Search found 101 matches
- Sat Mar 14, 2020 5:41 pm
- Forum: Ideal Gases
- Topic: Kc
- Replies: 7
- Views: 635
Re: Kc
You may only use aqueous or gas molecules since they have concentrations.
- Sat Mar 14, 2020 5:40 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Gibbs free energy
- Replies: 9
- Views: 743
Re: Gibbs free energy
G is not at standard state G* is at standard conditions.
- Sat Mar 14, 2020 5:39 pm
- Forum: Zero Order Reactions
- Topic: units of k
- Replies: 5
- Views: 506
Re: units of k
There are different units of k due to the powers involved in concentrations. Units could be more than the power of 1 which would change the unit of k.
- Sat Mar 14, 2020 5:37 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Ka and Kb
- Replies: 4
- Views: 520
Re: Ka and Kb
Correct, Ka is based on H+ concentration, Kb is based on OH- concentration. You can use these values to determine pH and pOH respectively given the formula.
- Sat Mar 14, 2020 5:35 pm
- Forum: General Science Questions
- Topic: Final Overview
- Replies: 5
- Views: 511
Re: Final Overview
I would prioritize Kinetics and also Thermodynamics. The other concepts should all be included, although Kinetics would be could be a main topic.
- Sun Mar 08, 2020 9:19 pm
- Forum: Van't Hoff Equation
- Topic: Van't Hoff Equation
- Replies: 6
- Views: 587
Re: Van't Hoff Equation
You can derive this equation when solving for different temperature phases or k's. Mainly, we would try to find k2/k1.
- Sun Mar 08, 2020 9:17 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Cell Diagram
- Replies: 21
- Views: 1226
Re: Cell Diagram
Anode should be on the left, cathode should be on the right in most diagrams.
- Sun Mar 08, 2020 9:16 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Exothermic vs. Endothermic
- Replies: 14
- Views: 990
Re: Exothermic vs. Endothermic
If activation energy is higher than products, exothermic. If higher than reactants, endothermic.
- Sun Mar 08, 2020 9:15 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Figuring out n
- Replies: 15
- Views: 1000
Re: Figuring out n
n is determined by the amount of electrons transferred in the reactions, easier to find in half-reactions.
- Sun Mar 08, 2020 9:13 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: calculating Q
- Replies: 12
- Views: 789
Re: calculating Q
Q should be anode/cathode.
- Sun Mar 01, 2020 9:12 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: first order
- Replies: 8
- Views: 656
Re: first order
Graph is linear and slope is usually negative.
- Sun Mar 01, 2020 9:11 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Work
- Replies: 14
- Views: 1039
Re: Work
Work done on system is positive, work done by the system is negative.
- Sun Mar 01, 2020 9:08 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: delta G=-nFE
- Replies: 7
- Views: 541
Re: delta G=-nFE
You can calculate n whether by the other information given, such as Gibbs Free Energy, or using the half reactions to determine the amount of electrons.
- Sun Mar 01, 2020 9:00 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: when to use K or Q
- Replies: 18
- Views: 1124
Re: when to use K or Q
Use K when reactions are at equilibrium, Q when they are not. Q determines which side of the reaction is favored.
- Sun Mar 01, 2020 8:58 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Kelvin or Celsius?
- Replies: 86
- Views: 6300
Re: Kelvin or Celsius?
Kelvin because the ideal gas constant is in terms of Kelvin not celsius.
- Sat Feb 22, 2020 2:09 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Adding Inert Gas
- Replies: 20
- Views: 1153
Re: Adding Inert Gas
Adding an inert gas increases the pressure of the system but in terms of equilibrium it has no effect. Only temperature can do that as it forces the reaction to favor one side or the other.
- Sat Feb 22, 2020 2:08 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic Cells
- Replies: 8
- Views: 492
Re: Galvanic Cells
Galvanic cells are cells that converts chemical energy into electrical energy.
