## Search found 90 matches

Sat Mar 14, 2020 6:11 pm
Forum: First Order Reactions
Topic: problem 7.27
Replies: 1
Views: 65

### Re: problem 7.27

First use the first order half life equation to find K. Using K, you can calculate the ratio of the final/initial concentrations. that ratio can be used to find what fraction of the 150mg have been used.
Sat Mar 14, 2020 6:07 pm
Forum: General Rate Laws
Topic: Rate Law and Order
Replies: 2
Views: 104

### Re: Rate Law and Order

the rate law tells you the overall rate of the reaction in terms of its reactants, this will include K. the rate order depends on the exponent on each reactant, which indicates the number of molecules of that substance that needs to collide. Molecularity refers to the number of species in an element...
Sat Mar 14, 2020 10:46 am
Forum: Bronsted Acids & Bases
Topic: determining if a substance is protonated
Replies: 1
Views: 178

### determining if a substance is protonated

Hi all,

I am looking at the midterm, question 4. How do I determine if a substance will or will not remain protonated by comparing PH between that substance and its surroundings?

Mon Mar 09, 2020 11:39 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Rate determining step and Ea
Replies: 2
Views: 67

### Rate determining step and Ea

Does the rate determining step always have the largest activation energy? How do I determine the rate determining step by looking at a reaction profile?
Mon Mar 09, 2020 4:06 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: temperature, K, and rate
Replies: 1
Views: 81

### temperature, K, and rate

In lecture Dr. Lavelle said that raising the temperature increases rate of reaction in both the forward and reverse reaction. However, I previously thought that raising the temperature increases the value of K, which as I understand is the ratio of the Ks of the forward and reverse reactions. Could ...
Sun Mar 08, 2020 11:41 pm
Forum: General Rate Laws
Topic: Pseudo rate law
Replies: 3
Views: 55

### Re: Pseudo rate law

a pseudo rate law is obtained under lab conditions. Consider a reaction with three reactants, A, B, C, each with n=1. The order would be considered 3. However, under lab conditions the concentrations of A and B can be made very high, and would be considered constant. Thus, the rate depends only on t...
Sun Mar 08, 2020 11:31 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Applying La Chateliers
Replies: 4
Views: 84

### Re: Applying La Chateliers

changing the concentration of the reactants changes E cell. Increasing the concentration of the products shifts the equilibrium to favor the products, thus E cell increases.
Sat Mar 07, 2020 4:26 pm
Forum: General Rate Laws
Topic: affect of temperature on K
Replies: 4
Views: 103

### affect of temperature on K

if a reaction is endothermic, and the temperature is raised, the rate constant of the forward reaction also is raised. Likewise, if a reaction is exothermic, does that mean with an increase in temperature k' will increase more than k of the forward reaction?
Fri Mar 06, 2020 5:08 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Elementary reactions
Replies: 5
Views: 108

### Elementary reactions

"elementary" is used in many practice problems to describe reactions. What exactly does it mean when a reaction is "elementary?"
Thu Mar 05, 2020 11:39 am
Forum: General Rate Laws
Topic: finding order of reactant with three reactants
Replies: 1
Views: 69

### finding order of reactant with three reactants

Im looking at chapter 7 problem 7A.17 given a table of concentrations and rates for multiple reactions, the question asks to find the order of each reactant. I know from class to find the order you compare two separate reactions when the concentration of one reactant changes while the other concentr...
Wed Mar 04, 2020 11:02 pm
Forum: General Rate Laws
Topic: conceptual question (zero order)
Replies: 3
Views: 78

### conceptual question (zero order)

If second order reactions take place when two molecules collide in the slow step, how do first and zero order reactions take place? In other words, could someone explain conceptually what takes place in a zero or first order reaction?
Mon Mar 02, 2020 12:48 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: different values for RT/F
Replies: 1
Views: 62

### different values for RT/F

Hi all. I want to clarify my understanding of the NERST equation. When using the natural log of Q, at 298K, RT/F = 0.025693. However, at the same temperature but when using log of Q, RT/F = 0.05926. Could someone confirm/correct my understanding?

