## Search found 68 matches

Fri Mar 15, 2019 11:36 pm
Forum: Reaction Mechanisms, Reaction Profiles
Replies: 2
Views: 122

Is steady state equilibrium going to be on the final?
Wed Mar 13, 2019 2:22 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity of Water
Replies: 6
Views: 415

### Heat Capacity of Water

The heat capacity of water is 4.184 J • C^-1 g^-1 or 4.184 J • K^-1 g^-1. Why is the heat capacity of water per celsius and per Kelvin the same? I thought that the conversion rate between Celsius and Kelvin is +273 K.
Sun Mar 10, 2019 11:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka2 in Acids
Replies: 2
Views: 131

### Ka2 in Acids

When is Ka2 considered negligible when performing calculations with polyprotic acids?
Sun Mar 10, 2019 12:22 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Combining K Values in 11.39
Replies: 1
Views: 123

### Combining K Values in 11.39

Use the information in Table 11.2 to determine the value of K at 300 K for the reaction 2 BrCl(g) + H2(g) <-> Br2(g) + 2 HCl(g). When combining K values, why must you multiply?
Sat Mar 09, 2019 10:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Initial Concentration and Equilibrium Concentration
Replies: 3
Views: 193

### Initial Concentration and Equilibrium Concentration

"If one starts with higher concentrations of reactants, the equilibrium concentrations of the products will be larger." Why is this statement true? Can there be a case where the equilibrium concentration of the product is smaller than the initial concentration of the reactants?
Sun Mar 03, 2019 11:06 pm
Forum: General Rate Laws
Topic: Difference between First Order Reactions and Second Order Reactions
Replies: 1
Views: 112

### Difference between First Order Reactions and Second Order Reactions

What is the difference between first-order reactions and second-order reactions? How does that change the value of n?
Wed Feb 27, 2019 5:04 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Half Reactions [ENDORSED]
Replies: 1
Views: 115

### Half Reactions[ENDORSED]

When balancing the half reaction in 14.11 O2 > OH-, how do you come to the conclusion that the reaction is occurring in a basic solution when not given that information?
Wed Feb 27, 2019 3:07 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 4
Views: 190

### Re: Cell Diagrams

Does the order of the species inside of the anode and cathode matter? For example, is the species before oxidation placed first and the species after it has been oxidized placed next?
Wed Feb 27, 2019 2:42 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 4
Views: 190

### Cell Diagrams

Does the order of the species in the cell diagrams matter? Besides the fact that the right side is the cathode and the left side is the anode.
Sun Feb 24, 2019 9:59 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Entropy and Reduction in moles of Gas
Replies: 2
Views: 294

### Entropy and Reduction in moles of Gas

Why is standard residual entropy negative or a smaller number than standard molar entropy when the number of moles of gas is reduced?
Sun Feb 24, 2019 9:54 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Difference between Molar Entropy and Standard Residual Entropy
Replies: 3
Views: 320

### Difference between Molar Entropy and Standard Residual Entropy

What is the difference between Molar Entropy and Standard Residual Entropy?
Sun Feb 24, 2019 4:39 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy
Replies: 2
Views: 157

### Gibbs Free Energy

What is the difference between Gibbs free energy of formation and Gibbs free energy of reaction conceptually? Does the way in which they are calculated differ?
Wed Feb 20, 2019 2:44 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 3
Views: 138

### Salt Bridge

What is the function of a salt bridge in a galvanic cell? How would the galvanic cell react without a salt bridge?
Tue Feb 19, 2019 10:20 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy Measurement
Replies: 5
Views: 216

### Re: Gibbs Free Energy Measurement

How do you measure Gibbs Free Energy experimentally? (Without the use of the equation)
Tue Feb 19, 2019 10:19 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity
Replies: 3
Views: 366

### Re: Spontaneity

In order for a spontaneous reaction to occur, delta G must be negative. For a spontaneous reaction to occur, delta H must be negative and delta S must be positive. For a nonspontaneous reaction to occur, delta H must be positive and delta S must be negative.
Tue Feb 19, 2019 10:13 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G
Replies: 3
Views: 153

