Search found 60 matches

by arif_latif_2G
Sat Mar 16, 2019 10:06 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Test 2 Question 5
Replies: 5
Views: 263

Re: Test 2 Question 5

From what I understand, you should compare the pH at the new temperature to 7. If it is less than 7, consider it as acidic. Since pH is based on the concentration of H+, you shouldn't compare it the OH- concentration.
by arif_latif_2G
Sat Mar 16, 2019 9:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cellm Potential
Replies: 1
Views: 46

Re: Cellm Potential

Most of the time, we flip the reduction half-reaction so we can use it as the oxidation half-reaction and many times, when we flip it, it becomes negative. However, when we want to calculate standard cell potential, we subtract E(anode) from E(cathode), so the negative values gets canceled out, and ...
by arif_latif_2G
Sat Mar 16, 2019 9:47 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Free Expansion
Replies: 3
Views: 191

Re: Free Expansion

When work done by the system is negative.
by arif_latif_2G
Sun Mar 10, 2019 6:45 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Homework 15.65
Replies: 1
Views: 62

Homework 15.65

Can someone help me through this question: For the reversible, one-step reaction 2 A <=>B B + C, the forward rate constant for the formation of B is 265 Lmol^-1min^-1 and the rate constant for the reverse reaction is 392 Lmol^-1min^-1. The activation energy for the forward reaction is 39.7 kJmol^-1 ...
by arif_latif_2G
Sun Mar 10, 2019 6:41 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Homework 15.63
Replies: 2
Views: 61

Homework 15.63

Can someone help me through this question:
The rate constant of the reaction between CO2 and OH- in aqueous solution to give the HCO3- ion is 1.5 x 10^10 Lmol^-1s^-1 at 25C. Determine the rate constant at blood
temperature (37 C), given that the activation energy for the reaction is 38 kJmol^-1.
.
by arif_latif_2G
Sun Mar 10, 2019 6:21 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Homework 15.61
Replies: 1
Views: 49

Homework 15.61

Can someone help me through this question:
The rate constant of the fi rst-order reaction 2 N2O(g) S
2 N2(g) -> O2(g) is 0.76 s1
at 1000. K and 0.87 s1
at 1030. K.
Calculate the activation energy of the reaction.
by arif_latif_2G
Sun Mar 03, 2019 8:26 pm
Forum: First Order Reactions
Topic: Homework #15.29
Replies: 1
Views: 64

Homework #15.29

Can someone walk me through this question: For the first-order reaction A -> 3 B + C, when [A]0 = 0.015 mol x L^-1, the concentration of B increases to 0.018 mol x L^-1 in 3.0 min. (a) What is the rate constant for the reaction expressed as the rate of loss of A? (b) How much more time would be need...
by arif_latif_2G
Sun Mar 03, 2019 7:56 pm
Forum: General Rate Laws
Topic: Reaction Order
Replies: 2
Views: 55

Reaction Order

How do we tell what order a reaction is?
by arif_latif_2G
Sun Mar 03, 2019 7:50 pm
Forum: First Order Reactions
Topic: Homework #15.21
Replies: 1
Views: 74

Homework #15.21

Can someone help me through this question: Beta blockers are drugs that are used to manage hypertension. It is important for doctors to know how rapidly a beta blocker is eliminated from the body. A certain beta blocker is eliminated in a first-order process with a rate constant of 7.6 X 10^-3 min^-...
by arif_latif_2G
Sun Feb 24, 2019 10:33 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n in -nFE
Replies: 6
Views: 86

Re: n in -nFE

Moles of electrons transferred.
by arif_latif_2G
Sun Feb 24, 2019 9:58 pm
Forum: Balancing Redox Reactions
Topic: Half Reaction
Replies: 2
Views: 50

Re: Half Reaction

A half reaction is either the oxidation or reduction reaction component of a redox reaction. A half reaction is obtained by considering the change in oxidation states of individual substances involved in the redox reaction. Often, the concept of half-reactions is used to describe what occurs in an e...
by arif_latif_2G
Sun Feb 24, 2019 9:31 pm
Forum: Balancing Redox Reactions
Topic: Mnemonic for Redox
Replies: 5
Views: 75

Mnemonic for Redox

Does anyone remember the mnemonics for remembering reducers and oxidizers from high school?
by arif_latif_2G
Sun Feb 17, 2019 8:18 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Non-spontaneous and spontaneous processes
Replies: 2
Views: 49

