## Search found 66 matches

Tue Mar 12, 2019 4:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test 2 #6 wording
Replies: 1
Views: 111

### Re: Test 2 #6 wording

Yes I believe so, but be careful in how you order the elements. I don't know your exact questions but if it asked for reducing power, then that means that how well a substance is oxidized. Oxidizing power would be how well a substance is reduced. Depending on how you flip the equations, you would ge...
Tue Mar 12, 2019 2:43 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Order of reaction
Replies: 3
Views: 378

### Re: Order of reaction

Let's say you have a reaction A + B --> C + D The equation for the rate of the reaction is as follows: rate = k[A]^n [B]^m The powers of [A] and [B] (n and m in the equation) are not affected by the coefficients of the chemical equation. If we had experimental data that showed that doubling [A] (the...
Tue Mar 12, 2019 2:37 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reaction mechanism on the final
Replies: 1
Views: 80

### Re: Reaction mechanism on the final

I think it would be similar to the HW. For example (from the 6th edition), question 15.53 asks which of the proposed reaction mechanisms fit the rate law. I attached a picture of the problem in case you don't have the 6th edition.

Tue Mar 12, 2019 2:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Organizing Reducing/Oxidizing Power
Replies: 2
Views: 113

### Re: Organizing Reducing/Oxidizing Power

I think the wording does matter. For me it was easier to think of it this way. Reducing power means that the substances are being oxidized. Thus increasing reducing power means Eo of oxidation goes from lowest to highest. In this way, the statement "going from their neutral to second oxidation ...
Wed Mar 06, 2019 10:17 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Q: Partial Pressures and Concentration?
Replies: 4
Views: 288

### Re: Q: Partial Pressures and Concentration?

Ok, in this case I understand since that's all that is given. However, when would you be able to differentiate between using Q with only concentrations or partial pressures and using Q with both? From previous chapters, we had to use the ideal gas law PV = nRT to convert from one to the other in ord...
Wed Mar 06, 2019 10:12 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: E cell
Replies: 5
Views: 174

### Re: E cell

E^o is the standard reduction potential. It is the reduction potential calculated at a 1 M solution or at 1 atm and at 25 degrees Celsius. E is the cell potential, and it can change based on concentrations of product/reactant, temperature, and other nonstandard conditions. The equation that relates ...
Tue Mar 05, 2019 4:40 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Q: Partial Pressures and Concentration?
Replies: 4
Views: 288

### Q: Partial Pressures and Concentration?

In number 37c in Ch. 14 from the 6th edition, the solution manual uses a formula for the reaction quotient that is, Q = P(H2)*P(CL2)/[H+]^2[Cl-]^2. I thought that Q (and K too) had to be only in terms of partial pressure or concentrations. Why is this formula acceptable? For reference, the problem a...
Wed Feb 27, 2019 10:51 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Cell Potential
Replies: 1
Views: 87

### Re: Cell Potential

A battery does work so the amount of energy that leaves the system is -w. Cell potential, E = -w/Charge Rearranging the above equation, we get: Work done, w(max) = -charge x E (since E is the max potential) Charge can be rewritten as the moles of electrons transferred times Faraday's Constant = nF S...
Wed Feb 27, 2019 10:41 pm
Forum: Balancing Redox Reactions
Topic: 6K.5
Replies: 2
Views: 111

### Re: 6K.5

Hello. I have the 6th edition, but I believe that this is the same problem (in basic solution). O3 -> O2 Add H2O on left side and 2 OH- on right side so that there are equal numbers of Os and Hs Add 2 electrons to left side so charges are -2 on both sides Half reaction: O3 + H2O + 2e- -> O2 + 2OH- I...
Wed Feb 27, 2019 10:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Water in Cell Diagrams
Replies: 2
Views: 137

### Re: Water in Cell Diagrams

You should add water in the cell diagram if it is the substance being oxidized or reduced. Otherwise, you usually do not not need to put water in the cell diagram because if any of the other substances are aqueous, then water is assumed to be present.
Thu Feb 21, 2019 12:46 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 4J.5) 7th edition of the textbook
Replies: 2
Views: 110

### Re: 4J.5) 7th edition of the textbook

Standard enthalpy and standard entropy (unless otherwise noted) are calculated under the standard temperature condition of 25 degrees celsius or 298K. So if you're using these values and the problem does not specify a temperature, you can assume it is 298K.
Thu Feb 21, 2019 12:05 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Negative ∆G means spontaneous reaction?
Replies: 5
Views: 384

