Search found 100 matches

by LNgo 1G
Thu Mar 12, 2020 9:09 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Pre-equilibrium vs Steady state approach
Replies: 3
Views: 49

Re: Pre-equilibrium vs Steady state approach

I don't believe that we are going to be responsible for knowing the steady-state method.
by LNgo 1G
Thu Mar 12, 2020 9:05 am
Forum: Administrative Questions and Class Announcements
Topic: Final exam content
Replies: 15
Views: 365

Re: Final exam content

I think the questions will be similar to the homework problems and the concepts will be taken from the homework, but all of the questions will not come from the homework assigned problems.
by LNgo 1G
Wed Mar 11, 2020 12:49 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Reaction orders
Replies: 3
Views: 32

Reaction orders

Are the stoichiometric coefficients always used as the order of the reactants?
by LNgo 1G
Wed Mar 11, 2020 12:44 pm
Forum: General Rate Laws
Topic: intermediates
Replies: 12
Views: 71

Re: intermediates

Right, generally they are not present in the written form of the overall reaction.
by LNgo 1G
Wed Mar 11, 2020 12:37 pm
Forum: General Rate Laws
Topic: Instantaneous rate
Replies: 4
Views: 62

Re: Instantaneous rate

We also learned how to calculate average rate of reaction. When would we use that equation rather than the instantaneous rate?
by LNgo 1G
Wed Mar 04, 2020 11:08 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Calculating Gibbs Free Energy
Replies: 6
Views: 100

Calculating Gibbs Free Energy

When calculating Gibbs free energy, do you take into account stoichiometric coefficients?
by LNgo 1G
Wed Mar 04, 2020 11:05 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Units for G°
Replies: 6
Views: 57

Re: Units for G°

I believe it is Joules per mol because the constant n in the equation delta G=nFE represents the number of electrons transferred but is represented by a unit less value.
by LNgo 1G
Tue Mar 03, 2020 11:43 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 3
Views: 55

Cell Diagrams

Are ions that are not involved in the oxidation/reduction half reactions included in cell diagrams? For instance, if there is a cell containing AgNO3(aq), and Ag+ + e- -> Ag(s), would you include NO3-(aq) in the cell diagram ?
by LNgo 1G
Tue Mar 03, 2020 11:38 am
Forum: Second Order Reactions
Topic: [A] v. Time
Replies: 16
Views: 185

[A] v. Time

For a first order reaction the [A] v Time plot is a decreasing exponential but what would the graph of [A] v Time look like for a second order reaction?
by LNgo 1G
Tue Mar 03, 2020 11:35 am
Forum: Zero Order Reactions
Topic: Difference
Replies: 5
Views: 91

Re: Difference

In each of the different order reactions, their reaction rates are affected by the concentration of reactants differently or not at all (in the case of zero order).
by LNgo 1G
Thu Feb 27, 2020 3:04 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: log and ln in Nernst
Replies: 8
Views: 78

Re: log and ln in Nernst

It doesn’t matter which you use but I think in lecture he said that biologist usually use log because pH is calculated using log.
by LNgo 1G
Thu Feb 27, 2020 2:54 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: nerst
Replies: 7
Views: 121

Re: nerst

The n in the Nernst equation stands for the number of electrons transferred in the balanced reaction. The book says that the units of n is not moles and is just a unit less number. Then when you solve of delta G you get a value in J/mol since the moles don’t cancel out in your calculation.
by LNgo 1G
Thu Feb 27, 2020 2:48 pm
Forum: Balancing Redox Reactions
Topic: Galvanic Cell - Favorability and oxidation number?
Replies: 3
Views: 50

Re: Galvanic Cell - Favorability and oxidation number?

I’m not sure but if the redox number you’re referring to is the E vale of the cell, then you can tell the reaction is favorable if the cell potential (E) is positive.
by LNgo 1G
Thu Feb 27, 2020 2:45 pm
Forum: General Science Questions
Topic: Test 2
Replies: 16
Views: 316

Re: Test 2

Kallista McCarty 1C wrote:It will cover the rest of thermodynamics that was not on the midterm and all of electrochemistry!

