Search found 106 matches

by Rory Simpson 2F
Sat Mar 14, 2020 10:44 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow step
Replies: 3
Views: 40

Re: Slow step

Your slow step would be the one that determines the rate, so you can compare the rate laws of the steps to whichever rate law is experimentally determined for the complete reaction.
by Rory Simpson 2F
Sat Mar 14, 2020 10:37 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: E vs Eo
Replies: 6
Views: 118

Re: E vs Eo

Eº is the standard cell potential which in this case refers to a cell under standard conditions (25ºC, 1atm, 1mol/L). E doesn't have these conditions, so you'd be calculating the cell potential for any differences in temperature or concentration, as the equation suggests.
by Rory Simpson 2F
Sat Mar 14, 2020 10:05 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 11
Views: 135

Re: Cell Diagram

Platinum is the most common electrode that you'd use if you need a solid electrode for a cell, so I'd assume that you can use it anytime you need to.
by Rory Simpson 2F
Sat Mar 14, 2020 10:02 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: intermediates
Replies: 8
Views: 94

Re: intermediates

Intermediates are any species that are initially formed at some step in the reaction and then are consumed entirely in the reaction process. So, they won't be in the final products but they will be apparent if you write out all of the steps of the reaction.
by Rory Simpson 2F
Sat Mar 14, 2020 9:58 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalyst's effect on overall reaction
Replies: 7
Views: 61

Re: Catalyst's effect on overall reaction

If the slow step is the rate determining step, then in order for a catalyst to speed up the reaction it would need to lower the activation energy of that slowest step. Changing the activation energy of the faster steps wouldn't do anything for the overall reaction because the rate is still determine...
by Rory Simpson 2F
Sun Mar 08, 2020 1:37 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: activation energy/ energy barrier
Replies: 6
Views: 77

Re: activation energy/ energy barrier

A reaction needs to reach the activation energy in order for the reactants to convert to products. You can calculate it numerically with the Arrhenius equation (which shows that it depends on the rate constant k and the temperature of the reaction).
by Rory Simpson 2F
Sun Mar 08, 2020 1:27 pm
Forum: General Rate Laws
Topic: Rate law
Replies: 3
Views: 86

Re: Rate law

I think that you should probably specify if there are multiple rates being dealt with (ie an equilibrium reaction with forward or reverse rates, or multiple reactions occurring) just to be clear as to what reactants are being included in which rate laws.
by Rory Simpson 2F
Sun Mar 08, 2020 1:16 pm
Forum: Zero Order Reactions
Topic: Rearranging First Order Integrated Rate Law
Replies: 1
Views: 47

Re: Rearranging First Order Integrated Rate Law

If you look at the initial and final equations, the numerator and the denominator of the ln of concentrations is flipped. That's where the negative sign went (since -ln(x/y) = ln(y) - ln(x) = ln(x/y) ).
by Rory Simpson 2F
Sun Mar 08, 2020 1:03 pm
Forum: General Rate Laws
Topic: slow step
Replies: 4
Views: 58

Re: slow step

If you are given the experimentally determined rate law or something like that, you can find an intermediate step that matches that rate law, making that the slowest step.
by Rory Simpson 2F
Sun Mar 08, 2020 12:53 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: concentration cells
Replies: 5
Views: 51

Re: concentration cells

In concentration cells, the same half reaction is occurring but in opposite directions. For the lower concentration, the half reaction would be increasing the amount of the species in solution, while the half reaction for the higher concentration would decreased the amount. The transfer of electrons...
by Rory Simpson 2F
Sat Feb 29, 2020 7:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagram order
Replies: 4
Views: 43

Re: Cell diagram order

You might want to put it so that the reactants are first and the products are second for the half reaction, just so that it is clear what is being oxidized and reduced in the reactions.
by Rory Simpson 2F
Sat Feb 29, 2020 7:06 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy Relation to Q
Replies: 1
Views: 35

Re: Gibbs Free Energy Relation to Q

The Gibbs free energy at any particular stage in the reaction is based on the concentrations of the reactants at that time. For finding the Gibbs free energy at a time, it is the difference of the molar Gibbs free energy of the products and reactants times the number of moles at the time. So, the Q ...
by Rory Simpson 2F
Sat Feb 29, 2020 5:41 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration Cells and Nernst Equation
Replies: 4
Views: 52

Re: Concentration Cells and Nernst Equation

You could use the Nernst equation for concentration cells since you could find the reaction quotient Q and then determine the cell potential using the equation. You can also use it for any cells that aren't at the standard potential (with different concentrations of species affecting the cell potent...
by Rory Simpson 2F
Sat Feb 29, 2020 5:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt bridges
Replies: 11
Views: 101