- Sat Feb 22, 2020 2:05 pm
- Forum: Balancing Redox Reactions
- Topic: Redox in Acid/ Basic Solutions
- Replies: 8
- Views: 547
Re: Redox in Acid/ Basic Solutions
Redox in both acidic and basic solutions are very similar. It comes down to adding the H+ or OH- to acidic and basic equations respectively to determine what is being oxidized and reduced.
- Sat Feb 22, 2020 2:02 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: converting T to kelvin
- Replies: 46
- Views: 3715
Re: converting T to kelvin
T to kelvin should only be applied when the the problem involves using constants or equations that use Kelvin instead of Temperature. In ideal gas law equations, you would use Kelvin (+273.15) if given celcsius.
- Sat Feb 22, 2020 2:00 pm
- Forum: Phase Changes & Related Calculations
- Topic: delta G0 versus delta G
- Replies: 15
- Views: 2647
Re: delta G0 versus delta G
Delta G will always be in the conditions given in the problem where as Delta G naught is in standard conditions.
- Fri Feb 14, 2020 2:21 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Constant Pressure and Volume
- Replies: 6
- Views: 463
Re: Constant Pressure and Volume
Cp=DeltaH/Delta T and Cv=DeltaU/Delta T. Calculations can also vary depending on if the atom is monoatomic, linear, etc this is when dealing with Cv,m and Cp,m.
- Fri Feb 14, 2020 2:19 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy equation
- Replies: 3
- Views: 306
Re: Entropy equation
You can use this when dealing with an isothermal process and also when dealing with phase changes.
- Fri Feb 14, 2020 2:17 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible vs Irreversible
- Replies: 13
- Views: 900
Re: Reversible vs Irreversible
Reversible is when the reaction is at equilibrium where as irreversible is not, an example of this would be combustion. Equations that relate to this would be work in which reversible process would be:-nRTlnV2/V1 and irreversible: -Pex*DeltaV
- Fri Feb 14, 2020 2:14 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: K and Q and G
- Replies: 6
- Views: 460
Re: K and Q and G
Q refers to when the reaction given is not at an equilibrium where as K would mean the reaction is at equilibrium. Usually, Q can = K such that delta g would be 0 and delta g naught would be -RT ln K at equilibrium.
- Fri Feb 14, 2020 2:11 pm
- Forum: Phase Changes & Related Calculations
- Topic: Equation Choice
- Replies: 5
- Views: 564
Re: Equation Choice
Phase change occurs when a molecule/reaction goes from solid to liquid, liquid to gas, etc. This denotes fusion, vaporization, in terms of change in enthalpy. We learned equations: Hvap=Hvap-Hliq and Hfus=Hliq-Hsol and Hsub=Hvap-Hsol which relate to phase changes.
- Sun Feb 09, 2020 9:59 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 10
- Views: 300
Re: Hess's Law
Since it is a state function, enthalpy values can be added together or subtracted.
- Sun Feb 09, 2020 9:56 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ICE BOX Reverse ?
- Replies: 4
- Views: 391
Re: ICE BOX Reverse ?
The problem should always allow you to find the concentration. If given a change in concentration you can use that to solve for the initial.
- Sun Feb 09, 2020 9:54 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ICE BOX
- Replies: 27
- Views: 929
Re: ICE BOX
If the number (x) is less than 10^-3
- Sun Feb 09, 2020 9:53 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: equations
- Replies: 4
- Views: 188
Re: equations
It usually depends on a lot of factors. If the problem were to give temperature change or volume change nCln (T2/T1) or -nRT ln (V2/V1) respectively. Those are usually the equations you would need to use when there is a change in some constant. Otherwise just know the equations that have work exclus...
- Sun Feb 09, 2020 9:50 pm
- Forum: Calculating Work of Expansion
- Topic: Ideal Gas Internal Energy
- Replies: 4
- Views: 180
Re: Ideal Gas Internal Energy
This value usually denotes Cv or Cp. The number depends on if the molecule is monoatomic, diatomic, etc.