Would that just be Gibbs Free Energy as the thermodynamics portion?
by LNgo 1G
Wed Feb 26, 2020 7:10 pm
Forum: Balancing Redox Reactions
Topic: Homework 6M1
Replies: 5
Views: 110

Re: Homework 6M1

Cu is the anode since it is losing electrons, and M is the cathode since it is gaining electrons. (I remember this by Red Cat and An Ox: Red uction- Cat hode, An ode- Ox idation :)). Eº=Eº(cathode)-Eº(anode), so you would plug in the voltages to solve for Eº(cathode). How do you know Cu is losing e...
by LNgo 1G
Fri Feb 21, 2020 9:12 am
Forum: Balancing Redox Reactions
Topic: Balancing Redox Reactions in Basic Solution
Replies: 4
Views: 51

Re: Balancing Redox Reactions in Basic Solution

Use H+ to balance the hydrogens first and then add OH- to both sides to balance the H+ ions.
by LNgo 1G
Fri Feb 21, 2020 9:10 am
Forum: Balancing Redox Reactions
Topic: balancing half reactions in a basic solution
Replies: 7
Views: 69

Re: balancing half reactions in a basic solution

Yes, add the same number of OH- molecules as you have H+ ions to both sides.
by LNgo 1G
Thu Feb 20, 2020 4:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Purpose of Salt Bridge
Replies: 12
Views: 117

Re: Purpose of Salt Bridge

When electrons move from one solution in the cell, they are replaced by negatively charged ions, and when they move into the solution in the other cell, positively charged ions balance the negative charge.
by LNgo 1G
Thu Feb 20, 2020 4:06 pm
Forum: Balancing Redox Reactions
Topic: oxidation numbers
Replies: 3
Views: 38

Re: oxidation numbers

Yes, because when the oxidation number increases, that would mean the negatively charged electrons are being lost by oxidation and vice versa for reduction.
by LNgo 1G
Thu Feb 20, 2020 3:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: standard hydrogen electrode
Replies: 3
Views: 37

Re: standard hydrogen electrode

A standard hydrogen electrode models the reduction of H+ to H2 and it is used as a comparison for other redox reactions.
by LNgo 1G
Thu Feb 13, 2020 5:35 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Cv vs Cp
Replies: 17
Views: 282

Re: Cv vs Cp

Use Cv when volume is constant and Cp when pressure is constant.
by LNgo 1G
Thu Feb 13, 2020 5:34 pm
Forum: Ideal Gases
Topic: initial values
Replies: 6
Views: 141

Re: initial values

I believe you use the initial volume because you are trying to find the number of moles at the beginning of the process.
by LNgo 1G
Thu Feb 13, 2020 12:27 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isobaric systems
Replies: 16
Views: 196

Re: Isobaric systems

In an isobaric system, pressure is constant, so delta P would equal zero. In this case, work can be calculated using the formula w=-PdeltaV and heat can be calculated using q=deltaH.
by LNgo 1G
Wed Feb 12, 2020 4:12 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermal Reversible
Replies: 6
Views: 75

Isothermal Reversible

Are reversible processes always isothermal?
by LNgo 1G
Tue Feb 11, 2020 5:44 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Standard Molar Entropies
Replies: 1
Views: 31

Standard Molar Entropies

Why are standard molar entropies always positive?
by LNgo 1G
Wed Feb 05, 2020 1:39 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: defintion
Replies: 6
Views: 74

Re: defintion

The energy from heat being added to the system is represented by q, while w represents the energy leaving the system due to work.
by LNgo 1G
Wed Feb 05, 2020 1:34 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Insulated system
Replies: 5
Views: 49

