Search found 64 matches
- Thu Mar 14, 2019 12:08 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Reduction of Oxygen half reaction?
- Replies: 1
- Views: 228
Re: Reduction of Oxygen half reaction?
For the anode (left half of the cell diagram), oxygen is oxidized. So H20 -> H+ + e- + O2. For the cathode (right half of the cell diagram), oxygen is reduced. So 02 + e- -> OH-.+ H20.
- Thu Mar 14, 2019 12:03 am
- Forum: General Rate Laws
- Topic: Problem 7A. 3 7th edition
- Replies: 3
- Views: 456
Re: Problem 7A. 3 7th edition
The unique reaction rate is equal to -1/a of the reaction rate of O2. So, given the unique reaction rate = 0.44, then 0.44 = -1/3 (rate of O2). So you would multiply both sides by 3, which gives you 1.3 for the rate of O2.
- Wed Mar 13, 2019 11:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium constants with partial pressures and concentrations?
- Replies: 2
- Views: 282
Re: Equilibrium constants with partial pressures and concentrations?
The equilibrium constant includes both gases and aqueous species.
- Wed Mar 13, 2019 11:58 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Thermodynamics learning outcome
- Replies: 1
- Views: 380
Re: Thermodynamics learning outcome
This is refereeing to delta S surrounding is equal to negative delta H divided by temperature.
- Wed Mar 13, 2019 11:57 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Calomel Electrode
- Replies: 1
- Views: 201
Re: Calomel Electrode
There were a few homework problems about this topic, so it could be tested on.
- Wed Mar 13, 2019 11:55 pm
- Forum: General Rate Laws
- Topic: reaction order and reaction quotient
- Replies: 1
- Views: 217
Re: reaction order and reaction quotient
When determining the rate of a reaction, the concentration of the reactants is raised to the power of the reaction order.
- Wed Mar 13, 2019 11:49 pm
- Forum: General Rate Laws
- Topic: 7th edition 7B.17
- Replies: 1
- Views: 279
Re: 7th edition 7B.17
B forms twice as fast as A is depleted. For 0.19M of B to form, 1/2 of that is lost form A. So the concentration of A is 0.15M - 1/2(0.19M).
- Wed Mar 13, 2019 11:44 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Bomb calorimeter
- Replies: 6
- Views: 868
Re: Bomb calorimeter
In a regular calorimeter, the reaction takes place in the water. In a bomb calorimeter, the reaction takes place in a sealed metal container.
- Wed Mar 13, 2019 11:38 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: ΔG equation
- Replies: 1
- Views: 220
- Wed Mar 13, 2019 11:30 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Concentration cell
- Replies: 1
- Views: 244
Re: Concentration cell
Due to the Nernst equation, Ecell > 0 when Q is < 0, so the concentration of the cathode will be greater than the concentration of the anode because Q = concentration of left (anode) divided by concentration of right (cathode).
- Wed Mar 13, 2019 11:27 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: exercise 15.17
- Replies: 1
- Views: 461
Re: exercise 15.17
The reaction rate is the change in concentration of one of the reactants or products at a selected stage of the reaction divided by the time interval over which the change takes place. The unique average rate of the reaction is the average rate divided by the stoichiometric coefficients, so the uniq...
- Wed Mar 13, 2019 11:20 pm
- Forum: Balancing Redox Reactions
- Topic: HW problem
- Replies: 2
- Views: 310
Re: HW problem
C is oxidized because its oxidation state in C2H5OH is -2 and its oxidation state in C2H4) is -1. So its oxidation number decreases which means it was oxidized because it lost 1 electron.
- Thu Mar 07, 2019 12:29 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Ka vs K
- Replies: 1
- Views: 222
Ka vs K
For problem 6.57 in the 7th edition, why is the value of Ka for HF the square root of K?
- Thu Feb 28, 2019 6:46 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: "Strongly oxidizing"
- Replies: 5
- Views: 996
Re: "Strongly oxidizing"
It means that Cu+ is a stronger oxidizing agent than H+.