- Sun Feb 02, 2020 2:00 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated System
- Replies: 4
- Views: 158
Re: Isolated System
Isolated systems cannot exchange heat or work for that reason delta u will be 0. (0+0=0)
- Sun Feb 02, 2020 1:59 pm
- Forum: Calculating Work of Expansion
- Topic: Gas constant
- Replies: 5
- Views: 294
Re: Gas constant
Gas constant values are dependent on the unit of pressure. Since atm is given, you would use the constant with atm as the units present.
- Sun Feb 02, 2020 1:57 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Definition of First Law
- Replies: 9
- Views: 370
Re: Definition of First Law
Conservation of energy, a function of heat and work. Delta U= q+w.
- Sun Feb 02, 2020 1:53 pm
- Forum: Ideal Gases
- Topic: pv=nrt
- Replies: 9
- Views: 408
Re: pv=nrt
Pressure, volume, moles, and temperature can all vary as R is is the Ideal gas law constant. Usually, there are relationships such as when volume increases, pressure decreases, while temperature and moles carry a similar relationship.
- Sun Feb 02, 2020 1:50 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy units
- Replies: 4
- Views: 234
Re: Entropy units
Answer should be based on the units given in the problem. Joules can be represented in many units kJ, kg.m^2, s^-2, etc. Just identify what the question asks and have consistent units.
- Sun Jan 26, 2020 10:59 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Changing K
- Replies: 13
- Views: 541
Re: Changing K
Only increasing or decreasing temperature can change the value of K.
- Sun Jan 26, 2020 10:57 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Gas Constant
- Replies: 13
- Views: 585
Re: Gas Constant
The Gas Constant value is determined based on the pressure usually and other components in the ideal gas law equation. Pressure can be measured in atm, bar, etc, and R is represented in many of those units.
- Sun Jan 26, 2020 10:55 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Pure solids & liquids
- Replies: 5
- Views: 352
Re: Pure solids & liquids
Pure solids and liquids are not included in solving for K. They also cannot dissolve or be used in ICE tables.
- Sun Jan 26, 2020 10:52 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kp to Kc
- Replies: 11
- Views: 611
Re: Kp to Kc
Yes as long as it is in the form of a gas. Any gas or aqueous reactant or product can be included in solving for K.
- Sun Jan 26, 2020 8:32 pm
- Forum: Ideal Gases
- Topic: R Constant
- Replies: 18
- Views: 1125
Re: R Constant
R constants are given and should be applied based on the units given in the problem. Pressure is the unit to look for as it determines which R constant to plug ig to PV = nRT
- Sun Jan 26, 2020 8:30 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Reaction Shifts Left or Right
- Replies: 15
- Views: 620
Re: Reaction Shifts Left or Right
In an exothermic reaction, the reaction will shift to the left when temperature is increased due to heat already being on the product and needing heat on the reactant side since the reverse reaction is endothermic.
- Sun Jan 19, 2020 6:20 pm
- Forum: Ideal Gases
- Topic: 5I.15
- Replies: 5
- Views: 468
Re: 5I.15
ICE tables only involve finding the concencentration using only aqueous or gas molecules. Solids or liquids are not included. You also use ICE tables when you are given intial concentrations.
- Sun Jan 19, 2020 5:16 pm
- Forum: Ideal Gases
- Topic: concentration
- Replies: 5
- Views: 192
Re: concentration
You can derive the concentration using the ideal gas law. PV=nRT (n/V = P/RT) where n/V gives the concentration.
- Sun Jan 19, 2020 5:14 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: ICE table
- Replies: 11
- Views: 403
Re: ICE table
An ICE table should be used when given a weak base/acid. When finding concentration always take note of the 5% rule.
- Sun Jan 19, 2020 4:40 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Reaction Shifts Left or Right
- Replies: 15
- Views: 620
Re: Reaction Shifts Left or Right
In this reaction, heat is on the product side. This indicates that the reverse reaction is endothermic. In this case, an increase in temperature would favor the reactants, caushing a shift to the left.