Insulated system

How does a system being thermally insulated affect its entropy?
by LNgo 1G
Wed Feb 05, 2020 1:25 pm
Forum: Calculating Work of Expansion
Topic: Reversible vs. Irreversible
Replies: 3
Views: 61

Re: Reversible vs. Irreversible

An expansion is reversible when temperature is constant, but pressure and volume are variables; it is irreversible when pressure is constant and temperature changes.
by LNgo 1G
Wed Feb 05, 2020 1:22 pm
Forum: Calculating Work of Expansion
Topic: Reversible Process
Replies: 2
Views: 31

Re: Reversible Process

The system is in equilibrium, so the Pint and Pext are essentially equal with very small shifts that are balanced by work.
by LNgo 1G
Wed Feb 05, 2020 1:20 pm
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: Calculating degeneracy
Replies: 1
Views: 26

Calculating degeneracy

When calculating the degeneracy (W) of a molecule, using X^N where X=the number of particles and N=the number of energy states, how is N determined? And can you give an example of this?
by LNgo 1G
Thu Jan 30, 2020 9:35 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Calculating enthalpy
Replies: 1
Views: 30

Calculating enthalpy

When do you use Hess' Law v. Enthalpies of formation?
by LNgo 1G
Thu Jan 30, 2020 9:32 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Constant Pressure
Replies: 7
Views: 73

Re: Constant Pressure

When a system has constant pressure, there is no change in pressure. It means the same for volume.
by LNgo 1G
Thu Jan 30, 2020 9:30 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Mondays Lecture Question
Replies: 3
Views: 36

Re: Mondays Lecture Question

Because the reaction in that example is between a string acid and a strong base, it is a neutralization acid and forms water. The density of pure water is about 1.0 g/mL.
by LNgo 1G
Thu Jan 30, 2020 9:26 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Delta H v. q
Replies: 5
Views: 70

Delta H v. q

What is the difference between delta H and q?
by LNgo 1G
Thu Jan 30, 2020 9:23 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalphy of Combustion
Replies: 2
Views: 38

Re: Enthalphy of Combustion

When given the enthalpy of combustion, you need to write out the combustion equations which would generally by the substance + O2 -> CO2 + H2O and from there you can use Hess' Law to manipulate the equations and add the enthalpies to find the enthalpy of the reaction.
by LNgo 1G
Thu Jan 23, 2020 9:43 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic vs. Endothermic reactions
Replies: 12
Views: 431

Re: Exothermic vs. Endothermic reactions

If it is asking about temperature effects/changes, I would assume that either endo/exothermic or the delta H value will be given and you can determine the other by knowing that exothermic reactions have a negative delta H value and endothermic reactions have a positive delta H value.
by LNgo 1G
Thu Jan 23, 2020 9:40 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Difference in PH between strong and weak acids
Replies: 11
Views: 144

Re: Difference in PH between strong and weak acids

Strong acids dissociate more than weak acids, resulting in a higher hydronium concentration in the solution. Where pH=-log[H3O+] a higher concentration of hydronium correlates to a lower pH value.
by LNgo 1G
Thu Jan 23, 2020 9:34 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Acidity Constant
Replies: 4
Views: 42

Re: Acidity Constant

In lecture this was described as the "conjugate seesaw" where strong acids/bases tend to have a weak conjugate base/acid and vice versa.
by LNgo 1G
Thu Jan 23, 2020 9:29 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le chatelier and Temperature
Replies: 9
Views: 108

Re: Le chatelier and Temperature

When a reaction is endothermic, it requires heat and has a positive delta H value, so you can think of heat as a reactant in a way. When it is exothermic, heat is given off during the reaction and delta H is negative, so heat can be thought of as a product of the reaction in this case.
by LNgo 1G
Thu Jan 23, 2020 9:22 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5% rule
Replies: 13
Views: 131

Re: 5% rule

I believe you can use it whenever you are calculating K using ICE table just as long as K<10^-3
by LNgo 1G
Thu Jan 16, 2020 4:40 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Endo/exothermic
Replies: 3
Views: 48

