## Search found 66 matches

Fri Mar 15, 2019 8:55 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre-equilibrium Approach
Replies: 2
Views: 353

### Pre-equilibrium Approach

By the pre-equilibrium approach, we relate the rate laws that might contain intermediates by the equilibrium constant, correct? What happens if a reactant is a solid or liquid? How do we account for them then?
Wed Mar 13, 2019 8:53 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Equation and Collision Theory
Replies: 1
Views: 118

### Arrhenius Equation and Collision Theory

How does the Arrhenius equation relate to collision theory, especially in regards to the Boltzmann distribution?
Wed Mar 13, 2019 8:40 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: P-T Graphs
Replies: 2
Views: 291

### P-T Graphs

Do we need to know how to use and draw P-T graphs?
Wed Mar 13, 2019 8:25 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: Calculating the Number of Orientations Mathematically
Replies: 1
Views: 258

### Calculating the Number of Orientations Mathematically

How do we calculate the number of possible orientations or states mathematically when finding the degeneracy? In other words, if degeneracy W = x^(n), where x= number of possible orientations or states and n= # of particles, how do we mathematically find x?
Wed Mar 06, 2019 10:24 am
Forum: First Order Reactions
Topic: Pseudo-First-Order Reaction
Replies: 5
Views: 206

### Pseudo-First-Order Reaction

How do we know if a reaction can be treated as a pseudo-first-order reaction?
Wed Mar 06, 2019 10:15 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Order of a Reaction
Replies: 1
Views: 131

### Order of a Reaction

Is using the experimental data in rate ratios the only way to determine the order of a reaction? Is there another way to determine the order?
Tue Mar 05, 2019 1:35 am
Forum: General Rate Laws
Topic: Rate Laws and Temperature
Replies: 4
Views: 123

### Rate Laws and Temperature

How do rate laws relate to temperature in regards to equations?
Wed Feb 27, 2019 11:22 pm
Forum: Balancing Redox Reactions
Topic: Basic Solutions
Replies: 5
Views: 144

### Re: Basic Solutions

For basic solutions, you first balance the O by using H2O. Then, you balance H by adding H2O to the side of the half reaction that needs H and adding OH- to the other side.
Wed Feb 27, 2019 11:18 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Redox Reactions and Cell Potentials
Replies: 2
Views: 99

### Re: Redox Reactions and Cell Potentials

Since standard electric potential is an intensive property, it stays the same when the half reaction is balanced.
Wed Feb 27, 2019 11:14 pm
Forum: Balancing Redox Reactions
Topic: Half Reactions in a Basic Solution
Replies: 4
Views: 146

### Re: Half Reactions in a Basic Solution

To balance a half reaction in basic solution, you first add H2O to the side with the least amount of oxygen (let's call this side 1) to balance the oxygen. Then, you add H2O on the opposite side (side 2) and add OH- back to the original side (side 1) to balance the H.
Thu Feb 21, 2019 12:36 am
Forum: Balancing Redox Reactions
Topic: Oxidation Numbers
Replies: 2
Views: 96

### Re: Oxidation Numbers

The oxidation number of hydrogen is +1 except when bonded to metals in binary compounds, which is when hydrogen would have an oxidation number of -1.
Thu Feb 21, 2019 12:30 am
Forum: Balancing Redox Reactions
Topic: Oxidation Numbers
Replies: 2
Views: 96

### Re: Oxidation Numbers

The oxidation number of oxygen (O) is 2-, except in H2O2 (O2 = 2-) and O2 (O2 = 2-), where O is -1.
Thu Feb 21, 2019 12:24 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy Meaning
Replies: 6
Views: 281

### Gibbs Free Energy Meaning

What really is Gibbs Free Energy, and what does it mean for a negative Gibbs Free Energy to result in a spontaneous reaction?
Tue Feb 12, 2019 8:10 pm
Forum: Administrative Questions and Class Announcements
Replies: 179
Views: 12570

On worksheet 3 Intro to Thermodynamics, problem 7, what equations are we supposed to use? My friend used the information given to make a cross multiplying equation but got an answer of 51.23g instead of 51.14g. How are we supposed to approach this problem?
Tue Feb 12, 2019 9:29 am
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: Thermodynamic and Statistical Property
Replies: 2
Views: 104

### Re: Thermodynamic and Statistical Property

LorenzoDuvergne3I wrote:Where is this discussed in the textbook?

