## Search found 74 matches

Thu Mar 14, 2019 1:34 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Catalyst vs. Intermediate
Replies: 8
Views: 259

### Re: Catalyst vs. Intermediate

A catalyst can be found in the beginning of the reaction, while an intermediate is found in the later steps.
Thu Mar 14, 2019 1:30 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Units for K
Replies: 4
Views: 163

### Re: Units for K

The units for k change depending on the order so that it can produce the correct units for the rate which is always in molarity per second.
Thu Mar 14, 2019 1:23 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: comparing forward and reverse rates
Replies: 4
Views: 152

### Re: comparing forward and reverse rates

The rate constants are different from the actual rate of the forward and reverse reaction. Also, the rate constant does not necessarily correspond to the rate of the reaction as it also depends on the concentrations and the order of the species.
Sat Mar 09, 2019 11:21 pm
Forum: Zero Order Reactions
Topic: Half-life
Replies: 6
Views: 480

### Half-life

What exactly is a half-life? I do not understand the concept behind this.
Sat Mar 09, 2019 11:19 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Microscopic reversibility
Replies: 4
Views: 140

### Re: Microscopic reversibility

Microscopic reversibility basically says that the reaction has the same path for both the forward and reverse directions.
Sat Mar 09, 2019 11:14 pm
Forum: First Order Reactions
Topic: Half-Life 1st Order Reaction
Replies: 6
Views: 194

### Re: Half-Life 1st Order Reaction

Yes, it is applicable to all first order rate reactions.
Sat Mar 09, 2019 11:10 pm
Forum: General Rate Laws
Topic: integrals
Replies: 8
Views: 315

### Re: integrals

You can find help in the class resources section. Also, you just need to understand the concepts behind it and how to use the final equations that are produced by calculus.
Fri Mar 01, 2019 5:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams (Using Platinum)
Replies: 10
Views: 318

### Cell Diagrams (Using Platinum)

When do we use platinum metal in the cell diagram, and why do we use platinum as the metal?
Fri Mar 01, 2019 5:01 pm
Forum: Balancing Redox Reactions
Replies: 13
Views: 508

### Re: Adding H+ and H2O

You must balance the elements other than oxygen and hydrogen first. Thus, you can do both.
Fri Mar 01, 2019 4:57 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Finding n
Replies: 12
Views: 394

### Re: Finding n

Yes, n is the number of moles of electrons transferred and can be found through the oxidation or reduction half reactions.
Sat Feb 23, 2019 1:45 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Favor ability of Cell portential
Replies: 5
Views: 272

### Re: Favor ability of Cell portential

A positive cell potential means that the reaction is spontaneous, while a negative cell potential means that the reaction is not spontaneous.
Sat Feb 23, 2019 1:39 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cathode vs. Anode
Replies: 9
Views: 292

### Re: Cathode vs. Anode

The cathode is the reduction half reaction, while the anode is the oxidation half reaction. Basically, whichever chemical species being reduced will be the cathode and whichever chemical species being oxidized will be the anode.
Sat Feb 23, 2019 1:36 am
Forum: Balancing Redox Reactions
Topic: Galcanic cell
Replies: 3
Views: 106

### Re: Galcanic cell

A galvanic cell and voltaic cell are essentially the same and are interchangeable.
Fri Feb 15, 2019 2:34 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: Finding W (degeneracy)
Replies: 4
Views: 365

### Re: Finding W (degeneracy)

Yes, you raise it to the number of Avogadro's constant if they ask you to use one mole of a substance.
Fri Feb 15, 2019 2:31 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Cv vs. Cp
Replies: 6
Views: 485

### Re: Cv vs. Cp

You use the value for Cv when the volume in the problem is constant, and you use the value for Cp when the pressure in the problem is constant.
Fri Feb 15, 2019 2:28 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: ΔS=q/t
Replies: 8
Views: 370

### Re: ΔS=q/t

Yes, you can use this when pressure is constant since the change in enthalpy is equal to q when pressure is constant.
Fri Feb 08, 2019 9:08 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed systems
Replies: 6
Views: 222

### Re: closed systems

Closed systems can have constant or changing pressure or volumes.
Fri Feb 08, 2019 9:06 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: w=-PdeltaV
Replies: 6
Views: 214