Endo/exothermic

In a reaction where X2 -> 2X is it considered endothermic or exothermic and why? (X stands for any element)
by LNgo 1G
Thu Jan 16, 2020 4:37 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Approximating -x
Replies: 3
Views: 44

Re: Approximating -x

You can approximate if the x value is less than or equal to 10^-3 I believe.
by LNgo 1G
Thu Jan 16, 2020 4:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When to find pressure for equilibrium problems
Replies: 3
Views: 28

Re: When to find pressure for equilibrium problems

I believe you only need to solve partial pressure when asked for the partial P for the individual compounds or if you need to solve for Kp.
by LNgo 1G
Wed Jan 15, 2020 11:44 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: calculating kP
Replies: 4
Views: 52

Re: calculating kP

I do not think the equilibrium constant will be different if the gases are in atm, bar, etc. as long as all of the pressure values have the same units because the equilibrium constant is a ration of products to reactants.
by LNgo 1G
Wed Jan 15, 2020 11:41 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Writing K for heterozygous reactions
Replies: 5
Views: 48

Re: Writing K for heterozygous reactions

Liquids are not included when calculating Kc, but if you have both aqueous and gaseous compounds you can calculate Kc including all gaseous and aqueous compounds.
by LNgo 1G
Thu Jan 09, 2020 3:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: solid/liquid
Replies: 7
Views: 48

Re: solid/liquid

It can be replaced with a 1 because it does not affect the calculation, but also I think it would okay to just not include the l/s molecules in the formula.
by LNgo 1G
Thu Jan 09, 2020 3:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp v. Kc
Replies: 5
Views: 40

Kp v. Kc

When given the equilibrium constant as K for a reaction with only gases, is it safe to assume that the K value is meant to be the Kp? If not, how do you know whether it is Kp r Kc?
by LNgo 1G
Thu Jan 09, 2020 3:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Purity
Replies: 3
Views: 57

Re: Purity

I think in lecture a "pure" substance was described as that in a liquid or solid state. When calculating the equilibrium constant, solids nor liquids are included in the formula.
by LNgo 1G
Thu Jan 09, 2020 3:38 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: Hydrogen Bond
Replies: 2
Views: 324

Re: Hydrogen Bond

I don't believe a hydrogen bond could form with an O2 molecule because hydrogen bonds are dipole-dipole interactions and O2, as a linear molecule, does not have a dipole moment.
by LNgo 1G
Thu Jan 09, 2020 3:34 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: How to interpret reactions based on quotient in relation to equilibrium constant
Replies: 5
Views: 65

Re: How to interpret reactions based on quotient in relation to equilibrium constant

When Q > K there is a larger amount of products than there are at equilibrium, so the reaction will proceed in the reverse direction to use up the excess products. When Q < K there is a larger amount of reactants than there are at equilibrium, so the reaction will proceed in the forward direction to...
by LNgo 1G
Fri Dec 06, 2019 5:17 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Size of nucleus = delta x?
Replies: 3
Views: 138

Re: Size of nucleus = delta x?

The uncertainty, or delta x value, represents the distance that the electron can be located. If the uncertainty is larger in the case of the example that we did in class, that would mean that the electron would exist outside the nucleus of the atom.
by LNgo 1G
Fri Dec 06, 2019 5:11 pm
Forum: Naming
Topic: cyano v. cyanido
Replies: 4
Views: 87

cyano v. cyanido

When would you use the -o ending versus the -ido ending when naming ligands? In the practice problems I saw both of them in different examples in the case of the cyanide molecule and cannot tell when to use one or the other.
by LNgo 1G
Tue Dec 03, 2019 10:20 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: acidic trends
Replies: 3
Views: 51