- Thu Feb 28, 2019 6:42 am
- Forum: General Science Questions
- Topic: Test 2 7th edition book
- Replies: 1
- Views: 567
Re: Test 2 7th edition book
For outline 4, it covers 6K, 6L, and 6M.
- Thu Feb 28, 2019 6:41 am
- Forum: Balancing Redox Reactions
- Topic: Oxidation state
- Replies: 2
- Views: 275
Re: Oxidation state
Yes, this is correct.
- Thu Feb 28, 2019 12:55 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic Cell E not
- Replies: 1
- Views: 208
Galvanic Cell E not
Does a galvanic cell always have a positive potential difference?
- Wed Feb 27, 2019 6:13 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Pt (s) [ENDORSED]
- Replies: 8
- Views: 923
Re: Pt (s) [ENDORSED]
Pt is included because in the cathode are two ion compounds in solution, so an inert electrode is needed.
- Wed Feb 27, 2019 11:11 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: test 2
- Replies: 6
- Views: 482
Re: test 2
Which topic sections will be covered on Test 2 in Focus 6?
- Tue Feb 26, 2019 11:36 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta S Fusion
- Replies: 2
- Views: 1455
Delta S Fusion
How does one calculate Delta S of fusion, as in the example provided in the 7th edition 4J.1?
- Wed Feb 13, 2019 11:17 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Change in Internal Energy
- Replies: 3
- Views: 412
Re: Change in Internal Energy
The change in internal energy equals 0 when it is an isothermal process.
- Wed Feb 13, 2019 11:14 am
- Forum: Calculating Work of Expansion
- Topic: Integrals
- Replies: 4
- Views: 528
Re: Integrals
no, no calculus will be required on the exam.
- Wed Feb 13, 2019 1:41 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Reversible Heat Transfer
- Replies: 1
- Views: 242
Reversible Heat Transfer
What does it mean if the transfer of heat is reversible?
- Wed Feb 13, 2019 1:28 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Entropy of Irreversible Expansion
- Replies: 2
- Views: 506
Entropy of Irreversible Expansion
Why can the change in entropy that has been calculated for a reversible path be used to calculate the change in entropy of the gas when it expands irreversibly?
- Wed Feb 13, 2019 1:15 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard Enthalpy and Enthalpy of Formation
- Replies: 1
- Views: 251
Standard Enthalpy and Enthalpy of Formation
What is the difference in units between the standard enthalpy and the enthalpy of formation?
- Tue Feb 12, 2019 9:22 pm
- Forum: Phase Changes & Related Calculations
- Topic: Steam vs Boiling Water
- Replies: 8
- Views: 1161
Steam vs Boiling Water
Why does steam at 100 degrees celsius cause a worse burn than boiling water at 100 degrees celsius?
- Tue Feb 12, 2019 10:43 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Temperature
- Replies: 3
- Views: 372
Temperature
When converting between celsius and kelvin, what are the significant figure rules?
- Sat Feb 09, 2019 4:47 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Closed, Open, and Isolated Systems
- Replies: 5
- Views: 523
Closed, Open, and Isolated Systems
What is the difference between a closed, an open, and an isolated system? And what are some examples?
- Tue Jan 22, 2019 4:26 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Pressure
- Replies: 8
- Views: 725
Re: Pressure
Why does a change in pressure due to an inert gas not affect the equilibrium?
- Tue Jan 22, 2019 4:23 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Temperature change
- Replies: 5
- Views: 564
Re: Temperature change
Why does an increase in temperature with an endothermic reaction favor the formation of products? Conversely, why does an increase in temperature with an exothermic reaction favor the formation of reactants?
- Tue Jan 22, 2019 4:19 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Seventh edition 5I. 27 error?
- Replies: 1
- Views: 172
Re: Seventh edition 5I. 27 error?
I also calculated it to be 4.84.
- Sun Jan 13, 2019 10:50 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 7
- Views: 456
Re: Le Chatelier's Principle
A change in one of the variables that describe a system at equilibrium produces a shift in the position of the equilibrium that counteracts the effect of this change. Le Chatelier's principle describes what happens to a system when something momentarily takes it away from equilibrium. This can be us...