Thanks!
Sun Mar 01, 2020 3:45 pm
Forum: Van't Hoff Equation
Topic: Half reactions 6L.9
Replies: 2
Views: 76

### Re: Half reactions 6L.9

The standard cell potentials are very helpful when the cell is spontaneous. The greater the magnitude of charge the stronger the reducer/oxidizer.
Sun Mar 01, 2020 3:44 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: precipitation reactions
Replies: 3
Views: 80

### Re: precipitation reactions

look at the states of the products - if there is a solid as a product that could be considered a precipitate.
Sun Mar 01, 2020 3:43 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cathode and Anode of Electrolytic Cells
Replies: 4
Views: 87

### Re: Cathode and Anode of Electrolytic Cells

In terms of electrolytic cells, it is important to keep in mind that it is not spontaneous, thus the voltage of the reduction reactions aren't super important because regardless of voltage, the cell will need additional energy to move the process.
Tue Feb 25, 2020 12:23 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: identifying strong reducing/oxidizing agents
Replies: 3
Views: 121

### identifying strong reducing/oxidizing agents

Hi,

How do I identify what substance is the strongest reducing/oxidizing agent based off of their E?

Tue Feb 25, 2020 11:41 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: standard potential of a redox reaction
Replies: 3
Views: 83

### standard potential of a redox reaction

Suppose I am balancing a redox reaction, and need to multiply one of the half reactions by some coefficient. Would the E for that half reaction also be multiplied by the same coefficient?
Sun Feb 23, 2020 9:06 pm
Forum: Balancing Redox Reactions
Topic: Hydroxide and H+
Replies: 6
Views: 125

### Re: Hydroxide and H+

I haven't come across any questions that require you to balance using OH and H unless the problem specifically mentions an acidic/basic solution.
Sun Feb 23, 2020 9:05 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Calculating pH using Nernst Equation
Replies: 2
Views: 77

### Re: Calculating pH using Nernst Equation

The Nernst equation can help you calculate concentration, from which you can use to find PH. Khan academy has a super helpful video on the Nerst Equation, just search on youtube!
Sat Feb 22, 2020 5:56 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Textbook progress
Replies: 3
Views: 73

### Textbook progress

How far in chapter 6 have we covered in lecture so far?
Sat Feb 22, 2020 5:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Using an inert electrode
Replies: 2
Views: 43

### Using an inert electrode

Hi all, I'm looking at question 6L.5.B. I don't understand why Pt is used as an inert conductor on BOTH sides. The answer key has Pt as an inert conductor even when there is solid iodine in the reaction. Could someone explain to me why Pt is used as in inert conductor despite there being a solid pre...
Sat Feb 22, 2020 4:22 pm
Forum: Balancing Redox Reactions
Topic: oxidizing AND reducing agent
Replies: 3
Views: 87

### Re: oxidizing AND reducing agent

in addition^ I understand how Chlorine was able to be oxidized, but I don't understand how to write out a reduction equation for chlorine in this case
Sat Feb 22, 2020 4:15 pm
Forum: Balancing Redox Reactions
Topic: oxidizing AND reducing agent
Replies: 3
Views: 87

### oxidizing AND reducing agent

Hi all, looking at question 6k.5.d, chlorine gas is both the oxidizing and reducing agent. Could someone help me understand how this happens?
Sat Feb 22, 2020 4:10 pm
Forum: Balancing Redox Reactions
Topic: Basic/Acidic solutions
Replies: 2
Views: 39

### Basic/Acidic solutions

Hi all,

Im having trouble understanding what it means when a redox reaction takes place in an acidic or basic solution. Could someone clarify how to balance and conceptually what takes place when a redox reaction takes place in an acidic or basic solution? Thanks!
Fri Feb 21, 2020 5:14 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: relationship between concentration and Ecell
Replies: 2
Views: 36