Re: acidic trends

There are different components that contribute the acidity of a molecule, but concerning electronegativity, acids containing a central atom with higher negativity allows for a more stable conjugate base, so the acid is more likely to dissociate.
by LNgo 1G
Tue Dec 03, 2019 10:17 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Neutral or Negative Acid
Replies: 2
Views: 48

Re: Neutral or Negative Acid

Since solutions with a pH of 6 are sometimes considered neutral and other times considered acidic, because it is lower than the neutral pH of 7. When the solution is more acidic, the acid dissociates as it gives of a proton (H+ ion), leaving the negatively charged conjugate base in the solution.
by LNgo 1G
Tue Dec 03, 2019 10:13 pm
Forum: Naming
Topic: Naming Compounds
Replies: 2
Views: 37

Naming Compounds

When haming compounds, when would you have an -o ending versus an -ato ending? For example, I have seen cyanide named -cyano- and -cyanato- in different compounds.
by LNgo 1G
Tue Nov 26, 2019 6:03 pm
Forum: Lewis Acids & Bases
Topic: Identifying Lewis Acids and Bases
Replies: 3
Views: 34

Re: Identifying Lewis Acids and Bases

When looking at the reaction equation you can tell which is an acid because it would have donated a hydrogen atom whereas the conjugate base would be the compound that received a hydrogen atom.
by LNgo 1G
Tue Nov 26, 2019 5:59 pm
Forum: Bronsted Acids & Bases
Topic: Difference
Replies: 3
Views: 41

Re: Difference

Lewis acids/bases are characterized by the donating or receiving of an electron pair while Bronsted acids/bases are characterized by the donating or receiving of a hydrogen ion.
by LNgo 1G
Tue Nov 26, 2019 5:56 pm
Forum: Lewis Acids & Bases
Topic: oxides
Replies: 3
Views: 42

Re: oxides

Oxides are compounds that include one or more oxygen atom. They are important in acid/base reactions because the oxygen atom forms a bond with one of the hydrogen atoms in a water molecule to create OH- and this reaction is used to characterize bases.
by LNgo 1G
Mon Nov 25, 2019 1:34 pm
Forum: Bronsted Acids & Bases
Topic: Why do acids and bases react?
Replies: 3
Views: 47

Re: Why do acids and bases react?

I believe this would be considered a substitution reaction, so the ions do essentially "switch". The bonds in the molecules break in water due to hydrogen bonding and are reformed in more stable structures.
by LNgo 1G
Mon Nov 25, 2019 1:30 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: polydentate
Replies: 3
Views: 46

Re: polydentate

This is when there are more than one central atoms that ligands bind too, a good example would be triphosphate where the oxygen atoms are the ligands and the phosphate atoms are the central atoms.
by LNgo 1G
Wed Nov 20, 2019 11:31 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw Shape
Replies: 12
Views: 145

Re: Seesaw Shape

The bond angles will be >180, 90, and <120 because the lone pairs exerts repulsive forces on the atoms.
by LNgo 1G
Wed Nov 20, 2019 11:27 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Why is CH2Cl2 polar?
Replies: 12
Views: 147

Re: Why is CH2Cl2 polar?

I think the electron repulsion plays a part in orienting the molecule so that the chlorine atoms are not on opposite poles as you might expect, but they are placed next to each other in the molecular structure.
by LNgo 1G
Tue Nov 19, 2019 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: IMFs and properties
Replies: 2
Views: 50

Re: IMFs and properties

The melting point is higher if the dispersion forces are stronger because it takes more energy to break stronger interactions between molecules.
by LNgo 1G
Tue Nov 19, 2019 11:22 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: Dissociation Energy?
Replies: 2
Views: 35

Re: Dissociation Energy?