- Sun Jan 13, 2019 10:48 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Le Chatelier's Principle
- Replies: 2
- Views: 141
Le Chatelier's Principle
Why does K remain constant when there is a change in pressure, but K changes when there is a change in temperature.
- Sun Jan 13, 2019 10:45 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chemical Equilibrium K expression
- Replies: 1
- Views: 102
Chemical Equilibrium K expression
Why are solids and liquids not included in the K expression?
- Thu Dec 06, 2018 10:14 am
- Forum: Dipole Moments
- Topic: Dipole moment trends
- Replies: 2
- Views: 253
Re: Dipole moment trends
Molecules with a dipole moment (polar molecules) dissolve in polar liquids like water.
- Thu Dec 06, 2018 10:10 am
- Forum: Ionic & Covalent Bonds
- Topic: Net dipole
- Replies: 2
- Views: 1316
Re: Net dipole
ClF3 has a net dipole because the shape of the molecule is T-shape and the dipoles do not cancel each other out. BF3 does not have a net dipole because the shape is trigonal planar and the dipoles cancel each other out.
- Thu Dec 06, 2018 10:09 am
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizable
- Replies: 1
- Views: 481
Re: Polarizable
Cl- < S-2 < P-3 < I- Large anions will be the most polarizable because the outer electrons are held more loosely and can be more easily distorted by the cation. Cs+ < Ba+2 < Ca+2 < Li+ Small cations will have the most polarizing power because they distort the electron cloud of the anion better due t...
- Sun Dec 02, 2018 5:28 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Induced Dipole
- Replies: 1
- Views: 246
Re: Induced Dipole
An induced dipole intermolecular force results from the presence of molecules that are permanent dipoles temporarily distorting the electron charge in other nearby polar or nonpolar molecules, thereby inducing further polarization. Van der Waals forces are temporary charges on an atom because of the...
- Sun Dec 02, 2018 5:23 pm
- Forum: Hybridization
- Topic: Hybrid Orbitals
- Replies: 3
- Views: 396
Re: Hybrid Orbitals
The number of hybrid orbitals equals the number of atomic orbitals mixed. The number of hybrid orbitals is equal to the steric number which the number of sigma bonds plus number of lone pairs of electrons around the atom.
- Sun Dec 02, 2018 5:19 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Definition of Ligand
- Replies: 2
- Views: 265
Re: Definition of Ligand
A ligand is a molecule or ion that bonds with a metal atom. What we're focusing on is ligands bonding to central transition metals to form coordination compounds. The transition metal itself is typically not the ligand.
- Mon Nov 26, 2018 11:30 am
- Forum: Hybridization
- Topic: Hybridization and Reactivity
- Replies: 2
- Views: 606
Re: Hybridization and Reactivity
This is no ordinary triple bond as the second π interaction results from a weak interaction of sp2 hybrid orbitals lying in the plane of the ring.
The triple bond is non-linear due to the constraints of the 6-membered ring. Benzyne is strained and highly reactive.
The triple bond is non-linear due to the constraints of the 6-membered ring. Benzyne is strained and highly reactive.
- Mon Nov 26, 2018 11:24 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: Dipole Forces
- Replies: 3
- Views: 372
Re: Dipole Forces
Dipole-dipole forces result from the difference between electronegativities of the atoms in molecules. It is large enough that the electrons aren't shared equally, and yet small enough that the electrons aren't drawn exclusively to one of the atoms to form positive and negative ions. The bonds in th...
- Mon Nov 26, 2018 11:10 am
- Forum: Hybridization
- Topic: Sigma vs Pi Bonds
- Replies: 2
- Views: 128
Re: Sigma vs Pi Bonds
A sigma bond ( σ bond) is a bond formed by the overlap of orbitals in an end-to-end fashion, with the electron density concentrated between the nuclei of the bonding atoms. A pi bond ( π bond) is a bond formed by the overlap of orbitals in a side-by-side fashion with the electron density concentrate...
