Search found 101 matches
- Mon Mar 16, 2020 11:04 pm
- Forum: *Enzyme Kinetics
- Topic: catalysts
- Replies: 4
- Views: 117
Re: catalysts
The catalyst would have an effect in whichever step it was involved in. It would affect both the forwards and reverse rate.
- Thu Mar 12, 2020 6:31 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: comparing rates
- Replies: 3
- Views: 54
Re: comparing rates
Yes, the rates would be the same because one mole of reactant results in one mole of product.
- Thu Mar 12, 2020 6:29 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius equation
- Replies: 5
- Views: 88
Re: Arrhenius equation
A is a variable that represents the proportion of interactions that have the minimum activation energy and are in the right orientation.
- Thu Mar 12, 2020 6:29 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 4
- Views: 142
Re: Le Chatelier's Principle
Le Chatlier's principle says that a system will adjust to maintain its conditions. For example, if temperature increases, the system will try to counteract the change.
- Thu Mar 12, 2020 6:05 pm
- Forum: Calculating Work of Expansion
- Topic: isobaric compression
- Replies: 7
- Views: 211
Re: isobaric compression
Using the formula PV=nRT, you can change V and P by accounting for differences in the other variables (ex: temperature).
- Thu Mar 12, 2020 6:03 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: How do you know a cell can do work?
- Replies: 7
- Views: 111
Re: How do you know a cell can do work?
A difference in cell potential (Ecell not Ecell naught) means the cell can do work.
- Thu Mar 12, 2020 6:02 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: activation energy units
- Replies: 3
- Views: 65
Re: activation energy units
The units for activation energy are joules/mol. Joules gives the energy and the moles makes it standard for the reaction.
- Thu Mar 12, 2020 6:01 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: U vs H
- Replies: 15
- Views: 370
Re: U vs H
Delta U is change in internal energy, while delta H is change in enthalpy. Under certain conditions, they can be equal to each other.
- Thu Mar 12, 2020 6:01 pm
- Forum: Ideal Gases
- Topic: reversing reactions
- Replies: 83
- Views: 447
Re: reversing reactions
When you reverse the reaction, you have to invert K. Therefore, for a forward reaction, the equilibrium constant is equal to K. For the reverse reaction, the equilibrium constant is equal to 1/K.
- Thu Mar 12, 2020 5:58 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: HW 6.57
- Replies: 6
- Views: 181
Re: HW 6.57
If you write the Ka out, it is [H+][A-] and in order to get [H+], you would need to take the square root of the value.
- Thu Mar 12, 2020 5:57 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: q and delta H
- Replies: 4
- Views: 173
Re: q and delta H
q is equal to delta H under the condition that pressure is constant.
- Thu Mar 12, 2020 5:56 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Enaught in Concentration Cells
- Replies: 4
- Views: 132
Re: Enaught in Concentration Cells
The equation that relates E and delta G uses Ecell and delta G, not delta G naught. As a result, even if Ecell naught is zero, Ecell could not be zero, so delta G does not have to be zero.
- Thu Mar 12, 2020 5:53 pm
- Forum: General Rate Laws
- Topic: Fast and Slow Step Reactions
- Replies: 5
- Views: 128
Re: Fast and Slow Step Reactions
The slow step is the rate determining step. The fast step could be before or after the sloe step.
- Wed Mar 11, 2020 2:49 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: same equation?
- Replies: 5
- Views: 87
Re: same equation?
The equations are the same, they’re just written differently.
- Sun Mar 08, 2020 2:46 pm
- Forum: General Rate Laws
- Topic: Instantaneous and average reaction rate
- Replies: 4
- Views: 86
Re: Instantaneous and average reaction rate
Rate laws are given for instantaneous rates.
- Sun Mar 08, 2020 2:45 pm
- Forum: First Order Reactions
- Topic: how to know actual order
- Replies: 4
- Views: 156
Re: how to know actual order
First order means the exponent is equal to one. The exponent is based on the rate order, not the coefficient.
