## Search found 60 matches

Fri Mar 15, 2019 2:07 pm
Forum: *Enzyme Kinetics
Topic: How do you tell if something is a catalyst vs an intermediate?
Replies: 16
Views: 1006

### Re: How do you tell if something is a catalyst vs an intermediate?

A catalyst is needed as a reactant in the first step while an intermediate is made in the first step (a product) and used as a reactant in the second step.
Fri Mar 15, 2019 2:05 pm
Forum: General Rate Laws
Topic: 15.19 6th edition
Replies: 4
Views: 109

### Re: 15.19 6th edition

Lasya Gudipudi 1A wrote:I am having the same issue too. Here is my work:

I did the problem the same way and got those answers as well.
Thu Mar 14, 2019 7:54 pm
Forum: General Rate Laws
Topic: 15.19 6th edition
Replies: 4
Views: 109

### 15.19 6th edition

Why is the answer for 15.19 c 2.85 x 10^12? I keep on only getting 2.85. I thought about changing the units to mols but the answer key has the answer in mmols.
Sat Mar 09, 2019 4:13 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating E naught
Replies: 5
Views: 233

### Calculating E naught

When given two reduction half equations, how do you know which one to make the cathode and which to make the anode for calculating E naught of the overall reaction?
Sat Mar 09, 2019 3:57 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Determining the slow step
Replies: 2
Views: 136

### Re: Determining the slow step

I believe that you determine the slow step by seeing what that reaction rate depends on. The slow step is the step that determines what the rate of the reaction is. For example, in lecture one of the rates had [NO2]^2, so the slow step was the step where [NO2] reacted together, because that is the s...
Thu Mar 07, 2019 4:36 pm
Forum: General Rate Laws
Topic: Reaction Order
Replies: 1
Views: 95

### Reaction Order

Can someone explain what exactly the order of a reaction means? I'm still confused about it.
Sun Mar 03, 2019 12:25 am
Forum: Balancing Redox Reactions
Topic: 14.13
Replies: 1
Views: 149

### Re: 14.13

I think you can split them up in this case because HCl is a strong acid, meaning it fully dissociates into H+ and Cl-.
Sun Mar 03, 2019 12:19 am
Forum: Balancing Redox Reactions
Topic: d from 14.13
Replies: 2
Views: 149

### Re: d from 14.13

Basically some Au+ will gain an e- (be reduced) to get to Au, and a different Au+ will lose 2e- (be oxidized) to get to Au3+.
Sun Mar 03, 2019 12:15 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: E vs E naught
Replies: 5
Views: 194

### Re: E vs E naught

E naught is an intensive property and it's measured for substances with respect to a standard hydrogen electrode.
Thu Feb 21, 2019 11:50 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 6th Ed. 9.65
Replies: 1
Views: 112

### 6th Ed. 9.65

Which of the following compounds become less stable with respect to the elements as the temperature is raised: (a) PCl5(g); (b) HCN(g); (c) NO(g); (d) SO2(g)? I was figuring this problem out using the delta H for the compounds and seeing that endothermic reactions have more stable products at higher...
Thu Feb 21, 2019 11:34 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G = 0
Replies: 4
Views: 132

### Re: Delta G = 0

we also set delta G to 0 when we want to find the minimum temp to make a reaction spontaneous.

Also, a reaction at equilibrium does no work, so at delta G = 0 the reaction can do no work.
Thu Feb 21, 2019 11:30 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy
Replies: 2
Views: 146

### Re: Gibbs Free Energy

I'm guessing it has to do with the fact that the definition of Gibbs free energy is the energy available to do work, which is probably hard to measure because it's not something you can measure like other forms of energy like heat.
Fri Feb 15, 2019 6:59 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Q. 9.47
Replies: 1
Views: 103

### Re: Q. 9.47

I think it has to do with the fact that no energy is transferred through a temp change or work of expansion to the surroundings. The only thing that changes is the volume of the system (free expansion = no work), and therefore the entropy increases with the volume increase.
Fri Feb 15, 2019 6:28 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs and Enthalpy
Replies: 4
Views: 176

### Gibbs and Enthalpy

What is the difference between delta G and delta H if both of them are energy released from a reaction?
Fri Feb 15, 2019 6:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: HW Problem 9.5
Replies: 2
Views: 155

### Re: HW Problem 9.5

Yes, calculate it for the 800 and 200 K system and surroundings using S = q/T and add them together.
Fri Feb 08, 2019 11:08 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cp vs Cv
Replies: 1
Views: 120