Re: Salt bridges

As the redox reaction continues in a cell, the electrons will move from the anode to the cathode. If the salt bridge weren't there, eventually the reaction would stop as one half reaction gets increasingly positive and the other gets increasingly negative. With the salt bridge, the ion flow countera...
by Rory Simpson 2F
Sat Feb 29, 2020 5:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: electrochemical series
Replies: 1
Views: 18

Re: electrochemical series

The electrochemical series organizes certain ions and compounds based on how well it is able to oxidize or reduce other species. The oxidizing ability of species on the left of half reactions increases as you go up (standard potential gets higher), while the reducing ability of species on the right ...
by Rory Simpson 2F
Sat Feb 22, 2020 5:48 pm
Forum: Balancing Redox Reactions
Topic: Redox in Acidic/Basic Solutions
Replies: 3
Views: 46

Re: Redox in Acidic/Basic Solutions

In acidic solutions, you have an excess of H+ which can be used along with H2O to balance H and O in the half reactions. In basic solutions, you have excess OH- which you would use to balance the half reactions. This is necessary to make sure that the charges and elements are balanced in the redox r...
by Rory Simpson 2F
Sat Feb 22, 2020 5:43 pm
Forum: Balancing Redox Reactions
Topic: Cell Diagrams
Replies: 5
Views: 81

Re: Cell Diagrams

Platinum is by far the most common electrode so it can be used if there aren't any solids in the problem that could conduct e-. In the problem in lecture for example, the side with Cu(s) didn't need Pt as an electrode because Cu was the electrode and is a conductive solid. However, the side with Fe3...
by Rory Simpson 2F
Sat Feb 22, 2020 5:36 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst Equation and Le Chatelier's Principle
Replies: 3
Views: 105

Re: Nernst Equation and Le Chatelier's Principle

Basically, the cell potential of a given reaction is dependent on the concentrations on the species in the reaction. At equilibrium in a reaction, the cell potential is zero because the reaction no longer does any work. The Nernst equation gives a quantitative answer as to how different concentratio...
by Rory Simpson 2F
Sat Feb 22, 2020 5:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrochemical Cells
Replies: 2
Views: 30

Re: Electrochemical Cells

Both voltage and electric potential are measured in volts, but voltage is the difference in the electric potentials across two points.
by Rory Simpson 2F
Sat Feb 22, 2020 5:28 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Cell Potentials
Replies: 4
Views: 48

Re: Standard Cell Potentials

By convention in writing out cell diagrams, the anode is typically on the left side and the cathode is typically on the right side. So, the standard cell potential would be the potential of the cathode minus the potential of the anode. You can tell if the left or right side is the cathode or anode b...
by Rory Simpson 2F
Sun Feb 16, 2020 5:25 pm
Forum: Van't Hoff Equation
Topic: When to use Van't Hoff equation
Replies: 2
Views: 33

Re: When to use Van't Hoff equation

The changes in are generally negligible with a change in temperature so we just assume that they are constant when deriving (delta G, on the other hand, does change significantly with temperature changes).
by Rory Simpson 2F
Sun Feb 16, 2020 5:12 pm
Forum: Balancing Redox Reactions
Topic: Half reactions
Replies: 7
Views: 71

Re: Half reactions

Half reactions separate the oxidation and the reduction reactions that occur in a redox reaction. You can use it to find out which elements are oxidized and reduced, and also balance redox reactions (since the number of electrons transferred should cancel out in the two half reactions combined.
by Rory Simpson 2F
Sun Feb 16, 2020 5:08 pm
Forum: Balancing Redox Reactions
Topic: Oxidation Reduction
Replies: 3
Views: 49

Re: Oxidation Reduction

Generally, oxygen will have an oxidation number of -2 and hydrogen will have an oxidation number of +1 across different compounds. However, there are a few exceptions to this (for example, H2O2 where oxygen has an oxidation number of -1.)
by Rory Simpson 2F
Sun Feb 16, 2020 5:04 pm
Forum: Van't Hoff Equation
Topic: K in Van't Hoff
Replies: 3
Views: 32

Re: K in Van't Hoff

The Van't Hoff equation gives us a quantitative means of relating the change in temperature to the change in the equilibrium constant (and we can find the new equilibrium constants for a reaction at different temperatures).
by Rory Simpson 2F
Sun Feb 16, 2020 5:01 pm
Forum: Balancing Redox Reactions
Topic: Electrons in Compounds
Replies: 1
Views: 26

Re: Electrons in Compounds

If you want to find the oxidation states of molecules, you can base it knowing that certain groups of elements tend to have certain oxidation states (Group 1 elements typically have +1, Group 2 have +2, halogens have -1, etc.) with a few exceptions. You can use those to find the oxidation numbers fo...
by Rory Simpson 2F
Sat Feb 08, 2020 3:56 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs free energy of ice and liquid water
Replies: 3
Views: 36