- Sun Jan 19, 2020 4:32 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc from K
- Replies: 3
- Views: 125
Re: Kc from K
K usually represents Kc or Kp. Kc deals with the concentrations of a reaction whereas Kp deals with partial pressures. I think we would just evaluate the reaction with how we normally calculate for K.
- Sun Jan 12, 2020 2:13 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ICE vs Normal Concentrations
- Replies: 5
- Views: 186
Re: ICE vs Normal Concentrations
ICE is used when we are given intial concentrations and we can use gasses from the product and reactant side to solve for x (final concentration).
- Sun Jan 12, 2020 1:54 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5H.1
- Replies: 2
- Views: 134
Re: 5H.1
For this problem, you would follow the procedure we've been doing K=[P]/[R]. If other temperatures were given, then there would be different K values so just be aware of that. For this problem, the products and reactants are all gasses and so all the concentrations of P and R would be present in the...
- Sun Jan 12, 2020 1:48 pm
- Forum: Ideal Gases
- Topic: Bars vs atmospheres
- Replies: 13
- Views: 397
Re: Bars vs atmospheres
Both can be used for measuring pressure, depending on the context of the problem it would be good to stay consistent with the units.
- Sun Jan 12, 2020 1:38 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Temperature and K
- Replies: 6
- Views: 280
Re: Temperature and K
Temperature is the only factor than can affect the value of K. Usually when K is given at 2 different temperatures, it is likely that those values would be different due to a difference in energy.
- Sun Jan 12, 2020 1:17 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: when to use Kc vs Kp
- Replies: 11
- Views: 471
Re: when to use Kc vs Kp
Kc usually deals with molar concentration and the activity of chemical reactions. Kp deals with partial pressure only when the products and reactants are forms of gasses.
- Wed Dec 04, 2019 9:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs linear
- Replies: 56
- Views: 4393
Re: Bent vs linear
A molecule would be linear if there is one central atom and no lone pairs on the central atom where as the molecule would be bent if there is a lone pair. The only exception is AX2E3 where it is also linear.
- Wed Dec 04, 2019 9:36 pm
- Forum: Lewis Acids & Bases
- Topic: HCl and HI
- Replies: 10
- Views: 594
Re: HCl and HI
HI is more stronger because chlorine is more electronegative and will have a stronger bond. The weaker the bond the stronger the acid.
- Wed Dec 04, 2019 9:28 pm
- Forum: Amphoteric Compounds
- Topic: H2O
- Replies: 8
- Views: 485
Re: H2O
H20 can be both since it can accept/give protons and it can also be amphoteric.
- Wed Dec 04, 2019 9:24 pm
- Forum: Polyprotic Acids & Bases
- Topic: Ka value
- Replies: 5
- Views: 473
Re: Ka value
Ka values will decrease the more negatively charged the ion becomes. The H+ ion would be harder to lose thus Ka1 would be the greatest.
- Wed Dec 04, 2019 9:19 pm
- Forum: Lewis Acids & Bases
- Topic: Lewis and Bronsted
- Replies: 3
- Views: 324
Re: Lewis and Bronsted
Bronsted bases and acids deal with protons (H+) where bases accept protons while acids give them off. Vice versa with Lewis bases and acids except it would be electrons instead of protons.
- Mon Nov 25, 2019 7:46 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular shape of carbon Dioxide
- Replies: 10
- Views: 655
Re: Molecular shape of carbon Dioxide
CO2 would have a molecular shape of Linear since it follows the AX2 model which corresponds to a bond angle of 180 degrees.
- Mon Nov 25, 2019 7:43 am
- Forum: Octet Exceptions
- Topic: expanded octet
- Replies: 7
- Views: 667
Re: expanded octet
Elements that can have expanded octets include the 3rd row and every element below. This is due to the d-block with some elements as an exception to this rule. Elements above the third row must fulfill the octet rule when drawing a lewis structure.