This is from lecture notes.
Tue Feb 12, 2019 9:29 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy Change by Volume and Pressure
Replies: 2
Views: 112

### Entropy Change by Volume and Pressure

If a system changes its conditions by both volume and pressure, do we have to solve for the entropy for both volume and pressure, even if the entropy is the same value for both conditions, since volume and pressure are inversely proportional?
Mon Feb 11, 2019 3:31 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: Thermodynamic and Statistical Property
Replies: 2
Views: 104

### Thermodynamic and Statistical Property

What does it mean that thermodynamic property means a "small" error in S and a statistical property means a "large" error in W in relation to the Boltzmann equation?
Thu Feb 07, 2019 10:17 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: q= -w
Replies: 8
Views: 226

### Re: q= -w

If a system has a net internal energy change of zero, then the energy transferred by work and heat are equal and opposite of each other.
Thu Feb 07, 2019 10:13 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal Energy, Enthalpy, and Heat
Replies: 2
Views: 118

### Internal Energy, Enthalpy, and Heat

Can someone explain in their own words what the relationship between internal energy, enthalpy, and heat is?
Thu Feb 07, 2019 10:10 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Purpose of ln
Replies: 2
Views: 72

### Re: Purpose of ln

The integral of a variable to the (-1) is natural log, which gives the natural log in the work equation for a reversible process.
Sat Feb 02, 2019 5:30 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capactiy
Replies: 5
Views: 183

### Re: Heat Capactiy

The heat required depends on the amount of substance, so heat capacity is an extensive property.
Sat Feb 02, 2019 5:28 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Angles
Replies: 5
Views: 164

### Re: Bond Angles

Energy is required to break bonds (positive enthalpy change), while energy is released to form bonds (negative enthalpy change).
Sat Feb 02, 2019 5:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy Symbol
Replies: 5
Views: 264

### Re: Enthalpy Symbol

Delta H naught of a reaction means the reactions are given in their standard state.
Mon Jan 21, 2019 2:03 pm
Forum: Administrative Questions and Class Announcements
Replies: 179
Views: 12570

On Worksheet 2, why is the concentration of CO3 the same as Ka2 for problem 4b?
Mon Jan 21, 2019 1:48 pm
Forum: Administrative Questions and Class Announcements
Replies: 179
Views: 12570

Did anyone happen to get around 0.077g for #2 on the acid-base review worksheet? The key says 0.10g, so I am unsure whether Karen rounded or I did the question incorrectly. I did the same thing at first. Make sure you use the initial concentration of HCOOH and not the equilibrium concentration of H...
Mon Jan 21, 2019 1:37 pm
Forum: Administrative Questions and Class Announcements
Replies: 179
Views: 12570

For number 7 on worksheet 1, why does high temperature favor the formation of bromine atoms if we don't know if the reaction is endothermic or exothermic?
Fri Jan 18, 2019 1:38 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Arrow
Replies: 7
Views: 355

### Equilibrium Arrow

Do only reactions using weak acids and bases use an equilibrium arrow?
Wed Jan 16, 2019 11:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Tricks for ICE tables
Replies: 5
Views: 194

### Re: Tricks for ICE tables

If the problem is asking you to solve for the pH, pOH, or concentration of a reaction involving a weak acid or base, you use an ICE table because you can't assume 100% dissociation. You can tell if the reaction involves a weak acid by looking at the molecules or by the acidic constant if it is less ...
Tue Jan 15, 2019 12:25 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Activity
Replies: 2
Views: 97

### Activity

What is activity?
Wed Jan 09, 2019 6:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Stability and Equilibrium Reactions
Replies: 1
Views: 72

### Stability and Equilibrium Reactions

How do you tell if one equilibrium reaction is more stable than another?
Tue Jan 08, 2019 7:42 pm
Forum: Ideal Gases
Topic: Activity
Replies: 3
Views: 145

### Activity

What does $P^{\circ}$ mean in the equation for activity?
Mon Jan 07, 2019 2:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Equilibrium Concentrations
Replies: 3
Views: 108

### Calculating Equilibrium Concentrations

How do we calculate the equilibrium concentrations of the products and reactants? Will they be given?
Fri Dec 07, 2018 5:23 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Compound Formation
Replies: 1
Views: 46

### Coordination Compound Formation

Can someone explain to me how coordination compounds form, especially how transition metals are able to accept electron pairs from ligands?
Fri Dec 07, 2018 5:21 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Iron in Myoglobin
Replies: 2
Views: 61

### Iron in Myoglobin

Why can iron in myoglobin form 6 bonds?
Tue Dec 04, 2018 5:31 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Naming Acids
Replies: 1
Views: 85

### Naming Acids

Is there a method to naming acids, or do we just need to memorize them?
Thu Nov 29, 2018 11:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bond angle
Replies: 6
Views: 216

### Re: bond angle

Yes, the approximation of the bond angle is acceptable, so < 120 degrees works.
Thu Nov 29, 2018 11:28 am
Forum: Lewis Acids & Bases
Topic: HF
Replies: 5
Views: 223