### Re: w=-PdeltaV

The first equation would only be used for questions that deal with reversible expansion, while the second equation of w=-PdeltaV would only be used for irreversible expansion.
Fri Feb 08, 2019 9:04 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated System
Replies: 4
Views: 119

### Re: Isolated System

Delta U would be 0 due to the fact that it is an isolated system. Since it is isolated, the internal energy will remain the same.
Fri Feb 01, 2019 10:40 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal Energy of Isolated Systems
Replies: 6
Views: 1290

### Re: Internal Energy of Isolated Systems

Yes, the change in internal energy of an isolated system is 0.
Fri Feb 01, 2019 10:34 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Thermo Test/Midterm
Replies: 9
Views: 277

### Re: Thermo Test/Midterm

Most likely not as we will be expected to already know how to draw Lewis structures from chem 14A.
Fri Feb 01, 2019 10:33 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed vs isolated
Replies: 14
Views: 333

### Re: closed vs isolated

A closed system can only exchange energy with its surroundings, while the isolated system cannot exchange anything with its surroundings.
Fri Feb 01, 2019 10:28 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Surroundings
Replies: 11
Views: 348

### Re: Surroundings

When referring to surroundings in chemistry, we usually mean everything outside the system that we are looking at. This means there really is not a boundary that exists for how far the surroundings can go.
Sat Jan 26, 2019 6:17 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes and Temperature
Replies: 3
Views: 102

### Phase Changes and Temperature

Why does the temperature not change during a phase change even though more heat energy is being added?
Sat Jan 26, 2019 6:14 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: heat capacity
Replies: 7
Views: 311

### Re: heat capacity

Heat capacity is the amount of heat needed to increase the temperature of one gram of a substance by one degree. It has a state property because it is independent of how the substance was prepared.
Sat Jan 26, 2019 6:08 pm
Forum: Phase Changes & Related Calculations
Topic: Why steam causes severe burns
Replies: 9
Views: 538

### Re: Why steam causes severe burns

Steam causes a more severe burn than that of boiling water even when they are at the same temperature due to the fact that steam holds more heat energy as becoming a vapor from a liquid requires a large amount of heat before it can change phases.
Sat Jan 19, 2019 9:15 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: "Shifting"
Replies: 15
Views: 1049

### Re: "Shifting"

Sitting to the left just means that the reactants are being favored over the products. Thus, if it is shifting left, the reactants are being favored to reach equilibrium.
Sat Jan 19, 2019 9:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium constant in different temperatures
Replies: 3
Views: 63

### Equilibrium constant in different temperatures

Why does the equilibrium constant change when the temperature changes?
Sat Jan 19, 2019 9:07 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ignoring solids
Replies: 6
Views: 279

### Re: ignoring solids

We leave out solids and liquids because they do not affect the equilibrium. We only account for species in the aqueous and gas phases when calculating equilibrium.
Sat Jan 12, 2019 9:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE table and cubic expressions
Replies: 1
Views: 124

### ICE table and cubic expressions

If an expression for an ice table becomes cubic and is no longer quadratic, how exactly would we solve for the x value to find the concentrations of the species?
Sat Jan 12, 2019 9:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Tables
Replies: 3
Views: 101

### Re: ICE Tables

You can calculate the C expression by combining the initial and change together. Then to find the value of the variable x in the C expression, you set all the expressions in the C category into the equilibrium constant form where products is over reactants and set it equal to the equilibrium constan...
Sat Jan 12, 2019 9:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc and Kp
Replies: 4
Views: 123

### Re: Kc and Kp

Both Kc and Kp are both equilibrium constants except that Kc is for molar concentrations while Kp is for partial pressures.
Sat Dec 08, 2018 10:07 pm
Forum: Lewis Acids & Bases
Topic: Lewis Acid
Replies: 6
Views: 227

### Lewis Acid

Why is HBr a stronger acid than HF?
Sat Dec 08, 2018 10:05 pm
Forum: Conjugate Acids & Bases
Topic: NH3, acid or base?
Replies: 12
Views: 2711

### Re: NH3, acid or base?

Yes, in most cases in which we work with NH3, it is considered in the terms of bronsted base.
Sat Dec 08, 2018 10:02 pm
Forum: Bronsted Acids & Bases
Topic: KOH
Replies: 1
Views: 374