Re: Gibbs free energy of ice and liquid water

I think they mean that there is a point where the Gibbs free energy of ice and Gibbs free energy of water are equal, so there is no change in it and it is at equilibrium. There is a graph in the section that has a diagram of temperature vs molar Gibbs free energy where the liquid and solid states in...
by Rory Simpson 2F
Sat Feb 08, 2020 3:51 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Using Cv,m and Cp,m
Replies: 2
Views: 32

Re: Using Cv,m and Cp,m

You would used Cv,m and Cp,m if you want to find Cv or Cp in calculating q (using q=CT). The values using R to calculate C are ways of estimating the heat capacities of certain molecules if you don't know it, but I don't really think he went over that.
by Rory Simpson 2F
Sat Feb 08, 2020 3:45 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units for heat of reaction
Replies: 9
Views: 89

Re: Units for heat of reaction

805097738 wrote:do you have to explicitly state per mole or is that implied already


You should explicitly state it per mole in the case of standard reaction enthalpy or standard formation enthalpy because those are definitionally for one mole of a compound. I guess it's mostly for the consistency of units, though.
by Rory Simpson 2F
Sat Feb 08, 2020 3:37 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Calculating bond enthalpies
Replies: 4
Views: 36

Re: Calculating bond enthalpies

The number that you multiply by depends on the number of bonds broken or formed. For example, if there are 2 C-C bonds broken in the reaction, then take the bond enthalpy for a C-C bond and multiply it by 2. You should probably know how to do it because certain problems might only give you the bond ...
by Rory Simpson 2F
Sat Feb 08, 2020 3:32 pm
Forum: Calculating Work of Expansion
Topic: Integral for work
Replies: 4
Views: 57

Re: Integral for work

When you have a reversible system, you would want to use the equation that you get from the integral because the changes in volume are infinitesimal. So, use w = -nRTln(V2/V1) for a reversible system, which you can derive from the integral.
by Rory Simpson 2F
Sun Feb 02, 2020 5:11 pm
Forum: Phase Changes & Related Calculations
Topic: Liquid/Steam
Replies: 3
Views: 38

Re: Liquid/Steam

Basically, during phase changes the temperature of a substance remains constant despite increasing amounts of energy (he showed us that phase diagram in lecture.) So, water at 100 degrees Celsius has much less energy in it than water vapor at 100 degrees Celsius because the vapor has additional ener...
by Rory Simpson 2F
Sun Feb 02, 2020 5:03 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy units
Replies: 5
Views: 49

Re: Enthalpy units

Enthalpy for a reaction would typically be given in joules or kilojoules. For molar enthalpy, standard reaction enthalpy or standard formation enthalpy, it would be given in J/mol or kJ/mol.
by Rory Simpson 2F
Sun Feb 02, 2020 5:00 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Three Methods
Replies: 3
Views: 53

Re: Three Methods

I think that depending on whichever method (I'm assuming for finding delta H) they'll give you the specific info that you need in the problem or just outright tell you. For example, if you need to use Hess's law then the problem will give some equations that you can use to find the enthalpy in the o...
by Rory Simpson 2F
Sun Feb 02, 2020 4:56 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Types of Systems
Replies: 3
Views: 49

Re: Types of Systems

I think it will either be given or at least obvious if the system or any energy transfer described in the problem. Just remember that open systems allow matter and energy to transfer with surroundings, closed systems only allow energy, and isolated systems don't allow any transfer with surroundings....
by Rory Simpson 2F
Sun Feb 02, 2020 4:52 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Degeneracy
Replies: 1
Views: 21

Re: Degeneracy

Boltzmann's formula in particular is a means of calculating statistical entropy based on W (the amount of different microstates with the same total energy.) The entropy S calculated there is equivalent to the thermodynamic definition of entropy. I think that if using the Boltzmann equation would get...
by Rory Simpson 2F
Sat Jan 25, 2020 4:54 pm
Forum: Ideal Gases
Topic: R Constant
Replies: 26
Views: 318

Re: R Constant

Just make sure that you choose the right R constant depending on the units for pressure and volume, or convert all the units so that you can 0.082 L*atm*mol^-1*K^-1.
by Rory Simpson 2F
Sat Jan 25, 2020 4:32 pm
Forum: Phase Changes & Related Calculations
Topic: Calculating Bond Enthalpies
Replies: 4
Views: 30

Re: Calculating Bond Enthalpies

He drew out the Lewis structures mainly to figure out what bonds were broken and what bonds were formed during the reaction. You want to add the bond enthalpies of the reactant bonds that are broken and subtract the bond enthalpies of the product bonds that are formed (accounting for bond enthalpies...
by Rory Simpson 2F
Sat Jan 25, 2020 4:28 pm
Forum: Phase Changes & Related Calculations
Topic: State Property
Replies: 6
Views: 51