- Sun Mar 08, 2020 2:44 pm
- Forum: First Order Reactions
- Topic: rate constants
- Replies: 20
- Views: 372
Re: rate constants
Yes, rate constants are always positive because they represent concentration which is based on mass (always positive).
- Sun Mar 08, 2020 2:42 pm
- Forum: First Order Reactions
- Topic: Graph
- Replies: 9
- Views: 230
Re: Graph
The graph will look linear and the slope is -k.
- Sun Mar 08, 2020 2:41 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: activation energy/ energy barrier
- Replies: 6
- Views: 106
Re: activation energy/ energy barrier
The activation energy is how much energy the reaction requires to proceed and this is for both endergonic and exergonic reactions. When there is not enough energy to overcome this barrier, the reaction will not proceed.
- Sun Mar 08, 2020 3:27 am
- Forum: General Rate Laws
- Topic: Slow and Fast step
- Replies: 2
- Views: 91
Re: Slow and Fast step
It will most likely be given to you, but you can also work backwards from the rate law to determine the slow step.
- Sun Mar 08, 2020 3:26 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: instantaneous rate
- Replies: 16
- Views: 253
Re: instantaneous rate
Instantaneous rate is more accurate for a specific time, while average gives you the overall rate of the reaction.
- Sun Mar 08, 2020 3:25 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: derivations
- Replies: 9
- Views: 212
Re: derivations
I would focus on the derivations that were given in class, specifically those for 1, 2, and 0 order.
- Sun Mar 08, 2020 3:24 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: units of T
- Replies: 11
- Views: 545
Re: units of T
Make sure units are consistent in all your calculations. Generally, time should be reported in seconds.
- Sun Mar 08, 2020 3:23 am
- Forum: General Rate Laws
- Topic: Units
- Replies: 3
- Views: 95
Re: Units
For units, make sure you use the units of the components that go in. The order of the rate constant will determine the units.
- Sun Mar 08, 2020 3:23 am
- Forum: General Rate Laws
- Topic: Units
- Replies: 3
- Views: 95
Re: Units
For units, make sure you use the units of the components that go in. The order of the rate constant will determine the units.
- Thu Feb 06, 2020 11:20 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Cp and Cv
- Replies: 4
- Views: 80
Re: Cp and Cv
Cp is the heat capacity at constant pressure. Cv is the heat capacity at constant volume. According to PV = nRT, if temperature is changing, that means one other variable also has to change and this could be number of moles, pressure, or volume. It is important to know which ones are constant when c...
- Thu Feb 06, 2020 11:18 am
- Forum: Calculating Work of Expansion
- Topic: units
- Replies: 9
- Views: 84
Re: units
w is given in joules. Some problems may represent it as kJ so it is important to pay attention.
- Thu Feb 06, 2020 11:17 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Constant pressure
- Replies: 19
- Views: 204
Re: Constant pressure
Yes, they would be referring to a constant external pressure.
- Thu Feb 06, 2020 11:17 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Textbook question 4A.13
- Replies: 5
- Views: 63
Re: Textbook question 4A.13
The reaction is transferring heat to its surroundings, so the system itself is losing heat. Therefore, it will have a negative value.
- Thu Feb 06, 2020 11:16 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Insulated system
- Replies: 5
- Views: 71
Re: Insulated system
Delta S = q / t. An insulated system has no change in temperature, so the value of T in the denominator is not going to change. However, even though the initial and final temperatures of the system are the same, it would change throughout the progress of the reaction. Therefore, there can still be h...
- Thu Feb 06, 2020 11:12 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: HW Question 4H.9
- Replies: 1
- Views: 48
Re: HW Question 4H.9
Vibrational activity would have more degeneracy than nonvibrational activity, so Sc>Sb. Monatomic gases have more degeneracy than diatomic gases because there are more possible states for them to exist in. Therefore, the final answer is Sb < Sc < Sa.