### Re: KOH

You would draw the lewis structure in terms of ionic compounds as it is not covalent, so thus you would draw K with a plus charge next to OH with a negative charge while showing the paired shared and lone electrons on and between the O and H. KOH is considered a strong lewis base and is usually not ...
Sat Dec 08, 2018 9:55 pm
Forum: Bronsted Acids & Bases
Topic: Strong acid
Replies: 6
Views: 452

### Re: Strong acid

HCl is a strong acid as the most of the halogens in group 7 except flourine form strong acids due to the fact that they pull the electron density from hydrogen, and as it goes down the group the bond gets weaker and thus increases the strength of the acidity.
Sat Dec 08, 2018 9:50 pm
Forum: Bronsted Acids & Bases
Topic: Strong base
Replies: 5
Views: 387

### Re: Strong base

NaOH is a strong base because any hydroxides bonded to group 1 elements are considered strong bases.
Sat Dec 01, 2018 8:50 pm
Forum: Naming
Topic: Water as a ligand
Replies: 4
Views: 91

### Re: Water as a ligand

It should be written as OH2 when you want to demonstrate that the oxygen is bonding to the central transition metal.
Sat Dec 01, 2018 8:48 pm
Forum: Lewis Acids & Bases
Topic: Lewis vs Bronsted
Replies: 2
Views: 104

### Lewis vs Bronsted

Can someone explain to me the difference between Lewis(acids and bases) and Bronsted(acids and bases)?
Sat Dec 01, 2018 8:43 pm
Forum: Naming
Topic: Spaces in naming
Replies: 2
Views: 120

### Re: Spaces in naming

You should write it without spaces just to be safe and yes you add an O to anionic ligands.
Sat Dec 01, 2018 8:36 pm
Forum: Naming
Topic: Oxidation State
Replies: 4
Views: 144

### Re: Oxidation State

You calculate the oxidation state of the transition metal by first finding the overall charge of the ligands attached to it. After you have found that, you will want to look at the overall charge of the whole compound. You should then be able to find the oxidation state of the transition metal as it...
Sat Nov 24, 2018 11:23 pm
Forum: Hybridization
Topic: Hybridization when dealing with pi and sigma bonds
Replies: 1
Views: 81

### Hybridization when dealing with pi and sigma bonds

How come hybridization does not occur when forming pi bonds, but it does occur when forming sigma bonds?
Sat Nov 24, 2018 11:21 pm
Forum: Sigma & Pi Bonds
Topic: Double Bonds
Replies: 9
Views: 554

### Re: Double Bonds

Yes, double bonds consist of one sigma bond and one pi bond.
Sat Nov 24, 2018 11:20 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi Bonds
Replies: 2
Views: 100

### Re: Sigma and Pi Bonds

Yes, sigma bonds are longer than pi bonds since pi bonds have a larger electron density and thus have greater attraction between the electrons and the nucleus's protons. Thus, pi bonds are shorter than sigma bonds.
Sat Nov 24, 2018 4:23 pm
Forum: Hybridization
Topic: Test 3
Replies: 13
Views: 377

### Re: Test 3

The test will be on everything after the midterm to now. Essentially, you must understand the last concepts in chemical bonding, intermolecular forces, and both VSEPR and valence bond theory.
Sat Nov 17, 2018 1:48 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Drawings of Molecular Shape
Replies: 2
Views: 91

### Drawings of Molecular Shape

Do we need to understand how to draw the molecular shape in which it shows how the atoms are in different dimensions using techniques, such as dotted lines?
Sat Nov 17, 2018 1:42 pm
Forum: Hybridization
Topic: Hybridization for VSPER model
Replies: 2
Views: 119

### Re: Hybridization for VSPER model

Yes, they are just considered one electron density.
Sat Nov 17, 2018 1:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: CH4 HW 4.43 6TH EDITION
Replies: 1
Views: 43

### Re: CH4 HW 4.43 6TH EDITION

As the s-character of a hybrid orbital increases, the bond angle increases.
Sat Nov 17, 2018 1:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw Shape
Replies: 2
Views: 89

### Re: Seesaw Shape

Yes, you are correct the angle is actually less than 90 degrees due to the electron repulsion from the electron lone pair.
Fri Nov 09, 2018 9:48 am
Forum: Dipole Moments
Topic: Dipole induced dipole
Replies: 3
Views: 126