### HF

Why is HF a weak acid?
Wed Nov 28, 2018 10:17 pm
Forum: Hybridization
Topic: Delocalized Pi Bonding
Replies: 3
Views: 122

### Delocalized Pi Bonding

Can someone explain what delocalized pi bonding is and when does it exist?
Tue Nov 20, 2018 12:12 am
Forum: Lewis Structures
Topic: Polar vs Nonpolar molecules
Replies: 7
Views: 376

### Re: Polar vs Nonpolar molecules

You check for electronegativity, dipole moments, and then molecular shape to determine is a molecule is polar or nonpolar.
Mon Nov 19, 2018 4:37 pm
Forum: Hybridization
Topic: Sigma and Pi Bonds [ENDORSED]
Replies: 12
Views: 462

### Re: Sigma and Pi Bonds[ENDORSED]

Also, sigma bonds are made from hybridized orbitals and pi bonds are made from unhybridized orbitals.
Mon Nov 19, 2018 4:31 pm
Forum: Hybridization
Topic: Hybridized vs. Unhybridized Orbitals
Replies: 4
Views: 1525

### Re: Hybridized vs. Unhybridized Orbitals

If this helps, a sigma bond is made up of hybridized orbitals and a pi bond is made up of unhybridized orbitals
Thu Nov 15, 2018 9:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Trigonal Planar
Replies: 5
Views: 165

### Re: Trigonal Planar

In the VSEPR Model, all bonds are treated as equivalent, so no, double bonds (or any type of bonds in general) are not significant to the structure. We only account for the regions of electron density.
Mon Nov 12, 2018 4:00 pm
Forum: Dipole Moments
Topic: Dipole Moments and Polar Molecules
Replies: 2
Views: 139

### Dipole Moments and Polar Molecules

How do you calculate for the dipole moment of a molecule and use it to determine whether a molecule is polar or nonpolar?
Mon Nov 12, 2018 1:08 pm
Forum: Lewis Structures
Topic: N2O Lewis Structure
Replies: 1
Views: 109

### N2O Lewis Structure

For N2O, why is nitrogen the central atom if oxygen has the lower ionization energy?
Fri Nov 09, 2018 1:21 am
Forum: Dipole Moments
Topic: London Forces
Replies: 2
Views: 145

### London Forces

Why do London forces exist?
Wed Nov 07, 2018 8:58 pm
Forum: Resonance Structures
Topic: Resonance Lewis Structures
Replies: 3
Views: 192

### Resonance Lewis Structures

Are resonance structures only in regards to bond location? Do they apply to the positions of lone pair electrons too?
Tue Nov 06, 2018 12:50 pm
Forum: Lewis Structures
Topic: Lewis Structure for NO2
Replies: 3
Views: 159

### Lewis Structure for NO2

If oxygen has a lower ionization energy than nitrogen, why is nitrogen the central atom in the NO2 Lewis Structure? Is it to maintain symmetry?
Fri Nov 02, 2018 1:55 pm
Forum: Properties of Electrons
Topic: De Broglie Formula vs. Speed of Light Formula
Replies: 5
Views: 408

### Re: De Broglie Formula vs. Speed of Light Formula

Thanks everyone! I realized that the question involves copper metal, which has resting mass, so we have to use the De Broglie Formula.
Fri Nov 02, 2018 10:22 am
Forum: Properties of Electrons
Topic: De Broglie Formula vs. Speed of Light Formula
Replies: 5
Views: 408

### Re: De Broglie Formula vs. Speed of Light Formula

In the case of Question 3C on Test 2, how do we know when to used the De Broglie equation then?
Fri Nov 02, 2018 2:56 am
Forum: Properties of Electrons
Topic: De Broglie Formula vs. Speed of Light Formula
Replies: 5
Views: 408

### De Broglie Formula vs. Speed of Light Formula

How do you know when to use the De Broglie formula versus the speed of light formula?
Wed Oct 31, 2018 9:21 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Oxidation Numbers
Replies: 3
Views: 214

### Oxidation Numbers

How do you know the oxidation number for an atom of an element?
Fri Oct 26, 2018 1:36 am
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 3
Views: 187

### Drawing Lewis Structures

When drawing a Lewis Structure, how do you know specifically where to bond the atoms? What are the steps to drawing accurate Lewis Structures of atoms bonded together?
Tue Oct 23, 2018 11:55 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty of an Electron's Velocity & Speed of Light
Replies: 4
Views: 271

### Uncertainty of an Electron's Velocity & Speed of Light

Why is the Incorrect Atomic Model disproved because the uncertainty in the velocity of the electron is greater than the speed of light? What is important about the speed of light that disproves this model?
Tue Oct 23, 2018 11:13 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Spectral Lines and Series
Replies: 3
Views: 182