Re: State Property

Heat isn't a state function because the amount of energy transferred as heat depends on how the change in energy occurs. On the other hand, enthalpy is a state function because no matter how the energy change occurs, it only depends on the state of the system.
by Rory Simpson 2F
Sat Jan 25, 2020 4:23 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Decreasing volume
Replies: 5
Views: 49

Re: Decreasing volume

The reaction would shift in a way that wants to minimize the resulting increase in pressure, so that reaction would shift to the side with fewer gas molecules because it would decrease the pressure of the system.
by Rory Simpson 2F
Sat Jan 25, 2020 4:16 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard enthalpy
Replies: 2
Views: 17

Re: Standard enthalpy

The standard enthalpy of formation is the enthalpy change that comes from forming one mole of a compound from the elements in its standard states. The standard reaction enthalpy is the change that comes from having all products and reactants in their standard states. You can find the standard enthal...
by Rory Simpson 2F
Sun Jan 19, 2020 3:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentrations
Replies: 12
Views: 87

Re: Concentrations

Concentration and pressure only affects Q and not K; the reaction will shift accordingly to return to a ratio of reactants and products equal to K. Temperature actually changes K because of the changes in energy that are involved in the reaction.
by Rory Simpson 2F
Sun Jan 19, 2020 3:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: autoprotolysis
Replies: 5
Views: 41

Re: autoprotolysis

Could someone explain how autoprotolysis of water leads to Kw? need help on this too; also, does anyone know how much we need to know about the topic of autoprotolysis for the test? In the autoprotolysis reaction 2H2O(l) \rightleftharpoons H3O+(aq) + OH-(aq), we get an equilibrium constant Kw = [H3...
by Rory Simpson 2F
Sun Jan 19, 2020 3:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc from K
Replies: 3
Views: 29

Re: Kc from K

I think the textbook is using K to refer to Kp, so the K value uses partial pressures. There's an equation to convert Kp to Kc in section 5.H, but I don't think we're expected to know it since he didn't go over it in lecture. Basically it's derived using the Ideal Gas Law to substitute in the K equa...
by Rory Simpson 2F
Sun Jan 19, 2020 2:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Change in K when reaction is endothermic?
Replies: 2
Views: 25

Re: Change in K when reaction is endothermic?

When the reaction is endothermic, heat energy is absorbed from surroundings. Because of this, K would increase with increasing the temperature since mean that there is greater heat energy to absorb. This would mean that the reaction would shift towards the products.
by Rory Simpson 2F
Sun Jan 19, 2020 2:47 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: approximation
Replies: 4
Views: 39

Re: approximation

When you have a very small value of x it is essentially negligible when compared to the initial concentration, so we can approximate to make the calculations much simpler as compared to using a quadratic equation.
by Rory Simpson 2F
Sat Jan 11, 2020 4:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE box
Replies: 9
Views: 82

Re: ICE box

The acceptable answers would be any that has it so that the equilibrium concentrations or partial pressures of the reactants or products are positive.
by Rory Simpson 2F
Sat Jan 11, 2020 4:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Table 5G.2
Replies: 5
Views: 49

Re: Table 5G.2

In the table I think that K is just referring to Kp based on the fact that all of the equations only have gases. So, use "K" in the table if you are solving using partial pressure and use "Kc" in the table if using concentrations.
by Rory Simpson 2F
Sat Jan 11, 2020 4:24 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Significance of principle
Replies: 6
Views: 51

Re: Significance of principle

Le Chatelier's principle is useful in describing how a chemical reaction shifts in response to changes in conditions. Changes in concentration of reactants or products, pressure, and temperature would result in shifts in the equilibrium, which is consistent with Le Chatelier's principle.
by Rory Simpson 2F
Sat Jan 11, 2020 3:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: finding change in concentration in ICE tables
Replies: 3
Views: 32

Re: finding change in concentration in ICE tables

You'd use the tables if you have an unknown change in the concentrations (represented by X). In the equation you said, the initial concentrations of each of the reactants would be changed by -X, while each of the products would be changed by +X. You would find the final equilibrium concentrations in...
by Rory Simpson 2F
Sat Jan 11, 2020 3:20 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Decreasing pressure by increasing volume [ENDORSED]
Replies: 4
Views: 48

Re: Decreasing pressure by increasing volume [ENDORSED]

Decreasing the pressure would cause the reaction to shift towards whichever side has more moles. Because of the pressure decrease and the volume increase, the concentrations would decrease resulting in the shift.
by Rory Simpson 2F
Sat Dec 07, 2019 4:38 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: NH3
Replies: 1
Views: 40

Re: NH3

NH3 has one lone pair if you draw out its Lewis structure, meaning that it can form one coordinate covalent bond with a central metal.
by Rory Simpson 2F
Sat Dec 07, 2019 3:46 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 1
Views: 51

