## Search found 61 matches

Sat Mar 16, 2019 11:42 am
Forum: First Order Reactions
Topic: Using Plots to determine order
Replies: 1
Views: 288

### Using Plots to determine order

If we were given a graph to determine the order of a reaction and the Y axis has the units ln(A) and the X axis has the units time but the slope is positive linear what does this tell us about the reaction? In other words if the slope does not match the normal graph for a first order reaction what c...
Sat Mar 16, 2019 11:37 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Combustion
Replies: 1
Views: 255

### Combustion

Why is combustion a spontaneous process? Wouldn't you have to put in energy (like a flame) for the combustion reaction to occur?
Sat Mar 16, 2019 11:35 am
Forum: General Rate Laws
Topic: exponential decay
Replies: 2
Views: 307

### exponential decay

Why do reactions slow as time goes on? Would a reaction still slow if we had excess reactants?
Sun Mar 10, 2019 5:22 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Chain Reaction
Replies: 1
Views: 86

### Chain Reaction

Can someone explain what a propagation step is in a chain reaction?
Sun Mar 10, 2019 5:14 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slowest step
Replies: 4
Views: 219

### Re: Slowest step

I read an example online that helped me understand the rate determining step: The rate determining step is like a funnel in which only so much substance can pass at a time. The reaction rate is limited by the width of the "funnel", not by the amount of substance being added to the funnel. ...
Sun Mar 10, 2019 5:06 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Steady State or Pre-Equilibrium approach
Replies: 1
Views: 88

### Re: Steady State or Pre-Equilibrium approach

I am not entirely sure if we need to know the steady state approach for the final but it wouldn't hurt to remember for the steady state approximation that the assumption is made that the concentrations of the intermediates remain low and do not change significantly in the course of the reaction. Thu...
Sat Mar 02, 2019 5:45 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Molecularity
Replies: 1
Views: 111

### Molecularity

How do you classify elementary reaction steps based on molecularity?
Sat Mar 02, 2019 5:43 pm
Forum: Second Order Reactions
Topic: Pseudo-first-order reaction
Replies: 4
Views: 187

### Pseudo-first-order reaction

What does it mean to turn a second order reaction into a pseudo-first-order reaction?
Sat Mar 02, 2019 5:29 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Order of a Reaction
Replies: 2
Views: 132

### Re: Order of a Reaction

It is important to know the order of a reaction to predict how a reaction will change over time. For example, if you know a reaction is first order then doubling the concentration of reactants will double the reaction rate.
Sun Feb 24, 2019 2:32 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Corrosion
Replies: 2
Views: 140

### Corrosion

Would we ever have to take corrosion into account when dealing with an oxidation half reaction?
Sun Feb 24, 2019 2:26 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Spontaneity in Cells
Replies: 2
Views: 128

### Spontaneity in Cells

Can you tell if a reaction is spontaneous based on the value of the standard cell potential?
Sun Feb 24, 2019 2:24 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 1
Views: 87

### Salt Bridge

In a galvanic cell what exactly is a salt bridge made of and how does the salt bridge function?
Sun Feb 17, 2019 6:20 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Specific Heat capacity
Replies: 2
Views: 181

### Re: Specific Heat capacity

Specific heat capacity and molar heat capacity are both intensive because both equations take into account the amount of substance (in either grams or moles). Therefore it does not matter how much of the substance you have, the ability to absorb heat is still the same.
Sun Feb 17, 2019 6:17 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: q=0
Replies: 4
Views: 232

### q=0

If a system has adiabatic walls can we assume q=0 and delta U=w?
Sun Feb 17, 2019 6:07 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Delta H given
Replies: 2
Views: 331

### Delta H given

Why is it that when delta H is given in a thermodynamics question that this implies constant pressure?
Sun Feb 10, 2019 4:06 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Thermal Disorder
Replies: 1
Views: 103

### Thermal Disorder

How can we apply information about thermal disorder in the problems we do in the homework or midterm?
Sun Feb 10, 2019 4:04 pm
Forum: Phase Changes & Related Calculations
Topic: Trouton's Rule
Replies: 2
Views: 138

