Search found 78 matches

by Helen Shi 1J
Sun Mar 18, 2018 9:37 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: isothermal = no internal energy change
Replies: 4
Views: 307

Re: isothermal = no internal energy change

Is delta U zero for all reversible reactions or just isothermal?
by Helen Shi 1J
Thu Mar 15, 2018 11:38 am
Forum: First Order Reactions
Topic: integrated rate
Replies: 1
Views: 184

integrated rate

Can we only find the concentration of reactants with integrated rate laws, or is the reverse law applicable to the concentration of products?
by Helen Shi 1J
Wed Mar 14, 2018 10:53 pm
Forum: First Order Reactions
Topic: Integrated Rate Laws
Replies: 4
Views: 285

Re: Integrated Rate Laws

Can we only find the concentration of reactants with integrated rate laws, or is the reverse law applicable to the concentration of products?
by Helen Shi 1J
Wed Mar 14, 2018 9:59 pm
Forum: First Order Reactions
Topic: Exam question 3
Replies: 4
Views: 232

Re: Exam question 3

Because the rate is constant, you can assume that this rate is zero order, which mean that the rate will just equal the reaction constant. Since the rate is in units of M/s, you can set the rate equal to an amount of change in the molarity over a time interval. Then you can plug in the change in mo...
by Helen Shi 1J
Wed Mar 14, 2018 9:47 pm
Forum: General Rate Laws
Topic: rate law vs integrated rate law
Replies: 2
Views: 139

rate law vs integrated rate law

What is the difference between the rate law and the integrated rate law?
by Helen Shi 1J
Wed Mar 14, 2018 9:46 pm
Forum: General Rate Laws
Topic: Test 3 #3
Replies: 1
Views: 104

Re: Test 3 #3

The rate of C2 gas consumption in this reaction is constant throughout and is given as 0.250 M/s. If you reaction vessel starts with 0.35M of ABC, how long will it take to get to 24.00M of ABC? The equation give is AB+C-->ABC. Can someone explain how they did this please. You basically balance the ...
by Helen Shi 1J
Wed Mar 14, 2018 9:40 pm
Forum: General Rate Laws
Topic: Rate Law
Replies: 6
Views: 449

Rate Law

So if given a chemical equation, does the coefficient in front of the reactant automatically translate into the exponent in the rate law? So 2NO as a reactant would have a rate law = k[NO]^2?
by Helen Shi 1J
Wed Mar 14, 2018 8:37 pm
Forum: First Order Reactions
Topic: Exam question 3
Replies: 4
Views: 232

Exam question 3

The rate of A2 gas consumption in this reaction is constant throughout and is given as .550 M/s. If your reaction vesset starts witih .45 M of AC how long will it tkae to get to 36.00M of AC?

A2+BC = AC + B2


How do you do this question?
by Helen Shi 1J
Thu Mar 08, 2018 11:07 am
Forum: General Rate Laws
Topic: Rate Constant k
Replies: 6
Views: 218

Rate Constant k

Can someone explain what exactly is the rate constant?
by Helen Shi 1J
Wed Mar 07, 2018 9:55 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.61
Replies: 1
Views: 93

15.61

How do you solve question 61?
by Helen Shi 1J
Mon Feb 26, 2018 11:00 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: 5.13
Replies: 2
Views: 142

5.13

Can someone explain 5.13 and how to get the initial reaction rate?
by Helen Shi 1J
Mon Feb 26, 2018 10:42 pm
Forum: General Rate Laws
Topic: Unique rate of reaction Hw 15.3
Replies: 4
Views: 493

Re: Unique rate of reaction Hw 15.3

So what is the unique rate of reaction for Hw 15.3 part c? There is no answer in the textbook.
by Helen Shi 1J
Mon Feb 26, 2018 10:34 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Textbook Problems 15.3 and 15.5
Replies: 7
Views: 497