- Mon Nov 25, 2019 7:40 am
- Forum: Dipole Moments
- Topic: Melting points
- Replies: 15
- Views: 1361
Re: Melting points
Melting point has a direct relationship with intermolecular forces. If the strength of a intermolecular force is strong, then the melting point must be high and vice versa with a weaker IMF. For example, molecules that have dispersion would have a lower melting point than for example a hydrogen bond...
- Mon Nov 25, 2019 7:38 am
- Forum: Sigma & Pi Bonds
- Topic: Molecular Shape
- Replies: 11
- Views: 749
Re: Molecular Shape
Sigma and pi bonds do not really affect molecular shape due to bonds (single, double, or triple) being considered as only one region of electron density.
- Mon Nov 25, 2019 7:35 am
- Forum: Bond Lengths & Energies
- Topic: Hydrogen Bonding and Dispersion
- Replies: 5
- Views: 375
Re: Hydrogen Bonding and Dispersion
Hydrogen bonding occurs when hydrogen is bonded to Nitrogen, Oxygen, or Fluorine. Dispersion occurs when two non polar molecules interact. Also dispersion is the most weakest intermolecular force, while hydrogen bonding is one of the strongest.
- Mon Nov 25, 2019 7:33 am
- Forum: Coordinate Covalent Bonds
- Topic: Covalent character: BeCl2 Vs MgCl2
- Replies: 4
- Views: 2753
Re: Covalent character: BeCl2 Vs MgCl2
BeCl2 has more covalent character due to the fact that the electronegativity difference is smaller than MgCl2.
- Mon Nov 25, 2019 7:31 am
- Forum: Coordinate Covalent Bonds
- Topic: carbon monoxide formal charges
- Replies: 5
- Views: 890
Re: carbon monoxide formal charges
This is due to the lewis structure as carbon monoxide requires a triple bond to fulfill the 10 valence electrons needed in the structure. Furthermore when conducting formal charge, carbon would have a +1 charge while oxygen would have a -1 charge.
- Mon Nov 25, 2019 7:29 am
- Forum: Properties of Light
- Topic: Frequency vs. Velocity
- Replies: 8
- Views: 878
Re: Frequency vs. Velocity
Frequency and velocity are not the same thing as frequency is obtained by dividing the speed of light over a give wavelength where as velocity is always a constant as "c" which is the speed of light.
- Mon Nov 25, 2019 7:25 am
- Forum: Sigma & Pi Bonds
- Topic: sigma and pi bonds
- Replies: 27
- Views: 1729
Re: sigma and pi bonds
Single bonds will always be a sigma bond. Double bonds will always have one pi and one sigma bond. Lastly, triple bonds will always have 2 pi bonds and one sigma bond.
- Mon Nov 25, 2019 7:24 am
- Forum: Coordinate Covalent Bonds
- Topic: Electronegativity
- Replies: 12
- Views: 1778
Re: Electronegativity
Electronegativity increases as you go up and to the right of the periodic table thus why Fluorine has the highest electronegativity. Based on electron affinity and ionization energy trends this also correlates with higher electronegativity.
- Sun Nov 17, 2019 3:23 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Repulsion
- Replies: 6
- Views: 339
Repulsion
How do you determine repulsion strength and finding the least amount of repulsion when given a structure?
- Sun Nov 17, 2019 3:16 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 2
- Views: 190
Bond Angles
How would you determine the angle of a bond and know that it should be lower than a specific type of angle bond? For example, if a molecule is trigonal planar, we would need to know that the bond angles would be exactly 120 degrees?
- Sun Nov 17, 2019 2:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Distortion
- Replies: 2
- Views: 192
Distortion
What does the term "distort" refer to when talking about naming molecules and angles?
