## Search found 103 matches

Mon Mar 16, 2020 12:00 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Exothermic rxns and heat
Replies: 6
Views: 133

### Re: Exothermic rxns and heat

q would be negative because heat is flowing out of the system.
Tue Mar 10, 2020 12:06 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalyst vs intermediate
Replies: 3
Views: 73

### Re: Catalyst vs intermediate

An intermediate is produced and then used up in the elementary reactions whereas a catalyst is usually seen as a reactant that helps start a reaction.
Tue Mar 10, 2020 9:46 am
Forum: Balancing Redox Reactions
Topic: Test 2
Replies: 19
Views: 244

### Re: Test 2

WYacob_2C wrote:
CynthiaLy4F wrote:I believe it will only cover topics from the midterm up until the end of kinetics.

Would it be up until the end of kinetics or the end of electrochemistry?

Sorry, I meant to say the end of electrochemistry.
Tue Mar 10, 2020 9:41 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: midterm 6 b
Replies: 6
Views: 52

### Re: midterm 6 b

For this problem, the answer would be the reaction that has the smallest change in entropy, which in this case is A.
Tue Mar 10, 2020 9:37 am
Forum: Administrative Questions and Class Announcements
Topic: Final exam content
Replies: 15
Views: 407

### Re: Final exam content

I believe that the final will have a format similar to the midterm. There will most likely be one question that comes directly from the assigned homework problems.
Mon Mar 09, 2020 5:52 pm
Forum: Balancing Redox Reactions
Topic: Balancing redox with h2o
Replies: 9
Views: 156

### Re: Balancing redox with h2o

If the reaction is under acidic conditions, you would balance the oxygen atoms with H2O and the hydrogen atoms with H+. If the reaction is under basic conditions, you would balance the oxygen and hydrogen atoms using H2O and OH-.
Mon Mar 09, 2020 5:43 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Collisions in Unimolecular Reactions
Replies: 2
Views: 53

### Re: Collisions in Unimolecular Reactions

The reactant would still collide with solvent molecules, but that is not shown in the rate law.
Mon Mar 09, 2020 5:31 pm
Forum: General Rate Laws
Topic: 7A 15
Replies: 4
Views: 61

### Re: 7A 15

A reactant would be independent of the rate if the initial rate does not get affected with respect to a change in the concentration of that reactant.
Thu Mar 05, 2020 10:18 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M5
Replies: 2
Views: 33

### Re: 6M5

Yes, Hg(l) acts as the electrode in this case so there is no need for a solid metal.
Thu Mar 05, 2020 10:14 pm
Forum: Balancing Redox Reactions
Topic: 6K.5 part d
Replies: 3
Views: 90

### Re: 6K.5 part d

You will first start off by balancing the P, and then balance the hydrogens by adding one water molecule for each hydrogen that is needed. Balance the O by adding the same number of OH- ions to the opposite side and then add the appropriate number of electrons balance the charges.
Thu Mar 05, 2020 10:05 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Inert electrodes
Replies: 5
Views: 106

### Re: Inert electrodes

You would add an inert electrode if there is no solid electrode present in that half reaction.
Thu Mar 05, 2020 9:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Question 6M.11
Replies: 2
Views: 39

### Re: Question 6M.11

You can determine which species gets oxidized or reduced by looking at the reduction potentials. The species with the higher reduction potential will be the oxidizing agent, which means it will be reduced. The species with the lower reduction potential will be the reducing agent, which means it will...
Thu Mar 05, 2020 9:51 pm
Forum: Balancing Redox Reactions
Topic: Strength of Reducing/Oxidizing Agents
Replies: 4
Views: 82

### Re: Strength of Reducing/Oxidizing Agents

The more negative the standard reduction potential is, the stronger the reducing agent. The more positive the standard reduction potential is, the stronger the oxidizing agent.
Fri Feb 28, 2020 11:27 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: concentration cells
Replies: 5
Views: 75