Re: Textbook Problems 15.3 and 15.5

How come the textbook answer for 15.3 part a) is 6.5 x 10^-3 mol/L*s? Why did they not divide by the number of moles (2)?
by Helen Shi 1J
Mon Feb 26, 2018 10:29 pm
Forum: General Rate Laws
Topic: Homework Help 15.1
Replies: 4
Views: 408

Re: Homework Help 15.1

Can someone explain part b and c too?
by Helen Shi 1J
Thu Feb 22, 2018 10:10 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.41
Replies: 4
Views: 443

Re: 14.41

When would you use the equation with E=E-RT/NF lnQ vs E=E-.05916V/N logQ?
by Helen Shi 1J
Thu Feb 22, 2018 10:44 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.19
Replies: 2
Views: 141

Re: 14.19

If CU2+/Cu is .34 volts then wouldn't the reverse reaction where copper loses electrons be -.34?
by Helen Shi 1J
Wed Feb 21, 2018 11:59 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.11 d)
Replies: 2
Views: 257

Re: 14.11 d)

Can someone explain how do part d, especially writing the half redox reaction for the left side? How did we know H2O was the reactant for the left but O2 the reactant for the right?
by Helen Shi 1J
Wed Feb 21, 2018 11:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: how to write a cell diagram [ENDORSED]
Replies: 6
Views: 403

Re: how to write a cell diagram [ENDORSED]

Curtis Wong 2D wrote:So the order is typically Inert Metal (if applicable) | (Anode reactant) | (anode product) || (Cathode reactant) | (cathode product)| (Inert Metal if applicable).


Then how come for problem 14.11 the cathode reactant and the cathode product is switched so that Cl- is before Cl2?
by Helen Shi 1J
Wed Feb 21, 2018 12:42 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: how to write a cell diagram [ENDORSED]
Replies: 6
Views: 403

Re: how to write a cell diagram [ENDORSED]

How come in the textbook pg 575 when the order of the galvanic cell | (Anode reactant) | (anode product) || (Cathode reactant) | (cathode product)| is flipped so that the cathode is on the left the voltage is negative, even when the electrons are still flowing from anode to cathode?
by Helen Shi 1J
Wed Feb 21, 2018 12:28 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: voltage
Replies: 1
Views: 87

voltage

What is voltage? Why do we need to multiply voltage with mols x Faraday's constant to get G?
by Helen Shi 1J
Wed Feb 21, 2018 10:10 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrode
Replies: 2
Views: 56

Electrode

What exactly is an electrode?
by Helen Shi 1J
Tue Feb 13, 2018 10:03 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Standard Molar Entropy Question
Replies: 3
Views: 315

Re: Standard Molar Entropy Question

So the complexity of the molecule overrules positional disorder?
by Helen Shi 1J
Sun Feb 11, 2018 11:58 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 11.19 and 11.83
Replies: 3
Views: 337

Re: 11.19 and 11.83

How do you solve for 11.19?
by Helen Shi 1J
Sat Feb 10, 2018 5:11 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Irreversible expansion and entropy [ENDORSED]
Replies: 1
Views: 107

Irreversible expansion and entropy [ENDORSED]

Why is it that in a free expansion (according to page 346 in the textbook) that delta S of the surroundings is equal to 0 but delta S (system) is not. The book reasons that no work is done in free expansion so q=0, but if that is the case how can delta S (system) or delta S (total) be anything other...
by Helen Shi 1J
Sat Feb 10, 2018 5:01 pm
Forum: Calculating Work of Expansion
Topic: Reversible reaction and Detla U
Replies: 3
Views: 153

Reversible reaction and Detla U

Why is it that in a reversible expansion delta U is equal to zero?
by Helen Shi 1J
Sat Feb 10, 2018 4:44 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: units conversion for entropy
Replies: 6
Views: 172

Re: units conversion for entropy

I understand that the units for entropy is J/K, but can someone explain the reasoning behind it other than that it comes from the equation: delta S= q/T?
by Helen Shi 1J
Sat Feb 10, 2018 1:07 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: entropy of irreversible and reversible reactions.
Replies: 2
Views: 120

Re: entropy of irreversible and reversible reactions.