### Delta G

Dr. Lavelle mentioned that a positive delta H (endothermic reaction) is, the more that it does not favor the forward process in the equation (delta g = delta h - temperature x delta s). Why does a positive delta H not favor the forward process? I thought that endothermic reactions do favor forward r...
Tue Feb 19, 2019 10:08 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy Measurement
Replies: 5
Views: 216

### Gibbs Free Energy Measurement

If Gibbs Free Energy (Delta G) is not measured directly like enthalpy of formation (Delta H), how is the Delta G of a reaction measured experimentally?
Sun Feb 10, 2019 9:02 pm
Forum: Phase Changes & Related Calculations
Topic: Celsius and Kelvin
Replies: 6
Views: 245

### Celsius and Kelvin

In what instances do we need to convert Celsius to Kelvin when calculating heat released (q)? In 8.19, Celsius is not converted into Kelvin.
Sat Feb 09, 2019 4:19 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.51 The enthalpy formation of trinitrotoluene
Replies: 1
Views: 191

### 8.51 The enthalpy formation of trinitrotoluene

8.51 The enthalpy of formation of trinitrotoluene (TNT) is -67 kJ·mol^-1, and the density of TNT is 1.65 g·cm^-3. In principle, it could be used as a rocket fuel, with the gases resulting from its decomposition streaming out of the rocket to give the required thrust. In practice, of course, it wo...
Fri Feb 08, 2019 10:28 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Negative
Replies: 4
Views: 281

### Re: Negative

The first law of thermodynamics states that energy is neither created nor destroyed, therefore the overall amount of heat (q) needs to be the same. system + surroundings = universe In heat transfer, if one substance X is losing heat to another substance Y, then substance Y must be gaining the heat ...
Fri Feb 08, 2019 7:34 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Negative
Replies: 4
Views: 281

### Negative

When performing heat transfer problems, why is heat that is lost a positive q value and why is heat that is gained a negative q value?
Mon Feb 04, 2019 1:18 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Combustion of Glucose
Replies: 2
Views: 158

### Combustion of Glucose

In the example where Dr. Lavelle demonstrated the combustion of glucose, how can we assume that the pressure is constant?
Mon Feb 04, 2019 1:16 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work
Replies: 6
Views: 278

### Work

How can we determine whether the work is performed by or on the system? What makes work positive or negative in terms of the system?
Fri Feb 01, 2019 2:10 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Analogy of Boulder
Replies: 5
Views: 291

### Analogy of Boulder

What was Dr.Lavelle referring to with the analogy of the boulder? The boulder is able to go down a hill without work, but for the boulder to go up a hill work is required. Can someone explain this in further detail?
Sun Jan 27, 2019 7:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5%
Replies: 10
Views: 413

### Re: 5%

The 5% rule allows one to ignore the x in the denominator if the equilibrium constant is less than 10^-3 when performing ICE table calculations. The change in concentration (x) must be less than or equal to 5% of the initial concentration. If the change in concentration (x) is greater than 5%, then ...
Sun Jan 27, 2019 7:49 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bonds Broken
Replies: 1
Views: 90

### Bonds Broken

How do we determine which bonds are broken and formed using bond enthalpies?
Wed Jan 23, 2019 10:04 pm
Forum: Polyprotic Acids & Bases
Topic: Question 12.79 (Sixth Edition)
Replies: 2
Views: 282

### Re: Question 12.79 (Sixth Edition)

H2SO4 is a strong acid and is fully ionized. Therefore, if the concentration of H2SO4 is 0.15 M, then the concentration of HSO4- and H3O+ would both have a concentration of 0.15 M.
Wed Jan 23, 2019 10:02 pm
Forum: Polyprotic Acids & Bases
Topic: Ignoring Deprotonations
Replies: 1
Views: 302

### Ignoring Deprotonations

While doing polyprotic acids and base calculations, what approximation justifies ignoring the second deprotonations?
Sat Jan 19, 2019 11:40 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Change in Pressure
Replies: 2
Views: 178

### Change in Pressure

If volume (V) decreases and pressure (P) increases and there are more moles of gas on the left, why does the reaction shift to the right? If there are more moles of gas on the right, why does the reaction shift to the left?
Sat Jan 19, 2019 6:47 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Replies: 4
Views: 172