Re: Non-spontaneous and spontaneous processes

When ΔH > 0 and ΔS > 0, at high temperatures, reactions are spontaneous. When ΔH < 0 and ΔS < 0, at low temperatures, reactions are spontaneous. When ΔH < 0 and ΔS > 0, at all temperatures, reactions are spontaneous. When ΔH > 0 and ΔS < 0, at all temperatures, reactions are non-spontaneous.
by arif_latif_2G
Sun Feb 17, 2019 8:00 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy
Replies: 3
Views: 54

Gibbs Free Energy

Does a more negative Gibbs Free Energy value mean that a reaction is more spontaneous? Meaning the rate of reaction is faster?
by arif_latif_2G
Sun Feb 17, 2019 6:55 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Spontaneous reactions
Replies: 7
Views: 1002

Re: Spontaneous reactions

Not necessarily. If the Gibbs Free Energy is negative, then the reaction is spontaneous, which can be attributed to a reaction that is very exothermic; however, just being an exothermic reaction does not mean the reaction is spontaneous.
by arif_latif_2G
Sun Feb 10, 2019 9:51 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermal meaning
Replies: 4
Views: 96

Re: Isothermal meaning

Isothermal means that the temperature stays the same, meaning to say, no heat energy can leave or enter the system.
by arif_latif_2G
Sun Feb 10, 2019 6:37 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units for enthalpy
Replies: 6
Views: 117

Re: Units for enthalpy

According to my TA, Jack, both KJ or J work.
by arif_latif_2G
Sun Feb 10, 2019 6:34 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Midterm Next Week
Replies: 6
Views: 114

Re: Midterm Next Week

There is no Gibb's Free Energy on the test.
by arif_latif_2G
Sun Feb 03, 2019 8:44 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpy of Formation
Replies: 3
Views: 60

Re: Standard Enthalpy of Formation

1. It always represents 1 mol of the product so if you can multiply by the number of moles necessary.
2. We will probably not need to memorize them.
by arif_latif_2G
Sun Feb 03, 2019 8:40 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 2
Views: 44

Re: Bond Enthalpies

You can tell which bonds are formed/broken by looking at the Lewis structure, but you can usually tell by looking at the balanced equations and seeing which elements are breaking off and combining with.
by arif_latif_2G
Sun Feb 03, 2019 7:27 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: What is pKa and Ka exactly?
Replies: 11
Views: 890

Re: What is pKa and Ka exactly?

Ka is the equilibrium constant of an acid. If Ka is less than 1, then the acid is considered very weak. pKa is the negative log of Ka, which is just used to make the math a bit easier. The smaller the pKa, the stronger the acid.
by arif_latif_2G
Sun Jan 27, 2019 4:14 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 3
Views: 46

Re: Bond Enthalpies

It is an average of all bond enthalpies seen in experimentation, so it will vary between samples.
by arif_latif_2G
Sun Jan 27, 2019 4:10 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy of Diatomic Molecules
Replies: 1
Views: 31

Re: Enthalpy of Diatomic Molecules

According to Lavelle, through experimentation, diatomic gases have exhibited an enthalpy of 0. So when calculating enthalpy, assume diatomic gases' enthalpies are 0.
by arif_latif_2G
Sun Jan 27, 2019 4:04 pm
Forum: Calculating Work of Expansion
Topic: WORK
Replies: 1
Views: 65

Re: WORK

"The fundamental molecular difference between work and heat is related to the orderliness with which atoms in the surroundings move. When energy is transferred as work, the system moves molecules in the surroundings in a definite direction (think of the atoms of a rising weight all moving upwar...
by arif_latif_2G
Sun Jan 20, 2019 9:47 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: amphoteric
Replies: 2
Views: 65

Re: amphoteric

Ammonia is not amphoteric. You are probably getting it confused with its conjugate acid, Ammonium, NH4(+).
by arif_latif_2G
Sun Jan 20, 2019 9:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pressure Notation
Replies: 5
Views: 99

Re: Pressure Notation

If not all chemicals involved are gases, you probably should use molarity rather than partial pressure.
by arif_latif_2G
Sun Jan 20, 2019 6:28 pm
Forum: Ideal Gases
Topic: Ideal Gas as Approximation
Replies: 2
Views: 47

Re: Ideal Gas as Approximation

I think that means you can use partial pressure in the finding the answer.
by arif_latif_2G
Sun Jan 13, 2019 11:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Le Chatelier's Principle
Replies: 2
Views: 37