I don't understand why the delta S of the surroundings is zero in an irreversible process. The textbook on page 346 says that no work is done in free expansion so w=0. Can someone explain that?
by Helen Shi 1J
Mon Feb 05, 2018 4:15 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: HW 9.25: Understanding Molor disorder of crystals
Replies: 4
Views: 464

Re: HW 9.25: Understanding Molor disorder of crystals

you use Avogadro's number because we want to find the amount of entropy per mol, so we need to take into account all the atoms within one mol.
by Helen Shi 1J
Mon Feb 05, 2018 11:58 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Delta U (Concept Clarification)
Replies: 6
Views: 161

Re: Delta U (Concept Clarification)

In what cases is delta U=0? Why is delta U zero in an isothermal expansion?
by Helen Shi 1J
Mon Feb 05, 2018 8:41 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy
Replies: 7
Views: 191

Re: Gibbs Free Energy

Another way to think of entropy is the a state of relaxed disorder. Since Gibbs free energy is the amount of energy free do do work and the change in Gibbs is the energy that was needed to do work (or make a reaction happen) it is affected by the amt of heat or energy coming and leaving the system (...
by Helen Shi 1J
Wed Jan 31, 2018 11:45 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Define Entropy
Replies: 4
Views: 134

Re: Define Entropy

Can someone explain why we divide q by temperature?
by Helen Shi 1J
Wed Jan 31, 2018 11:36 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy change when Temperature changes [ENDORSED]
Replies: 5
Views: 435

Re: Entropy change when Temperature changes [ENDORSED]

Can someone explain how you solve number 9.5? Like what do you divide the heat with?
by Helen Shi 1J
Thu Jan 25, 2018 9:16 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.49
Replies: 5
Views: 187

Re: 8.49

Since using Kelvin or Celcius will give different answers, which one should we use?
by Helen Shi 1J
Thu Jan 25, 2018 8:38 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: What are the types of calorimeters we learned about/ covered in class?
Replies: 4
Views: 193

Re: What are the types of calorimeters we learned about/ covered in class?

So what is the system and surroundings in a calorimeter with constant pressure and a bomb calorimeter?
by Helen Shi 1J
Thu Jan 25, 2018 6:22 pm
Forum: Phase Changes & Related Calculations
Topic: enthaply
Replies: 3
Views: 132

Re: enthaply

H is simply enthalpy whereas delta H is the change in enthalpy. Enthalpy itself is the total heat content (energy) of a system: aka the internal energy plus the product of pressure and volume. My guess as to why we use the change in enthalpy is because it is easier to calculate through experiments.
by Helen Shi 1J
Thu Jan 25, 2018 5:44 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpies vs enthalpy of rxn - conceptual [ENDORSED]
Replies: 3
Views: 168

Re: Bond enthalpies vs enthalpy of rxn - conceptual [ENDORSED]

However, when bonds are broken isn't energy released as well? So why is it not exothermic?
by Helen Shi 1J
Sat Jan 20, 2018 8:42 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Finding change in enthalpy when given bond enthalpies
Replies: 3
Views: 122

Re: Finding change in enthalpy when given bond enthalpies

Could you also add up all the bond enthalpies for all bonds of the products minus all the bond enthalpies for the reactants to find the reaction enthalpy?
by Helen Shi 1J
Sat Jan 20, 2018 12:41 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Constant Volume vs Constant Pressure
Replies: 6
Views: 227

Constant Volume vs Constant Pressure

I am a little confused about how systems under constant volume differ from those under constant pressure. For systems under constant volume, how is pressure changing and how do we find the work enacted on the system?
by Helen Shi 1J
Sat Jan 20, 2018 12:06 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: PV=nRT
Replies: 4
Views: 170