- Thu Feb 06, 2020 11:10 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Heat capacity
- Replies: 4
- Views: 43
Re: Heat capacity
If you are not given a specific heat, you can use the generic formula for a gas. It depends on both the shape and conditions of the molecules observed. For an ideal gas in atomic form, Cv = (3/2)R and Cp = (5/2)R.
- Thu Feb 06, 2020 11:08 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 4F12
- Replies: 3
- Views: 22
Re: 4F12
R is the gas constant and C is a heat capacity.
- Thu Feb 06, 2020 11:05 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Question 4.37
- Replies: 2
- Views: 38
Re: Question 4.37
In general, if delta G is negative, then the reaction is spontaneous. Simply knowing change in entropy or heat does not directly tell you if a reaction is spontaneous or not.
- Thu Feb 06, 2020 11:02 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy Decreasing, Temperature Increasing
- Replies: 6
- Views: 59
Re: Entropy Decreasing, Temperature Increasing
At a higher temperature, entropy is already higher than it would be at a lower temperature. As a result, the change in entropy will be lower.
- Mon Jan 20, 2020 6:34 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: q vs k
- Replies: 62
- Views: 221
Re: q vs k
Q represents the current state of the system but K is the equilibrium state. Eventually, Q will go towards K.
- Mon Jan 20, 2020 6:32 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: definition of a buffer
- Replies: 8
- Views: 136
Re: definition of a buffer
A buffer is a solution that resists changes in pH and it’s made by mixing a weak acid/base with its conjugate.
- Mon Jan 20, 2020 6:31 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Delta H
- Replies: 10
- Views: 400
Re: Delta H
If delta H is negative, it is exothermic. If delta H is positive, it is endothermic.
- Mon Jan 20, 2020 6:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Writing K Expression
- Replies: 6
- Views: 59
Re: Writing K Expression
You include all aqueous solutions and gases in the K expression.
- Mon Jan 20, 2020 6:28 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE tables
- Replies: 5
- Views: 53
Re: ICE tables
You use an ICE table to observe how concentrations change at equilibrium.
- Wed Jan 15, 2020 1:27 pm
- Forum: Ideal Gases
- Topic: Combined gas law
- Replies: 3
- Views: 62
Re: Combined gas law
You use the combined gas law to convert from liters of gas to moles.
- Wed Jan 15, 2020 1:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: increasing yield
- Replies: 2
- Views: 24
Re: increasing yield
Remove products from the reaction so Q is less than K.
- Wed Jan 15, 2020 1:24 pm
- Forum: Phase Changes & Related Calculations
- Topic: Autoprotolysis
- Replies: 15
- Views: 185
Re: Autoprotolysis
It is when a molecule transfers a proton to another one of the same molecule.
- Wed Jan 15, 2020 1:23 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 6
- Views: 49
Re: Le Chatelier's Principle
If the change in pressure changed the volume, it affects the concentration. If the change in pressure was caused by the addition of an intert gas, the volume hasn't changed so the concentrations have not changed.
- Wed Jan 15, 2020 1:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When to omit "x-term"
- Replies: 6
- Views: 97
Re: When to omit "x-term"
You omit the -x term when the equilibrium constant is very small (less than 10^3) because those changes are too small to have a significant effect on the concentration of reactants.
- Fri Jan 10, 2020 4:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Exercise 5G.1
- Replies: 4
- Views: 65
Re: Exercise 5G.1
C is asking about the equilibrium constant, which is a fixed value. D is asking about equilibrium concentrations, which depend on the initial reactions.
- Fri Jan 10, 2020 2:52 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Pressure and Volume
- Replies: 8
- Views: 56
Re: Pressure and Volume
The value of K would depend on whether pressure would change from a change in volume (would change) or addition of an inert gas (no change) based on how concentration would change.
