## Search found 102 matches

Thu Mar 12, 2020 6:57 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration cell question
Replies: 3
Views: 39

### Re: Concentration cell question

How were you able to figure out that Q is [anode]/[cathode]?
Wed Mar 11, 2020 1:06 am
Forum: General Rate Laws
Topic: Instantaneous rate
Replies: 4
Views: 83

### Instantaneous rate

Are we supposed to use the instantaneous rates when looking at the rates of reactants and products? If so, why?
Wed Mar 11, 2020 1:00 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Derivation of Arrhenius Equation
Replies: 6
Views: 123

### Re: Derivation of Arrhenius Equation

If the original equation is the Arrhenius equation, what happens to the lnA when you derive the equation used to calculate rate constants at different temperatures (the one written in the original question)?
Wed Mar 11, 2020 12:42 am
Forum: First Order Reactions
Topic: Equilibrium constant and elementary reaction rate constants
Replies: 5
Views: 63

### Re: Equilibrium constant and elementary reaction rate constants

The equilibrium constant is equal to k(forward)/k(reverse). This is helpful when converting the concentration of intermediate species into concentrations of reactants of the overall reaction when given elementary reactions.
Wed Mar 11, 2020 12:38 am
Forum: General Rate Laws
Topic: Stoichiometric coefficients vs order
Replies: 4
Views: 121

### Stoichiometric coefficients vs order

When do the orders of the rate equal the stoichiometric coefficients of a reaction, and when do they not? Thank you in advance.
Fri Mar 06, 2020 7:04 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: units of T
Replies: 11
Views: 496

### Re: units of T

Generally, time is in seconds, so it would be easier to convert all units to seconds.
Fri Mar 06, 2020 6:31 pm
Forum: Zero Order Reactions
Topic: order of reactions
Replies: 4
Views: 75

### Re: order of reactions

Another good way to determine whether a reaction is in the zeroth, first, or second order is to look at the units of k, the rate constant. If the units of k is M/s, it is in the zeroth order; if k is 1/s, it is in the first order; if k is 1/M*s, it is in the second order.
Fri Mar 06, 2020 6:28 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: determine n
Replies: 16
Views: 654

### Re: determine n

In kinetics, n refers to the order of the reactants in a reaction. If n=1, this tells us the rate is directly proportional to the concentration of [reactant].
Fri Mar 06, 2020 6:25 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: units of k
Replies: 9
Views: 166

### Re: units of k

For the units of k, the zeroth order is M/s, the first order is 1/s, and the second order is 1/M*s. A good way to remember this is to divide by M when going from zeroth to first to second order.
zeroth order: M/s --> divide by M --> first order: 1/s --> divide by M --> second order:1/M*s
Fri Mar 06, 2020 6:18 pm
Forum: General Rate Laws
Topic: Rate laws
Replies: 4
Views: 117

### Re: Rate laws

Also if given a chemical equation, does the coefficient in front of the reactant automatically translate into the exponent in the rate law? The coefficient does not automatically translate into the exponent in the rate law. The exponent in the rate law is the order of the reaction which is found us...
Sat Feb 29, 2020 1:08 am
Forum: Balancing Redox Reactions
Topic: Homework redox reactions
Replies: 2
Views: 67

### Homework redox reactions

Could someone explain why species that undergo oxidation are called the reducing agent, as species that undergo reduction are called the oxidizing agent? Thank you in advance.
Sat Feb 29, 2020 1:06 am
Forum: Balancing Redox Reactions
Topic: Test 2
Replies: 19
Views: 266

### Re: Test 2

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?
Sat Feb 29, 2020 1:01 am
Forum: Van't Hoff Equation
Topic: Derive [ENDORSED]
Replies: 4
Views: 193

### Derive[ENDORSED]

How can you derive ln(K1/K2)= -delta H/R (1/T1 - 1/T2) from the Van't Hoff equation given on the formula sheet: lnK=-delta H/RT + delta S/R ? Thank you in advance.
Sat Feb 29, 2020 12:51 am
Forum: Balancing Redox Reactions
Topic: Acidic and Basic solutions
Replies: 11
Views: 158

### Re: Acidic and Basic solutions

In acidic solutions, you balance redox reactions using H2O and H+. The hydronium ions produce the acidic solution.
Sat Feb 29, 2020 12:28 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Spontaneous reactions
Replies: 6
Views: 91