Re: PV=nRT

If the system expands or is compressed is there still a change in the net number of moles? If not, would the equation P∆V=∆nRT still hold true because the net number of moles aren't changing?
by Helen Shi 1J
Fri Jan 19, 2018 11:47 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Thermochemical equation
Replies: 5
Views: 238

Re: Thermochemical equation

Can someone explain why the thermochemical equation on pg 288 example 8.7 is that change in enthaply= q x (2 mol)/n? Why would you divide the stoichiometric coefficient of original equation by the number of mols?
by Helen Shi 1J
Fri Jan 19, 2018 10:00 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Change in internal energy
Replies: 3
Views: 992

Re: Change in internal energy

Is there a change in work in the form of volume or pressure? isn't the reaction already contains a mol of OF2? How do you calculate the change in work if so.
by Helen Shi 1J
Fri Jan 19, 2018 10:24 am
Forum: Phase Changes & Related Calculations
Topic: Chapter 8 Homework Question 8.37
Replies: 2
Views: 892

Re: Chapter 8 Homework Question 8.37

When it asks for the enthalpy of vaporization is it always have to be in mols? or can it be in KJ/g as well.
by Helen Shi 1J
Thu Jan 18, 2018 6:30 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Problem 7.27 Need some help
Replies: 5
Views: 1460

Re: Problem 7.27 Need some help

what does it mean for heat to be released at a constant volume? Can someone explain why it corresponds to a new heat capacity (C)
by Helen Shi 1J
Sat Jan 13, 2018 11:25 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter
Replies: 1
Views: 89

Calorimeter

When the textbook refers to the internal energy in example 8.4 on pg 271, is it refering to the heating device or the calorimeter? If it is the calorimeter, wouldn't the change in the internal energy be positive?
by Helen Shi 1J
Fri Jan 12, 2018 9:15 pm
Forum: Calculating Work of Expansion
Topic: Calculating required heat
Replies: 3
Views: 2101

Re: Calculating required heat

I don't really get why you need to add the heat of the kettle and the heat of the water together. I thought it was just asking for the heat supplied to the kettle to heat it up to 100 degrees Celsius.
by Helen Shi 1J
Thu Jan 11, 2018 11:41 am
Forum: Phase Changes & Related Calculations
Topic: Open, Closed, or Isolated Systems
Replies: 6
Views: 2685

Re: Open, Closed, or Isolated Systems

Can someone explain exercise 8.1 part e? Why would mercury in a thermometer be a closed system rather than isolated?
by Helen Shi 1J
Tue Jan 09, 2018 10:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Office Hours [ENDORSED]
Replies: 1
Views: 136

Office Hours [ENDORSED]

Lavelle's office hours conflict with my LS30B math class. Is there any other way I can meet up with him to ask questions or is the only other option the TA office hours?
by Helen Shi 1J
Thu Dec 07, 2017 10:09 pm
Forum: Bronsted Acids & Bases
Topic: 12.115
Replies: 1
Views: 162

12.115

Acetic acid is used as a solvent for some reactions between acids and bases. (a) Nitrous acid and carbonic acids are both weak acids in water. Will either of them act as a strong acid in acetic acid? Explain your answer. (b) Will ammonia act as a strong or weak base in acetic acid? Explain your answ...
by Helen Shi 1J
Wed Dec 06, 2017 11:27 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 11.59
Replies: 2
Views: 1244

Re: 11.59

Why does this answer differ from the table 12.1 acidity constants? Shouldn't the Ka of HClO2 be the same?
by Helen Shi 1J
Tue Dec 05, 2017 9:28 pm
Forum: Conjugate Acids & Bases
Topic: HW: 12.17
Replies: 4
Views: 486

Re: HW: 12.17

Can someone explain why BaO is basic and As2O3 and Bi2O3 amphoteric?
by Helen Shi 1J
Tue Dec 05, 2017 8:14 pm
Forum: Photoelectric Effect
Topic: Midterm question [ENDORSED]
Replies: 6
Views: 370

Re: Midterm question [ENDORSED]