### Spectral Lines and Series

Why are spectral lines important? Why are the Balmer and Lyman series significant? I know the Balmer series represents visible light, and the Lyman series represents UV light, but why is that important?
Wed Oct 17, 2018 4:56 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Number L [ENDORSED]
Replies: 3
Views: 207

### Quantum Number L[ENDORSED]

What does orbital angular momentum show us, and why is it important?
Wed Oct 17, 2018 4:51 pm
Forum: Quantum Numbers and The H-Atom
Topic: Principal Quantum Number (n)
Replies: 3
Views: 142

### Principal Quantum Number (n)

What does the principal quantum number (n) refer to? Does it refer to shell size? Could someone give their own explanation of how the quantum numbers n, l, ml, and ms relate to each other, and their purpose in the atomic structure?
Wed Oct 17, 2018 4:45 pm
Forum: Quantum Numbers and The H-Atom
Topic: Wavefunction of the Ground State of the Hydrogen Atom
Replies: 1
Views: 150

### Wavefunction of the Ground State of the Hydrogen Atom

In the wavefunction of the ground state of the hydrogen atom, where $\Psi$ (r, $\Theta, \Phi$) = Ne^(-r/a0), what does N represent? What purpose does N serve?
Wed Oct 10, 2018 10:22 pm
Forum: *Particle in a Box
Topic: Purpose of Particle in a Box
Replies: 2
Views: 559

### Purpose of Particle in a Box

What is the purpose of the particle in a box concept, and what does it tell us exactly?
Wed Oct 10, 2018 7:21 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Meaning of Quanta/Quantized
Replies: 2
Views: 96

### Meaning of Quanta/Quantized

Can someone explain what "quanta" and "quantized" means?
Mon Oct 08, 2018 1:05 pm
Forum: Limiting Reactant Calculations
Topic: Maximum Product Produced
Replies: 2
Views: 124

### Re: Maximum Product Produced

Additional Information: one mole of A is mixed with one mole of B. Update after asking a TA: Since the mole ratio between A and C is 2:3, that means 1 mole of A would yield 1.5 moles of C. The mole ratio between B and C is 1:3, which means 1 mole of B would yield 3 moles of C. Therefore, A is the li...
Fri Oct 05, 2018 11:23 am
Forum: Molarity, Solutions, Dilutions
Replies: 3
Views: 429

5.00 g of KMnO4 is dissolved in a 150.00 mL flask of water. If 20.00 mL of this solution is removed and placed in a new 2nd 250.00 mL flask and filled with water, what is the concentration of the solution in the 2nd flask? Molar Masses: K (39.10 g/mol), Mn (54.94 g/mol), O (16.00 g/mol) How do you s...
Fri Oct 05, 2018 10:07 am
Forum: Limiting Reactant Calculations
Topic: Maximum Product Produced
Replies: 2
Views: 124

### Maximum Product Produced

In the balanced equation 2A + 1B ---> 3C, how do you find the maximum product produced?

*This is under Question 30 in the Limiting Reactant Calculations Audio-Visual Focus Topics Post-Assessment.*
Fri Oct 05, 2018 10:05 am
Forum: Limiting Reactant Calculations
Topic: Compensating for Mole Ratios in Limiting Reactants
Replies: 3
Views: 158

### Compensating for Mole Ratios in Limiting Reactants

In the chemical reaction 4NH3(g) + 5O2(g) ---> 4NO(g) + 6H2O(g), how do you find the limiting reactant if 21.4 g NH3 is reacted with 42.5 g of O2? How do you compensate for the mole ratio when calculating?
Fri Oct 05, 2018 7:40 am
Forum: Limiting Reactant Calculations
Topic: Excess Reactant Calculation
Replies: 2
Views: 122

### Excess Reactant Calculation

What are the steps to finding the excess of a reactant in a chemical reaction?
Tue Oct 02, 2018 11:23 pm
Forum: Balancing Chemical Reactions
Topic: Mole Ratios & Stoichiometric Relations
Replies: 2
Views: 192

### Mole Ratios & Stoichiometric Relations

Do stoichiometric relations and mole ratios describe the same relationship between substances? What are stoichiometric relations used for? Is it just another way to express a mole ratio?
Mon Oct 01, 2018 7:25 pm
Forum: Balancing Chemical Reactions
Topic: Law of Conservation of Mass [ENDORSED]
Replies: 7
Views: 299

### Re: Law of Conservation of Mass[ENDORSED]

Yes, basically the total mass before a reaction is always equal to the total mass after. Also I liked this concept too: in chemical reactions, atoms are not created or destroyed; they are rearranged.