Introducing an inert gas in a chemical equilibrium will change the volume and the pressure of the vessel that the reactants and products occupy. However, the inert gas will not change the concentration/partial pressure of the reactants and products and therefore will not affect the chemical equilibr...
Sat Jan 19, 2019 6:39 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: when is x negligible
Replies: 7
Views: 1800

### Re: when is x negligible

X is negligible when the equilibrium constant/acid dissociation constant (Ka)/base dissociation (Kb) constant is smaller than 10^-3. Also, as repeated above, X is negligible when it is less than 5% of the initial concentration.
Sat Jan 19, 2019 6:33 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Direction of an Acid/Base Reaction
Replies: 2
Views: 350

### Direction of an Acid/Base Reaction

How can we determine whether an acid/base reaction will favor the forward reaction or the reverse reaction? Why do acids favor forward reactions, while bases favor reverse reactions?
Mon Jan 14, 2019 1:05 am
Forum: Ideal Gases
Topic: Reducing Volume
Replies: 3
Views: 181

### Reducing Volume

What is the effect of adding an inert gas to a system at equilibrium compared to using a piston to reduce the volume of the gases at equilibrium?
Mon Jan 14, 2019 1:00 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pure Liquids and Pure Solids
Replies: 5
Views: 1772

### Pure Liquids and Pure Solids

Pure liquids and pure solids are able to react in chemical reactions. Therefore, I do not completely understand the reason why pure liquids and pure solids are not contained in the equilibrium constant. Can someone explain this to me?
Mon Jan 14, 2019 12:57 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Change in Concentration
Replies: 2
Views: 81

### Change in Concentration

Why does a change in concentration of reactants or products not affect the equilibrium constant at a certain temperature?
Sun Dec 09, 2018 1:07 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Degeneracy of the s orbital [ENDORSED]
Replies: 1
Views: 414

### Degeneracy of the s orbital[ENDORSED]

Does the s orbital have any degeneracies? The internet says that it does not, but I have heard that it has a degeneracy as one. Degeneracy is defined as orbitals with the same energy. However, the s orbital does not have another orbital with the same energy.
Sun Dec 09, 2018 12:00 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Difference between Tetrahedral and Square Planar
Replies: 2
Views: 680

### Difference between Tetrahedral and Square Planar

How do we tell the difference if a coordination compound is square planar or tetrahedral? Does the molecular shape of tetrahedral change the number of bonding sites compared to square planar?
Sat Dec 08, 2018 11:58 pm
Forum: Naming
Topic: Coordination Compound Charges
Replies: 1
Views: 98

### Coordination Compound Charges

If the total charge of a coordination complex is negative, then do we have to add a negative charge outside of the brackets?
Fri Dec 07, 2018 2:16 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Boiling Point
Replies: 6
Views: 2029

### Boiling Point

How do you determine which compound has the higher boiling point if they both have similar intermolecular forces? For example, H2S and H2Se.
Fri Nov 30, 2018 10:36 pm
Forum: Resonance Structures
Topic: Resonance
Replies: 4
Views: 316

### Resonance

How do you determine which structure is the most stable? For example, why does the resonance structure of SO4^2- prefer to form a two double bond with two oxygen instead of forming a double bond with one sulfur and one oxygen? Sulfur and Oxygen both have the same amount of valence electrons.
Fri Nov 30, 2018 10:20 pm
Forum: Sigma & Pi Bonds
Topic: Strength of Sigma and Pi Bonds
Replies: 5
Views: 677

### Strength of Sigma and Pi Bonds

Is there a reason why sigma bonds are stronger than pi bonds?
Fri Nov 30, 2018 10:15 pm
Forum: Sigma & Pi Bonds
Topic: Number of Sigma and Pi Bonds
Replies: 6
Views: 547

### Number of Sigma and Pi Bonds

Why does only one sigma bond form between two atoms? Why can multiple pi bonds form between two atoms?
Fri Nov 23, 2018 9:55 pm
Forum: Hybridization
Topic: Number of Hybrid Orbitals
Replies: 3
Views: 141

### Re: Number of Hybrid Orbitals

Hybridization is defined as the combination of atomic orbitals to form new hybrid orbital that explain the structure of the molecules in the VSEPR model. The number of hybrid orbitals is dependent on the number of regions of electron densities around the atoms.
Fri Nov 23, 2018 9:49 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Degeneracy
Replies: 4
Views: 2550