Re: Le Chatelier's Principle

K is dependent on temperature on the basis that a temperature change can prefer either the forward or reverse reaction if the said change compliments an endothermic or exothermic reaction. Since pressure is not directly tied to temperature, it wouldn't change the K value.
by arif_latif_2G
Sun Jan 13, 2019 10:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question 11.11
Replies: 2
Views: 41

Question 11.11

6th Edition The following flasks show the dissociation of a diatomic molecule, X2, over time. (a) Which flask represents the point in time at which the reaction has reached equilibrium? (b) What percentage of the X2 molecules have decomposed at equilibrium? (c) Assuming that the initial pressure of ...
by arif_latif_2G
Sun Jan 13, 2019 7:55 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q and K
Replies: 4
Views: 63

Re: Q and K

Both are the reaction quotient, but K is when the reaction is at equilibrium, while Q can represent the reaction quotient at any given moment. If Q is lower than K, then the forward reaction is favored. Similarly, if Q is greater than K, then the reverse reaction is favored.
by arif_latif_2G
Sat Dec 08, 2018 9:21 pm
Forum: Identifying Acidic & Basic Salts
Topic: net ionic equations
Replies: 2
Views: 163

Re: net ionic equations

We probably won't be graded on writing the net ionic equation, but you need the basic understanding that acids and bases and consequential products. The understanding of spectator ions will help you figure what products will be formed and concentrations of [H+] and [OH-].
by arif_latif_2G
Sat Dec 08, 2018 8:53 pm
Forum: Polyprotic Acids & Bases
Topic: Polyprotics on Final
Replies: 3
Views: 263

Re: Polyprotics on Final

Just know polyprotics can dissociate more than once. For example, H2S04, which is a strong acid, dissociates to H+ and HSO4-. However, HSO4- could then dissociate to SO4^2- and H+. Also, know that the second dissociation is a lot harder than the first one, meaning that the second acid is a weaker ac...
by arif_latif_2G
Sat Dec 08, 2018 8:36 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Churro #34
Replies: 1
Views: 66

Re: Churro #34

First, find the number of moles and molarity of each molecule.
Then find the balanced equation: 2HCl+ Ca0 -> H20 + CaCl2
Then find which one is the limiting reactant.
Find the remaining amount of H+ left.
Then -log[H+] to find the pH.

I hope this helps.
by arif_latif_2G
Sun Dec 02, 2018 9:01 pm
Forum: Naming
Topic: Naming Question
Replies: 5
Views: 100

Re: Naming Question

The sum of the oxidation numbers in a polyatomic ion is equal to the charge of the ion. The water molecules are neutral (0) so can be ignored. Cl is -1. So to find Fe, the charge of Fe + the charge of Cl = 1 (charge of the ion) so this becomes x - 1= 1, which makes Fe a charge of +2. Here are some g...
by arif_latif_2G
Sun Dec 02, 2018 8:53 pm
Forum: Amphoteric Compounds
Topic: Amphoteric compounds besides water
Replies: 6
Views: 116

Re: Amphoteric compounds besides water

Water will most likely be the only one we need to know, otherwise, it will be specified if a compound is amphoteric.
by arif_latif_2G
Sun Dec 02, 2018 8:19 pm
Forum: Lewis Acids & Bases
Topic: 6th editions Fundamentals J #1
Replies: 3
Views: 74

Re: 6th editions Fundamentals J #1

There is a formula to calculate p: -log[H+], where you need to know the molarity of H+. Since you do not know the molarity, you can assume whatever molecule that will dissociate into H+ will be acids and ones that will dissociate into OH- will be bases. H2SO3 becomes 2H+ and SO3- and Ca(OH)2 becomes...
by arif_latif_2G
Sun Nov 25, 2018 8:34 pm
Forum: Hybridization
Topic: S character
Replies: 4
Views: 93

Re: S character

As the S Character increases, the number of electron densities that exist around a central atom also increases and to avoid repulsion and to increase the stability, the electrons are arranged at a greater angle.
by arif_latif_2G
Sun Nov 25, 2018 8:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: e- Density
Replies: 4
Views: 86

Re: e- Density

We do consider double and triple bonds; however, we just consider them to be singular areas of electron densities probably because electrons in a double or triple bond are so "close" together that is seems to be one area rather than 2 or 3 areas between atoms.
by arif_latif_2G
Sun Nov 25, 2018 8:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sigma Bond vs. Pi Bond
Replies: 3
Views: 87

