topic: lone pair effect on hybridization
Replies: 3
Views: 142

Re: lone pair effect on hybridization

A lone pair (like a single, double, or triple bond) counts as a region of electron density when determining hybridization. For example, oxygen in a water molecule has two single bonds and two lone pairs. 2+2=4 regions of electron density, creating the sp3 hybrid.
by Meredith Steinberg 2E
Tue Nov 21, 2017 10:14 am
Forum: Naming
Topic: Diaqaua
Replies: 9
Views: 362

Re: Diaqaua

Diaqua means there are two water molecules (H2O) in the coordination complex
by Meredith Steinberg 2E
Tue Nov 14, 2017 5:07 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Memorizing Shapes
Replies: 2
Views: 117

Re: Memorizing Shapes

We definitely need to know the shapes we learned in class, and also the shapes of molecules based on the regions of electron density before lone pairs are taken into account. Even though we didn't go over T-shaped, we had homework problems assigned that incorporated that shape, so I would definitely...
by Meredith Steinberg 2E
Tue Nov 14, 2017 5:00 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Most Favorable Formal Charge
Replies: 5
Views: 302

Re: Most Favorable Formal Charge

It's most favorable for the central atom to have a formal charge of zero. This is why an expanded octet on the central atom can be more stable than a regular octet. For example, SF6 has an expanded octet on the sulfur atom, but that is the most stable lewis structure.
by Meredith Steinberg 2E
Tue Nov 07, 2017 11:28 am
Forum: Lewis Structures
Topic: Central atom
Replies: 2
Views: 125

Re: Central atom

If you think about trends on the periodic table, ionization energy decreases to the left, as does electronegativity (so you can think about it both ways). For SCN-, the overall trend for ionization energy is that it decreases down and to the left of the periodic table (carbon is further left, and th...
by Meredith Steinberg 2E
Tue Nov 07, 2017 11:21 am
Forum: Dipole Moments
Topic: Dipole Moment and Formal Charge
Replies: 1
Views: 190

Re: Dipole Moment and Formal Charge

Formal charge changes depending on the way in which you draw the lewis structure of the compound. If the compound is not drawn in its most stable structure, I don't think the formal charge will always accurately display the most electronegative atom. When constructing the dipole moment, the arrow is...
by Meredith Steinberg 2E
Tue Oct 31, 2017 9:04 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Difference between subshell and orbital [ENDORSED]
Replies: 9
Views: 855

Re: Difference between subshell and orbital [ENDORSED]

A shell corresponds to the principal quantum number (n). Inside each shell are subshells, which are the angular momentum quantum numbers (l). Depending on the subshell, there is a specific amount of orbitals. For example, in the subshell l=1 (p-orbital) there are 3 orbitals where 6 electrons can occ...
by Meredith Steinberg 2E
Tue Oct 31, 2017 9:02 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: d and s blocks
Replies: 16
Views: 540

Re: d and s blocks

You write the electron configuration in order of increasing energy. Since n=3 is lower energy than n=4, 3d is written before 4s even though 4s comes first in the periodic table.
by Meredith Steinberg 2E
Thu Oct 26, 2017 11:43 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Writing Electron Configuration for Excited element [ENDORSED]
Replies: 2
Views: 180

Re: Writing Electron Configuration for Excited element [ENDORSED]

Writing the electron configuration for an excited atom IS different than writing it in its ground state. When electron is in an excited state, it's in a higher energy level than its normal ground state. Therefore, when writing the electron configuration, you can put electrons in higher energy levels...
by Meredith Steinberg 2E
Thu Oct 26, 2017 11:36 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Possible Quantum numbers given n=6
Replies: 3
Views: 187

Re: Possible Quantum numbers given n=6

If given n=6 on our test the correct answer for the possible l values are 0 to n-1. Even though we don't go beyond the f-orbital, there are levels of angular momentum beyond l=3.
by Meredith Steinberg 2E
Tue Oct 17, 2017 7:01 pm
Forum: Properties of Electrons
Topic: Energy Levels
Replies: 3
Views: 214

Re: Energy Levels

Electrons can move up and down energy levels and the changes in energy are modeled by the difference in En for the hydrogen atom. Make sure that when you're finding Efinal-Einitial, the negative sign in the equation for En doesn't get lost.
by Meredith Steinberg 2E
Mon Oct 16, 2017 4:58 pm
Forum: Properties of Light
Topic: Rydberg's Constant
Replies: 4
Views: 313

Re: Rydberg's Constant

I used the one given in Hz or s^-1 for question 1.13, and I think all of them should use the number in those units. When you're working on 1.13, don't forget the negative sign in the equation (this helped me realize a mistake I made in that problem).
by Meredith Steinberg 2E
Wed Oct 11, 2017 3:44 pm
Forum: Properties of Light
Topic: Clarification on C=λv
Replies: 10
Views: 722

Re: Clarification on C=λv

Since speed of light is constant (3.00 x 10^8 m/s) and therefore cannot change, if wavelength increases, frequency must decrease to keep their product equal to speed of light.
by Meredith Steinberg 2E
Mon Oct 09, 2017 10:04 pm
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 113
Views: 33061

Re: Rusty on High School Chem [ENDORSED]

I took chemistry in high school too and I still feel behind in some topics we're going to be learning soon. I found that the best way to learn the material was to do as many practice problems as possible and to find random youtube videos that describe processes in a creative way to make it help stic...

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