- Fri Jan 10, 2020 2:50 pm
- Forum: Ideal Gases
- Topic: ICE table
- Replies: 7
- Views: 455
Re: ICE table
Set up and ICE table with initial, change, and equilibrium and use x to represent an unknown change.
- Fri Jan 10, 2020 2:49 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Le Chatelier's Principle
- Replies: 7
- Views: 146
Re: Le Chatelier's Principle
Le Chatlier's Principle states that if a system is disturbed, it will counteract the disturbance.
- Fri Jan 10, 2020 2:46 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5I.13
- Replies: 2
- Views: 35
Re: 5I.13
Kc uses concentration while K uses partial pressure.
- Fri Jan 10, 2020 2:44 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Why Q would be greater than K
- Replies: 5
- Views: 39
Re: Why Q would be greater than K
Q would be greater than K if there are too many products. An external change could cause the system to have Q greater than K.
- Sun Dec 08, 2019 2:52 pm
- Forum: Conjugate Acids & Bases
- Topic: Bronsted vs Conjugate
- Replies: 3
- Views: 167
Re: Bronsted vs Conjugate
Bronsted can accept or donate protons. Conjugate Avis is the conjugate of a base.
- Sun Dec 08, 2019 2:51 pm
- Forum: Polyprotic Acids & Bases
- Topic: Polyproptic Acids/Bases
- Replies: 4
- Views: 152
Re: Polyproptic Acids/Bases
They would have multiple H or OH.
- Sun Dec 08, 2019 2:50 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: salt solutions
- Replies: 7
- Views: 163
Re: salt solutions
You need to know whether they are neutral, acidic, or basic.
- Sun Dec 08, 2019 2:49 pm
- Forum: Biological Examples
- Topic: b12?
- Replies: 3
- Views: 165
Re: b12?
Cobalt is the coordinating metal in the middle.
- Sun Dec 08, 2019 2:49 pm
- Forum: Significant Figures
- Topic: pH sig figs
- Replies: 9
- Views: 256
Re: pH sig figs
The number of dog figs starts after the decimal place for pH. So, if there are two dig figs you would use 2.46.
- Sun Dec 01, 2019 3:02 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: strong or weak base?
- Replies: 13
- Views: 245
Re: strong or weak base?
A strong base completely dissociates in water and there are only a few. A weak base does not completely dissociate in water.
- Sun Dec 01, 2019 3:00 am
- Forum: Conjugate Acids & Bases
- Topic: Product of Acid and Base
- Replies: 5
- Views: 97
Re: Product of Acid and Base
The reaction between an acid and base is a neutralization reaction. The products of this reaction are a salt and water.
- Sun Dec 01, 2019 2:58 am
- Forum: Bronsted Acids & Bases
- Topic: Bronsted Acid and base
- Replies: 8
- Views: 136
Re: Bronsted Acid and base
A bronsted acid donates protons while a bronsted base accepts protons.
- Sun Dec 01, 2019 2:56 am
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Sigma and Pi Bonds
- Replies: 12
- Views: 643
Re: Sigma and Pi Bonds
A triple bond would have 1 sigma bond and 2 pi bonds.
- Sun Dec 01, 2019 2:54 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Shape
- Replies: 1
- Views: 46
Re: Shape
The shape of a coordination compound that has 3 ligands is trigonal planar.
- Mon Nov 25, 2019 1:06 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs linear
- Replies: 56
- Views: 1362
Re: Bent vs linear
Bent has lone pairs while linear does not.
- Mon Nov 25, 2019 1:06 am
- Forum: Bond Lengths & Energies
- Topic: Hydrogen Bonding and Dispersion
- Replies: 5
- Views: 186
Re: Hydrogen Bonding and Dispersion
Dispersion occurs between two nonpolar atoms/molecules. Hydrogen bonding occurs when an H is bonded to a highly electronegative atom.