Wouldn't increasing the frequency of a light even if it originally did not have the energy to emit an electron eventually lead to an electron being emitted from the metal, because if E=hv and v increases, wouldn't the energy of the photon increase until it surpasses the work function?
by Helen Shi 1J
Sat Dec 02, 2017 10:44 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Strong acid vs weak acid [ENDORSED]
Replies: 7
Views: 316

Re: Strong acid vs weak acid [ENDORSED]

What makes a strong acid completely ionize or disassociate as opposed to a weak one?
by Helen Shi 1J
Mon Nov 27, 2017 10:16 am
Forum: Naming
Topic: Oxidation Number [ENDORSED]
Replies: 1
Views: 153

Oxidation Number [ENDORSED]

What is the oxidation number?
by Helen Shi 1J
Sat Nov 25, 2017 8:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.11
Replies: 2
Views: 187

11.11

A 0.10-mol sample of pure ozone, O3, is placed in a sealed 1.0-L container and the reaction 2 O3(g)∆3 O2(g) is allowed to reach equilibrium. A 0.50-mol sample of pure ozone is placed in a second 1.0-L container at the same temperature and allowed to reach equilibrium. Without doing any calculations,...
by Helen Shi 1J
Sat Nov 25, 2017 7:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium
Replies: 2
Views: 116

Equilibrium

Why in equilibrium the reaction of reactants turning into products and vice versa is still happening? Why doesn't the reactants completely react with each (so their concentration reaches zero) to form the product?
by Helen Shi 1J
Tue Nov 21, 2017 10:50 am
Forum: Hybridization
Topic: 4.95
Replies: 3
Views: 170

4.95

Can someone explain what does the numbers in front of the hybrid orbitals mean? Like 2(sp2) or 1S. Is it the number of hybrid orbitals there are or is it related to the row on the periodic table?
by Helen Shi 1J
Mon Nov 20, 2017 7:52 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: HW 4.75
Replies: 2
Views: 184

HW 4.75

An organic compound distilled from wood was found to have a molar mass of 32.04 g·mol"1 and the following composition by mass: 37.5% C, 12.6% H, and 49.9% O. (a)Write the Lewis structure of the compound and determine the bond angles about the carbon and oxygen atoms. (b) Give the hybridization ...
by Helen Shi 1J
Wed Nov 15, 2017 5:42 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm re-grade?
Replies: 2
Views: 208

Midterm re-grade?

Is there any way to re-grade the midterm, because I checked the solutions for midterm and for Q8B I feel like I should get partial credit for saying that the compound was a radical even if Lewis structure might be slightly off. Also how many points should be taken off with we make one mistake, like ...
by Helen Shi 1J
Tue Nov 14, 2017 10:37 pm
Forum: Hybridization
Topic: Diapole
Replies: 4
Views: 257

Diapole

Can someone explain what dipole is?
by Helen Shi 1J
Tue Nov 14, 2017 10:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Electron Density [ENDORSED]
Replies: 4
Views: 229

Re: Electron Density [ENDORSED]

Why do we not count the lone pairs on other atoms bonded to the central atom as regions of electron density?
by Helen Shi 1J
Fri Nov 10, 2017 4:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Electron Density [ENDORSED]
Replies: 4
Views: 229

Electron Density [ENDORSED]

Do we only count the lone pairs on the central atom as regions of electron density?
by Helen Shi 1J
Mon Nov 06, 2017 9:04 pm
Forum: Lewis Structures
Topic: Radicals
Replies: 4
Views: 283

Re: Radicals

Can someone explain what a radical is?
by Helen Shi 1J
Sat Nov 04, 2017 9:45 pm
Forum: Lewis Structures
Topic: Lewis Structure
Replies: 4
Views: 455

Re: Lewis Structure

Why is the element with the lowest ionizing energy is in the center?
by Helen Shi 1J
Sat Nov 04, 2017 9:32 pm
Forum: Ionic & Covalent Bonds
Topic: Giving the chemical formula of compounds.
Replies: 3
Views: 604

Re: Giving the chemical formula of compounds.