### Re: concentration cells

Concentration cells are galvanic/voltaic cells comprised of the same electrodes, but differing in concentrations. Electrons will typically transfer from the cell with lower concentration to the one with higher concentration.
Fri Feb 28, 2020 11:13 pm
Forum: Balancing Redox Reactions
Topic: Test 2
Replies: 19
Views: 244

### Re: Test 2

I believe it will only cover topics from the midterm up until the end of kinetics.
Fri Feb 28, 2020 11:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6m5a
Replies: 2
Views: 39

### Re: 6m5a

The diagram does not include a solid in this case because Hg(l) is being used as the electrode on the anode side.
Fri Feb 28, 2020 11:00 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: platinum electrode
Replies: 2
Views: 33

### Re: platinum electrode

You would add a platinum when there is no solid electrode present in the reaction. The reasoning behind adding this platinum electrode is because it is a good inert conductor that does not get too involved in the redox reaction.
Fri Feb 28, 2020 10:53 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: electrolysis
Replies: 3
Views: 50

### Re: electrolysis

Electrolysis essentially takes place in an electrolytic cell and uses an electric current to drive a non-spontaneous reaction. During this process, electrical energy is converted to chemical energy through some sort of power supply, which could then be used to electroplate metals, decompose compound...
Fri Feb 21, 2020 10:03 pm
Forum: Identifying Acidic & Basic Salts
Topic: Midterm 3C
Replies: 6
Views: 310

### Re: Midterm 3C

NH4Cl can be used to lower the pH because it can act as an acid and donate a proton when it dissociates.
Fri Feb 21, 2020 5:41 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating Standard Cell Potentials
Replies: 2
Views: 41

### Re: Calculating Standard Cell Potentials

No, you would not multiply the standard cell potential by 2 because it is considered an intensive property so it does not depend how many times the reaction has occurred.
Fri Feb 21, 2020 5:20 pm
Forum: Balancing Redox Reactions
Topic: Homework 6K1
Replies: 4
Views: 40

### Re: Homework 6K1

If it does not specify the overall charge of the compound, then you would assume it is zero.
Fri Feb 21, 2020 5:15 pm
Forum: Balancing Redox Reactions
Topic: Redox in Acid/ Basic Solutions
Replies: 8
Views: 100

### Re: Redox in Acid/ Basic Solutions

The main difference is how you would balance the half reactions in the redox reaction. Under acidic conditions, you would balance the hydrogen atoms by adding protons (H+). For reactions in basic conditions, you would follow the same process as if it was under acidic conditions, but you would add hy...
Fri Feb 21, 2020 5:03 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Midterm question 3D
Replies: 1
Views: 184

### Re: Midterm question 3D

If the pH is greater than the pKa, then the acid would deprotonate and result in a net charge of -1. If the pH is lower than the pKa, then the acid would remain in its neutral form.
Fri Feb 14, 2020 10:23 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: DeltaS
Replies: 2
Views: 68

### DeltaS

Why does deltaS of surroundings equal to 0 in an isothermal, free expansion?
Fri Feb 14, 2020 10:13 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpies of Formation
Replies: 10
Views: 145

### Re: Standard Enthalpies of Formation

Yes, some standard enthalpies of formation can be zero if the elements are in their most stable form. Some examples include H2, F2, N2, O2, and C(s).
Fri Feb 14, 2020 10:07 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Pizza Rolls 3E
Replies: 4
Views: 77

### Re: Pizza Rolls 3E

This is false because during phase changes, the removal of heat does not necessarily cause temperature to decrease. This can be seen by the plateaus on heating curves.
Fri Feb 14, 2020 9:57 pm
Forum: Calculating Work of Expansion
Topic: work = 0
Replies: 14
Views: 271

### Re: work = 0

The work done under a vacuum is equal to 0 because the external pressure is equal to 0. This is also known as free expansion where there is no opposing force that allows for work to be done.
Fri Feb 14, 2020 9:39 pm
Forum: Calculating Work of Expansion
Topic: Determining Expansion Work
Replies: 4
Views: 131

### Re: Determining Expansion Work

You can tell when a system does expansion work if the number of moles of gas on the product side is greater than the number of moles on the reactant side.
Fri Feb 07, 2020 6:11 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: GFE dividing by temp
Replies: 3
Views: 33