- Sun Nov 17, 2019 2:41 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR Model
- Replies: 5
- Views: 166
Re: VSEPR Model
Electron arrangement refers to the placement of electrons, while the molecular shape would determine the bound atoms of a molecule and show the actual regions of electron density, allowing us to determine the name of the shape of the molecule.
- Sun Nov 17, 2019 2:05 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Electron Density
- Replies: 2
- Views: 219
Re: Electron Density
Since an electron is present, this represents a region of electron density. If it were a bond or lone pair or just a single electron present, as long as there is one electron, it is a region.
- Fri Nov 08, 2019 11:53 am
- Forum: DeBroglie Equation
- Topic: De Broglie Equation Derivation and Use
- Replies: 7
- Views: 1196
Re: De Broglie Equation Derivation and Use
De Broglie Equation is used to find the wavelength of a particle with momentum, usually dealing with an electron. The equation is wavelength (lambda)=h/p where p can be rewritten as mass * velocity, while h represents Planck's constant.
- Fri Nov 08, 2019 11:48 am
- Forum: DeBroglie Equation
- Topic: Light waves
- Replies: 2
- Views: 231
Re: Light waves
You only use De Broglie when dealing with a particle with momentum, typically having mass and velocity. When solving for light waves, you would use E=Hv, and c=wavelength*v
- Fri Nov 08, 2019 11:46 am
- Forum: Photoelectric Effect
- Topic: frequency and ejection of electrons
- Replies: 7
- Views: 830
Re: frequency and ejection of electrons
Based on the photoelectric effect, the ejection of electrons are determined by the frequency. If the light source has a short wavelength then it can eject electrons since the frequency would be high.
- Fri Nov 08, 2019 11:42 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: central atom
- Replies: 21
- Views: 1067
Re: central atom
The central atom should be the most electronegative and while creating Lewis Structures, you want the formal charge to be as close to 0 as possible. You may need to change/add bonds such as by adding double bonds to fulfill that formal charge, it just depends on the compound given.
- Fri Nov 08, 2019 11:41 am
- Forum: Lewis Structures
- Topic: Exceptions to Octet Rule
- Replies: 7
- Views: 424
Re: Exceptions to Octet Rule
Elements in the third period can have more than 8 electrons and are the only exceptions to the octet rule. For example, Cl would be an exception.
- Sun Nov 03, 2019 6:57 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge and Energy
- Replies: 4
- Views: 359
Re: Formal Charge and Energy
Formal charge shows us which atom has the highest energy due to it indicating if electrons were gained or lost during the bond. Based on the charge, we would determine which Lewis Structure would be best based on having the lowest formal charges.
- Sun Nov 03, 2019 6:38 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic vs Covalent
- Replies: 14
- Views: 902
Re: Ionic vs Covalent
You can tell if a bond is ionic or covalent based on the atoms present. Ionic bonds are bonds between a metal and nonmetal whereas covalent bonds are bonds between two nonmetals. Knowing this, you can determine whether a bond is ionic or covalent.
- Sun Nov 03, 2019 6:35 pm
- Forum: DeBroglie Equation
- Topic: Confused about equations
- Replies: 7
- Views: 438
Re: Confused about equations
When mass is given, use De Broglie hence the "m" in the equation and not on the other light equations. Also the light equations given, usually relate to photons where as De Broglie relates to electrons.
- Sun Nov 03, 2019 6:19 pm
- Forum: Lewis Structures
- Topic: Steps to Drawing a Lewis Structure
- Replies: 6
- Views: 503
Re: Steps to Drawing a Lewis Structure
First, count the amount of valence electrons. Second, determine what atom is most electronegative, this will be the central atom. Next, fill in bonds and dots based on the amount of electrons and the octet rule. Next, calculate the formal charges and keep manipulating bonds until you get the lowest ...
- Sun Nov 03, 2019 5:59 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Dilution Equation
- Replies: 4
- Views: 314
Re: Dilution Equation
It just depends on the question and the units given. If V2/V1 was given in mL, and you were to find the other volume using the dilution equation, you would to have your final answer be in mL as well.