### relationship between concentration and Ecell

Today in lecture Dr.Lavelle said that Le Chatelier's principle is used to explain the change in Ecell when the concentration of a product/reactant is changed. Could someone further explain/clarify exactly how changing the concentration of a product/reactant influences Ecell?
Fri Feb 21, 2020 5:12 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: sign of Ecell
Replies: 2
Views: 49

### sign of Ecell

If E cell is negative, does that indicate that the reaction is not favorable? Can there every be a negative value for E cell?
Fri Feb 21, 2020 5:10 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Wmax
Replies: 2
Views: 40

### Wmax

I did not catch in lecture today what Dr. Lavelle was explaining about the relationship with Wmax and deltaG, are they always equal?
Tue Feb 18, 2020 11:41 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: relationship between K and temp
Replies: 2
Views: 83

### relationship between K and temp

Hello,
I thought that when temperature increased, so did K. However I'm looking at 5J.13 and the K given for a higher temperature is smaller than the K given for a lower temperature. Could someone clarify the relationship between temperature and K?
Sun Feb 09, 2020 11:52 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: when to change sign of enthalpies
Replies: 7
Views: 138

### when to change sign of enthalpies

Hi, i'm looking at question 4 on the Pizza Rolls review sheet. When do I know to change the sign of the enthalpies given?
Wed Feb 05, 2020 2:29 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: calculating q: moles or mass?
Replies: 2
Views: 16

### calculating q: moles or mass?

I know the equation Q=mc(deltaT), where m=mass of substance. However I have come across a very similar equation, Q=nc(deltaT), where n=moles of substance. How do I know if I should use the mass or the moles of a substance when finding Q? One idea I had was to use moles when calculating at a constant...
Wed Feb 05, 2020 2:16 pm
Forum: Calculating Work of Expansion
Topic: Kelvin vs Celsius
Replies: 5
Views: 54

### Kelvin vs Celsius

How do I know when to convert to kelvin/celsius when solving problems? Is it safe to always use kelvin?
Wed Feb 05, 2020 2:05 pm
Forum: Calculating Work of Expansion
Topic: Understanding equation for work at constant pressure
Replies: 3
Views: 35

### Understanding equation for work at constant pressure

Hey.
Could someone explain where the equation for work, W=nR(deltaT) comes from? This is for calculating work at constant pressure.
Wed Feb 05, 2020 10:13 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: equations with q
Replies: 2
Views: 27

### equations with q

Could someone explain when solving for q: when we include moles, when we include mass, and when we don't include any value for mass/moles?
Sun Feb 02, 2020 9:02 pm
Forum: Calculating Work of Expansion
Topic: Internal energy
Replies: 5
Views: 41

### Internal energy

Could someone clarify exactly what U, internal energy, is? Beyond the equation U=q+W, why is U significant?
Sun Feb 02, 2020 9:00 pm
Forum: Calculating Work of Expansion
Topic: systems at equilibrium
Replies: 1
Views: 14

### systems at equilibrium

when considering Work, the energy from work of expansion, why is it important that the system is at equilibrium?
Sun Feb 02, 2020 8:58 pm
Forum: Calculating Work of Expansion
Topic: Integrals
Replies: 1
Views: 25

### Integrals

In Wednesday's lecture, (the 29th) an equation put W, work, in an integral. Could someone explain what this equation means and why is is helpful? Thanks in advance.
Sun Feb 02, 2020 8:53 pm
Forum: Calculating Work of Expansion
Topic: Thermochemistry and thermodynamics
Replies: 3
Views: 34

### Re: Thermochemistry and thermodynamics

I highly recommend watching the Organic Chemistry tutor on youtube. I find his videos super helpful. He goes very slowly, but does many practice problems as well as conceptual explanations as he solves them. I also recommend khan academy.
Sun Jan 26, 2020 2:01 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard enthalpy of element in most stable form
Replies: 5
Views: 67

### Standard enthalpy of element in most stable form

Could someone explain why the standard enthalpy of formation of an element in its most stable form is zero?
Sun Jan 26, 2020 1:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: clarification from lecture - "state function"
Replies: 2
Views: 25

### clarification from lecture - "state function"

Hi. In lecture, it was stated that enthalpy was a state property, meaning its value is "determined by its current state." Could someone expand what
determined by its current state" means?