### Trouton's Rule

Can someone further explain Trouton's rule and how it relates to vaporization?
Sun Feb 10, 2019 4:02 pm
Forum: Calculating Work of Expansion
Topic: Work on System vs Surrondings
Replies: 3
Views: 163

### Work on System vs Surrondings

How does work change depending if the work is done on the system or the surroundings?
Wed Jan 30, 2019 10:24 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpy not given
Replies: 3
Views: 95

### Bond enthalpy not given

If the bond enthalpy is not given how would we calculate the reaction enthalpy?
Wed Jan 30, 2019 10:16 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Most stable form enthalpy
Replies: 3
Views: 216

### Most stable form enthalpy

Why is it that an element in its lost stable form has ethalpy of formation equal to zero?
Wed Jan 30, 2019 10:15 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard State
Replies: 3
Views: 137

### Standard State

Why must our gas or solution be put into standard state? (1 atm or 1M)
Sun Jan 27, 2019 4:21 pm
Forum: Phase Changes & Related Calculations
Topic: reversible/irreversible
Replies: 8
Views: 264

### Re: reversible/irreversible

In terms of thermodynamics a reversible reaction has no change in entropy, so no extra energy is needed to reverse the reaction. Irreversible reactions on the other hand cause an entropy increase to reverse the reaction.
Sun Jan 27, 2019 4:11 pm
Forum: Phase Changes & Related Calculations
Topic: Relationship between heat and work
Replies: 2
Views: 108

### Re: Relationship between heat and work

Another way to relate heat and work is with the equation U= q + w. U is the change in internal energy, q is heat, and w is work.
Sun Jan 27, 2019 4:08 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Replies: 4
Views: 184

I read in the textbook about adiabatic and diathermic walls, how would we use this information in our calculations?
Wed Jan 16, 2019 4:01 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Inert Gases
Replies: 5
Views: 219

### Inert Gases

Why does adding an inert gas to a reaction have no effect on equilibrium composition?
Wed Jan 16, 2019 3:58 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pure Solids and Pure Liquids
Replies: 4
Views: 210

### Pure Solids and Pure Liquids

Is equilibrium affected by addition/removal of a pure solid or pure liquid?
Wed Jan 16, 2019 3:55 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature and Equilibrium
Replies: 3
Views: 146

### Temperature and Equilibrium

Why does increasing the temperature of an endothermic reaction shift the reaction towards products and why does increasing the temperature of an exothermic reaction shift the reaction towards reactants?
Sun Jan 13, 2019 4:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Criteria
Replies: 4
Views: 191

### Equilibrium Criteria

How do you know if a reaction system is at equilibrium?
Sun Jan 13, 2019 4:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: converting between partial pressure and concentration
Replies: 2
Views: 1837

### Re: converting between partial pressure and concentration

The main use of the ideal gas law, PV=nRT, for us is to convert between Kc and Kp (concentration and partial pressure). You can think of the ideal gas equation as Kp=Kc(RT)^(n). In this case n=(c+d)-(a+b) according to the reaction form aA+bB=cC+dD.
Sun Jan 13, 2019 4:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: solids and liquids
Replies: 5
Views: 225

### Re: solids and liquids

Pure liquids and solids have definite molar concentrations. Gases and aqueous solutions have variable molar concentrations because there is a certain amount of moles of a substance in a certain volume, hence the molarity= moles/Liters. Therefore when pure solids and liquids are involved in a reactio...
Sun Jan 13, 2019 4:11 pm
Forum: Ideal Gases
Topic: When to Use PV=nRT
Replies: 8
Views: 564

### Re: When to Use PV=nRT

The main use of the ideal gas law, PV=nRT, for us is to convert between Kc and Kp (concentration and partial pressure). You can think of the ideal gas equation as Kp=Kc(RT)^(n). In this case n=(c+d)-(a+b) according to the reaction form aA+bB=cC+dD.
Fri Dec 07, 2018 9:03 pm
Forum: Naming
Topic: Naming Coordinate Compounds
Replies: 3
Views: 202