- Sun Oct 27, 2019 5:41 pm
- Forum: Lewis Structures
- Topic: 2C15
- Replies: 1
- Views: 173
2C15
Two contributions to the resonance structure are shown below for each species. Determine the formal charge on each atom and then, if possible, identify the Lewis structure of lower energy for each species. a) Shows two structures of (HS03)^- one with a double bond one without no double bond. b) Show...
- Sun Oct 27, 2019 5:28 pm
- Forum: Ionic & Covalent Bonds
- Topic: Double bond placement
- Replies: 15
- Views: 918
Re: Double bond placement
In most cases, double bond placement does not really matter as long as you fulfill the amount of electrons required to represent the molecule and that you follow the octet rule. If you see Hydrogen, Oxygen, Nitrogen, or Carbon, just note that Hydrogen prefers 1 bond, Oxygen (2), Nitrogen (3), and Ca...
- Sun Oct 27, 2019 5:22 pm
- Forum: Lewis Structures
- Topic: Creating Lewis Structures
- Replies: 7
- Views: 308
Creating Lewis Structures
If we were to be given a compound such as ONF, how would we know which atom would be in the middle of the structure?
- Sun Oct 27, 2019 5:20 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Exceptions to Electron Configuration
- Replies: 7
- Views: 370
Re: Exceptions to Electron Configuration
Furthermore to Copper and Chromium being the only exceptions, half full/ full d sub-shells have lower energy thus they are more stable. With Cr and Cu having 1 electron on the 4s sub-shell that electron would be willing to be moved to the d sub shell to fulfill that stability.
- Sat Oct 26, 2019 11:39 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic and Covalent Bonds
- Replies: 5
- Views: 287
Re: Ionic and Covalent Bonds
Ionic Bonds is when an ion with a positive charge bonds with an ion with a negative charge. This is when a metal typically bonds with a non metal. On the other hand, Covalent Bonds is when two nonmetals form a bond through the sharing of electrons.
- Sun Oct 20, 2019 5:15 pm
- Forum: DeBroglie Equation
- Topic: DeBroglie Equation
- Replies: 11
- Views: 383
Re: DeBroglie Equation
DeBroglie Equation is used to calculate DeBroglie Wavelength. You use this when given given that a particle has momentum and are trying to find the wavelength. To find this number you must use Planck's constant and divide that by the mass and velocity of the particle. Since we are calculating wavele...
- Sun Oct 20, 2019 4:59 pm
- Forum: Photoelectric Effect
- Topic: 1B19
- Replies: 3
- Views: 249
1B19
Protons and neutrons have nearly the same mass. How different are their wavelengths? Calculate the wavelength of each particle when traveling at 2.75 * 10^5 m*s^-1 in a particle accelerator and report the difference as a percentage of the wavelength of the neutron. I am confused on how to calculate ...
- Sun Oct 20, 2019 4:25 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Hund's rule and Pauli Exclusion Principle
- Replies: 14
- Views: 863
Re: Hund's rule and Pauli Exclusion Principle
Hund's Rule and Pauli Exclusion Principle share a relationship in which both relate to the building-up principle. Hund's Rule states that electrons in same subshell disperse through different orbitals with the same spins (parallel), where as Pauli Exclusion Principle allows a maximum of two electron...
- Sun Oct 20, 2019 3:03 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Frequencies
- Replies: 7
- Views: 488
Re: Frequencies
It would be beneficial if you at least had a general understanding of the electromagnetic spectrum, particular visible light (400-700 nm). There was a question on the textbook, (1A5) I believe where it asks to put some of the radiation in the order of increasing energy, so that may be something to n...
- Sun Oct 20, 2019 2:34 pm
- Forum: DeBroglie Equation
- Topic: Wavelike properties of protons
- Replies: 2
- Views: 155
Re: Wavelike properties of protons
Yes, protons, neutrons, and electrons all have wavelike properties. Based on De Broglie's Equation, any moving particle with moment has wavelike properties, thus neutrons and protons would fit this property.