### Dipole induced dipole

How exactly does a dipole induce another dipole onto a neutral atom if the neutral atom only has London dispersion forces?
Fri Nov 09, 2018 9:45 am
Forum: Bond Lengths & Energies
Topic: MIDTERM Bond Length Question
Replies: 15
Views: 528

### Re: MIDTERM Bond Length Question

Since they actually exist as a hybridization resonance structure, the true bond lengths exist between 120 and 140. We need further experimental data to get a more accurate answer of the true bond length.
Fri Nov 09, 2018 9:23 am
Forum: Bond Lengths & Energies
Topic: Larger to weaker bond correlation
Replies: 3
Views: 172

### Re: Larger to weaker bond correlation

A larger bond results in a weaker bond due to the fact that there is more distance the bond is covering. Using coulomb's law, F=(K(q1*q2))/r^2, as distance, r, increases, the force becomes weaker as it is inversely proportional to force.
Fri Nov 09, 2018 9:15 am
Forum: Bond Lengths & Energies
Topic: Dispersion Force/State of Matter Correlation
Replies: 2
Views: 133

### Re: Dispersion Force/State of Matter Correlation

Dispersion forces increased as we go down the periodic table due to increased electrons which lead to more London dispersion forces as there is more temporary interactions between electrons. As these forces increased, atoms are held more tightly together, which leads to states, such as liquids and s...
Fri Nov 02, 2018 4:57 pm
Forum: Lewis Structures
Topic: How to decide central atom?
Replies: 6
Views: 311

### How to decide central atom?

Is the central atom in the Lewis structures based off of which atom has the lowest electronegativity or which atom has the lowest ionization energy?
Fri Nov 02, 2018 4:54 pm
Forum: Lewis Structures
Topic: 6th edition 3.35b Lewis Structure of BrO-
Replies: 1
Views: 60

### Re: 6th edition 3.35b Lewis Structure of BrO-

Yes, the oxygen carries the formal charge due to the fact that it is the most electronegative. Also, because bromine can only have one shared bond pair, which forces oxygen to hold the negative charge.
Fri Nov 02, 2018 4:47 pm
Forum: Lewis Structures
Topic: Lewis Structure Shortcuts
Replies: 1
Views: 130

### Re: Lewis Structure Shortcuts

A shortcut you can use when dealing with larger molecules, such as CH3NH2, is that you split up the molecule by the different compounds within it. In this case, you place the carbon with the three hydrogen atoms and the nitrogen with the 2 hydrogen atoms as there are two separate compounds within it...
Fri Nov 02, 2018 4:42 pm
Forum: Lewis Structures
Topic: H Element
Replies: 2
Views: 93

### Re: H Element

Hydrogen atoms can only form one bond known as a duet as it cannot form an octet. In covalent bonding, a central atom must have enough available electrons to form at least two bonds.
Sun Oct 28, 2018 12:00 pm
Forum: Ionic & Covalent Bonds
Topic: Second ionization of alkali metals
Replies: 3
Views: 111

### Second ionization of alkali metals

Why does the second ionization energy of the alkali metals increase so dramatically after the first ionization energy?
Sun Oct 28, 2018 11:47 am
Forum: Ionic & Covalent Bonds
Topic: Ground State Electron Configurations
Replies: 7
Views: 176

### Re: Ground State Electron Configurations

An element like Argon is used as it is the closest noble gas that can be used for writing short-hand ground state electron configurations based off of noble gases.
Sun Oct 28, 2018 11:44 am
Forum: Ionic & Covalent Bonds
Topic: Valence electrons
Replies: 8
Views: 227

### Re: Valence electrons

Valence electrons can be determined by looking at their group number at the top. For, example chlorine is in group 7, so thus it has 7 electrons. In cases of ions like Ag+, one should write out the ground state electron configuration to figure out the valance electrons as they differ from the regula...
Sun Oct 28, 2018 11:34 am
Forum: Ionic & Covalent Bonds
Topic: ionization energy [ENDORSED]
Replies: 4
Views: 108

### Re: ionization energy[ENDORSED]

Removing the second electron from an atom is more difficult due to the higher ionization energy required to remove it. This is due to the fact that the nuclear charge has a stronger pull on the remaining electrons as there is now one less electron. Thus, with a stronger attraction due to a positive ...
Fri Oct 19, 2018 1:37 pm
Forum: Trends in The Periodic Table
Replies: 4
Views: 302