### Re: GFE dividing by temp

I believe the purpose for that was to manipulate the equation to show how -deltaG/T of the system is equal to deltaS of the universe, which means that in order for a spontaneous process to occur where deltaS is positive, then deltaG must be negative.
Fri Feb 07, 2020 4:54 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Change in internal energy
Replies: 3
Views: 41

### Re: Change in internal energy

The change in internal energy is equal to 0 at constant temperature and is equal to q at constant volume.
Fri Feb 07, 2020 4:40 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy
Replies: 2
Views: 44

### Re: Entropy

Residual entropy is the entropy of a sample at T=0 that arise from positional disorder.
Fri Feb 07, 2020 4:31 pm
Forum: Phase Changes & Related Calculations
Topic: Negative Work
Replies: 18
Views: 346

### Re: Negative Work

Work will be negative when the system is doing the work, such as through expansion. Work is positive when is being done on the system, such as through compression.
Fri Feb 07, 2020 4:28 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW 4.15
Replies: 2
Views: 59

### Re: HW 4.15

You would first write a balanced chemical equations and then determine the limiting reagent, which should be zinc. Then calculate the enthalpy of the reaction by using the given enthalpies of formation and find the energy released by the reaction of 8.5g of zinc. After you would use the formula q= m...
Fri Jan 31, 2020 10:16 pm
Forum: Phase Changes & Related Calculations
Topic: 4A5
Replies: 2
Views: 28

### Re: 4A5

I think we do need to be familiar with that equation for the midterm because it was a part of the outline for thermodynamics.
Fri Jan 31, 2020 10:08 pm
Forum: Phase Changes & Related Calculations
Topic: internal energy
Replies: 11
Views: 149

### Re: internal energy

Calculating internal energy corresponds to the deltaU equation, where deltaU = q + w.
Fri Jan 31, 2020 10:05 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A.11
Replies: 3
Views: 25

### Re: 4A.11

The equation used to solve this is q=C*deltaT, which can also be rewritten as C=q/deltaT to find the heat capacity of the calorimeter. q is the heat supplied, which in this case it 22.5 kJ and deltaT is the temperature rise, which can be found by subtracting the two given temperatures.
Fri Jan 31, 2020 9:52 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4B.13
Replies: 2
Views: 51

### Re: 4B.13

For part b, that is the correct equation to use but you would first use the ideal gas law, which is PV=nRT, to calculate the number of moles. Then you would plug it into the equation, w=-nRTln(v2/v1) to calculate the work done.
Thu Jan 30, 2020 10:11 pm
Forum: Calculating Work of Expansion
Topic: Work equation
Replies: 5
Views: 43

### Re: Work equation

There is a negative sign in the work equation because when a system does work, such as through expansion, it is losing energy. When work is done on the system, such as through compression, then it will be a positive value.
Thu Jan 23, 2020 9:59 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: removing H2 from N2 + 3H2 -> 2NH3
Replies: 7
Views: 138

### Re: removing H2 from N2 + 3H2 -> 2NH3

Decreasing H2 from the reaction would cause the equilibrium to shift to the left and produce more reactants in order to minimize the effect of that change.
Thu Jan 23, 2020 9:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q<K
Replies: 11
Views: 91

### Re: Q<K

The forward reaction is favored when Q<K because at that given stage of the reaction, there is a lot more reactants than products. Therefore, for Q to increase and reach equilibrium, more products must be produced.
Thu Jan 23, 2020 9:47 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Changing K
Replies: 13
Views: 116

### Re: Changing K

Temperature is the only factor that can change K. Changes in concentration or pressure does not affect K.
Thu Jan 23, 2020 9:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: homework 6A.23
Replies: 2
Views: 37

### Re: homework 6A.23

For this problem, since it gives you the number of grams of Ba(OH)2, you would convert that into moles and divide it by the given volume of the solution to get the concentration of [Ba2+]. For the concentration of [OH-], you would multiply the concentration of [Ba2+] by 2 because the are 2 moles of ...
Thu Jan 23, 2020 9:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Stoichiometric Coefficients
Replies: 2
Views: 67