Dissociation energy is the energy required to break a bond. Stronger IMFs, such as ion-ion interactions, have greater dissociation energy and weaker IMFs, such as dispersion forces, have lower dissociation energy because the stronger the bond is, the more energy it takes to break it.
by LNgo 1G
Tue Nov 19, 2019 11:19 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: Nonpolar Hydrogen Bonding
Replies: 1
Views: 42

Re: Nonpolar Hydrogen Bonding

I don't believe so since hydrogen bonding is a form of dipole-dipole interactions which do not take place in nonpolar molecules since they do not have dipole moments.
by LNgo 1G
Thu Nov 14, 2019 11:33 pm
Forum: Dipole Moments
Topic: For which of the following molecules will dipole–dipole inter- actions be important
Replies: 2
Views: 58

Re: For which of the following molecules will dipole–dipole inter- actions be important

I believe there would be a dipole moment in the direction of the chlorine atoms, which would both be on the same side of the molecule, not at opposite poles.
by LNgo 1G
Thu Nov 14, 2019 11:26 pm
Forum: Bond Lengths & Energies
Topic: Bond lengths
Replies: 8
Views: 85

Re: Bond lengths

I believe that we should know that as bond strength increases, bond length decreases.
by LNgo 1G
Tue Nov 12, 2019 10:16 pm
Forum: Dipole Moments
Topic: When is there a dipole moment?
Replies: 3
Views: 46

Re: When is there a dipole moment?

Dipole moments result from differences in electronegativity as more electronegative atoms pull the electrons of less electronegative atoms closer to them. This same effect also makes a molecule polar as electrons are being shared unequally.
by LNgo 1G
Tue Nov 12, 2019 10:14 pm
Forum: Dipole Moments
Topic: Dipole Moments
Replies: 4
Views: 69

Re: Dipole Moments

Dipole moments are created from differences in electronegativity, so since Cl is more electronegative than C and H, there will be a dipole moment in the direction of the Cl atoms.
by LNgo 1G
Tue Nov 12, 2019 10:11 pm
Forum: Dipole Moments
Topic: Why doesn't CH3CHO form a hydrogen bond?
Replies: 3
Views: 42

Re: Why doesn't CH3CHO form a hydrogen bond?

I believe it would because O is an electronegative atom which would form H bonds with the H from other CH3CHO molecules.
by LNgo 1G
Thu Nov 07, 2019 6:52 pm
Forum: Lewis Structures
Topic: Radicals
Replies: 5
Views: 122

Radicals

When drawing the Lewis structure for a radical molecule, how do you know which atom the single lone electron belongs to?
by LNgo 1G
Thu Nov 07, 2019 6:50 pm
Forum: Ionic & Covalent Bonds
Topic: Bond Strength
Replies: 12
Views: 215

Bond Strength

Which bonds are stronger: ionic or covalent?
by LNgo 1G
Thu Nov 07, 2019 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: Comparing forces of attraction
Replies: 4
Views: 51

Re: Comparing forces of attraction

Hydrogen bonds are very strong dipole-dipole interactions that occur due to the attraction between partial charges.
by LNgo 1G
Thu Nov 07, 2019 5:23 pm
Forum: Lewis Structures
Topic: Lewis structure
Replies: 5
Views: 60

Re: Lewis structure

Phosphorus can only have 5 bonds total since there are only 10 electron places in the d shell that it uses to expand its octet.
by LNgo 1G
Thu Nov 07, 2019 5:10 pm
Forum: Lewis Structures
Topic: Lewis Structure
Replies: 4
Views: 89

Re: Lewis Structure

The most stable structure will have the most atoms with lower formal charges, closest to or equal to zero.
by LNgo 1G
Thu Oct 31, 2019 5:21 pm
Forum: Resonance Structures
Topic: Difference between Resonance and Lewis structures
Replies: 5
Views: 81

Re: Difference between Resonance and Lewis structures

Resonance occurs when the Lewis structure of a molecule has double or triple bonds that can be applied amongst different atoms, yielding multiple different forms.
by LNgo 1G
Thu Oct 31, 2019 5:09 pm
Forum: Octet Exceptions
Topic: expanded valence shell confusion
Replies: 3
Views: 57