### Re: Spontaneous reactions

When the cell potential is positive, the reaction is spontaneous. When you are given the standard cell potentials of different reduction reactions, typically the more positive value is more spontaneous, and therefore the reduction reaction.
Sat Feb 22, 2020 2:40 pm
Forum: Balancing Redox Reactions
Topic: HW problem 6k.1
Replies: 3
Views: 37

### Re: HW problem 6k.1

After looking at the overall net charge of all the species on both sides of the reaction, you determine how many electrons you need to add in order to have the charges equal on both sides of the reaction. From here, you need to multiply the oxidation half reaction by 3 to turn the 2 electrons into 6...
Sat Feb 22, 2020 2:35 pm
Forum: Balancing Redox Reactions
Topic: Homework 6K1
Replies: 4
Views: 57

### Re: Homework 6K1

If the net charge is not indicated on the upper right hand corner of the species, then the species have an overall net charge of zero.
Sat Feb 22, 2020 2:32 pm
Forum: Balancing Redox Reactions
Topic: Basic conditions
Replies: 6
Views: 106

### Basic conditions

How do we go about balancing redox reaction in basic solutions? How different is it from having a redox reaction in acidic reaction? Thank you in advance.
Sat Feb 22, 2020 2:29 pm
Forum: Balancing Redox Reactions
Topic: 6K.1
Replies: 3
Views: 46

### Re: 6K.1

After balancing the oxidation half-reactions by adding 2H+ ions, the two side of the half-reactions have unequal charge. By adding the 2 e- on the right side of the reaction, it balances out the 2+ charge from the H+ ion.
Sat Feb 22, 2020 2:21 pm
Forum: Balancing Redox Reactions
Topic: Calculating the reaction Gibbs free energy
Replies: 7
Views: 146

### Re: Calculating the reaction Gibbs free energy

n refers to the number of moles of e-
Sat Feb 15, 2020 4:36 pm
Forum: Van't Hoff Equation
Topic: When to apply the Van't Hoff Equation
Replies: 5
Views: 405

### Re: When to apply the Van't Hoff Equation

You can use this equation when you are trying to calculate K at different temperatures if delta H is known.
Sat Feb 15, 2020 4:30 pm
Forum: Balancing Redox Reactions
Topic: redox reactions
Replies: 3
Views: 71

### redox reactions

Could someone explain the how and why redox reactions occur? Thank you in advance.
Sat Feb 15, 2020 4:19 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs and K value
Replies: 3
Views: 82

### Gibbs and K value

Can someone explain how the K value can impact the sign of delta G. Thank you in advance.
Sat Feb 15, 2020 4:06 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equilibrium
Replies: 5
Views: 84

### Re: Equilibrium

At equilibrium, delta G will be zero, but I don't believe that always mean that delta H and delta S will also be zero.
Sat Feb 15, 2020 3:50 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: PV=nRT
Replies: 5
Views: 73

### Re: PV=nRT

Typically, when you are dealing with an ideal gas and need to find lets say the work, but certain components of the equation are missing, you can use PV=nRT. This will allow you to solve for what you're missing and use it to find the work, for example.
Fri Feb 07, 2020 11:17 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Spontaneous vs Nonspontaneous
Replies: 4
Views: 67

### Spontaneous vs Nonspontaneous

How can you tell whether a system is spontaneous, non-spontaneous, or reversible based off the change in entropy? Thank you in advance.
Fri Feb 07, 2020 11:11 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: Microstates and Entropy
Replies: 1
Views: 19

### Microstates and Entropy

In what ways are microstates important in biological processes? Thank you in advance.
Fri Feb 07, 2020 10:53 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: heat given off by rxn = - heat absorbed by solution
Replies: 6
Views: 93

### Re: heat given off by rxn = - heat absorbed by solution

I believe the correct statement is: -(heat given off by system)=(heat gained by surroundings). This statement is true if the system is isolated because the heat given off my a system must be transferred to the surroundings.
Fri Feb 07, 2020 10:48 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: open system
Replies: 5
Views: 73

### Re: open system

A car engine is an open system because it allows for the exchange of matter and energy between the system and the surroundings.
Fri Feb 07, 2020 10:45 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Important conditions
Replies: 3
Views: 68