Thanks!
Sun Jan 26, 2020 1:54 pm
Forum: Phase Changes & Related Calculations
Topic: Combustion
Replies: 5
Views: 51

### Combustion

is oxidizing/burning/breaking down the same thing as combustion?
Mon Jan 20, 2020 5:02 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: concentration of conjugate acid/nase
Replies: 1
Views: 79

### concentration of conjugate acid/nase

Is the concentration of a conjugate acid always equal to the concentration of hydroxide ions? Similarly is the concentration of the conjugate base of a reaction equal to the concentration of hydronium ions?
Mon Jan 20, 2020 4:16 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Difference in PH between strong and weak acids
Replies: 11
Views: 171

### Difference in PH between strong and weak acids

could someone explain why, at the same concentration, a weak acid would have a higher PH than a strong acid?
Sun Jan 19, 2020 5:03 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: temperature change in reactions
Replies: 11
Views: 111

### Re: temperature change in reactions

K will change in response to change in temperature depending if it is endothermic or exothermic. If the reaction is endothermic, thinking of heat as a reactant, and the reaction will favor formation of the products to reduce stress on the overall reaction. Likewise, if the reaction is exothermic, he...
Sun Jan 19, 2020 5:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.I.11/13
Replies: 2
Views: 35

### Re: 5.I.11/13

To avoid calculation errors, yes, it is best to convert to mols. If you don't you need to be careful with your units throughout the entire problem. Since Molarity is in Mol/L, it is easiest to convert to mols.
Sun Jan 19, 2020 4:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: % Ionization
Replies: 3
Views: 22

### Re: % Ionization

It can be calculated by (conjugate acid)/(initial base) * 100%.
for an acid, it would be (conjugate base)/(initial acid) * 100%
Sun Jan 19, 2020 4:57 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Identifying endothermic vs exothermic
Replies: 7
Views: 87

### Identifying endothermic vs exothermic

If a problem doesn't specifically state if it is endothermic or exothermic, how do we determine which it is based off the stoichiometric equation?
Thu Jan 16, 2020 11:14 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Kw
Replies: 16
Views: 144

### Re: Kw

In lecture Lavelle said that Kw is a constant, 1.0 x 10^-14. I'm looking at a homework problem, and it gives kw as 2.1 x 10^-14, could someone clarify the meaning of the value of Kw? The homework question im referring to is 6A.21
Wed Jan 15, 2020 9:10 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Real reason explaining Le Chatelier's principle
Replies: 4
Views: 53

### Real reason explaining Le Chatelier's principle

In class Dr. Lavelle said that when pressure increases, equilibrium will favor the side with less mols of gas. He said however, that reasoning is not sufficient as an explanation. Could someone explain what would be an appropriate explanation for why an equilibrium would favor the side with less mol...
Tue Jan 14, 2020 2:02 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework 5I.25
Replies: 4
Views: 59

### Re: Homework 5I.25

Also having trouble with this problem. I follow your work until you plug into the Kc formula. Could you explain how you solved for x? Could you also explain why you omitted the x variable in the denominator with 0.06?
Sun Jan 12, 2020 8:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Comparing K
Replies: 9
Views: 79

### Re: Comparing K

The value of K helps us determine how favored the reaction, forward or backwards, is. A very small K indicates high concentration of reactions, while a very large K indicates there is a high concentration of products.
Thu Jan 09, 2020 8:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Clarification on equilibrium
Replies: 3
Views: 38