Re: Polydentate

If you're drawing it out, the nitrogen with one H bonded together would be central and bonded to two carbons (you can pretty much figure out the order of the chain based on the order of the formula, especially if its written out at NH2CH2CH2NHCH2CH2NH2). The formal charge would be zero for everythin...
by Rory Simpson 2F
Sat Dec 07, 2019 3:30 pm
Forum: Lewis Acids & Bases
Topic: Strong bases
Replies: 2
Views: 86

Re: Strong bases

The strong bases that I think we have to know are the Group 1 and 2 hydroxides and oxides.
by Rory Simpson 2F
Sat Dec 07, 2019 3:18 pm
Forum: Conjugate Acids & Bases
Topic: How was this equation derived?? Marshmallow #34
Replies: 1
Views: 122

Re: How was this equation derived?? Marshmallow #34

The reaction between HCl and CaO would be a neutralization reaction between an acid and base that results in the formation of a salt and water. The balanced reaction would be 2HCl + CaO -> CaCl2 + H2O. Basically once you have the equation you want to find out how much of either HCl or CaO is leftove...
by Rory Simpson 2F
Sat Dec 07, 2019 3:06 pm
Forum: Dipole Moments
Topic: CCl2H2
Replies: 2
Views: 243

Re: CCl2H2

The molecular shape for CCl2H2 would be tetrahedral using VSEPR, so the dipoles wouldn't actually cancel each other out and there would be a net dipole.
by Rory Simpson 2F
Sun Dec 01, 2019 11:31 pm
Forum: Amphoteric Compounds
Topic: Amphoteric compounds
Replies: 1
Views: 38

Re: Amphoteric compounds

Amphoteric compounds are compounds that can react both as acids and bases and have both acidic and basic character. Amphoteric oxides are certain oxide compounds that have those characteristics, and the metals that form them are in a diagonal line just left of the metalloids in the periodic table (F...
by Rory Simpson 2F
Sun Dec 01, 2019 11:24 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Deprotonated Acids
Replies: 2
Views: 50

Re: Deprotonated Acids

The calculations are more complicated and involve chemical equilibrium which is something that I don't think gets covered until 14B, so I think you just need to know the basics for now.
by Rory Simpson 2F
Sun Dec 01, 2019 11:15 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Strong Acids
Replies: 3
Views: 63

Re: Strong Acids

If you look at the equation for chemical equilibrium, a larger Ka value would result if there is a greater amount of product than reactant at equilibrium (and so there would be a lower pKa value because pKa is -log Ka). Since strong acids almost entirely dissociate, there would be a much greater con...
by Rory Simpson 2F
Sun Dec 01, 2019 11:11 pm
Forum: Conjugate Acids & Bases
Topic: conjugate acids/bases
Replies: 1
Views: 38

Re: conjugate acids/bases

Generally the conjugate base of an acid is the species remaining after removing a proton, and the conjugate acid of a base is the species after accepting a proton.
by Rory Simpson 2F
Sun Dec 01, 2019 11:07 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Shapes and Corners
Replies: 2
Views: 28

Re: Shapes and Corners

It's possible for there to be odd numbers of ligands, though rarer. The textbook says that the most common coordination numbers for the central metal atom are 6 and 4, so those are probably the ones that you would see the most as examples.
by Rory Simpson 2F
Sun Dec 01, 2019 11:01 pm
Forum: Naming
Topic: Order of Ligands
Replies: 4
Views: 41

Re: Order of Ligands

You want to always name the ligands in alphabetical order based on the root (not the prefix), regardless of the formula order.
by Rory Simpson 2F
Sat Nov 23, 2019 9:46 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted Acids vs Lewis acids
Replies: 4
Views: 49

Re: Bronsted Acids vs Lewis acids

I think that a Bronsted definition of acids means that acids require a hydrogen (because a proton H+ needs to be released), whereas a Lewis acid means that some compounds without hydrogen can still be acids in certain reactions.
by Rory Simpson 2F
Sat Nov 23, 2019 9:16 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydenate vs Chelate
Replies: 1
Views: 51

Re: Polydenate vs Chelate

A polydenate is essentially a ligand that has multiple bonds with the central metal atom in coordinate complexes. Polydenates are able to form chelates, which are a type of coordinate complex that has a ring-like structure.
by Rory Simpson 2F
Sat Nov 23, 2019 9:03 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Denticity
Replies: 2
Views: 47

Re: Denticity

The denticity refers to the number of lone pairs of a ligand that are bonding to the central metal atom. For example, a monodentate ligand would have one available lone pair to make a coordinate complex with a metal.
by Rory Simpson 2F
Wed Nov 20, 2019 1:29 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Why is CH2Cl2 polar?
Replies: 12
Views: 146

Re: Why is CH2Cl2 polar?