### Re: Stoichiometric Coefficients

Yes, that is correct!
Fri Jan 17, 2020 11:56 am
Forum: Equilibrium Constants & Calculating Concentrations
Replies: 10
Views: 102

If you use the quadratic formula and get two positive answers, you would choose the answer where if you subtract it from any of the initial conditions given it would be result in a reasonable and nonnegative concentration or pressure.
Fri Jan 17, 2020 10:09 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids and Equilibrium
Replies: 9
Views: 105

### Re: Solids and Equilibrium

Solids and liquids do not affect equilibrium or the equilibrium constant because solids do not have concentrations and and pure liquids usually act as a solvent in large excess so its concentration is relatively unchanged.
Fri Jan 17, 2020 10:06 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Tips for Test
Replies: 23
Views: 279

### Re: Tips for Test

I would recommend doing all the assigned homework problems, reading the textbook, and going over the concepts on the outlines posted on the class website.
Fri Jan 17, 2020 10:00 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: increasing N2
Replies: 5
Views: 95

### Re: increasing N2

When you increase the amount of N2, it will shift towards the products to make more ammonia. This will result in a decrease in the amount of H2 because the reactants are being used to make products.
Fri Jan 17, 2020 9:55 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook question 6D.5
Replies: 1
Views: 34

### Re: Textbook question 6D.5

The percent protonation should be 1.5%. I believe it was just a typo in the solutions manual.
Fri Jan 10, 2020 10:35 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: predicting effects
Replies: 9
Views: 156

### Re: predicting effects

Removing SO3 would result in an increase of NO because the reaction will try to make more product to minimize the effect of that change.
Fri Jan 10, 2020 10:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.13 Part C
Replies: 2
Views: 33

### Re: 5I.13 Part C

Cl2 is more thermodynamically stable relative to its atoms because it is less likely to dissociate due to its smaller equilibrium constant.
Fri Jan 10, 2020 9:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating K 5I.33
Replies: 2
Views: 29

### Re: Calculating K 5I.33

Yes, you would first find the moles of both the products and then calculate their concentrations and plug it into the equilibrium expression to find Kc.
Fri Jan 10, 2020 9:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units for K
Replies: 10
Views: 88

### Re: Units for K

K is unitless because it is the activities of products over the activities of reactants. Since activities do not have units, K will not have units.
Fri Jan 10, 2020 8:53 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Calculating the Equilibrium Quotient
Replies: 3
Views: 87

### Re: Calculating the Equilibrium Quotient

The reaction basically measures the relative amounts of products and reactants present at any stage of the reaction. It is calculated similarly to how you would calculate for equilibrium constant where the activities of the partial pressures or molar concentrations of the products are divided by the...
Sat Dec 07, 2019 12:21 am
Forum: Naming
Topic: writing formula of a given name
Replies: 5
Views: 112

### Re: writing formula of a given name

I don't think writing the ligands in alphabetical order when writing the formula from the name matters.
Sat Dec 07, 2019 12:10 am
Forum: Naming
Topic: Coordination Number
Replies: 3
Views: 59

### Re: Coordination Number

The coordination number is determined based on the number of points ligands are attached to the central metal atom.
Sat Dec 07, 2019 12:03 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: HW 9C.9
Replies: 2
Views: 64

### Re: HW 9C.9

en would be a bidentate because it binds to the central atom at two points because of the lone pairs on two of its nitrogens. edta would be a hexadentate and bind to the central atom at six points.
Fri Dec 06, 2019 11:51 pm
Forum: Dipole Moments
Topic: London Dispersion Forces
Replies: 5
Views: 136

### Re: London Dispersion Forces

Yes, all molecules have London dispersion forces because there are always instantaneous dipole moments happening as electrons are moving around the molecule.
Fri Dec 06, 2019 11:43 pm
Forum: Conjugate Acids & Bases
Topic: determining conj. acids& bases
Replies: 2
Views: 136