### Important conditions

I was wondering which conditions should we know for our midterm? So far I know we should understand an isothermal system and an adiabatic system; are there any other important conditions we should know and could you give a small description of it as well. Thank you in advance.
Sat Feb 01, 2020 1:46 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: state property
Replies: 8
Views: 59

### Re: state property

A state function is a property that is independent of how the substance was created; it only depends on the initial and final state. Some examples include: pressure, density, temperature, volume, enthalpy, internal energy, Gibbs free energy, and entropy.
Sat Feb 01, 2020 1:37 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated vs Closed [ENDORSED]
Replies: 34
Views: 1030

### Re: Isolated vs Closed[ENDORSED]

An open system can exchange energy and matter with its surroundings. A closed system can exchange energy but not matter with its surroundings. An isolated system cannot exchange energy and matter with its surroundings. Therefore, an insulated system is an isolated system.
Sat Feb 01, 2020 1:33 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work and ideal gas law
Replies: 4
Views: 48

### Work and ideal gas law

Can someone explain the relationship between work and the ideal gas law? I believe a problem was done in class where work was found using the ideal gas law. Thank you in advance.
Sat Feb 01, 2020 1:30 am
Forum: Phase Changes & Related Calculations
Topic: Enthalpy vs Change in Internal Energy
Replies: 4
Views: 68

### Enthalpy vs Change in Internal Energy

Can someone explain the main difference between enthalpy and the change in internal energy?
Sat Feb 01, 2020 1:23 am
Forum: Phase Changes & Related Calculations
Topic: Calorimeter
Replies: 8
Views: 129

### Calorimeter

What is the difference between a calorimeter and a bomb calorimeter? Thank you in advance.
Fri Jan 24, 2020 8:23 pm
Forum: Ideal Gases
Topic: Kc vs Kp
Replies: 109
Views: 930

### Re: Kc vs Kp

Kp is used when dealing with partial pressures, so typically gases. Kc is used when dealing with concentration, so aqueous species.
Fri Jan 24, 2020 8:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: solvent
Replies: 10
Views: 71

### Re: solvent

Due to an activity of 1, solids and liquids are not included since they would have no impact on the equilibrium constant. Knowing this, you only include (aq) and (g) species to calculate the equilibrium constant.
Fri Jan 24, 2020 8:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q<K
Replies: 11
Views: 95

### Re: Q<K

Q is also equal [products]/[reactants]. If Q is less than K, that means the concentration of reactants is too much, causing the ratio between products and reactants to be small. In order to fix this, the chemical reaction will favor the formation of products to increase this ratio, in hopes of meeti...
Fri Jan 24, 2020 8:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Percent Ionization
Replies: 12
Views: 104

### Re: Percent Ionization

To calculate percent ionized, you would first perform an ICE table on a chemical reaction. Typically, the equilibrium concentration of hydronium is represented by x. Solve for x using the Ka value and formula. The formula for percent ionized is = [x]/[acid(initial)] x 100%.
Fri Jan 24, 2020 7:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium concentration help
Replies: 4
Views: 70

### Re: Equilibrium concentration help

When dealing with liquids and solids, you completely disregard those species in the chemical reaction when doing an ICE table.
Thu Jan 16, 2020 11:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Acids and Bases on test?
Replies: 3
Views: 32

### Re: Acids and Bases on test?

Test 1 will cover chemical equilibrium calculations, equilibrium shifts (Le Chatelier's), and weak acid/base calculation. Essentially, content covered in the first two weeks.
Thu Jan 16, 2020 10:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: concentration
Replies: 2
Views: 22

### Re: concentration

In order to go from molarity to mass, you would need to convert molarity to moles. This requires you to be given the volume so the units can cancel out. From the number of moles, you can use molar mass (g/mol) to obtain the mass.
Thu Jan 16, 2020 10:48 pm
Forum: Ideal Gases
Topic: Kp given instead of Kc
Replies: 8
Views: 142

### Re: Kp given instead of Kc

If you are given moles or grams, you can first convert into molarity, and from there you can use the equation, P=(n/v)RT to find the partial pressure of each gas in the reaction. Then, these numbers can be used to calculate Kp.
Thu Jan 16, 2020 10:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Determining molar concentration
Replies: 2
Views: 69

### Determining molar concentration

The question to the problem is: "Consider the following reaction - PCl5 (aq) ⇌ PCl3 (aq) + Cl2 (aq) Given that 1.0g of PCl5 is placed in a 250 mL reaction vessel, determine the molar concentration in the mixture at equilibrium." How would I start off this question? Should I first find the ...
Thu Jan 16, 2020 10:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework 6B.5
Replies: 1
Views: 20

### Homework 6B.5

I'm having trouble figuring out how to do this homework problem. Any help is appreciated.