### Re: Naming Coordinate Compounds

A couple things that could help you name coordination compounds is to remember to first name the cation then the anion. Also, remember to name the ligands before naming the central metal ion. Furthermore, for anions, the central metal ion has a special name (for example iron would be called ferrate ...
Fri Dec 07, 2018 8:59 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Iron in Myoglobin
Replies: 2
Views: 62

### Re: Iron in Myoglobin

Iron can form six bonds because it is one of the atoms that can form an expanded octet. Iron can have an expanded octet because electrons can go into the d-orbital found in the third principal energy level.
Fri Dec 07, 2018 8:55 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Compound Formation
Replies: 1
Views: 47

### Re: Coordination Compound Formation

Coordination compounds form out of a Lewis acid-base reaction in which neutral or anion molecules bond to a central metal ion. The bond formed is a coordinate covalent bond between the central metal ion and the ligands.
Sun Dec 02, 2018 4:34 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular shape in relation to polarity and boiling point
Replies: 5
Views: 710

### Molecular shape in relation to polarity and boiling point

Once you find the shape of a compound and determine if the compound is polar or non-polar how does this affect our analysis of the compound's boiling point. In other words, how do shape and polarity play into a compounds boiling point?
Sun Dec 02, 2018 4:28 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Types of intramolecular forces
Replies: 4
Views: 220

### Re: Types of intramolecular forces

To determine the forces present in the molecule it is easiest to first draw out the Lewis structure. First look for ionic forces, look for an interaction between a cation and an anion (Such as Na+ and Cl-). Then, you can look for hydrogen bonding. Hydrogen bonding occurs when a hydrogen is bonded to...
Sun Dec 02, 2018 4:17 pm
Forum: Hybridization
Topic: Hybridization Question
Replies: 1
Views: 82

### Hybridization Question

Can hybridization go past d2sp3? For example, how could you write the hybridization if there were 7 orbitals involved?
Sun Nov 25, 2018 9:07 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Orbital Overlap
Replies: 2
Views: 161

### Orbital Overlap

Can someone explain orbital overlap and the role that orbital overlap plays on bond strength?
Sun Nov 25, 2018 9:04 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: sigma and pi bonds
Replies: 4
Views: 207

### sigma and pi bonds

Why can sigma bonds rotate, but not pi bonds?
Sun Nov 25, 2018 9:01 pm
Forum: Hybridization
Topic: promoted hybridization
Replies: 4
Views: 187

### promoted hybridization

What does it mean when an electron is promoted? Also, what effect does electron promotion play on the overall molecule or atom?
Sat Nov 17, 2018 7:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity
Replies: 3
Views: 175

### Polarity

What are the characteristics that make a compound polar or non-polar?
Sat Nov 17, 2018 7:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Drawings of Molecular Shape
Replies: 2
Views: 102

### Re: Drawings of Molecular Shape

Drawing the molecular shape in three dimensions is useful for understanding and determining the shape. Use a dashed triangle for elements going away from us and use a solid triangle for elements coming towards us.
Sat Nov 17, 2018 7:21 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Electrostatic potential surface
Replies: 1
Views: 118

### Electrostatic potential surface

How does a density isosurface relate to the electrostatic potential surface? Also, how would you analyze an electrostatic potential surface?
Sun Nov 11, 2018 3:54 pm
Forum: Octet Exceptions
Topic: Number of electrons in relation to Octet
Replies: 3
Views: 181

### Number of electrons in relation to Octet

I read in the book that "a molecule might have an odd number of electrons, so octet formation is numerically impossible". Would it be possible for the molecule to form an octet by gaining or losing an electron? I don't understand why the molecule would not be able to form an octet.
Sun Nov 11, 2018 3:48 pm
Forum: Lewis Structures
Topic: Hypervalent compound vs variable covalence
Replies: 2
Views: 177