- Sun Oct 13, 2019 6:52 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: M1V1=M2V2
- Replies: 11
- Views: 87129
Re: M1V1=M2V2
You use M1V1=M2V2 in dilution problems, typically asking for either the concentration or volume in either the initial side or final side of the equation. One to thing to note is to look closely at what the question is asking for. Just because you are given 2 volume measurements and 1 concentration v...
- Sun Oct 13, 2019 6:24 pm
- Forum: SI Units, Unit Conversions
- Topic: Unit conversion
- Replies: 15
- Views: 1593
Re: Unit conversion
To convert from angstrom to any other units you must first understand the scientific notation of each measurement. Knowing that information you should use dimensional analysis, in other words, you would be making conversions in which you are cancelling out terms to where the units you want are in th...
- Sun Oct 13, 2019 5:49 pm
- Forum: Significant Figures
- Topic: Sig Figs at the Beginning or End
- Replies: 14
- Views: 4910
Re: Sig Figs at the Beginning or End
You want your answer to be as accurate as possible so definitely focus on significant figures at the end of your calculation. In most cases, you could get away with rounding Oxygen's atomic mass to 16 grams or Hydrogen to 1.01 grams, but essentially you want to keep those significant figures and rou...
- Sun Oct 13, 2019 5:16 pm
- Forum: DeBroglie Equation
- Topic: Wave properties of electrons
- Replies: 3
- Views: 139
Re: Wave properties of electrons
Based on quantum mechanics, all matter has wavelike properties, including neutrons. As long as there is no indication that the the velocity or mass of an object is 0, it can be inferred that a particle has wavelike properties. We are only able to identify this if a particle has a relative low mass w...
- Sun Oct 13, 2019 4:58 pm
- Forum: Properties of Light
- Topic: Photoelectric vs. Atomic spectra
- Replies: 4
- Views: 198
Re: Photoelectric vs. Atomic spectra
The difference between the photoelectric effect and atomic spectroscopy is that one focuses on the analysis of light being either emitted or absorbed by a substance (spectroscopy) where as the other focuses on the emission of electrons when light hits a substance, for example metal. In spectroscopy,...
- Fri Oct 04, 2019 1:10 am
- Forum: SI Units, Unit Conversions
- Topic: scientific notation
- Replies: 7
- Views: 332
Re: scientific notation
I would use scientific notation when you have an answer that is either very large or very small, involving a lot of zeros as place holders for instance. You want to make sure your answer looks simplified. For example, even Avogadro's constant number is in scientific notation since the number itself ...
- Fri Oct 04, 2019 1:02 am
- Forum: Molarity, Solutions, Dilutions
- Topic: Converting Before or After?
- Replies: 10
- Views: 615
Re: Converting Before or After?
You should always convert after you've completed all steps necessary. For example if it is asking for volume, evidently the answer should be in some form of liter measurement. In these types of cases, just pay attention to the units given and determine whether you would need it to be in milliliters,...
- Fri Oct 04, 2019 12:46 am
- Forum: Significant Figures
- Topic: How would sig figs be used in a problem?
- Replies: 7
- Views: 214
Re: How would sig figs be used in a problem?
Usually, you would need to identify the least amount of significant figures given in the problem. Your answer should reflect that number. One example, could be multiplying the values (17.2) and (2.9) after calculations you would get 49.88 but as you can see, (2.9) has 2 significant figures thus your...
- Thu Oct 03, 2019 6:40 pm
- Forum: Limiting Reactant Calculations
- Topic: M19
- Replies: 3
- Views: 251
M19
M19) A stimulant in coffee and tea is caffeine, a substance of molar mass 194 g*mol^-1. When 0.376 g of caffeine was burned, 0.682 g of carbon dioxide, 0.174 g of water, and 0.110 g of nitrogen were formed. Determine the empirical and molecular formulas of caffeine, and write the equation for its co...