### Re: Negative ∆G means spontaneous reaction?

When the change in Gibbs Free Energy is negative, that means that the substance has lost energy or gone from a higher energy state to a lower and presumably more stable energy state. It makes sense that this process would be spontaneous as the substance would be releasing energy. If the change in Gi...
Thu Feb 21, 2019 11:58 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic/Voltaic Cells
Replies: 4
Views: 214

### Re: Galvanic/Voltaic Cells

They are interchangeable. The difference in name comes from scientists who worked on similar ideas for an early battery around the same time frame.
Wed Feb 13, 2019 10:20 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Entropy of Irreversible Expansion
Replies: 2
Views: 297

### Re: Entropy of Irreversible Expansion

Since entropy is a state function, the path that you take to create a change in entropy doesn't matter. This means, it doesn't affect the result if you calculate a change in entropy based on a reversible or irreversible pathway. However, work is NOT a state function, which is why for calculating wor...
Wed Feb 13, 2019 10:18 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: When to assume constant pressure or reversible?
Replies: 1
Views: 108

### Re: When to assume constant pressure or reversible?

For an isothermal or reversible reaction, the problem typically has to specify it since these aren't natural conditions in real life or the lab. For constant pressure, if there's nothing in the problem specifying it, you can usually safely assume that the reaction is taking place under constant pres...
Wed Feb 13, 2019 10:15 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Cv and Cp
Replies: 3
Views: 138

### Re: Cv and Cp

If there's nothing specified, you usually use Cp since you can assume that under normal conditions, the pressure is constant. However, if you're calculating entropy with a temperature and volume change, you break up the calculations into 2 parts. One is the entropy change when the temperature is con...
Sat Feb 09, 2019 8:29 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Average Kinetic Energy vs U?
Replies: 1
Views: 82

### Average Kinetic Energy vs U?

How are average kinetic energy and U (internal energy) related? I know we have the equation U = nRT(3/2) for an ideal gas, and then in 8.103 (6th edition), the question asks for average kinetic energy. The solution manual gives the equation, average kinetic energy = RT(3/2) so I'm a little confused ...
Thu Feb 07, 2019 10:11 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: q= -w
Replies: 8
Views: 226

### Re: q= -w

The only way for a system to gain internal energy is for the surroundings to do work on it or for the system to absorb heat. It loses energy when it does work on its surroundings or releases heat. Thus, we have the delta U (internal energy) = q (heat) + w (work). In an isothermal, reversible system ...
Thu Feb 07, 2019 10:04 pm
Forum: Phase Changes & Related Calculations
Topic: 6th Edition, 8.91
Replies: 1
Views: 110

### Re: 6th Edition, 8.91

It takes .5 hours for the water at 0 degrees celsius to go to 5 degrees celsius. It takes 10.5 hours for the ice to go from being ice to being water at 5 degrees celsius. The ice therefore must take some amount of time to become water at 0 degrees celsius and some other amount of time to go from bei...
Thu Feb 07, 2019 10:01 pm
Forum: Calculating Work of Expansion
Topic: L*atm conversion to Joules
Replies: 2
Views: 109

### Re: L*atm conversion to Joules

I don't know which problem you're referring to, but you can figure out which constant you need to use based on the units of the numbers in your equation. Typically, you want all the units except joules to cancel out, but it depends on the problem. I don't think it should change the answer whether yo...
Wed Jan 30, 2019 9:19 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 6th edition 8.61
Replies: 2
Views: 88

### Re: 6th edition 8.61

So you have to manipulate the reactions given, either by reversing them (in which case, the delta H of the reaction changes sign), or by multiplying them by a constant (in which case, delta H is also multiplied by the constant), such that when the reactions are added together, you get the final reac...
Wed Jan 30, 2019 9:08 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Specific Heat Capacity
Replies: 2
Views: 89

### Re: Specific Heat Capacity

Heat capacity (kj/degrees C) is the heat required to raise the temperature of an object by 1 degrees Celsius. Heat capacity is extensive because it depends on the amount of substance you have. The amount of heat needed to raise a swimming pool's worth of water by 1 degrees Celsius overall will be mu...
Wed Jan 30, 2019 10:45 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpy not given
Replies: 3
Views: 85