### Re: determining conj. acids& bases

A conjugate base of an acid is the species remaining when an acid donates a proton. For example, the conjugate base of HCN would be CN-. A conjugate acid of a base is the species remaining when the acid donates a proton. For example, the conjugate acid of NH3 would be NH4+.
Fri Nov 29, 2019 5:37 pm
Forum: Lewis Acids & Bases
Topic: acidic oxide/basic oxide
Replies: 2
Views: 70

### Re: acidic oxide/basic oxide

Acidic oxides are molecular compounds, usually of non-metals, that form acids when they react with water. Basic oxides are oxides that react with water to form metal hydroxides.
Fri Nov 29, 2019 5:14 pm
Forum: Lewis Acids & Bases
Topic: 6A.13
Replies: 7
Views: 72

### Re: 6A.13

Ag+ is considered a Lewis acid because it is an electron pair acceptor. The electrons are electrostatically attracted to its positive charge.
Fri Nov 29, 2019 5:09 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted vs. Lewis
Replies: 5
Views: 72

### Re: Bronsted vs. Lewis

A Bronsted acid is a proton donor and a Bronsted base is a proton acceptor. A Lewis acid is an electron pair acceptor and a Lewis base is an electron pair donor.
Fri Nov 29, 2019 5:02 pm
Forum: Student Social/Study Group
Topic: Midterm 2a
Replies: 4
Views: 78

### Re: Midterm 2a

I think Lavelle got the equation v=E/h by just manipulating the equation E=h*v.
Fri Nov 29, 2019 4:56 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: coordination number
Replies: 8
Views: 90

### Re: coordination number

The coordination number is based off of the number of points at which ligands are attached to the central metal atom of the complex.
Fri Nov 22, 2019 7:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AXE Format
Replies: 34
Views: 324

### Re: AXE Format

When there is only one X or one E, writing just X or E would be fine.
Fri Nov 22, 2019 7:41 pm
Forum: Octet Exceptions
Topic: Homework 2E.19d
Replies: 3
Views: 129

### Re: Homework 2E.19d

SnCl2 is not a radical because it has an even number of electrons. Sn does not need a complete octet because bonding with two chlorine atoms and having one lone pair will give it stable formal charge of 0.
Fri Nov 22, 2019 7:28 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: london forces
Replies: 9
Views: 101

### Re: london forces

The molecule with the greater number of electrons will have stronger London dispersion forces.
Fri Nov 22, 2019 7:24 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: 3F.5
Replies: 4
Views: 81

### Re: 3F.5

Butanol has a higher melting point because it is capable of having a hydrogen bond unlike diethyl ether. This can be seen when drawing out the lewis structures.
Fri Nov 22, 2019 7:18 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: polarizability
Replies: 9
Views: 224

### Re: polarizability

The higher the polarizability, the higher the boiling/melting points due to stronger intermolecular forces.
Fri Nov 15, 2019 7:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T-shaped
Replies: 3
Views: 48

### Re: T-shaped

A t-shaped molecule has three bonds and 2 lone pairs. A molecule with a trigonal planar shape has only 3 bonds and a molecule with a trigonal pyramidal shape has 3 bonds and 1 lone pair.
Fri Nov 15, 2019 7:47 pm
Forum: Electronegativity
Topic: Ionization Energy vs. Electronegativity
Replies: 9
Views: 284

### Re: Ionization Energy vs. Electronegativity

Ionization energy is the amount of energy required to remove an electron. Electronegativity is the likelihood that an atom will gain an electron.
Fri Nov 15, 2019 7:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Notation used in VSEPR
Replies: 8
Views: 149

### Re: Notation used in VSEPR

I think it would be very helpful to know it because it'll help determine the different molecular shapes of molecules.
Fri Nov 15, 2019 7:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E problem #13b.
Replies: 3
Views: 73

### Re: 2E problem #13b.

The bond angles are not distorted because there are no lone pairs on the central atom. Therefore, the angles are still expected to be 109.5 degrees because it has a tetrahedral shape.
Fri Nov 15, 2019 7:25 pm
Forum: Dipole Moments
Topic: CH
Replies: 3
Views: 64