Re: expanded valence shell confusion

Elements that can expand their octet are able to do so because they have the d-orbital to use to hold electrons.
by LNgo 1G
Thu Oct 31, 2019 5:06 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge Calculation
Replies: 4
Views: 79

Re: Formal Charge Calculation

The resonance form with the most formal charges equal to zero means that there is a more equal sharing of electrons since there are no partial charges on the atom(s).
by LNgo 1G
Thu Oct 31, 2019 5:04 pm
Forum: Octet Exceptions
Topic: Half-Full Shell Stability
Replies: 4
Views: 62

Re: Half-Full Shell Stability

The stability of the half-full d orbital may be attributed to the electron shielding effect since the half-full shell allows for a more stable placement of electrons with respect to electron repulsive forces.
by LNgo 1G
Thu Oct 31, 2019 5:02 pm
Forum: Electronegativity
Topic: electronegative
Replies: 6
Views: 118

Re: electronegative

The more electronegative atom pulls the electrons closer to it, resulting in a partial negative charge on that atom and a partial positive charge on the other.
by LNgo 1G
Sat Oct 26, 2019 6:20 pm
Forum: Ionic & Covalent Bonds
Topic: Expanded Valence Shells
Replies: 4
Views: 57

Re: Expanded Valence Shells

Elements in period 3 have access to the d-block orbital which allows them to hold more than the 8 electrons that the period 1 and 2 elements can.
by LNgo 1G
Thu Oct 24, 2019 8:34 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Orbital Box Diagram
Replies: 5
Views: 63

Re: Orbital Box Diagram

Technically it doesn't matter whether the arrow is up or down because it just represents electrons with opposite spins, not in any specific direction, but generally the up arrow goes first.
by LNgo 1G
Thu Oct 24, 2019 8:32 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: order of electron configuration
Replies: 4
Views: 63

Re: order of electron configuration

It depends how many electrons are in the d orbital. If there are 5 or 10 electrons in the d orbital the d will go before the s because it is more stable due to electron shielding; otherwise the s goes before the d orbital.
by LNgo 1G
Thu Oct 24, 2019 8:24 pm
Forum: Lewis Structures
Topic: Bond strength
Replies: 7
Views: 105

Re: Bond strength

Ionic bonds are stronger because they involve the giving and accepting of electrons between atoms while in covalent bonds, the electrons are only shared.
by LNgo 1G
Wed Oct 23, 2019 2:01 pm
Forum: Resonance Structures
Topic: Bond lengths
Replies: 4
Views: 49

Re: Bond lengths

The molecule shifts between all three structures based on where it will be most stable, so it results in the measurement of “partial double bonds”
by LNgo 1G
Fri Oct 18, 2019 4:45 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra
Replies: 5
Views: 89

Re: Atomic Spectra

Atoms in the same energy level are close together on the spectrum which would explain the chunks. The gaps represent the jump between energy levels since they are quantized rather than continuous.
by LNgo 1G
Fri Oct 18, 2019 4:30 pm
Forum: Quantum Numbers and The H-Atom
Topic: Spectral Series
Replies: 3
Views: 90

Spectral Series

If given the wavelength, how can you tell which series (Lyman, Balmer, etc.) a photon falls under?
by LNgo 1G
Wed Oct 16, 2019 2:32 pm
Forum: *Shrodinger Equation
Topic: Wave Functions
Replies: 2
Views: 47

Re: Wave Functions

Wave functions are the path that electrons travel around the nucleus. They can be represented by sin/cos graphs because the electron oscillates as it moves in a circular orbit, not just in a straight path. In chemistry, wave functions can be used to determine the shape of different types of electron...
by LNgo 1G
Wed Oct 16, 2019 2:26 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal plane for s-orbitals?
Replies: 3
Views: 51

Re: Nodal plane for s-orbitals?