### Re: Bond enthalpy not given

There are two other ways. One is that the enthalpy of the reaction equals the sum of the enthalpies of formations of the products minus the sum of the enthalpies of formation for the products. The other way is to use Hess's method and add together the enthalpies of different reactions if, together, ...
Tue Jan 22, 2019 4:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Finding Ka or Kb
Replies: 2
Views: 254

### Re: Finding Ka or Kb

Most of the time, if you don't see the K value for the acid or base you need, it's because the table lists a K value for the substance's respective conjugate acid/base. For example, let's say you need to find the Kb value for NaCH3CO2 (aq). In water, this substance would separate into its ions, Na+ ...
Tue Jan 22, 2019 4:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: PH of Weak Acids and Bases
Replies: 1
Views: 84

### Re: PH of Weak Acids and Bases

For all reactions, there is an extremely small concentration of H+ protons given off by water due to its autoprotolysis (10^-7 M). Since this number is so small, we don't add the value on to the H+ concentrations that come from weak acids because it wouldn't make a difference in the pH of the water ...
Tue Jan 22, 2019 4:12 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Hmwrk 11.79 6th edition
Replies: 2
Views: 146

### Re: Hmwrk 11.79 6th edition

I believe you have to use a graphing calculator or a computer software to answer that problem. For tests, I believe that you will never have to solve more than a quadratic equation. If the variable seems more complicated (cubic, quartic, etc.), then check to see if the equilibrium constant is small ...
Tue Jan 22, 2019 1:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Hmwrk 11.57 6th edition
Replies: 2
Views: 119

### Re: Hmwrk 11.57 6th edition

What numbers are you inputting? Don't forget to add the appropriate power for concentrations of substances that have coefficients in the chemical reaction. For me, I have Kc = [CH4][H2O]/[CO][H2]^3 = (.0478)(.0478)/(.152)(.157)^3 = 3.88. Let me know if you have any questions about where these number...
Wed Jan 16, 2019 8:41 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 7th Edition 5J.1
Replies: 3
Views: 93

### Re: 7th Edition 5J.1

You could go about this two ways. One is to create a Q value, [CO2][H2]/[CO][H2O]. If the CO concentration is increased that means that the denominator for Q will be bigger than whatever this ratio is for K. Thus, overall Q will be less than K. To balance out this change and go back toward equilibri...
Wed Jan 16, 2019 8:36 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Percentage Ionization
Replies: 3
Views: 163

### Re: Percentage Ionization

Yes. Percentage ionization is the amount of the weak acid that deprotonated (gave away a H+ to form H3O+).
Wed Jan 16, 2019 7:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th Edition 12.23
Replies: 1
Views: 23

### Re: 6th Edition 12.23

I believe that if you square root what you gave, you get 1.449... x 10^-7. It's a weird case where I suppose you could round up or down based on how you decide. I wouldn't worry about it too much though since rounding will probably be more obvious in other problems.
Sat Jan 12, 2019 11:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th Edition, 11.63
Replies: 1
Views: 76

### Re: 6th Edition, 11.63

Yes you can do that! I'm not quite sure when an amount is small enough for it to be essentially insignificant overall, but a good way to check is to do the problem backwards. In other words, once you find the equilibrium partial pressure values, if you calculate the Kp value and it is the same as wh...
Wed Jan 09, 2019 5:39 pm
Forum: Ideal Gases
Topic: units for PV=nRT
Replies: 5
Views: 178

### Re: units for PV=nRT

P: Pressure: varies, can be atm, bar, and some others - it'll depend on the problem
V: Volume: Liters
n: moles
R: Gas constant, can change depending on what unit P is in
T: Temperature in Kelvin
Wed Jan 09, 2019 5:35 pm
Forum: Ideal Gases
Topic: ideal gas constant
Replies: 4
Views: 160

### Re: ideal gas constant

On the 14B website, there's a link to a Constants and Equations PDF that essentially has everything we would need to know for the class. From there, you can see that the R value (Gas constant) is 8.314 J·K^-1·mol^-1 or 8.206 x 10^2 L·atm·K^-1·mol^-1 or 8.314 x 10^2 L·bar·K^-1·mol^-1 or 62.364 L·Torr...
Wed Jan 09, 2019 5:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.1 Hmwrk 6th edition
Replies: 1
Views: 98