### Re: Degeneracy

Degeneracy is defined as having two or more quantum states in a quantized energy level. For example, the p orbital has three degeneracies because it has three quantum states (or three orbitals of the same energy). The d orbital has five degeneracies because it has five quantum states (or five orbita...
Fri Nov 23, 2018 9:43 pm
Forum: Balancing Chemical Reactions
Topic: Why do we balance chemical equations?
Replies: 13
Views: 1364

### Re: Why do we balance chemical equations?

We balance chemical equations due to the law of conservation of mass, which states that mass can neither be created or destroyed. Therefore, in a chemical reaction, the total mass of the reactants must be equal to the total mass of the products. Balancing equations accounts for the total mass of the...
Fri Nov 16, 2018 9:26 pm
Forum: Dipole Moments
Topic: Vectors for Dipole Moments
Replies: 1
Views: 103

### Vectors for Dipole Moments

When drawing the Lewis structure of a compound, how do we determine the vectors for each atom? From the vectors, how do we deduce that a molecule is polar or nonpolar?
Fri Nov 16, 2018 9:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Planar vs Pyramidal
Replies: 5
Views: 239

### Re: Planar vs Pyramidal

When there are three electron densities around the central atom, the electron arrangement is trigonal planar. Since there are no lone pairs, the molecular shape is also trigonal planar. When there are four electron densities around the central atom, the electron arrangement is tetrahedral. However, ...
Fri Nov 16, 2018 9:05 pm
Forum: Sigma & Pi Bonds
Topic: Double Bonds and Triple Bonds
Replies: 2
Views: 202

### Double Bonds and Triple Bonds

According to the information we learned in lecture, double bonds consist of one sigma bond and one pi bond and that triple bonds consist of one sigma bond and two pi bonds. Why can't double bonds and triple bonds consist of solely sigma bonds or solely pi bonds?
Fri Nov 09, 2018 7:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs
Replies: 4
Views: 221

### Lone Pairs

How does the presence of lone pairs in an atom affect the deflection angle of an atom?
Fri Nov 09, 2018 6:54 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Placement of the 3d orbital
Replies: 1
Views: 184

### Placement of the 3d orbital

Why is the 3d orbital placed before the 4s orbital? When viewing ptable.com (Dynamic Periodic Table), the 3d orbital is placed after the 4s orbital.
Fri Nov 09, 2018 6:48 pm
Forum: Dipole Moments
Topic: Hydrogen Bonds and Melting Points
Replies: 1
Views: 61

### Hydrogen Bonds and Melting Points

How do hydrogen bonds affect the boiling and melting point of a substance? What accounts for the difference in the boiling and melting point in H2O and H2S? I was confused about the difference in the boiling and melting point of the H2O and H2S during lecture because they both have the same amount o...
Fri Nov 02, 2018 9:36 pm
Forum: Properties of Electrons
Topic: Isoelectronicity
Replies: 3
Views: 514

### Isoelectronicity

What is the isoelectronicity? How do we find if one element is isoelectronic to another element?
Fri Nov 02, 2018 9:33 pm
Forum: Trends in The Periodic Table
Replies: 2
Views: 726

Fri Nov 02, 2018 9:32 pm
Forum: Trends in The Periodic Table
Replies: 2
Views: 131

Arrange S^-2, Cl-1, P-3 in order of increasing ionic radius. The correct order according to the textbook of increasing ionic radius is Cl^1-,S^2-,P^3-. Why is it in that order? My thought process is the same as atomic radius: as you add valence electrons, the ionic radius decreases. Using that proce...
Sun Oct 28, 2018 3:21 pm
Forum: *Particle in a Box
Topic: Particle in a box
Replies: 2
Views: 452

### Re: Particle in a box

In the particle in a box model, a particle is confined by barriers. These barriers cannot be penetrated by the particle. The particle is free to move at any speed and it can be in any position within the barriers of the box. At certain positions known as spatial nodes, the particle may not be detect...
Sun Oct 28, 2018 2:55 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen Bonds
Replies: 5
Views: 231