The atomic radius would not increase across a period due to the fact that the quantum number stays the same and that there are now more protons, which essentially produces a larger effective nuclear charge on the electrons.
Fri Oct 19, 2018 1:31 pm
Forum: *Shrodinger Equation
Topic: Schrodinger Equation
Replies: 2
Views: 128

### Schrodinger Equation

To what extent of the Shrodinger Equation will we have to understand for the upcoming test on quantum? Do we just need to understand the concepts behind it or must we understand how to calculate solutions using the equation as well?
Fri Oct 19, 2018 1:29 pm
Forum: Properties of Electrons
Topic: Rydberg formula
Replies: 5
Views: 217

### Re: Rydberg formula

Adding on, you can use the formula E=hR(1/n^2(final)-1/n^2(initial)) to find the energy difference in one step. Then plugging it back into the equation E=hv to find frequency and then using C=wavelength(frequency) to find wavelength.
Fri Oct 19, 2018 1:25 pm
Forum: Properties of Electrons
Topic: Nodal Plane
Replies: 5
Views: 306

### Re: Nodal Plane

A nodal plane is a plane in space where the electron probability reaches zero. Usually, there exists nodal planes at the nucleus. The s subshell is the only subshell that is symmetrical and thus does not have a nodal plane.
Sun Oct 14, 2018 6:27 pm
Forum: Trends in The Periodic Table
Topic: 6th Edition Ch.2 Number 93
Replies: 2
Views: 28

### 6th Edition Ch.2 Number 93

The solutions manual suggests that A=Na B=Cl C=Na ion and D=Cl ion based off the diagram given, but chlorine should have a smaller atomic radius than that of sodium at ground state. So is this a typo and if not can someone explain to me how they got that answer?
Sun Oct 14, 2018 10:16 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: G and H orbitals
Replies: 1
Views: 74

### G and H orbitals

Is there any element that actually incorporates g and h orbitals and is it even under the scope of our class that we must learn this?
Sun Oct 14, 2018 10:10 am
Forum: Properties of Light
Topic: C=Wavelength*Frequency
Replies: 11
Views: 620

### Re: C=Wavelength*Frequency

C is a constant value for the speed of light which is 3.00X10^8 meters/second.
Sun Oct 14, 2018 10:09 am
Forum: Properties of Light
Topic: Measuring Wavelength
Replies: 5
Views: 222

### Re: Measuring Wavelength

Most likely there is not a maximum for the length of a wavelength. We most likely will not have to deal with this as it is probably outside the scope of which this class teaches as it was not mentioned in lecture.
Sun Oct 14, 2018 9:57 am
Forum: Properties of Electrons
Topic: photoelectric effect question
Replies: 2
Views: 61

### Re: photoelectric effect question

Adding on to the earlier response before me, the formula, Ke=1/2mv^2, is just a physics formula we used to find the kinetic energy of a system. In this case, we are trying to find the kinetic energy held by the released electron that is left over after subtracting the energy given by the light sourc...
Sun Oct 07, 2018 11:18 pm
Forum: SI Units, Unit Conversions
Topic: Dilutions Equations
Replies: 2
Views: 142

### Dilutions Equations

I was confused when to use the equation M1V1=M2V2 vs the equation molarity=moles/volume when doing dilution problems?
Thu Oct 04, 2018 1:42 am
Forum: Limiting Reactant Calculations
Topic: Significant figures in textbook 7th edition [ENDORSED]
Replies: 5
Views: 176

### Significant figures in textbook 7th edition[ENDORSED]

Some of the solutions in the back of the textbook have different significant figures in their answers than what was given. An example would be that the given has three significant figures, while the solution in the back has four significant figures. Why is that if anyone knows?
Thu Oct 04, 2018 1:39 am
Forum: Limiting Reactant Calculations
Topic: Combustion Analysis? [ENDORSED]
Replies: 7
Views: 230

### Re: Combustion Analysis?[ENDORSED]

It might appear on the test just as an equation to be used for another topic like limiting reagents.
Thu Oct 04, 2018 1:37 am
Forum: Limiting Reactant Calculations
Topic: Homework Questions [ENDORSED]
Replies: 4
Views: 150

### Re: Homework Questions[ENDORSED]

You can do any seven questions out of all the categories as long as it is on the topics that we have already covered in class.