You should think of this molecule in the 3d form. In a tetrahedral, no matter where you put the atoms the Chlorine atoms will always be next to each other. I can't Draw a picture on here, but just look one up it might be helpful. The lewis structure looks like u can orient the chlorines to be oppos...
by Rory Simpson 2F
Wed Nov 20, 2019 1:26 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 4
Views: 59

Re: Ligands

I think that by definition ligands are those that bind to the central atom of the coordination complex, so they can't be the central atom.
by Rory Simpson 2F
Fri Nov 15, 2019 1:39 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: Atom size vs. boiling point
Replies: 4
Views: 62

Re: Atom size vs. boiling point

The strength of the Van Der Waal's forces in the atom increases because of the greater number of electrons, which would increase the polarizability and thus the strength of IMFs.
by Rory Simpson 2F
Fri Nov 15, 2019 1:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Lone Pair Location
Replies: 3
Views: 49

Re: Determining Lone Pair Location

It mainly depends on the VSEPR structure. Since lone pair-lone pair repulsion forces are the strongest, you want the lone pairs to be the farthest away from each other and have the greatest bond angle in considering the position of each of the electron density regions (bonds and lone pairs).
by Rory Simpson 2F
Fri Nov 15, 2019 1:21 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: How do we determine bond angles?
Replies: 4
Views: 40

Re: How do we determine bond angles?

You can generally predict the bond angle based on the VSEPR molecular structure (eg a tetrahedral molecule would have bond angles of 109.5 degrees). If a central atom has lone pairs, using VSEPR you can approximate the bond angle just knowing that the lone pair-atom repulsions are greater than atom-...
by Rory Simpson 2F
Fri Nov 15, 2019 1:10 pm
Forum: Hybridization
Topic: Relationship btw arrangement and hybrid orbitals
Replies: 2
Views: 54

Re: Relationship btw arrangement and hybrid orbitals

If you mean arrangement as in VSEPR, then it relates to hybridization because the hybridization is according to the number of bonds (and thus electron density regions which affects molecular shape).
by Rory Simpson 2F
Fri Nov 15, 2019 1:00 pm
Forum: Dipole Moments
Topic: Shape of Molecules affect boiling point?
Replies: 7
Views: 122

Re: Shape of Molecules affect boiling point?

Rod shaped molecules have a larger surface area that are close to each other, meaning that there is less distance between molecules and stronger interaction of Van Der Waal's forces. The stronger intermolecular forces causes an increase in the boiling point for rod-shaped molecules as compared to sp...
by Rory Simpson 2F
Mon Nov 11, 2019 8:00 pm
Forum: Resonance Structures
Topic: What is a Resonance "Structure"
Replies: 12
Views: 333

Re: What is a Resonance "Structure"

Resonance structures are just all of the possible Lewis structures that work for the atom when it has resonance, representing that the bonding of the resonance hybrid is an average of the resonance structure.
by Rory Simpson 2F
Mon Nov 11, 2019 7:47 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: melting points
Replies: 6
Views: 56

Re: melting points

905416023 wrote:So hydrogen bonds make the molecule harder to break apart? So then they have a higher boiling point?


Yes, the strength of hydrogen bonds causes the molecules to have a greater intermolecular attraction which increases their melting and boiling points.
by Rory Simpson 2F
Mon Nov 11, 2019 7:37 pm
Forum: Dipole Moments
Topic: Dipole-Dipole Forces
Replies: 2
Views: 44

Re: Dipole-Dipole Forces

I think it would be a lower energy orientation because the molecule would have the positive and negative ends of adjacent atoms would be near each other, since it would be favorable to be attracted and have the molecules stay in that orientation longer.
by Rory Simpson 2F
Wed Nov 06, 2019 11:09 am
Forum: Octet Exceptions
Topic: When to use Expanded Octet?
Replies: 2
Views: 65

Re: When to use Expanded Octet?

If you want to find the most stable Lewis structure, you would want to minimize formal charge and then use expanded octets if possible. Remember that expanded octets only apply for atoms in the 3rd period and after because they have d-orbitals available in their valence shell.
by Rory Simpson 2F
Wed Nov 06, 2019 10:59 am
Forum: Photoelectric Effect
Topic: Intensity in Photoelectric Effect
Replies: 6
Views: 223

Re: Intensity in Photoelectric Effect

For the photoelectric effect, if the energy of the photons is not enough to pass the threshold energy, then electrons won't be ejected regardless of intensity. This is important because it goes against the wave model since electrons wouldn't be ejected regardless of intensity, since a wave model wou...
by Rory Simpson 2F
Fri Nov 01, 2019 1:35 pm
Forum: Coordinate Covalent Bonds
Topic: Distinguishing a coordinate covalent bond
Replies: 5
Views: 110

Re: Distinguishing a coordinate covalent bond

In looking at a coordinate covalent bond specifically, where two shared electrons are coming from the same atom, it's probably best to look at the Lewis structure and look at how the bond formed in the first place from reaction (where by looking at the valence shells you can see if a single atom is ...
by Rory Simpson 2F
Fri Nov 01, 2019 1:20 pm
Forum: Bond Lengths & Energies
Topic: Lone electron pairs weakening bonds
Replies: 4
Views: 34