- Sun Nov 18, 2018 9:33 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar molecules
- Replies: 5
- Views: 755
Re: Polar molecules
Not sure if you mean NF3, but if so it is because the dipoles do not cancel each other due to the lone pair giving the shape of trigonal pyramidal. So, the N-F polar bonds make the whole molecule polar.
- Sun Nov 18, 2018 9:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: T Shaped
- Replies: 3
- Views: 550
Re: T Shaped
Three orbitals are arranged around the equator of the molecule with bond angles of 120 degrees. Two orbitals are arranged along the vertical axis at 90 degrees from the equatorial orbitals. The shape of the orbitals is trigonal bipyramidal. Two of the equatorial orbitals contain lone pairs of electr...
- Sun Nov 18, 2018 9:27 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Distorted Bond Angles
- Replies: 3
- Views: 3084
Re: Distorted Bond Angles
Bond angles will deviate from their ideal values according to the rule that lone pairs repel other electrons more strongly than bonding pairs. Although lone pairs are clearly smaller than atoms, they need to be closer to the nucleus of an atom than a bonding pair. Being closer to the central atom ca...
- Sun Nov 11, 2018 9:57 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Difference in models
- Replies: 2
- Views: 284
Re: Difference in models
A molecule will be trigonal planar if it has 3 pairs of bonding electrons around the central atom. It will be trigonal pyramid if it has 3 bonding pairs of electrons and 1 lone pair of electrons around the central atom. It will be T-shape if it has 3 bonding pairs of electrons and 2 lone pairs of el...
- Sun Nov 11, 2018 9:54 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: determining VSEPR models
- Replies: 6
- Views: 534
Re: determining VSEPR models
The seesaw, tetrahedral, and square planar models differ in their number of lone pair of electrons. The tetrahedral model has 4 bonding pairs of electrons around the central atom, the seesaw has 4 bonding pairs and 1 lone pair of electrons around the central atom, and the square planar model has 4 b...
- Sun Nov 11, 2018 9:46 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: London Forces
- Replies: 2
- Views: 254
Re: London Forces
Because of the constant motion of the electrons, an atom or molecule can develop a temporary (instantaneous) dipole when its electrons are distributed unsymmetrically about the nucleus. A second atom or molecule, in turn, can be distorted by the appearance of the dipole in the first atom or molecule...
- Sun Nov 04, 2018 10:02 pm
- Forum: Lewis Structures
- Topic: Lewis Structure for Ammonium chloride
- Replies: 3
- Views: 2507
Re: Lewis Structure for Ammonium chloride
Ammonium chloride is a molecule joined by an ionic bond, so for the lewis structure it is represented by its respective ions NH4+ and Cl-.
- Sun Nov 04, 2018 9:58 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Ms quantum number relevancy on the midterm
- Replies: 4
- Views: 465
Re: Ms quantum number relevancy on the midterm
The Ms quantum number is important because 2 electrons in the same orbital cannot have the same the spin. They must have opposite spins. This is known as the Pauli Exclusion Principle. This allows for electrons in the same orbital to have different quantum numbers.
- Sun Nov 04, 2018 9:55 pm
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 5
- Views: 552
Re: Electronegativity
If the electronegativity difference between atoms is greater than 2, then the atoms will form an ionic bond. If the electronegativity difference between atoms is less than 1.5, then the atoms will form a covalent bond.
- Sun Oct 28, 2018 11:20 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbitals
- Replies: 3
- Views: 334
Re: Orbitals
Ms is the spin quantum number. An electron will always be either spin up or spin down. Ms will either be +1/2 or -1/2. You can choose if you want the electron to have the quantum number +1/2 or -1/2. Due to Hund's Rule, electrons in the same subshell occupy different orbitals with parallel spin. If ...
- Sun Oct 28, 2018 11:14 pm
- Forum: Lewis Structures
- Topic: Lewis Structures
- Replies: 13
- Views: 991
Re: Lewis Structures
Yes, every atom can have potentially 8 valence electrons besides H and He.