### Re: 11.1 Hmwrk 6th edition

11.1 (a) False, In class we learned that equilibrium means that the forward and reverse reactions are taking place at the same rate so it doesn't stop. The reactants are becoming products, and then the products are becoming reactants but because they're happening at the same rate, there is no overal...
Wed Dec 05, 2018 2:32 pm
Forum: Bronsted Acids & Bases
Topic: Withdrawing e- density
Replies: 1
Views: 109

### Re: Withdrawing e- density

Atoms that are able to withdraw electron density means that they are able to pull the electrons in the molecule toward them. I think it's easiest to explain with the example we did in class. In the anion ClO-, the lewis structure shows a single bond between Cl and O. Thus the formal charge on the O ...
Wed Dec 05, 2018 2:23 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Terminology
Replies: 2
Views: 102

### Re: Terminology

I believe so. Metal (specifically transition metal) atoms are able to form the complexes in coordination compounds with chelating agents and others because of their extra d orbitals which allow them to form more bonds. I don't think it would be very common, if at all, for other ions to do this.
Wed Dec 05, 2018 2:19 pm
Forum: Naming
Topic: Polyatomic ions and naming
Replies: 7
Views: 212

### Re: Polyatomic ions and naming

There's a list of ions under Naming Coordination Compounds on the 14A website. I don't necessarily think you should memorize them all but just being familiar with them is good. We've discussed most of them in class at length already (CN-, SO4^2-, etc.)
Thu Nov 29, 2018 10:10 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Resonance structure
Replies: 1
Views: 114

### Re: Resonance structure

Yes so for VSEPR, I do not believe resonance structures matter very much as you're only looking at regions of electron density instead of types of bonds (as you said, double or triple bonds don't affect if a molecule is linear or trigonal planar, they are unrelated.) Regardless, I think that resonan...
Thu Nov 29, 2018 10:01 am
Forum: Biological Examples
Topic: Chelating compounds
Replies: 2
Views: 63

### Re: Chelating compounds

Specifically, chelating compounds tend to have a ligand that is essentially a string of atoms attached to each other through sigma bonds. Sigma bonds, unlike pi bonds, are flexible so individual atoms in the string can rotate/move around. This characteristic allows the string of atom to bend so that...
Thu Nov 29, 2018 9:53 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Transition metals
Replies: 1
Views: 82

### Re: Transition metals

No, coordination compounds are not limited to transition metals in the 4th period, but in this class and in general chemistry, I believe those are among the most common transition metals that form coordination compounds.
Sun Nov 25, 2018 8:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Boron
Replies: 1
Views: 108

### Re: Boron

I believe that atoms such as Boron are still hybridized during bonding but since they can only hold fewer than an octet, their hybridized orbitals have to correspond accordingly. For example, boron in BF^3 would have one s orbital and 2 p orbitals that form 3 sp^2 hybridized orbitals. After all, wit...
Sun Nov 25, 2018 8:38 pm
Forum: Hybridization
Topic: 2F.1 7th Edition
Replies: 1
Views: 43

### Re: 2F.1 7th Edition

From class, we know that the number of hybrid orbitals equals the regions of electron density. (a) One s orbital and 3 p orbitals hybridize to create 4 sp^3 orbitals. This means that there are 4 regions of electron density around the central atom so there must be a tetrahedral arrangement. (b) One s...
Sun Nov 25, 2018 8:34 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: e- Density
Replies: 4
Views: 164

### Re: e- Density

Single, double, and triple bonds all count as one region of electron density because they're all interacting with the same thing. The electrons in these bonds are being shared, given, or donated together so they're not acting against each other in terms of electron repulsion. Any type of bond can ha...
Wed Nov 14, 2018 8:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Chapter 4 Homework Number 1
Replies: 6
Views: 162

### Re: Chapter 4 Homework Number 1

In 4.1 (6th edition) part a, the drawing depicts a central atom with 2 other atoms bonded to it. If there were no lone pairs of electrons, then the only regions of electron density would be those associated with the 2 bonding atoms. To be the most stable structure and reduce electron repulsion, we m...
Wed Nov 14, 2018 8:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 6
Views: 226

### Re: Molecular Shape

ICl3 has 3 bonding pairs of electrons (I - Cl), and then the central atom, I, also has two lone pairs. As discusses in class, the electron repulsion of lone pairs and lone pairs is higher than that of a lone pair and a bonding pair which is higher than that of two bonding pairs. Because of these lon...
Wed Nov 14, 2018 8:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: How are polarity and polarizability different?
Replies: 3
Views: 606