### Clarification on equilibrium

In lecture Dr.Lavelle used the word "favored" when describing if equilibrium "sits" to the left or to the right. Could someone clarify what it means for equilibrium to "favor" a side? Thanks!
Thu Jan 09, 2020 8:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: finding the equilibrium constant
Replies: 2
Views: 30

### finding the equilibrium constant

I'm confused when to use partial pressure or when to use concentration for K, when a problem doesn't specifically ask for one or the either. If the products and reactants are in the gas phase, does that mean I should always use partial pressure? Thanks in advance!
Thu Jan 09, 2020 8:03 pm
Forum: Ideal Gases
Topic: Rate of reaction
Replies: 2
Views: 38

### Rate of reaction

What factors influence rate of reaction for a reaction reaching equilibrium? For example, does higher concentration influence rate of reaction to equilibrium?
Thu Jan 09, 2020 7:59 pm
Forum: Ideal Gases
Topic: Understanding equilibrium
Replies: 2
Views: 26

### Understanding equilibrium

What exactly happens to products and reactants at equilibrium? I know there is still movement, but why doesn't a reaction stop when it reaches equilibrium?
Fri Dec 06, 2019 1:37 pm
Forum: Naming
Topic: Naming coordinate compounds
Replies: 1
Views: 34

### Naming coordinate compounds

I am confused about the order of naming in the compound [Co(H2NCH2CH2NH)2(CN)(Cl)]Cl. the correct name is, chlorocyanobis(ethylenediamine)cobalt(III)chloride, however, I don't understand the thinking behind the positioning of the names of the two Cl ions. If Cl is an anion, why does it lead in the n...
Tue Dec 03, 2019 6:57 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Equations involving P and C.
Replies: 1
Views: 114

### Equations involving P and C.

Im confused when to use, or not to use equations involving momentum(p). Furthermore, how do I know when mass plays a factor in calculations in relationship to wavelength, frequency, etc. Similarly, when is it not right to use the equation C=(wavelength)(frequency)?

Mon Dec 02, 2019 10:35 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Strength of bases BrO- and C17H19O3N
Replies: 2
Views: 77

### Strength of bases BrO- and C17H19O3N

Explain why hypobromite is a stronger base than morphine. I my thought process was first that since morphone has more oxygen atoms, and that Nitrogen is more electronegative than Bromine, thus morphone would be stronger. Could someone explain why hypobromite is actually a stronger base?
Mon Dec 02, 2019 8:59 am
Forum: Amphoteric Compounds
Topic: Acidic vs Basic oxides
Replies: 2
Views: 48

### Acidic vs Basic oxides

From reading in the textbook I am confused on the difference between acidic and basic oxides. Furthermore, are all oxides (acidic or basic) amphoteric? The section of textbook I am referring to is 6A.3. Thanks in advance!
Sun Dec 01, 2019 7:32 pm
Forum: Hybridization
Topic: hybridization
Replies: 2
Views: 88

### Re: hybridization

Hybridization is when orbitals fuse together forming a new orbital- with new properties that influence shape etc. This allows for bonding, and is more energetically favorable.
Sun Dec 01, 2019 7:23 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Difference in Concentrations
Replies: 3
Views: 35

### Re: Difference in Concentrations

the concentrations of hydronium and hydroxide are characteristics of acids and bases. Since acids donate a proton (H ion), that proton reacts with water, forming hydronium. Thus, when an acid reacts with water, there is a higher concentration of hydronium. Similar for bases, except with hydroxide. B...
Sun Dec 01, 2019 7:19 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Acid and Base Equations
Replies: 1
Views: 55

### Re: Acid and Base Equations

First identify the type of reaction. A strong acid completely dissociates in water, thus the result will be hydronium + anion. Similarly, a strong base also completely dissociates in water, but the result will be hydroxide instead of hydronium.
Sun Dec 01, 2019 7:06 pm
Forum: Conjugate Acids & Bases
Topic: Acid and Base naming
Replies: 1
Views: 54