Re: Sigma Bond vs. Pi Bond

A sigma bond has electron densities along the bond axis while a pi bond has electron densities above and below the bond axis. Due to this, the pi bond cannot rotate the same way a sigma bond can rotate because it would break the pi bond interaction.
by arif_latif_2G
Sun Nov 18, 2018 9:55 pm
Forum: Hybridization
Topic: Promotion
Replies: 3
Views: 80

Re: Promotion

Electron promotion is when an electron is relocated to a higher energy orbital. You will be able to tell through the electron configuration because lower energy orbitals may not be filled before higher energy orbitals start having electrons in them.
by arif_latif_2G
Sun Nov 18, 2018 9:35 pm
Forum: Sigma & Pi Bonds
Topic: Visualizing sigma and pi bonds
Replies: 7
Views: 144

Re: Visualizing sigma and pi bonds

http://www.chembio.uoguelph.ca/educmat/chm729/band/New-5.jpg *This is the URL to the picture* This is a good picture for visualizing sigma and pi bonds. The image shows (from top to bottom) a sigma bond between two p-orbitals a sigma bond between a single p-orbital and s-orbital a sigma bond between...
by arif_latif_2G
Sun Nov 18, 2018 9:28 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Types of Bonds
Replies: 4
Views: 75

Re: Types of Bonds

Sigma bonds are formed by the end-to-end overlap of orbitals while Pi bonds are formed by the lateral overlap of orbitals. Since the overlap in sigma bonds is larger than the overlap in Pi bonds, sigma bonds are stronger.
by arif_latif_2G
Sun Nov 11, 2018 5:06 pm
Forum: Coordinate Covalent Bonds
Topic: Coordinate Covalent Bond formation
Replies: 3
Views: 226

Re: Coordinate Covalent Bond formation

They form when a central atom can complete its octet if an additional atom or ion with a lone pair of electrons forms a bond by providing both electrons.
by arif_latif_2G
Sun Nov 11, 2018 4:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 12
Views: 266

Re: Bond Angles

In the lecture outlines, it is mentioned on how we need to know " lone pairs are more likely to found in certain locations around a central atom and how and why they affect the bond angles in a molecule, cation, or anion;" so it is not out of the question that we may need to know bond angl...
by arif_latif_2G
Sun Nov 11, 2018 3:38 pm
Forum: Properties of Light
Topic: Wave-Particle Duality
Replies: 1
Views: 82

Re: Wave-Particle Duality

The photoelectric effect documents light's particle properties while de Broglie's wavelength hypothesis along with Davisson's and Germer's experiments showed light's wavelength properties. There are probably other experiments/theories/hypotheses that exist but these two are the ones we learned about...
by arif_latif_2G
Sun Nov 04, 2018 11:25 pm
Forum: Trends in The Periodic Table
Topic: ionization energy & electron affinity
Replies: 3
Views: 108

Re: ionization energy & electron affinity

Ionization energy is the energy required to remove an electron from a gaseous atom while electron affinity is the energy released when an electron is added to a gaseous atom.
by arif_latif_2G
Sun Nov 04, 2018 11:11 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge Equation
Replies: 13
Views: 2571

Re: Formal Charge Equation

Formal Charge = Valence electrons - The number of electrons that are not in a bond(# of lone pairs * 2) - the number of bonds
by arif_latif_2G
Sun Oct 28, 2018 7:53 pm
Forum: Lewis Structures
Topic: shape of lewis structures
Replies: 1
Views: 48

Re: shape of lewis structures

The presence of lone pairs will affect the shape. In accordance to the VSEPR theory, the lone pairs can be seen as repelling the electrons in a chemical bond into a position of equilibrium so the "place of chemical bonding" is moved, therefore the atoms must orient themselves accordingly, ...
by arif_latif_2G
Sun Oct 28, 2018 7:12 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: px,py,pz???
Replies: 6
Views: 275

Re: px,py,pz???