### Re: How are polarity and polarizability different?

I think the difference is small but notable. To my understanding, polarity refers to the unequal sharing of electrons or the existence/strength of a dipole in a molecule. On the other hand, polarizability explains how easily the electrons (electrons cloud) can be distorted or how easily a dipole can...
Thu Nov 08, 2018 8:33 pm
Forum: Bond Lengths & Energies
Topic: Bond Lengths with Larger Atoms
Replies: 1
Views: 223

### Re: Bond Lengths with Larger Atoms

What you say is true. The electronegativity of large atoms is less because with more electrons at higher energy levels, more of the core electrons are shielding those valence electrons and other electrons from the pull of the nucleus. On a simpler level though, bigger atoms have a bigger radius so t...
Thu Nov 08, 2018 8:20 pm
Forum: Bond Lengths & Energies
Topic: Formula/ Memorization of Bond lengths?
Replies: 3
Views: 114

### Re: Formula/ Memorization of Bond lengths?

I also do not believe we will ever need to memorize different bond lengths. However, it's important to understand the trends behind bond lengths so that you can make predictions based on the information given. For example, triple bonds are shorter than single bonds. The bigger the atom, the larger t...
Thu Nov 08, 2018 8:12 pm
Forum: Octet Exceptions
Topic: Octet vs formal charge
Replies: 16
Views: 1028

### Re: Octet vs formal charge

What's already been mentioned is true, but you shouldn't get so caught up with making the formal charge 0 that you forget about the octet rule and its exceptions. For example, carbon would never have more than an octet. In that cases, it would be better to have some formal charge that is not 0 (but ...
Thu Nov 08, 2018 8:08 pm
Forum: Resonance Structures
Topic: Dominant resonance structure
Replies: 4
Views: 275

### Re: Dominant resonance structure

Yes, the structure where the formal charge(s) are closest to 0 is dominant. However, when there are resonance structures (for example, NO3-), that means that for the Lewis structures, we draw different configurations of electrons (single bond, double bond, etc) among the same configuration of atoms....
Sat Nov 03, 2018 3:26 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Topics 6th Edition
Replies: 2
Views: 86

### Re: Midterm Topics 6th Edition

I believe it means up till section 3.11 (The Unusual Structures of Some Group 13 Compounds) which is under Exceptions to the Octet Rule.
Wed Oct 31, 2018 6:58 pm
Forum: Trends in The Periodic Table
Topic: Periodicity on midterm?
Replies: 2
Views: 124

### Re: Periodicity on midterm?

Yes, periodic trends will be on the midterm! Some potential applications for these trends in questions include diagrams in which the atoms involved in a reaction are shown with differing sizes and we have to infer which atoms are which based on our knowledge of atomic radii. Also, when drawing Lewis...
Wed Oct 31, 2018 6:54 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Degeneracy
Replies: 4
Views: 465

### Re: Degeneracy

Is degeneracy associated with a number? From what I understood, degenerate orbitals have the same energy level and become filled evenly. For example, when there are 3 2p orbitals in an atom, those orbitals all have the same energy level. s orbitals at different n levels, however, should have differe...
Wed Oct 31, 2018 6:42 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 4
Views: 215

### Re: Lewis Structures

What's already been said is true, but I also wanted to add that it's possible for B (boron) to complete its octet if another atom provides two electrons in what's called a coordinate covalent bond. To reiterate the example from today's lecture, BF3 + F^- --> BF4^-. In the product, B forms an octet d...
Wed Oct 24, 2018 6:30 pm
Forum: Trends in The Periodic Table
Topic: Atomic Properties 2.71
Replies: 1
Views: 87

### Re: Atomic Properties 2.71

Look at 2 elements in the periodic table that are diagonal to each other (touching corners), and see if there are any relationships between them. For example, like we learned in class, the size of atoms increases as we go down the periodic table (due to the number of electron orbitals/shielding) and...
Wed Oct 24, 2018 6:20 pm
Forum: Trends in The Periodic Table
Topic: Atomic, Covalent, and Ionic Radius
Replies: 5
Views: 280