### Re: Acid and Base naming

Some quick tips: acids are named based on their anion, the ion that is produced when dissolved in water. For strong bases, since most contain the compound OH, a polyatomic ion, strong bases follow the rules for naming ionic compounds. Weak bases can also follow these same rules for ionic compounds, ...
Sun Dec 01, 2019 6:59 pm
Forum: Lewis Acids & Bases
Topic: Bases
Replies: 4
Views: 87

### Re: Bases

You will need to identify first if the base is strong or weak. From that identification you can then conclude if there was complete dissociation.
Tue Nov 19, 2019 6:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Effect of lone pair repulsion on single vs double bonds
Replies: 1
Views: 23

### Effect of lone pair repulsion on single vs double bonds

Does a lone pair have the same repulsion effect on single bonded electrons as double bonded electrons?
Tue Nov 19, 2019 6:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Axial vs equatorial lone pairs
Replies: 1
Views: 58

### Axial vs equatorial lone pairs

The text book reads that the lowest energy level structure of a molecule is achieved when the lone pairs are on the equatorial plane. Could someone explain the difference between axial and equatorial planes and how to identify them when placing lone pairs of electrons on an atom?
Tue Nov 19, 2019 4:00 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: effect of lone pairs on molecular angles
Replies: 1
Views: 23

### effect of lone pairs on molecular angles

I know that lone pairs push bonded atoms away, so atoms atoms with lone pairs have smaller angles. Is there a set number of degrees that a lone pair causes an angle to decrease? Or do i just need to memorize angles.
Sun Nov 17, 2019 7:49 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: Intermolecular Forces
Replies: 2
Views: 58

### Re: Intermolecular Forces

I think we additionally will need to know how the intermolecular forces affect properties of the molecules.
Sun Nov 17, 2019 7:48 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Purpose of electron geometry
Replies: 2
Views: 69

### Purpose of electron geometry

What is the purpose of electron geometry? If we use molecular geometry to name the shape of a compound, why do we look at electron geometry?
Sun Nov 17, 2019 7:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: HW# 2E.26
Replies: 2
Views: 43

### Re: HW# 2E.26

If a molecule is polar, this is an uneven charge distribution. Meaning, the molecule does not have an even distribution of charges. A quick trick is to look at the actual structure of the molecule, looking for symmetry. Symmetric molecules tend to be non-polar. However, the most sure way is to look ...
Sun Nov 17, 2019 7:38 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Relation of the Shape of a Molecule with strength of interactions
Replies: 2
Views: 33

### Re: Relation of the Shape of a Molecule with strength of interactions

The shape of a molecule does influence strength of attraction. For example, different shapes allow for some molecules to "fit" together better than others. Thus shape can influence the strength of attraction between different molecules.
Sun Nov 17, 2019 7:33 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: Dispersion Forces
Replies: 3
Views: 61

### Re: Dispersion Forces

Dispersion forces for different elements impact their boiling/melting points. Although elements within the same group have similar qualities, they are not identical. For example, down a group the atomic radii increases. Larger atoms are more polarizable, thus have stronger forces.
Sun Nov 03, 2019 9:04 pm
Forum: Resonance Structures
Topic: Showing resonance
Replies: 8
Views: 112

### Re: Showing resonance

I would either write out all resonance structures, or, if all resonances structures contribute equally to the hybrid, draw the solid and double lines in one structure.
Sun Nov 03, 2019 9:02 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: L quantum number
Replies: 5
Views: 201

### Re: L quantum number

l can be any value that satisfies n-1. Thus, if n=12, l could have any value between 0 and 11.
Sun Nov 03, 2019 8:59 pm
Forum: Quantum Numbers and The H-Atom
Topic: Orbital vs Subshells
Replies: 3
Views: 78

### Orbital vs Subshells

What is the difference between subshells and orbitals? Many practice questions asked to determine the number of orbitals/subshells from a given set of quantum numbers, for example, "how many orbitals can have the given quantum numbers: n=2, l=1." I do know that "number of orbitals&quo...
Sun Nov 03, 2019 8:54 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Acidic and Basic lewis structures
Replies: 1
Views: 46