- Mon Nov 25, 2019 1:05 am
- Forum: Hybridization
- Topic: Sigma and Pi Bonds
- Replies: 5
- Views: 54
Re: Sigma and Pi Bonds
Sigma bond is the first bond that is formed and it the overlapping of two orbitals. Pi bonds are all the remaining bonds and they are formed by side by side orbitals.
- Mon Nov 25, 2019 1:04 am
- Forum: Hybridization
- Topic: Are terminal atoms hybridized?
- Replies: 2
- Views: 54
Re: Are terminal atoms hybridized?
Each atom is hybridized based on the number of electron domains it has.
- Mon Nov 25, 2019 1:04 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Transition Metals
- Replies: 7
- Views: 131
Re: Transition Metals
Yes, all transition metals can form coordinate compounds.
- Sun Nov 17, 2019 11:11 pm
- Forum: Ionic & Covalent Bonds
- Topic: Strength and Length
- Replies: 18
- Views: 290
Re: Strength and Length
The shorter the bond, the stronger it is.
- Sun Nov 17, 2019 11:11 pm
- Forum: Hybridization
- Topic: Hybridization
- Replies: 6
- Views: 67
Re: Hybridization
Hybridization is when 2 or more orbitals combine. For example, if a carbon has 4 bonds, all 4 of those bonds are the same. All the electrons cannot be in the same orbital, so in order for them to be equal, the orbitals have to hybridize.
- Sun Nov 17, 2019 11:09 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Naming the Molecular Shapes
- Replies: 7
- Views: 178
Re: Naming the Molecular Shapes
The molecular shape names of the electron domains have roots that you can memorize. Then, try to memorize how you remove electrons to figure out the ones where there are lone pairs.
- Sun Nov 17, 2019 10:49 pm
- Forum: Lewis Structures
- Topic: Oxygen
- Replies: 9
- Views: 326
Re: Oxygen
Oxygen can have triple bonds, but it is usually most stable with two.
- Sun Nov 17, 2019 10:48 pm
- Forum: Trends in The Periodic Table
- Topic: Trend for Polarizability
- Replies: 6
- Views: 193
Re: Trend for Polarizability
Larger molecules are more polarizable than smaller ones, so the general trend is decreases across the row and increases down the column. Anions are more polarizable than cations because they are larger.
- Sun Nov 10, 2019 11:56 pm
- Forum: Electronegativity
- Topic: Noble Gases
- Replies: 40
- Views: 2159
Re: Noble Gases
No, neon gases are not included in the electronegativity trend, so neon is not more electronegative than fluorine.
- Sun Nov 10, 2019 11:56 pm
- Forum: Bond Lengths & Energies
- Topic: Size
- Replies: 13
- Views: 162
Re: Size
Larger size means larger bond length.
- Sun Nov 10, 2019 11:55 pm
- Forum: Dipole Moments
- Topic: Dipole dipole forces
- Replies: 2
- Views: 76
Re: Dipole dipole forces
A dipole-dipole force occurs when both compounds naturally have dipoles (HI). Induced dipoles occur when both molecules don't have a dipoles, and the induced dipole is caused by a random shift in the electron cloud.
- Sun Nov 10, 2019 11:54 pm
- Forum: Ionic & Covalent Bonds
- Topic: Water molecules and ionic substances
- Replies: 5
- Views: 126
Re: Water molecules and ionic substances
Hydrogen bonding and the polarity of the water molecule allow ionic substances to dissolve in water.
- Sun Nov 10, 2019 11:53 pm
- Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
- Topic: Viscosity
- Replies: 22
- Views: 612
Re: Viscosity
A liquid has high viscosity when it has strong intermolecular forces so it tends to by sticky and slow-moving.
- Mon Nov 04, 2019 3:21 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: 2D.5 - Electronegativity
- Replies: 4
- Views: 110
Re: 2D.5 - Electronegativity
You would have to follow the electronegativity trend. You would have to look at the electronegativity difference of O and S, not S and C. O is more electronegative than S, so there would be a greater difference between O and C compared to S and C, so CO2 would be more ionic than CS2.