### Re: CH

No, there is no dipole moment when carbon is bonded to hydrogen because they have very similiar electronegativities.
Sat Nov 09, 2019 12:26 am
Forum: Trends in The Periodic Table
Replies: 7
Views: 160

Atomic radius decreases across the periodic table because the increased number of protons causes a greater effective nuclear charge that pulls electrons in, resulting in a smaller radius.
Sat Nov 09, 2019 12:21 am
Forum: Quantum Numbers and The H-Atom
Topic: Quantum numbers
Replies: 12
Views: 303

### Re: Quantum numbers

L is the quantum number for angular momentum. It can be any value from 0 to n-1.
Sat Nov 09, 2019 12:18 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar v. Nonpolar
Replies: 11
Views: 1497

### Re: Polar v. Nonpolar

A molecule is polar when there is an unequal sharing of electrons between two atoms that arise due to differences in electronegativity. A molecule is nonpolar if electrons are shared equally, resulting in no dipole moment.
Sat Nov 09, 2019 12:06 am
Forum: Student Social/Study Group
Topic: Dipole Moment
Replies: 5
Views: 88

### Re: Dipole Moment

A dipole moment is basically what occurs when two atoms share electrons unequally. When one atom is more electronegative than the other, that atom is pulling more tightly on the shared pair of electrons. The differences in electronegativity give rise to partial positive or partial negative charges o...
Fri Nov 08, 2019 11:57 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 18
Views: 404

### Re: Resonance Structures

Resonance structures are other possible equivalent lewis structures that show the delocalization of electrons without changing the position of the atoms.
Wed Oct 30, 2019 8:09 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy
Replies: 5
Views: 80

### Re: Ionization Energy

The ionization energy increases from left to right because as atomic radius decreases, electrons become more attracted to the nucleus. This means that they are more tightly bound and harder to remove.
Wed Oct 30, 2019 8:05 pm
Forum: Lewis Structures
Topic: 2B. 1C
Replies: 5
Views: 74

### Re: 2B. 1C

It's better to put a double bond between O and N and a single bond between N and F because this structure has all the formula charges as 0, which means it is the most stable.
Wed Oct 30, 2019 7:58 pm
Forum: Lewis Structures
Topic: Bonds:
Replies: 3
Views: 50

### Re: Bonds:

One bond represents 2 electrons.
Wed Oct 30, 2019 7:55 pm
Forum: Lewis Structures
Topic: Creating Lewis Structures
Replies: 7
Views: 102

### Re: Creating Lewis Structures

The central atom would be the one that has the lowest ionization energy or is the least electronegative which in this case is Nitrogen.
Wed Oct 30, 2019 7:53 pm
Forum: Octet Exceptions
Topic: Can P,S,Cl have less than 8 electrons?
Replies: 3
Views: 54

### Re: Can P,S,Cl have less than 8 electrons?

They usually do not have less that 8 electrons because that would mean they are not stable. Since these elements have d-orbitals, they could have expanded octets to fit more than 8 electrons.
Fri Oct 25, 2019 10:05 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Effective Nuclear Charge
Replies: 2
Views: 39

### Re: Effective Nuclear Charge

The effective nuclear charge is the net charge an electron experiences in an atom when there are other electrons.
Fri Oct 25, 2019 10:01 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 4
Views: 55

### Re: Electron Affinity

Electron affinity is negative when energy is released when an electron is added and positive when energy is needed in order to add an electron.
Fri Oct 25, 2019 9:54 pm
Forum: Properties of Light
Topic: Hz vs. frequency
Replies: 7
Views: 242

### Re: Hz vs. frequency

Hertz is just a unit for frequency. Frequency is usually expressed in Hertz (s^-1).
Fri Oct 25, 2019 9:40 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 1D. 17 prob
Replies: 2
Views: 50