### Hypervalent compound vs variable covalence

Based on what I read in the textbook hypervalent compounds and variable covalence is basically the same. Is there a difference between the two terms?
Sun Nov 11, 2018 3:41 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 3
Views: 155

### Re: Resonance Structures

In resonance structures, the bond is shifted to different configurations, and this can change the lone pairs of the surrounding atoms. For example, carbonate has a resonance structure where one of the outer oxygen molecules has a double bond, while the other two oxygens have single bonds. This doubl...
Sun Nov 04, 2018 12:14 pm
Forum: Bond Lengths & Energies
Topic: Bond order
Replies: 4
Views: 194

### Bond order

I understand single bonds, double bonds, and triple bonds, but I do not understand what the bond order tells us. Can someone explain bond order and give an example?
Sun Nov 04, 2018 12:10 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Finding the lowest energy structure
Replies: 5
Views: 282

### Re: Finding the lowest energy structure

The formal charge gives an indication of the extent to which atoms have gained or lost electrons in the process of covalent bond formation. Atom arrangements and Lewis structures with the lowest formal charges are likely to have the lowest energy.
Sun Nov 04, 2018 12:01 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 11
Views: 396

### Lewis Structures

How do we know which atom to put in the center of a Lewis structure?
Sun Oct 28, 2018 8:51 pm
Forum: Octet Exceptions
Topic: Expanded Valence Shells
Replies: 3
Views: 177

### Expanded Valence Shells

Are compounds with an expanded valence shell considered stable? Also, how would an expanded valence shell occur?
Sun Oct 28, 2018 8:48 pm
Forum: Lewis Structures
Topic: Delocalized Electrons
Replies: 5
Views: 186

### Delocalized Electrons

I don't understand how delocalized electrons work. How are the electrons distributed over several atoms?
Sun Oct 28, 2018 8:42 pm
Forum: Ionic & Covalent Bonds
Topic: Variable Valence
Replies: 2
Views: 50

### Variable Valence

Can someone give me an example of a situation where an element displays variable valence?
Sun Oct 21, 2018 8:23 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Effective Nuclear Charge
Replies: 1
Views: 95

### Effective Nuclear Charge

How does shielding from electrons in a multi electron atom effect the nuclear charge?
Sun Oct 21, 2018 8:20 pm
Forum: Quantum Numbers and The H-Atom
Topic: spin magnetic quantum number
Replies: 3
Views: 85

### spin magnetic quantum number

What is meant by a positive or negative spin of an electron? Also, why do electron spins have the values of +1/2 and -1/2?
Sun Oct 21, 2018 8:16 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Ionization
Replies: 2
Views: 87

### Ionization

What happens to the extra or left over energy when an election is ionized from an atom?
Sun Oct 14, 2018 10:36 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Replies: 3
Views: 118

What is the difference between an atomic radius and a covalent radius?
Sun Oct 14, 2018 10:28 pm
Forum: Properties of Light
Topic: Wavelength and Energy
Replies: 2
Views: 133

### Wavelength and Energy

Why do shorter wavelengths have higher energy light and longer wavelengths have lower energy light?
Sun Oct 14, 2018 10:22 pm
Forum: Properties of Light
Topic: Light Intensity
Replies: 3
Views: 138

### Light Intensity

What is the significance and use of light intensity when solving electromagnetic radiation questions?
Sun Oct 07, 2018 6:24 pm
Forum: Limiting Reactant Calculations
Topic: Theoretical Yield
Replies: 7
Views: 419

### Theoretical Yield

Why is the theoretical yield always larger than the actual yield?
Sun Oct 07, 2018 6:12 pm
Forum: Limiting Reactant Calculations
Topic: Reactants and Reagents
Replies: 4
Views: 226

### Reactants and Reagents

Are the terms reactants and reagents interchangeable? I know that reactants are the starting materials that are used up in a chemical reaction, but I am still slightly confused by the term reagent.
Sun Oct 07, 2018 5:48 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Atomic Weight vs Molecular Weight
Replies: 2
Views: 133

### Atomic Weight vs Molecular Weight

What is the difference between atomic weight and molecular weight?