- Mon Nov 04, 2019 12:33 pm
- Forum: Ionic & Covalent Bonds
- Topic: Covalent and Ionic Bonds
- Replies: 6
- Views: 119
Re: Covalent and Ionic Bonds
You can use the electronegativity difference between the two atoms to determine whether it has more ionic or covalent character. If the difference is greater than 1.5, it is ionic. If it is between 0.5 and 1.5, it is polar covalent. If it is less than 0.5, it is nonpolar covalent.
- Mon Nov 04, 2019 12:28 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic Solids
- Replies: 2
- Views: 104
Re: Ionic Solids
In an ionic solid, there is an anion with a negative charge and a cation with a positive charge. The electrostatic attraction between the charged ions holds the solid together.
- Mon Nov 04, 2019 12:27 pm
- Forum: Octet Exceptions
- Topic: Radicals: Homework Problem #2C1
- Replies: 8
- Views: 114
Re: Radicals: Homework Problem #2C1
NO2- has 18 electrons. Since 18 is an even number, there aren't going to be any unpaired electrons, so it would not be a radical. NO2 on the other hand would have an unpaired electron, so it would be a radical.
- Mon Nov 04, 2019 12:25 pm
- Forum: Properties of Light
- Topic: General Concept
- Replies: 3
- Views: 77
Re: General Concept
The dual nature of light refers to its properties as a wave and particle. Formulas like c = λv are based of light's wave-like properties. The E = hv formula treats light as quantized photons.
- Sun Oct 27, 2019 4:30 pm
- Forum: Bond Lengths & Energies
- Topic: C-C bond lengths
- Replies: 4
- Views: 87
Re: C-C bond lengths
There was a discrepancy in these numbers because C-C bonds have resonance. So, they are partial single/double bonds.
- Sun Oct 27, 2019 4:29 pm
- Forum: Ionic & Covalent Bonds
- Topic: Valence Electrons
- Replies: 16
- Views: 273
Re: Valence Electrons
You look at the number of electrons in the outermost shell. This is the number of valence electrons.
- Sun Oct 27, 2019 4:27 pm
- Forum: Lewis Structures
- Topic: Dots vs Lines in Lewis Structures
- Replies: 6
- Views: 113
Re: Dots vs Lines in Lewis Structures
When drawing a bond, both dots and lines are synonymous. Lines are usually clearer in depicting the bonds. Unbonded electrons are always shown as dots.
- Sun Oct 27, 2019 4:16 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Shielding
- Replies: 3
- Views: 38
Re: Electron Shielding
Electron shielding refers to the blocking of valence shell electron attraction by the nucleus due to the presence of inner-shell electrons. Penetration describes the proximity to which an electron can approach to the nucleus. The principal quantum number gives you an idea of how close the electron i...
- Sun Oct 27, 2019 4:09 pm
- Forum: Trends in The Periodic Table
- Topic: 1F.3
- Replies: 3
- Views: 86
Re: 1F.3
You need to look at the number of protons and effective nuclear charge to determine the order.
- Sun Oct 20, 2019 1:38 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Short Hand
- Replies: 11
- Views: 125
Re: Short Hand
You put the last noble gas configuration in brackets and then continue using spdf normally after that.
- Sun Oct 20, 2019 1:36 pm
- Forum: Properties of Light
- Topic: Baler v. Lyman Series
- Replies: 10
- Views: 202
Re: Baler v. Lyman Series
The Balmer series is when the electron falls to the n = 2 energy level. The Lyman series is when the electron falls to the n = 1 energy level.
- Sun Oct 20, 2019 1:35 pm
- Forum: *Black Body Radiation
- Topic: Energy of photons
- Replies: 4
- Views: 192
Re: Energy of photons
E = hv calculates the energy of an individual photon.