### Cp vs Cv

What do the different subscripts mean for the heat capacities, such as Cp and Cv?
Fri Feb 08, 2019 11:05 pm
Forum: Calculating Work of Expansion
Topic: Which P to use? 6th edition, 8.27
Replies: 3
Views: 144

### Re: Which P to use? 6th edition, 8.27

For b) the equation is w= -nRTln(Vf/Vi), and to find n you use PV=nRT and use the original given P value I believe (1.79 atm).
Fri Feb 08, 2019 10:58 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Negative
Replies: 4
Views: 242

### Re: Negative

The heat loss should be negative and the heat gained should be positive.
Wed Jan 30, 2019 12:01 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 1
Views: 82

### Bond Enthalpies

Why are bond enthalpies averages from many different molecules?
Wed Jan 30, 2019 11:53 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Extensive vs. Intensive
Replies: 5
Views: 450

### Extensive vs. Intensive

What is the difference between an extensive and intensive property? I know general heat capacity in extensive and specific heat capacity is intensive, but what do these words mean?
Wed Jan 30, 2019 11:44 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Regular heat capacity: why?
Replies: 4
Views: 175

### Re: Regular heat capacity: why?

I think one of the points of heat capacity is that you don't always want to know how much energy it takes to raise only one gram by one degree Celsius. Sometimes you have different amounts of a substance. I agree that specific heat capacity is more useful, but sometimes you might need to find out th...
Wed Jan 23, 2019 12:04 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Acids and Bases
Replies: 6
Views: 194

### Re: Acids and Bases

I think we've been using the Bronsted definition.
Wed Jan 23, 2019 12:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5% rule and % ionization
Replies: 2
Views: 143

### Re: 5% rule and % ionization

To find the % ionization you use an ICE table to find the concentrations of the initial concentration of the unionized substance and the concentration of the ionized version of the substance at equilibrium. Then do [ionized]/[initial unionized] * 100. This is the percent. This relates to the 5% rule...
Wed Jan 23, 2019 10:56 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Number 7 chapter 11
Replies: 1
Views: 60

### Re: Number 7 chapter 11

Flask 3 represents equilibrium because from the third to the fourth flask there is no change in the number of products and reactants, meaning that equilibrium has been reached because a stable number of products and reactants is reached.
Wed Jan 16, 2019 11:23 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: bases and acids
Replies: 2
Views: 162

### Re: bases and acids

I believe that Q would be calculated the same way as non acid and base reactions Q is calculated, and can be used in the same way to determine the direction of the reaction by comparing Q and K for the reaction at the specific temperature.
Wed Jan 16, 2019 11:14 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Converting Between Kp and Kc
Replies: 3
Views: 108

### Converting Between Kp and Kc

I'm confused about how to convert between Kp and Kc and when you would need to do it?
Tue Jan 15, 2019 3:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pure Liquids and Pure Solids
Replies: 5
Views: 1762

### Re: Pure Liquids and Pure Solids

I'm still confused about this concept. For example, with the reaction CaCO3(s) <--> CaO(s) + CO2(g), how do the molar concentrations of the solids not change?
Wed Jan 09, 2019 9:22 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Lecture Example of Calculating the equilibrium composition
Replies: 2
Views: 95

### Re: Lecture Example of Calculating the equilibrium composition

The subtraction occurred on the ATP side because we were given the initial and final amounts of ATP, with the final amount being smaller than the initial amount. This means that 8.434x10^-3 was subtracted from the given initial amount to get to the given final amount. Since matter is conserved, all ...
Wed Jan 09, 2019 12:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K and Kc
Replies: 8
Views: 241

### Re: K and Kc

Jordan Lo 2A wrote:Do we need to memorize the formula in the book for converting between the 2?