Re: Lone electron pairs weakening bonds

The lone pair electrons of fluorine would be interacting with each other because of the small size of fluorine atoms, causing a repelling force that would weaken the overall bond. That's why fluorine has a fairly small dissociation energy because of these lone pair electron interactions between the ...
by Rory Simpson 2F
Fri Nov 01, 2019 1:14 pm
Forum: Ionic & Covalent Bonds
Topic: Anions and Cations
Replies: 9
Views: 130

Re: Anions and Cations

Anions would be larger because the extra electrons would cause greater electron-electron repulsion in the atom and would decrease the effective nuclear charge. Cations would be the opposite, since less electrons means less electron-electron repulsion.
by Rory Simpson 2F
Fri Nov 01, 2019 1:06 pm
Forum: Bond Lengths & Energies
Topic: bond lengths
Replies: 10
Views: 234

Re: bond lengths

The more Bonds means a stronger pull so consequently you also get a smaller length because of the increased attraction. So the smaller the bond, the stronger it is? A stronger bond will typically be shorter and have a larger dissociation energy because there are more electrons acting in the bond, m...
by Rory Simpson 2F
Fri Nov 01, 2019 1:01 pm
Forum: Octet Exceptions
Topic: Expanded Valence Shells
Replies: 2
Views: 43

Re: Expanded Valence Shells

I think that if you're looking at the amount of expanded octet bonds or lone pairs for those elements you would want to consider formal charge. For example, PCl5 would have phosphorus with 5 single bonds, and phosphorus has 5 valence electrons, so the P atom would have a formal charge of 0.
by Rory Simpson 2F
Thu Oct 24, 2019 6:42 pm
Forum: Lewis Structures
Topic: Double Bonds and Electron Numbers
Replies: 4
Views: 78

Re: Double Bonds and Electron Numbers

when do you know to turn into a double bond instead of leaving the electrons on the other side of the element when drawing a lewis structure? It would depend on the total number of electrons you have to work with (valence electrons of every atom, adjusting for net charge if there is any). Otherwise...
by Rory Simpson 2F
Thu Oct 24, 2019 6:33 pm
Forum: Trends in The Periodic Table
Topic: Homework Question 1F.19
Replies: 5
Views: 64

Re: Homework Question 1F.19

The lower ionization energy means that the s-block metals are very likely to lose their valence electrons. This tendency makes them highly reactive.
by Rory Simpson 2F
Thu Oct 24, 2019 6:10 pm
Forum: Lewis Structures
Topic: Ion lewis structure
Replies: 9
Views: 103

Re: Ion lewis structure

As long as you follow the octet rule (besides any exceptions), then it wouldn't matter where the additional electron is since you'll have satisfied the octet rule for every atom. For your example of BrO-, just make sure that you have the right amount of electrons. So, count out the valence electrons...
by Rory Simpson 2F
Thu Oct 24, 2019 6:05 pm
Forum: Trends in The Periodic Table
Topic: Calculated vs Observed Value
Replies: 6
Views: 71

Re: Calculated vs Observed Value

Electronegativity is a value that is calculated from an formula. In the textbook section 2D.1, it mentions that the values were first calculated with an expression that determines the differences in electronegativity between bonds by using dissociation energies of that bond. All of the other periodi...
by Rory Simpson 2F
Thu Oct 24, 2019 5:52 pm
Forum: Resonance Structures
Topic: Different Resonance Structures
Replies: 4
Views: 54

Re: Different Resonance Structures

If a Lewis structure has resonance it doesn't mean that there are actually different structures, but it means that the actual structure has bonds that are intermediate in properties. For example, Dr. Lavelle used nitrate as an example in class, which has 2 N-O single bonds and 1 N-O double bond. In ...
by Rory Simpson 2F
Fri Oct 18, 2019 8:11 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals in relation to arrows
Replies: 10
Views: 214

Re: Orbitals in relation to arrows

The Pauli exclusion principle says that there can be no more than 2 e- per orbital; that's why the arrows are grouped in pairs with opposite spins. If you're filling out diagrams like that, you'd start by adding electrons with a maximum of 2 e- for each orbital, and adding up spin electrons first if...
by Rory Simpson 2F
Fri Oct 18, 2019 12:36 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Spin State
Replies: 17
Views: 148

Re: Spin State

The total magnetic spin for the shell would add up to zero if it was full. Because of the Pauli exclusion principle (in that no two electrons can have the same exact quantum number configurations), an atom would need paired electrons with a positive and negative spin value in an full orbital.
by Rory Simpson 2F
Fri Oct 18, 2019 12:22 am
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Numbers
Replies: 3
Views: 51