- Sun Oct 28, 2018 11:05 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbitals
- Replies: 1
- Views: 311
Re: Orbitals
The electron structure for Chromium and Copper are examples of elements with incomplete orbitals. For Chromium there is an unfilled 4s orbital with only 1 electron in it, and it has a half filled 3d orbital. For Copper there is an unfilled 4s orbital with only 1 electron in it, and it has a full 3d ...
- Fri Oct 19, 2018 6:30 pm
- Forum: Properties of Light
- Topic: How many photons
- Replies: 3
- Views: 297
Re: How many photons
First you have to calculate the energy from the lamp, which is simply 32J/s *2s = 64J (1 W = 1 J/s). Next you are given the wavelength of the light that the lamp emits. You can calculate the energy corresponding to that wavelength (using E=hc/wavelength), which would give the the energy PER PHOTON o...
- Fri Oct 19, 2018 6:26 pm
- Forum: Properties of Electrons
- Topic: Balmer vs Lyman Series [ENDORSED]
- Replies: 5
- Views: 537
Re: Balmer vs Lyman Series [ENDORSED]
For the Lyman series,which corresponds to UV light, the electrons come to rest at the energy level n=1.
For the Balmer series, which corresponds to visible light, the electrons come to rest at the energy level n=2.
For the Balmer series, which corresponds to visible light, the electrons come to rest at the energy level n=2.
- Thu Oct 18, 2018 1:28 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Homework 1E.13 Silver
- Replies: 2
- Views: 142
Homework 1E.13 Silver
Why is the ground state electron configuration for silver [Kr] 4d^10 5s^1 rather than [Kr] 4d^9 5s^2?
- Sun Oct 14, 2018 9:51 pm
- Forum: General Science Questions
- Topic: Electron Energy Levels
- Replies: 2
- Views: 372
Re: Electron Energy Levels
When an electron moves to its highest energy state, for this example let's say it came from the first energy level. When the electron moves down to a lower energy state, it will lose a certain amount of energy that is quantized to correspond to a certain energy level. If the electron moves back to t...
- Sun Oct 14, 2018 9:41 pm
- Forum: Properties of Electrons
- Topic: Electron Question
- Replies: 6
- Views: 570
Re: Electron Question
The energy of a particle is quantized, meaning it is restricted to a series of discrete values, called energy levels. According to quantum mechanics, because there are boundary conditions on wave functions and each wavelength corresponds to a different energy energy is quantized. Because an electron...
- Sun Oct 14, 2018 9:35 pm
- Forum: Properties of Electrons
- Topic: energy transitions
- Replies: 6
- Views: 379
Re: energy transitions
The orbital angular momentum quantum number (l) corresponds to the orbitals of a shell and the subshells, or group of orbital that have the sam value of l. For example, when n = 3, l can have any of the 3 values 0, 1, or 2. When l = 0, there is an s type of orbital. When l = 1, there is a p type of ...
- Sun Oct 07, 2018 6:48 pm
- Forum: Limiting Reactant Calculations
- Topic: Reactants and Reagents
- Replies: 4
- Views: 464
Re: Reactants and Reagents
Typically reagent is what you point to in the lab.
Reactant is what you point to in the balanced chemical equation.
Although, this distinction is not often made (and not that important).
Reactant is what you point to in the balanced chemical equation.
Although, this distinction is not often made (and not that important).
- Sun Oct 07, 2018 6:47 pm
- Forum: Limiting Reactant Calculations
- Topic: Theoretical Yield
- Replies: 7
- Views: 912
Re: Theoretical Yield
Theoretical yield is the maximum yield of a product that is found through calculations. Due to side reactions, impurities, product sticking to the side of walls, human error, etc. during experiments the actual yield will be less.
- Sun Oct 07, 2018 6:39 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Molarity Formula [ENDORSED]
- Replies: 1
- Views: 179
Re: Molarity Formula [ENDORSED]
Molarity (M) = moles of solute (n) / volume of solution (v) in Liters = mol . L ^-1