My guess would be no, because we rarely if ever have to memorize any formulas.
Wed Jan 09, 2019 12:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc for Gases
Replies: 2
Views: 43

### Kc for Gases

In the 6th edition number 11.9 asks for Kc for a reaction that involves gases. I thought you were suppose to always use Kp for gases, can someone explain why that's not the case?
Thu Dec 06, 2018 10:55 pm
Forum: Trends in The Periodic Table
Topic: Expanded Valence Shells
Replies: 3
Views: 311

### Re: Expanded Valence Shells

Elements in period three and above have expanded octets because they have access to the d orbitals for extra e- to go into.
Thu Dec 06, 2018 10:48 pm
Forum: Hybridization
Topic: Labeling hybridization in Test 3
Replies: 2
Views: 82

### Labeling hybridization in Test 3

For test 3 number 3c., I was asked to write the hybridization a nitrogen atom that was bonded to a carbon and two hydrogens, and had a lone pair. I thought that it would have a tetrahedral formation with the four e- densities, so I labeled it sp3 and it was wrong. What's the correct hybridization an...
Thu Dec 06, 2018 10:37 pm
Forum: Naming
Replies: 2
Views: 108

In lecture for naming, chloride became chloro when naming a coordination compound, but in the book it says it should be chlorido. Am I missing something here?
Mon Nov 26, 2018 11:21 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Dipole Forces
Replies: 3
Views: 150

### Re: Dipole Forces

An example of a dipole would be H2O, where the difference in electronegativity causes a negative charge on the O and a positive charge on the H's. An induced dipole would be species that is usually non-polar but could have a high polarizability because it has many electrons. These electrons can be i...
Mon Nov 26, 2018 11:13 am
Forum: Octet Exceptions
Topic: Atoms with expanded octets
Replies: 4
Views: 387

### Re: Atoms with expanded octets

Mon Nov 26, 2018 11:12 am
Forum: Dipole Moments
Topic: Polarizability vs Polarizing power
Replies: 8
Views: 292

### Re: Polarizability vs Polarizing power

Polarizability is how easily an atom or molecule can be polarized, and polarizing power is how well a species can polarize another species.
Mon Nov 19, 2018 11:35 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle
Replies: 8
Views: 312

### Re: Bond Angle

No, I believe you have to look up the angles as there isn't a set amount to reduce the angle by. You just know it's slightly less.
Mon Nov 19, 2018 11:33 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Rotation from Sigma and Pi bonds
Replies: 2
Views: 140

### Rotation from Sigma and Pi bonds

Why can atoms with sigma bonds rotate, but a pi bond will not allow it to rotate?
Mon Nov 19, 2018 11:22 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pair distortion
Replies: 2
Views: 109

### Lone Pair distortion

Why does a long pair cause the bond angle to be slightly less than the atom without a lone pair?
Wed Nov 14, 2018 8:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bent structure? also, intermolecular interactions
Replies: 3
Views: 108

### Re: bent structure? also, intermolecular interactions

Also, a factor that plays into Van der Waals forces is the number of electrons. If there are many electrons, the interactions could be from the distorted electron clouds.
Wed Nov 14, 2018 8:25 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability
Replies: 4
Views: 179

### Re: Polarizability

I think polarizability can also apply to atoms and molecules, because their electron densities can change. The more electrons they have, the easier it is for their electrons to be distorted by an ion, for example.
Wed Nov 14, 2018 8:09 pm
Forum: Determining Molecular Shape (VSEPR)
Replies: 1
Views: 72

I wasn't sure about this either, but I googled it and I found that you are right. A single electron does repel count as an electron density, but with less strength of repulsion than a lone pair of electrons. The result is a larger bond angle as well because there is less repulsion, whereas a lone pa...
Tue Nov 06, 2018 10:46 pm
Forum: Lewis Structures
Topic: Central Atom
Replies: 3
Views: 151

### Central Atom

Do you determine the central atom of a Lewis structure using least ionization energy or electronegativity? Or does it not matter?
Tue Nov 06, 2018 10:27 pm
Forum: Lewis Structures
Topic: Formal charge question
Replies: 9
Views: 368

### Re: Formal charge question

For me, I go by number of electrons, least electronegative at the center, and symmetry before I look at formal charge. Formal charge is the main criteria I use after getting the basic structure.
Tue Nov 06, 2018 10:24 pm
Forum: Lewis Structures
Topic: Octet rule question
Replies: 6
Views: 272

### Re: Octet rule question

Most atoms form an octet, H, He, and Be can have 2 valence, and elements in the 3rd period and up can have expanded octets into the d orbitals. B and Al sometimes only have 6 valence. Also, I believe that free radicals can mess up the octet rule. I am guessing that there are no atoms that MUST have ...
Wed Oct 31, 2018 11:30 am
Forum: Octet Exceptions
Topic: Odd Lewis Structures
Replies: 3
Views: 200

### Re: Odd Lewis Structures

I'm confused about this too but I believe in this case that since F is more electronegative, you could know that F would get the electrons.
Wed Oct 31, 2018 11:21 am
Forum: Lewis Structures
Topic: Valence Electrons
Replies: 7
Views: 222