6B.5: "Calculate the pH and pOH of each of the following aqueous solutions of a strong acid or base: (a) 0.0146 M HNO3(aq); (b) 0.11 M HCl(aq); (c) 0.0092 M Ba(OH)2(aq)"
Wed Jan 08, 2020 5:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Finding K without aq
Replies: 4
Views: 54

### Finding K without aq

In class, we discussed finding the equilibrium constant while ignoring species in a reaction at the solid or liquid phase. If all species in a chemical reaction are solids/liquids what would the value of K be? Would there be a value of K? Thank you in advance.
Wed Jan 08, 2020 12:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Small K value and Large K value
Replies: 10
Views: 153

### Small K value and Large K value

What is the cut off for the value of K to say that the reaction strongly favors the formation of reactions and the reaction strongly favors the formation of products? Thank you in advance.
Wed Jan 08, 2020 12:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs Kp vs Kc
Replies: 9
Views: 124

### Re: K vs Kp vs Kc

If in a reaction, all species are in the gas phase, typically you would use their partial pressures, meaning you would use Kp. If the species in a reaction are aqueous, you would use the concentrations and Kc.
Wed Jan 08, 2020 12:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Increasing the concentration of products?
Replies: 3
Views: 27

### Re: Increasing the concentration of products?

If you increase the concentration of the products, and then proceed to find the reaction quotient, you'll see that Q>K, meaning the concentration of products > concentration of reactants. As a result, the reverse reaction is favored.
Wed Jan 08, 2020 12:24 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Quotient > Equilibrium Constant
Replies: 4
Views: 61

### Reaction Quotient > Equilibrium Constant

In the video module, Lavelle says that when Q>K, the reaction hasn't reached equilibrium yet because there is too much product, so it goes from right to left (reverse reaction) to reach equilibrium. My question is: how is it possible to have more product than reactant without going against the idea ...
Mon Dec 02, 2019 11:40 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: H2O as a monodenate ligand
Replies: 1
Views: 25

### H2O as a monodenate ligand

Why is H2O a monodenate ligand? When you draw the lewis structure of H2O, the oxygen has two lone pairs, but the molecule as a whole is classified as a monodenate. Could someone explain this to me. Thank you in advance.
Mon Dec 02, 2019 8:53 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelating complexes
Replies: 6
Views: 101

### Re: Chelating complexes

If something is a chelate what does that tell us and how would we identify it? Is there more to know other than just the definition of it? I think a good way to see if something is a chelate is to ask yourself "does this central atom have multiple polydentate ligands attached to it?" If t...
Mon Dec 02, 2019 5:11 pm
Forum: Naming
Topic: Hw 9c.1 part c
Replies: 5
Views: 118

### Re: Hw 9c.1 part c

Why is it colbalt (III)? What is the oxidation number of the metal? Cobalt has an oxidation number of 3+ because we see that there is an overall charge of 2-, there are 5 CN- molecules and 5 OH2 molecules. Because CN has a charge of -1, there is a total -5 charge from them alone. OH2 has no charge ...
Mon Dec 02, 2019 12:28 am
Forum: Naming
Topic: Hw 9c.1 part c
Replies: 5
Views: 118

### Hw 9c.1 part c

For [Co(CN)5(OH2)]2-,
why is it called aquapentacyanocobaltate(III) ion instead of aquapentacyanocobalt(III) ion?
Sun Dec 01, 2019 11:38 pm
Forum: Naming
Topic: Latin names
Replies: 2
Views: 61

### Latin names

Will we be expected to know the latin names of metals in coordination compounds?
Sun Dec 01, 2019 11:37 pm
Forum: Naming
Topic: Coordination compounds latin names
Replies: 2
Views: 29

### Coordination compounds latin names

When are we supposed to substitute metals with their latin name when naming coordination compounds?
Fri Nov 29, 2019 10:29 pm
Forum: Biological Examples
Topic: biological significance [ENDORSED]
Replies: 1
Views: 55