Can someone explain specifically how you get the chemical formula for part (c) aluminum hydride and (e)bismuth(III)fluoride?
by Helen Shi 1J
Sat Nov 04, 2017 12:08 am
Forum: Trends in The Periodic Table
Topic: why carbon has a higher electron affinity than nitrogen.
Replies: 5
Views: 2662

Re: why carbon has a higher electron affinity than nitrogen.

It is because the orbitals of Carbon is only 1/3 filled whereas Nitrogen has 3 out of the 6 electrons which is more balanced, thus it does not require another electron as much.
by Helen Shi 1J
Sat Nov 04, 2017 12:04 am
Forum: Electronegativity
Topic: Difference between electron affinity and electronegativity
Replies: 3
Views: 902

Re: Difference between electron affinity and electronegativity

Why is energy released when electrons is added to a gas phase atom?
by Helen Shi 1J
Sat Oct 28, 2017 11:56 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence-shell configuration [ENDORSED]
Replies: 3
Views: 1548

Re: Valence-shell configuration [ENDORSED]

Can someone explain to me why the answer to part (c) is (n-1)d^5ns^2 rather than (n-1)d^3ns^2?
by Helen Shi 1J
Fri Oct 27, 2017 1:31 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Quick Question about SO4
Replies: 8
Views: 682

Re: Quick Question about SO4

If both structures have the same net charge then why is one "better" than the other?
by Helen Shi 1J
Fri Oct 27, 2017 1:26 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Homework 2.37 [ENDORSED]
Replies: 7
Views: 1745

Re: Homework 2.37 [ENDORSED]

What is the effective nuclear charge?
by Helen Shi 1J
Fri Oct 27, 2017 1:25 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Homework 2.37 [ENDORSED]
Replies: 7
Views: 1745

Re: Homework 2.37 [ENDORSED]

Can someone explain how electron shielding works?
by Helen Shi 1J
Fri Oct 27, 2017 1:21 pm
Forum: Ionic & Covalent Bonds
Topic: Cations and Anions [ENDORSED]
Replies: 12
Views: 879

Re: Cations and Anions [ENDORSED]

How can an atom have the same properties when they lose an electron if different elements are separated with just a one-electron one proton difference.
by Helen Shi 1J
Fri Oct 13, 2017 7:31 pm
Forum: Properties of Light
Topic: 1.3 homework [ENDORSED]
Replies: 11
Views: 470

Re: 1.3 homework [ENDORSED]

How does the amplitude of the waves correspond with the lower frequency?
by Helen Shi 1J
Thu Oct 12, 2017 9:40 pm
Forum: Photoelectric Effect
Topic: Photoelectric effect post-quiz 17-19 [ENDORSED]
Replies: 5
Views: 2953

Re: Photoelectric effect post-quiz 17-19 [ENDORSED]

How did you get 2.5x10^-19 as the work energy?
by Helen Shi 1J
Thu Oct 05, 2017 4:04 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E.27 [ENDORSED]
Replies: 2
Views: 299

E.27 [ENDORSED]

Can someone explain part a) Calculate the mass, in grams, of one water molecule?
by Helen Shi 1J
Thu Oct 05, 2017 3:55 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E.27
Replies: 2
Views: 217

E.27

Can someone explain part a) Calculate the mass, in grams, of one water molecule?
by Helen Shi 1J
Mon Oct 02, 2017 10:16 pm
Forum: Molarity, Solutions, Dilutions
Topic: G17
Replies: 2
Views: 2027

Re: G17

For part b) First, find the number of moles for just K2S because that is the only molecule that has sulfide: .500 grams/(39.1(2) +32.06) = .00453 moles Then multiply .00453 by ratio of moles of sulfide over K2S, which is 1/1 so you get. Then plug the numbers into the formula: moles/volume= molarity;...

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