### Re: Valence Electrons

Is phosphorus more stable with 10 or 8 electrons?
Wed Oct 31, 2018 11:18 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence Electrons Counting
Replies: 1
Views: 117

### Valence Electrons Counting

Why do only the s and p electrons count as valence electrons for most atoms?
Sat Oct 27, 2018 3:25 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence Electrons
Replies: 3
Views: 87

### Re: Valence Electrons

And the 8 electrons come from the full s and p orbitals and not the d orbitals (2 +6 = 8)?
Fri Oct 26, 2018 11:47 am
Forum: Ionic & Covalent Bonds
Topic: Ionization Energy vs. Electronegativity
Replies: 5
Views: 199

### Re: Ionization Energy vs. Electronegativity

Ionization energy is the energy it takes to form an ion of that atom, aka to remove a valence electron. Electronegativity is how likely an atom is to attract an electron. They are basically opposites, so an atom like F has high ionization energy because it does not want to lose a valence electron (i...
Fri Oct 26, 2018 11:29 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence Electrons
Replies: 3
Views: 87

### Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom, and atoms are more stable when they have a full valence shell. Is this number of electrons always 8? For example, Fl has 7 valence electrons, so it forms the ion Fl- to have 8 valence electrons to be like a noble gas. Is a full v...
Fri Oct 19, 2018 11:12 pm
Forum: Einstein Equation
Topic: Spectroscopy experimenting
Replies: 4
Views: 173

### Re: Spectroscopy experimenting

I read more about what happens when the photon energy equals the threshold energy and one thing I found is that that electron with zero kinetic energy could fall back to the metal and release a photon the same as that one that emitted the electron in the first place.
Fri Oct 19, 2018 10:58 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Prob 1.15 6th Ed.
Replies: 2
Views: 108

### Prob 1.15 6th Ed.

In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line. Can someone explain this problem with steps and intermediate numbers as we...
Fri Oct 19, 2018 10:40 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum number M [ENDORSED]
Replies: 7
Views: 380

### Re: Quantum number M[ENDORSED]

To respond to the first question, l can be different numbers so if you only have n=2, then l can be 0 or 1. So I think it would make sense to choose the higher l so that you include the widest range of m values that cover all the possibilities of m.
Thu Oct 11, 2018 1:57 am
Forum: Properties of Light
Topic: Wave Model of Light
Replies: 1
Views: 91

### Wave Model of Light

I'm very confused about the wave model of light with the magnetic and electric fields, hence electromagnetic radiation. Can someone give a general explanation of what the two fields have to do with light?
Thu Oct 11, 2018 1:46 am
Forum: Einstein Equation
Topic: Spectroscopy experimenting
Replies: 4
Views: 173

### Re: Spectroscopy experimenting

I think you're referring to the photoelectric effect, where light is shined on a metal to eject electrons to see how much energy is needed to do so. Spectroscopy is the analysis of light emitted or absorbed by a substance with a spectrometer (you analyze the specific wavelengths/spectral lines). For...
Tue Oct 09, 2018 9:30 pm
Forum: Properties of Light
Topic: Microwaves
Replies: 1
Views: 66

### Microwaves

I was looking at the electromagnetic spectrum and I saw that microwaves have longer wave lengths, lower frequency, and less energy than visible light, so why do they heat up our food while visible light doesn't?
Wed Oct 03, 2018 10:48 pm
Forum: Empirical & Molecular Formulas
Topic: Definition of Empirical Formula
Replies: 8
Views: 291

### Re: Definition of Empirical Formula

So for glucose, the empirical formula would be CH2O, with a 1:2:1 ratio of C:H:O atoms.
Wed Oct 03, 2018 6:15 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Moles and Atomic Masses/Weights
Replies: 4
Views: 194

### Re: Moles and Atomic Masses/Weights

Oh wait does it have to do with the fact that they used 12.000 g and the atomic mass for C is 12? So it's a 1:1 ratio...?
Wed Oct 03, 2018 1:49 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Moles and Atomic Masses/Weights
Replies: 4
Views: 194

### Moles and Atomic Masses/Weights

I'm confused about why the atomic masses on the periodic table are the amount of grams in a mole of that element. In other words, I know that the atomic masses are the molar masses for elements, but I don't understand why they are. What do the atomic masses, (which are in amu?) have to do with the a...