### biological significance[ENDORSED]

How much information are we expected to know on the biological importance of coordination compounds?
Fri Nov 29, 2019 10:24 pm
Forum: Dipole Moments
Topic: Polar or nonpolar?
Replies: 4
Views: 3603

### Polar or nonpolar?

Is CH2BR2 polar or nonpolar? Do the dipole moments cancel out?
Fri Nov 29, 2019 10:13 pm
Forum: Hybridization
Topic: Resonance Structures and hybridization
Replies: 1
Views: 45

### Resonance Structures and hybridization

Let's say a structure has resonance structures due to delocalized electrons, but each structure has different hybridizations. Which hybridization would be considered correct?
Fri Nov 29, 2019 10:05 pm
Forum: Hybridization
Topic: Writing the hydrization
Replies: 10
Views: 263

### Re: Writing the hydrization

I think it's the same thing, but with the energy level, it's more specific for an atom.
Fri Nov 29, 2019 9:59 pm
Forum: Hybridization
Topic: Homework 2F.11
Replies: 1
Views: 53

### Homework 2F.11

The question for 2F.11 says, "White phosphorus, P4, is so reactive that it bursts into flame in air. The four atoms in P4 form a tetrahedron in which each P atom is connected to three other P atoms. (a) Assign a hybridization scheme to the P4 molecule." As I was drawing the lewis structure...
Sat Nov 23, 2019 1:28 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: dipole-dipole in a solid phase vs gas phase
Replies: 15
Views: 310

### Re: dipole-dipole in a solid phase vs gas phase

Dipole-dipole in the gas phase is also equal to induced dipole - induced dipole, so dipole-dipole in the solid phase would have stronger IMFs.
Sat Nov 23, 2019 1:22 pm
Forum: Lewis Acids & Bases
Topic: Week 9 Homework
Replies: 5
Views: 102

### Re: Week 9 Homework

I'm assuming 9C, but I haven't heard anything from my TA.
Sat Nov 23, 2019 1:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity
Replies: 7
Views: 104

### Re: Polarity

A dipole moment is formed due to a significant enough difference in electronegativity between two atoms. Remember that electronegativity is the ability to attract electrons.
Sat Nov 23, 2019 1:06 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Sphere
Replies: 2
Views: 29

### Coordination Sphere

Could someone explain the coordination sphere. Thank you in advance.
Sat Nov 23, 2019 1:03 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: [Fe(CN)6]4-
Replies: 5
Views: 70

### Re: [Fe(CN)6]4-

The CN- ions are considered the ligands, and these ions provide the electron pairs that form bonds to Fe2+
Thu Nov 14, 2019 12:22 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Trigonal Bipyramidal angles
Replies: 2
Views: 59

### Trigonal Bipyramidal angles

Can someone explain the different bond angles within the trigonal bipyramidal shape? Thank you in advance.
Thu Nov 14, 2019 12:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Arrangement vs Shape
Replies: 3
Views: 33

### Re: Arrangement vs Shape

I was wondering the same thing. In the textbook they use NH3 as an example where its electron arrangement is considered tetrahedral, but its shape is trigonal pyramidal. Can anyone explain this?
Thu Nov 14, 2019 11:54 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Repulsion strength
Replies: 1
Views: 21

### Repulsion strength

In lecture, Lavelle said that repulsion strength follows this pattern:
lone-lone pair>lone-bonding pair>bonding-bonding pair.
Thu Nov 14, 2019 11:47 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: H-bonds
Replies: 4
Views: 52

### H-bonds

Do hydrogen bonds also have dipole moments? Could you characterize a molecule that has hydrogen bonds as it also having dipole forces?
Thu Nov 14, 2019 11:45 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Homework 2E.5
Replies: 2
Views: 37

### Homework 2E.5

Can someone help me with this problem? It states, " (a) What is the shape of a ClO2+ ion? (b) What is the expected OClO bond angle?"
Sat Nov 09, 2019 10:07 pm
Forum: Dipole Moments
Topic: Instantaneous dipoles
Replies: 2
Views: 28

### Instantaneous dipoles

What are instantaneous dipoles? Can someone please explain this to me.
Sat Nov 09, 2019 9:54 pm
Forum: Electronegativity
Topic: Ionization Energy
Replies: 3
Views: 53