I think that the points or planes that mark the separation of these lobes are called nodal planes and since s-orbitals have only a single lobe, there is no point of separation in the orbital. Hope this helps!
by LNgo 1G
Wed Oct 16, 2019 2:18 pm
Forum: Properties of Light
Topic: Difference between Quanta and photons?
Replies: 6
Views: 83

Re: Difference between Quanta and photons?

Quanta is the general term for particles or pieces that make up a whole, like how quantum mechanics refers to the mechanisms behind very small objects. Photons are a quantum measurement of light.
by LNgo 1G
Tue Oct 08, 2019 4:13 pm
Forum: Empirical & Molecular Formulas
Topic: F 17
Replies: 2
Views: 79

Re: F 17

You divide the molar mass given by the empirical mass and then multiply the subscripts of the empirical formula by this number to get the molecular formula.
by LNgo 1G
Tue Oct 08, 2019 4:09 pm
Forum: Limiting Reactant Calculations
Topic: Excess reactants
Replies: 3
Views: 117

Re: Excess reactants

You can use stoichiometry to calculate the amount of the excess reactant that is used in the reaction with the amount of the limiting reactant that you have. Then subtract the value of the excess reactant used in the reaction from the amount given.
by LNgo 1G
Tue Oct 08, 2019 3:55 pm
Forum: Empirical & Molecular Formulas
Topic: empirical to molecular formula [ENDORSED]
Replies: 9
Views: 394

Re: empirical to molecular formula [ENDORSED]

You divide the given molar mass by the empirical mass. The empirical mass will always be smaller than the molecular mass because it is the smallest ratio of the atoms so you can try to remember that you divide by the smaller number.
by LNgo 1G
Tue Oct 08, 2019 3:46 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty of speed
Replies: 5
Views: 63

Re: Uncertainty of speed

I believe the uncertainty would be 5.0. The plus and minus signs just mean that the variation can go either direction.
by LNgo 1G
Tue Oct 08, 2019 3:43 pm
Forum: Molarity, Solutions, Dilutions
Topic: Help with Textbook problem G.21
Replies: 2
Views: 93

Re: Help with Textbook problem G.21

You can use the mole ratios of the individual ions to the compounds given to find the moles of each ion in the solution and divide by volume to get the concentration from there.
by LNgo 1G
Tue Oct 01, 2019 5:15 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Avogadro's Number [ENDORSED]
Replies: 12
Views: 405

Re: Avogadro's Number [ENDORSED]

You use Avogadro's number when you are trying to find the number of particles, atoms, or formula units of a substance.
by LNgo 1G
Tue Oct 01, 2019 5:13 pm
Forum: Limiting Reactant Calculations
Topic: Identifying the Limiting Reactant
Replies: 4
Views: 46

Re: Identifying the Limiting Reactant

I do the limiting reactant problems a little differently. So instead of comparing the moles, I just calculate how many moles of the product each reactant can produce. The reactant that produces the least amount of product is the limiting reactant.
by LNgo 1G
Sun Sep 29, 2019 2:03 pm
Forum: Molarity, Solutions, Dilutions
Topic: homework question G5
Replies: 2
Views: 47

Re: homework question G5

This is a dissociation equation, so it does split into ions, but you might have to take into consideration the solubility of the solution to see how much of the solution dissolves and how much solid is left.
by LNgo 1G
Sun Sep 29, 2019 1:56 pm
Forum: Balancing Chemical Reactions
Topic: Balancing equations
Replies: 7
Views: 671

Re: Balancing equations

It is okay to use fractions when balancing equations; you can compute them into integers by multiplying the entire equation by the denominator. Technically you can't have a fraction of an atom because atoms are the smallest basic units of matter, so generally chemical equations only have whole numbe...
by LNgo 1G
Sun Sep 29, 2019 1:46 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Formula
Replies: 6
Views: 83

Re: Empirical Formula

Using the empirical formula makes it easier to name compounds and to determine the composition of a substance because it represents the smallest whole number ratio of the individual atoms.

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