Re: Quantum Numbers

You basically just have to familiarize yourself with the conditions for the values of each quantum number. So, n = 1,2,3,...; l = 0,1,2,...,n-1; ml = l, l-1, l-2,..., -l; and ms = +1/2 or -1/2. 2,0,0 should theoretically be possible values for n, l, and ml.
by Rory Simpson 2F
Fri Oct 18, 2019 12:13 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Wave Function
Replies: 2
Views: 31

Re: Wave Function

The wave function is a way that we can model the wave-like properties of atomic particles. The orbital is the same thing, as a math function that represents the wave function nature of electrons in atoms, where orbitals can be made into a three-dimensional model for the space where certain electrons...
by Rory Simpson 2F
Thu Oct 17, 2019 11:52 pm
Forum: Photoelectric Effect
Topic: Quick Question
Replies: 3
Views: 71

Re: Quick Question

Ionization energy refers to the minimum energy needed to remove an electron in its gas phase specifically, whereas the threshold energy is seen in the photoelectric effect (typically seen in solid metals).
by Rory Simpson 2F
Thu Oct 10, 2019 10:14 pm
Forum: Properties of Light
Topic: HW 1A11
Replies: 1
Views: 43

Re: HW 1A11

Each of the spectral line groupings ends with the electron at a certain energy level. For example, the Lyman series is a reduction to an energy level of n=1 (ground state), so the spectral lines result from transitions from n \geq 2 to n=1. The Balmer series is a reduction to an energy level of n=2,...
by Rory Simpson 2F
Thu Oct 10, 2019 9:58 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect
Replies: 3
Views: 76

Re: Photoelectric Effect

In the case of atomic spectra, the electron is not ejected and is still attached; a photon is emitted because of the transition from the higher to lower energy states for the electrons, and the atomic spectra lines are showing that. That's why the spectral lines correspond with the specific energy l...
by Rory Simpson 2F
Thu Oct 10, 2019 9:36 pm
Forum: Einstein Equation
Topic: Energy of photons to Moles
Replies: 2
Views: 86

Re: Energy of photons to Moles

For a mole of photons, it would just be the energy of a single photon (so, using a formula like E=hv) multiplied by Avogadro's number.
by Rory Simpson 2F
Thu Oct 10, 2019 12:23 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Large Objects and Heisenberg Uncertainty
Replies: 1
Views: 30

Re: Large Objects and Heisenberg Uncertainty

The uncertainty principle definitely isn't noticeable and has no real practical effect on a larger object because the relative uncertainty is negligible compared to the macroscopic object; the principle mainly applies to subatomic particles where measurements have to be precise. Additionally, it wou...
by Rory Simpson 2F
Thu Oct 10, 2019 12:04 pm
Forum: Properties of Light
Topic: Hydrogen Atoms for White Light
Replies: 3
Views: 28

Re: Hydrogen Atoms for White Light

It's true that hydrogen is the simplest to analyze because it only has a single electron. The substitution for other elements refers to the fact that any element could theoretically be substituted as long as it only has a single electron (for example, He+ or Li2+). Otherwise, the interactions betwee...
by Rory Simpson 2F
Sun Oct 06, 2019 5:16 pm
Forum: Limiting Reactant Calculations
Topic: How to determine limiting reactants
Replies: 3
Views: 77

Re: How to determine limiting reactants

Another way would be to compare the moles of reactants that you are given to the molar ratios of the stoichiometric coefficients. For each reactant, divide the moles by the stoichiometric coefficient of the reactant, and whichever is the least is the limiting reactant :)
by Rory Simpson 2F
Sat Oct 05, 2019 12:27 am
Forum: Balancing Chemical Reactions
Topic: H 7 a.
Replies: 3
Views: 84

Re: H 7 a.

For H7a, the unbalanced equation would be Ca(s) + H2O(l) -> H2(g) + Ca(OH)2(aq). Generally for balancing equations you would just go through each element step-by-step (starting with the least occurring element) and make sure that they are all balanced individually. Ca is already balanced, so we can ...
by Rory Simpson 2F
Fri Oct 04, 2019 5:49 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Use of Avogadro's number
Replies: 3
Views: 53

Re: Use of Avogadro's number

Avogadro's constant would be used if you want to find the number of molecules or atoms of something, since one mole of a substance has 6.0221*10^23 molecules of that substance. For example, if you are asked to find the number of individual atoms of an element in some amount of moles, then you would ...
by Rory Simpson 2F
Fri Oct 04, 2019 5:36 pm
Forum: SI Units, Unit Conversions
Topic: Fundamental E.1
Replies: 5
Views: 107

Re: Fundamental E.1

pm is picometers, and 1 pm = 10^-12 m. So, 1.73*10^26 pm (10^-12 m/ 1 pm) = 1.73 * 10^14 m

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