### Ionization Energy

Why does nitrogen have a lower ionization energy than nitrogen if ionization energy increases across a period?
Sat Nov 09, 2019 9:52 pm
Forum: Electronegativity
Topic: Periodic Trend
Replies: 13
Views: 241

### Re: Periodic Trend

Electronegativity is the ability to pull in an electron. It increases across a period because the nuclear charge of atoms increase, meaning its ability to pull in an electron is greater. It increases up a group also because the nuclear charge of atoms increase.
Sat Nov 09, 2019 9:32 pm
Forum: Electronegativity
Topic: Polar Molecules
Replies: 4
Views: 102

### Re: Polar Molecules

It depends on the difference in electronegativity. If the difference between the molecules' electronegativity values is larger than 2.0, the molecule is polar. Polarity is simply the unequal pull of electrons. If electronegativity is the ability to pull an electron, two molecules with very different...
Sat Nov 09, 2019 9:26 pm
Forum: Ionic & Covalent Bonds
Topic: Polarizability
Replies: 4
Views: 78

### Re: Polarizability

Large anions are more polarizable because their electron cloud is larger and their nuclear charge is smaller, allowing the outermost electrons to get distorted easier. Larger atoms are more polarizable.
Sat Nov 02, 2019 3:35 pm
Forum: Lewis Structures
Topic: BF3
Replies: 3
Views: 51

### BF3

Can someone explain the lewis dot structure of BF3 please. Thank you.
Sat Nov 02, 2019 3:33 pm
Forum: Photoelectric Effect
Topic: important part of photoelectric effect
Replies: 5
Views: 128

### Re: important part of photoelectric effect

It's important to know that
the energy of a photon - threshold energy = electron's kinetic energy.
Sat Nov 02, 2019 3:24 pm
Forum: DeBroglie Equation
Topic: Converting mass to kilograms for de broglie
Replies: 7
Views: 60

### Re: Converting mass to kilograms for de broglie

You would need to find the mass. The molar mass is given in grams/mol, so first you would need to convert into atoms using (6.022 x10^23 atoms/mol). Then, convert grams into kilograms. Anything with mass and velocity has a wavelength, so it will work out, you just need to use dimensional analysis to...
Sat Nov 02, 2019 3:19 pm
Forum: Lewis Structures
Topic: Drawing Structures for Ionic Bonds
Replies: 2
Views: 34

### Drawing Structures for Ionic Bonds

How could we draw the lewis structures for ionic bonds? Can someone explain how that would work since the atoms wouldn't be sharing electrons. Thank you.
Sat Nov 02, 2019 3:13 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Minimizing Formal Charges
Replies: 5
Views: 73

### Re: Minimizing Formal Charges

The best/most stable lewis structures come from a structure that has the most atoms with a formal charge of zero, the lowest magnitude of formal charges, and if there is a negative formal charge, it's on the most electronegative atom.
Fri Oct 25, 2019 11:44 pm
Forum: Formal Charge and Oxidation Numbers
Topic: FC in lecture
Replies: 4
Views: 84

### FC in lecture

In lecture, Lavelle said "charged delocalization tends to be more stable." Could someone please explain this?
Fri Oct 25, 2019 11:35 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 5
Views: 93

### Re: Formal Charge

APatel_4A wrote:How do we know what the formal charge for the molecule should add up to? Is it always most stable if it adds up to 0?

Yes, the goal is to get a formal charge of 0. This tells us this is when it's most stable, and the lewis structure will best describe its real structure.
Fri Oct 25, 2019 11:32 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 4
Views: 60

### Re: Electron Affinity

Electron affinity can be either negative or positive. It is defined as the energy associated with the release or addition of an electron. When an electron is added, electron affinity will be negative. On the other hand, when an electron is released, electron affinity will be positive.
Fri Oct 25, 2019 11:13 pm
Forum: Ionic & Covalent Bonds
Topic: Partial Bond
Replies: 2
Views: 41

### Partial Bond

Can someone further explain the idea of having a "partial bond" character? It was discussed in lecture when we were going over the nitrate ion.
Fri Oct 25, 2019 11:06 pm
Forum: Ionic & Covalent Bonds
Topic: Electronegativity
Replies: 4
Views: 76

### Electronegativity

Can someone explain electronegativity and its relationship to ionization energy, if there is one.
Fri Oct 18, 2019 9:06 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Hund's Rule
Replies: 4
Views: 91