Dr. Lavelle did it to show us the different ways of writing the p orbitals. You can write out the p orbitals in any electron configuration but when you get to elements with a lot more electrons, it tends to get very difficult to write out Npx, Npy, Npz over and over and it becomes quite tedious. So ...
by arif_latif_2G
Sun Oct 28, 2018 7:06 pm
Forum: Trends in The Periodic Table
Topic: Question 2.81 (Sixth Edition)
Replies: 2
Views: 86

Re: Question 2.81 (Sixth Edition)

"Oxygen is the first element encountered in which the p-electrons must be paired. This added electron-electron repulsion energy causes the ionization energy to be lower." This is the answer from the solutions manual so you might want to ask your TA or Dr. Lavelle for clarification.
by arif_latif_2G
Sun Oct 21, 2018 7:18 pm
Forum: Photoelectric Effect
Topic: Conditions that allow electron to be ejected from metal surface
Replies: 12
Views: 401

Re: Conditions that allow electron to be ejected from metal surface

It has to be greater otherwise the metal just absorbs the energy and the electron will not be ejected. If the light energy equals the work function then the electron is ionized but it cannot be ejected from the metal because it has no kinetic energy.
by arif_latif_2G
Sun Oct 21, 2018 6:38 pm
Forum: DeBroglie Equation
Topic: HW Problem 1.39 (6th Edition)
Replies: 4
Views: 141

Re: HW Problem 1.39 (6th Edition)

You have to use de Broglie equation: wavelength = h/p [p = momentum = mass(kg) * velocity (m/s)]. So convert 5.15oz into kg: 5.15 * 28.9 * 10^-3 = 0.148835kg. Then mutliply the weight that is in kg by velocity( which needs to be converted into m/s from mi/h [92mi/h * 1609.34/3600 -> .4470388889mi/s]...
by arif_latif_2G
Sun Oct 21, 2018 6:27 pm
Forum: DeBroglie Equation
Topic: Smallest Detectable Wavelength
Replies: 2
Views: 69

Re: Smallest Detectable Wavelength

I think he said 10^-18, but he said 10^-15 is more realistic.
by arif_latif_2G
Sun Oct 14, 2018 11:20 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Modifying the Atomic Spectrum of Hydrogen for other elements
Replies: 2
Views: 38

Modifying the Atomic Spectrum of Hydrogen for other elements

Out of pure curiosity, does anyone know how to modify the atomic spectrum formula for Hydrogen, -hR/n^2, so it can be used for other elements that are considered as one electron atoms for the equation?
by arif_latif_2G
Sun Oct 14, 2018 8:10 pm
Forum: Properties of Light
Topic: 1A.3 Atomic Spectra
Replies: 2
Views: 40

Re: 1A.3 Atomic Spectra

I am assuming that when they said, "Fall apart," it meant that the H2 gas separates into 2H+ and 2e-. Since the gas becomes ionized, they called it a plasma. It requires a lot of energy to remove the single electron from a hydrogen atom. The electron gains a lot of energy in order for it t...
by arif_latif_2G
Sun Oct 14, 2018 7:56 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Energy of bound and free electrons
Replies: 3
Views: 88

Re: Energy of bound and free electrons

"Free" means that the electron is not a part of an atom so it is just an electron that is "free-roaming"
Bound means that the electron is part of an atom so its "Bound to the nucleus"
I hope this clear up any confusion.
by arif_latif_2G
Sun Oct 07, 2018 11:26 pm
Forum: SI Units, Unit Conversions
Topic: Dilutions Equations
Replies: 2
Views: 86

Re: Dilutions Equations

It depends on the question. If you are diluting a solution, whose molarity and initial volume is known, by adding more water/solvent then you should use M1V1 = M2V2 because the number of moles stays the same. But you take out some solution and add that to a fixed amount to water, then the number of ...
by arif_latif_2G
Sun Oct 07, 2018 5:16 pm
Forum: Significant Figures
Topic: Multiplication/Division and Addition/Subtraction in Sig Figs
Replies: 2
Views: 61

Re: Multiplication/Division and Addition/Subtraction in Sig Figs

Addition or Subtraction: The last digit retained is set by the first doubtful digit. (e.x.: 2.042 + 3.2 - 0.123 = 5.365-> 5.4 since the 3.2 is the most doubtful because it only has one digit after the decimal so you round to that decimal point) Multiplication or Division: The answer contains no more...
by arif_latif_2G
Wed Oct 03, 2018 5:40 pm
Forum: Molarity, Solutions, Dilutions
Topic: Limiting Reactants
Replies: 3
Views: 54

Re: Limiting Reactants

First, you should figure out the molecular formulas of the products and reactants. Reactants: Cu(NO3)2 and NaOH Products: Cu(OH)2 and NaNO3 (not mentioned within the question) So you get Cu(NO3)2 + NaOH -> Cu(OH)2 + NaNO3 Now to balance the equation: On the reactant side, you can see that you have 2...

Go to advanced search