### Hydrogen Bonds

Why are hydrogen bonds weaker than ionic and covalent bonds?
Sun Oct 28, 2018 2:48 pm
Forum: Properties of Electrons
Topic: Effective Nuclear Charge
Replies: 2
Views: 213

### Effective Nuclear Charge

What is the effective nuclear charge? How does it affect electrons?
Fri Oct 19, 2018 10:04 pm
Forum: DeBroglie Equation
Topic: Application to Classical Objects
Replies: 2
Views: 96

### Application to Classical Objects

Can someone please explain how the DeBroglie Equation can be applied to classical objects (such as a baseball or a table)? Do classical objects have a wavelength?
Fri Oct 19, 2018 9:54 pm
Forum: Properties of Light
Topic: Equations
Replies: 7
Views: 205

### Re: Equations

RoopshaChatterjee 1G wrote:With all the equations in this section how do we know when a v is frequency and when it represents velocity?

In response to your question, there are different notations for frequency and velocity. Frequency is denoted with the Greek letter nu, while velocity is denoted with the letter v.
Fri Oct 19, 2018 9:42 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Replies: 1
Views: 247

### Re: Angular vs. Radial Nodes

Radial nodes are spherical regions, while angular nodes are flat planes (or cones). The probability of finding an electron in both of these regions is zero. Radial nodes have fixed radii, while angular nodes have fixed angles. For radial nodes, the principal quantum number determines the number in a...
Fri Oct 12, 2018 12:30 am
Forum: Properties of Electrons
Topic: Electron Energy Levels
Replies: 2
Views: 150

### Electron Energy Levels

Why are electron energy levels quantized? Why can't electrons exist in between quantized electron energy levels?
Fri Oct 12, 2018 12:22 am
Forum: Properties of Light
Topic: Threshold Energies
Replies: 5
Views: 164

### Threshold Energies

Why do different metals have different threshold energies?
Fri Oct 12, 2018 12:09 am
Forum: Properties of Light
Topic: Threshold Energy
Replies: 11
Views: 346

### Re: Threshold Energy

Threshold energy is the amount of energy required to remove a single electron from a metal surface. Different metals have different threshold energies due to the difference in electronegativity. Each photon must have enough energy to remove an electron regardless of the amount of photons present in ...
Fri Oct 05, 2018 11:36 am
Forum: SI Units, Unit Conversions
Topic: E23 (6th Edition)
Replies: 4
Views: 145

### Re: E23 (6th Edition)

The use of Avogadro's number is only necessary when the problem is asking for the atoms of a molecule or formula units of a compound. In this case, the question is asking you to find the moles of each unit; therefore, it is unnecessary to multiply by Avogadro's number. Simply, convert the mass of th...
Thu Oct 04, 2018 11:28 pm
Forum: SI Units, Unit Conversions
Topic: mol vs. mmol
Replies: 12
Views: 921

### Re: mol vs. mmol

The prefix "milli-" denotes multiplication by 10^-3. One millimole is equivalent to 10^-3 moles.
Thu Oct 04, 2018 11:18 pm
Forum: SI Units, Unit Conversions
Topic: Hecto as SI Unit [ENDORSED]
Replies: 4
Views: 123

### Re: Hecto as SI Unit[ENDORSED]

The hectometer is an SI unit, however it is rarely used.
Thu Oct 04, 2018 11:15 pm
Forum: SI Units, Unit Conversions
Topic: Exercise E1 (Question regarding unit conversions) [ENDORSED]
Replies: 3
Views: 119

### Re: Exercise E1 (Question regarding unit conversions)[ENDORSED]

The Student Solutions Manuals shows that the answer (1.73 x 10^26 picometers) must be converted to meters and then kilometers. However, the Student Solutions Manual does not state why. Will we lose points on the test if we convert an answer to the wrong units?
Thu Oct 04, 2018 11:09 pm
Forum: SI Units, Unit Conversions
Topic: Exercise E1 (Question regarding unit conversions) [ENDORSED]
Replies: 3
Views: 119

### Exercise E1 (Question regarding unit conversions)[ENDORSED]

In exercise E.1, I multiplied 6.022 x !0^23 to 288 picometer and received a final answer of 1.73 x 10^26 picometers. Is it necessary to change the final answer from picometers to meters or kilometers? If so, why?