### Re: Hund's Rule

Hund's rule says that electrons at the same energy level occupy different orbitals before pairing up. This is due to the fact that electrons are all negatively charged, meaning they repel each other, so they would rather be in a separate, empty orbital if it's available. Once each orbital has an ele...
Fri Oct 18, 2019 9:00 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: building up principle
Replies: 5
Views: 60

### Re: building up principle

The Aufbau principle basically says that electrons fill the lowest energy levels before they move onto the next energy level. Notice how every time we move down the period table (and into a new energy level) or even across the periodic table (and into a new orbital), the previous energy levels / orb...
Fri Oct 18, 2019 12:38 pm
Forum: Einstein Equation
Topic: HW 1.B.7 (b and c)
Replies: 3
Views: 89

### HW 1.B.7 (b and c)

1.B.7 says "Sodium vapor lamps, used for public lighting, emit yellow light of wavelength 589 nm. How much energy is emitted by (a) an excited sodium atom when it generates a photon; (b) 5.00 mg of sodium atoms emitting light at this wavelength; (c) 1.00 mol of sodium atoms emitting light at th...
Fri Oct 18, 2019 12:21 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Hw problem 1E.7 part(c)
Replies: 1
Views: 33

### Hw problem 1E.7 part(c)

On the homework, problem 1.E.7 asks to "Determine whether each of the following electron configurations represents the ground state or an excited state of the atom given." part (c) has Be as the element along with the electron configuration diagram. I'm confused as to why they placed one e...
Fri Oct 18, 2019 12:14 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Cr and Cu Exceptions
Replies: 2
Views: 53

### Cr and Cu Exceptions

Can someone further explain why Cr and Cu are exceptions for the electron configuration rules we talked about in lecture.
The correct configuration:
Cr: [Ar] 3d^5 4s^1
Cu: [Ar] 3d^10 4s^1
Why aren't they:
Cr: [Ar] 3d^4 4s^2
Cu: [Ar] 3d^9 4s^2
Sat Oct 12, 2019 2:10 pm
Forum: Properties of Light
Topic: Equations
Replies: 4
Views: 53

### Equations

Which equations apply to electromagnetic radiation and which ones would not work?
Sat Oct 12, 2019 1:54 pm
Forum: Photoelectric Effect
Topic: Energy in Photoelectric Effect
Replies: 5
Views: 49

### Energy in Photoelectric Effect

When the threshold energy is met, will electrons be emitted? Or does the energy of the photon have to exceed the threshold energy in order for electrons to be emitted?
Sat Oct 12, 2019 1:47 pm
Forum: Properties of Electrons
Topic: Wavelike properties of electrons
Replies: 3
Views: 69

### Wavelike properties of electrons

Why is it that wavelike properties are only noticed in electrons? It was discussed in lecture, but I didn't get all the information, so I'm having trouble understanding.
Sat Oct 12, 2019 1:42 pm
Forum: Properties of Light
Topic: Constructive & Destructive
Replies: 4
Views: 55

### Constructive & Destructive

Can someone explain the difference between constructive and destructive interference, and how larger waves are created in constructive interference while smaller waves are created through destructive.
Thu Oct 10, 2019 5:42 pm
Forum: Photoelectric Effect
Topic: How the Photoelectric Effect Proves Light is a Photon
Replies: 4
Views: 101

### Re: How the Photoelectric Effect Proves Light is a Photon

From my understanding, in order for the electrons to be ejected, we need a specific frequency (or kinetic energy) to meet the threshold energy of the metal. This kinetic energy is found in particles. Therefore, light is also a particle.
Thu Oct 03, 2019 10:52 pm
Forum: Limiting Reactant Calculations
Topic: How do you find the percentage yield for M.3 on page F104?
Replies: 3
Views: 67

### Re: How do you find the percentage yield for M.3 on page F104?

A tip to make sure you are on your way to correctly calculating the percent yield is to see if your actual yield is less than your theoretical yield. Generally, this is the case due to measuring discrepancies.
Thu Oct 03, 2019 10:40 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Replies: 16
Views: 392

Do you think we will have to memorize the Avogadro's Number for test? I am wondering if I will be given the Avogadro's Number when I get the questions that ask for atoms' number. I'm not that sure if we will need to know it for this class, but I heard that Lavelle does give constants on exams, but ...
Thu Oct 03, 2019 10:37 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Replies: 16
Views: 392