E = 1/2mv^2 calculates the kinetic energy of a particle. Since photons have no mass, this equation is not applicable.
E = 1/2mv^2 calculates the kinetic energy of a particle. Since photons have no mass, this equation is not applicable.
- Sun Oct 20, 2019 1:34 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Focus 1B.25 & 27 Homework
- Replies: 3
- Views: 53
Re: Focus 1B.25 & 27 Homework
The Heisenberg equation states that the product of the uncertainty in momentum times the uncertainty in position has to be greater than or equal to h/4π. This means there is a minimum number of uncertainty at all times.
- Sun Oct 20, 2019 1:31 pm
- Forum: Properties of Light
- Topic: Unit for Wavelength
- Replies: 34
- Views: 503
Re: Unit for Wavelength
The standard unit for wavelength is m, and this is the output of equations relating to light. However, nanometers (10^-9) are also a common unit of measurement.
- Sat Oct 12, 2019 4:24 pm
- Forum: Properties of Electrons
- Topic: Electron After Excited State
- Replies: 7
- Views: 117
Re: Electron After Excited State
An electron jumps to a higher energy state when it absorbs energy. It falls back to its original state when it emits that energy.
- Sat Oct 12, 2019 4:17 pm
- Forum: Properties of Electrons
- Topic: Atomic Spectra Post Module
- Replies: 4
- Views: 54
Re: Atomic Spectra Post Module
The energy transition from n=5 to n=1 requires more energy than the energy transition from n=4 to n=2. More energy means shorter wavelength (E=hv), so the electron going from n=5 to n=1 would emit more energy.
- Sat Oct 12, 2019 4:13 pm
- Forum: Properties of Light
- Topic: Wave Properties of Electrons
- Replies: 3
- Views: 59
Re: Wave Properties of Electrons
The wave nature of electrons affects the electron's energy levels. Electrons form standing waves and each energy level has to have a whole number of wavelengths for the standing wave to exist. So, the wave property of electrons dictates how there are fixed energy levels for each electron.
- Thu Oct 10, 2019 11:43 am
- Forum: Einstein Equation
- Topic: Energy Problem
- Replies: 4
- Views: 147
Re: Energy Problem
Use the formula E=hv. We know that h is planck's constant (6.626*10^-34 m^2kg/s) and that v is frequency (1.09 x 10^15 s-1). If we plug these into the equation, we get E = (6.626*10^-34) (1.09 x 10^15) = 7.22 x 10^-19 J. Using the minimum frequency will also give the minimum amount of energy.
- Thu Oct 10, 2019 11:37 am
- Forum: Significant Figures
- Topic: Do we use molar mass ?
- Replies: 8
- Views: 95
Re: Do we use molar mass ?
Use the number of significant digits given to you in the problem. Make sure you round your answer at the end to avoid losing precision.
- Thu Oct 03, 2019 11:51 pm
- Forum: Significant Figures
- Topic: When to round for sig figs?
- Replies: 12
- Views: 216
Re: When to round for sig figs?
Round at the end of your calculation so you don't loose precision.
- Thu Oct 03, 2019 11:50 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactants or Reagents Module
- Replies: 2
- Views: 58
Re: Limiting Reactants or Reagents Module
I believe he wanted you to focus on the reactants for the purpose of finding the limiting reactant.
- Thu Oct 03, 2019 11:42 pm
- Forum: SI Units, Unit Conversions
- Topic: 2.Mass Percentage and Decimal Rounding:
- Replies: 10
- Views: 168
Re: 2.Mass Percentage and Decimal Rounding:
I would use the same number of significant figures as what is given in the problem.
- Thu Oct 03, 2019 11:38 pm
- Forum: General Science Questions
- Topic: Rusty on High School Chem [ENDORSED]
- Replies: 220
- Views: 143085
Re: Rusty on High School Chem [ENDORSED]
The best thing you can do is to review problems that focus on fundamentals. Make sure you check your answers and try to figure out what you can improve on!