### Re: Atomic, Covalent, and Ionic Radius

So I believe atomic radius is just referring to the radius of a single atom at a time. Covalent radii refers to the radius of the two atoms involved in the covalent bond and can be found, as you say, essentially by taking the average (or dividing in half the distance between the two atoms' nuclei) i...
Wed Oct 24, 2018 6:14 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2.33 6th Edition: Electron Transitions
Replies: 1
Views: 73

### 2.33 6th Edition: Electron Transitions

Question 2.33 from the 6th Edition asks: "Which of the following increase when an electron in a lithium atom undergoes a transition from the 1s-orbital to a 2p-orbital? (a) Energy of the electron (b) Value of n (c) Value of l (d) Radius of atom. " I understand that the specific electron wi...
Wed Oct 17, 2018 4:02 pm
Forum: Einstein Equation
Topic: Energy Equations
Replies: 4
Views: 183

### Re: Energy Equations

These equations should both find the energy for a photon (J). However, they use different variables to find E such as p (momentum), c (speed of light), h (Planck's constant), and v (wavelength). Depending on what you're given, you can use either one. This is a bit more than you asked, but you can al...
Wed Oct 17, 2018 3:53 pm
Forum: Properties of Light
Replies: 3
Views: 179

When I think about a change in the electrical field, I think it refers to a change in amplitude. Waves can get bigger or smaller, and as that happens, their electric field also gets bigger or smaller. If you imagine the drawing of a wave, the waves get kind of flattened when the frequency decreases ...
Wed Oct 17, 2018 3:48 pm
Forum: Properties of Light
Topic: Intensity of Light
Replies: 2
Views: 79

### Re: Intensity of Light

In addition to what we discussed in class, there's a really nice summary in the textbook that cleared up this concept for me. Hopefully, it's helpful for you too! I've posted it below. Electromagnetic radiation (light) has wave-particle duality. "In the wave model, the intensity of the radiatio...
Thu Oct 11, 2018 9:48 am
Forum: Photoelectric Effect
Replies: 2
Views: 134

### Re: Frequency vs. Wavelength adn energy of electronmagnetic radiation HW question

To answer your question: (a) You are correct. The speed stays the same (as according to the equation you posted above). (b) Yes. (c) So I believe when the question asks about a change in electrical field, it's referring to a change in amplitude. I think of it as though as the wave gets taller or sho...
Thu Oct 11, 2018 9:40 am
Forum: Properties of Electrons
Topic: Context?
Replies: 3
Views: 104

### Re: Context?

Hello, So imagine the hydrogen atom, which has a nucleus and then one electron floating around the nucleus. This electron can be at many different energy levels depending on the state of the hydrogen atom/how "excited" the electron is. It may be close to the nucleus or far. If an electron ...
Thu Oct 11, 2018 9:30 am
Forum: Properties of Light
Topic: Photoelectric effect
Replies: 4
Views: 90

### Re: Photoelectric effect

Yup! The photoelectric effect states that electrons are emitted from a metal when an incident light shines on the metal. However, the electron can't be emitted unless the energy of the photon is equal to or greater than the threshold energy/work of the metal. If the photon is able to emit the electr...
Wed Oct 03, 2018 5:05 pm
Forum: Molarity, Solutions, Dilutions
Topic: Difference between molecules, atoms, and formula units
Replies: 3
Views: 13275

### Re: Difference between molecules, atoms, and formula units

Hi. This is a question I was initially confused with, and I saw lots of posts on this community about it. In fact, I think there are endorsed answers to this question in the announcement section, which is at the top before the list of topics. In case you can't find it, the Chem_Mod has posted about ...
Tue Oct 02, 2018 4:12 pm
Forum: Empirical & Molecular Formulas
Topic: Metal Hydroxides and sulfides
Replies: 2
Views: 236

### Re: Metal Hydroxides and sulfides

You can find out what metal it is without any complicated concepts! The problem gives you the molecular formula M(OH)2. We need to find what element M is. We know that the molar mass of the entire compound is 74.10 g/mol. We don't know what the molar mass of M (the unknown metal) is but we do know t...
Tue Oct 02, 2018 3:58 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Moles!
Replies: 7
Views: 251

### Re: Moles!

Just like 12 inches make up 1 foot, 6.022 x 10^23 (Avogadro’s number) atoms make up one mole of atoms. Molar mass is the number of grams in one mole of a substance. On the periodic table under carbon, you can see the atomic mass of carbon which is 12.01 atomic units. This relates to moles because ev...