### Re: 1D. 17 prob

Yes, that's right. The magnetic quantum number takes values of +l, l-1, and -l.
Fri Oct 25, 2019 9:28 pm
Forum: Quantum Numbers and The H-Atom
Topic: Magnetic Quantum Number
Replies: 5
Views: 62

### Re: Magnetic Quantum Number

You cannot say ml is equal to 5 because it is not the actual value. It's best to list them all out.
Sat Oct 19, 2019 3:30 pm
Forum: Properties of Electrons
Topic: 1B.15
Replies: 4
Views: 72

### Re: 1B.15

You could use De Broglie's equation.
Sat Oct 19, 2019 3:24 pm
Forum: Properties of Light
Topic: Baler v. Lyman Series
Replies: 10
Views: 164

### Re: Baler v. Lyman Series

The Balmer series corresponds to the visible light region of the spectrum and the Lyman Series corresponds to the UV region of the spectrum. In the Balmer series, the electrons come to rest at the energy level n=2 and in the Lyman series, the electrons come to rest at n=1.
Sat Oct 19, 2019 3:14 pm
Forum: DeBroglie Equation
Topic: 1B.15 a
Replies: 4
Views: 65

### Re: 1B.15 a

The mass would be that of an electron which is 9.1095*10^-31 kg.
Sat Oct 19, 2019 2:56 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Paired Electrons
Replies: 5
Views: 62

### Re: Paired Electrons

When electrons are paired, they occupy the same orbital with opposite spin. There can be no more than 2 electrons in an orbital based on the Pauli Exclusion Principle. When electrons are parallel, they occupy different orbitals with the same spin. This occurs because there is electron repulsion betw...
Sat Oct 19, 2019 2:45 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Inner e- and Outer e-
Replies: 14
Views: 152

### Re: Inner e- and Outer e-

The outer electrons feel a reduced electrostatic attraction because the inner electrons shield the outer electrons from the positive nucleus.
Fri Oct 11, 2019 9:10 pm
Forum: Einstein Equation
Topic: E=hv
Replies: 8
Views: 120

### Re: E=hv

The h represents Planck's constant, which is 6.626*10^-34 J*s.
Fri Oct 11, 2019 9:00 pm
Forum: Limiting Reactant Calculations
Topic: percent yield
Replies: 10
Views: 353

### Re: percent yield

You don't have to worry about finding the percent yield unless the question specifically asks for you to find it.
Fri Oct 11, 2019 8:53 pm
Forum: Empirical & Molecular Formulas
Topic: empirical = molecular?
Replies: 15
Views: 570

### Re: empirical = molecular?

If the molar mass is the same for the empirical and molecular formula, then the chemical formula would just be the same for both.
Fri Oct 11, 2019 8:47 pm
Forum: Significant Figures
Topic: Sig Figs
Replies: 5
Views: 198

### Re: Sig Figs

It's best to just use the correct number of sig figs in your final answer to reduce any small errors from rounding in the middle of your calculations.
Fri Oct 11, 2019 8:42 pm
Forum: Limiting Reactant Calculations
Topic: Exercise M.1
Replies: 3
Views: 267

### Re: Exercise M.1

First you divide you're 35.0 g of NH3 by the molar mass of NH3 and then use mole ratios to find the number of moles of N2H2. Then multiply the number of moles of N2H4 by its molar mass and you will get the theoretical yield of N2H4. Divide the actual yield of N2H4 by the theoretical yield and multip...
Wed Oct 02, 2019 9:08 pm
Forum: SI Units, Unit Conversions
Topic: Sig figs
Replies: 18
Views: 341

### Re: Sig figs

No, the number of sig figs can vary because it is based on the least amount of sig figs present in the problem. However, any conversion factors do not count when determining the number of sig figs.
Tue Oct 01, 2019 3:50 pm
Forum: Limiting Reactant Calculations
Topic: Another question on E9 but now on part b
Replies: 2
Views: 30

### Re: Another question on E9 but now on part b

Yes, you would find the moles of the compound first by dividing the number of grams given by the molar mass of magnesium sulfate heptahydrate and then multiply it by Avogadro's constant (6.022 X 10^23) to get the number of formula units of the compound.