### Re: Acidic and Basic lewis structures

I believe it is just a property. compounds that donate a proton (H+) are considered an acid, while compounds that accept a proton, are considered basic.
Hope this helped!
Sun Nov 03, 2019 8:51 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability vs delocalized electrons
Replies: 2
Views: 77

### Polarizability vs delocalized electrons

I'm confused what the differences are between polarizability and delocalized electrons. This is in context of the chemical bonds unit.
Sun Nov 03, 2019 8:44 pm
Forum: Octet Exceptions
Topic: Expanded Octets
Replies: 5
Views: 71

### Re: Expanded Octets

Today in a review session the TA said 18, but I have not encountered in problems that use electrons past 10.
Sun Oct 13, 2019 8:15 pm
Forum: Balancing Chemical Reactions
Topic: Writing Out Reactions
Replies: 6
Views: 222

### Re: Writing Out Reactions

I have come across many problems where the reactants were named without the chemical equation. I would suggest you learn common compounds/naming compounds and be able to write out the reactions. However, I think we are given tables on exams with equations.
Sun Oct 13, 2019 8:08 pm
Forum: Quantum Numbers and The H-Atom
Topic: Blamer and Lyman
Replies: 1
Views: 45

### Re: Blamer and Lyman

The Balmer series has electrons rest at energy level2 and is for visible light, while the Lyman series has electrons rest at energy level1 and is for UV light
Sun Oct 13, 2019 8:01 pm
Forum: Properties of Light
Topic: Intensity & Amplitude
Replies: 7
Views: 155

### Re: Intensity & Amplitude

The intensity of light is proportional to the square of its amplitude
Sun Oct 13, 2019 7:58 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: energy levels
Replies: 1
Views: 30

### Re: energy levels

That is the Rydberg formula, it is used to find the wavelength(for frequency) of light emitted when an electron changes energy levels.
Sun Oct 13, 2019 7:56 pm
Forum: General Science Questions
Topic: THe mole
Replies: 5
Views: 87

### Re: THe mole

In the past there have been different standards set for the atomic scale, such as oxygen because its many bonding characteristics. However Oxygen has many isotopes that that vary in weight etc, so carbon 12 was chosen which as similar to the previous scale.
Sun Oct 13, 2019 7:53 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect
Replies: 2
Views: 48

### Re: Photoelectric Effect

When electrons go down in energy levels, they release energy that can be mapped. For this reason it is helpful measure these wavelengths to identify an atom.
Sun Oct 06, 2019 1:29 pm
Forum: Molarity, Solutions, Dilutions
Topic: Confusion with the formula M1V1=M2V2
Replies: 4
Views: 95

### Confusion with the formula M1V1=M2V2

I don't understand in dilution, when a question states that, for example, when a 10mL solution is diluted with 20mL, is the final volume 30mL or 20mL? Would the "final" volume that would be used in the equation be the total volume of the final solution, or the amount added?
Sun Oct 06, 2019 1:25 pm
Forum: Properties of Light
Topic: Visible vs. Invisible Waves
Replies: 1
Views: 32

### Re: Visible vs. Invisible Waves

Some animals do see on a different light spectrum. Just as humans see some colors differently than some animals, spiders and insects have the ability to see ultraviolet light.
Sun Oct 06, 2019 1:21 pm
Forum: Properties of Light
Topic: Photons
Replies: 4
Views: 55

### Re: Photons

I wouldn't group photons with electrons or protons. Although there are some commonalities, their movement is independent of mass and do not carry a charge.
Sun Oct 06, 2019 1:17 pm
Forum: Balancing Chemical Reactions
Topic: Hydrates
Replies: 1
Views: 47

### Hydrates

When calculating molar mass do you include the mass of the hydrate? For example, CuSO4 • 5H2O, would the molar mass be just the CuSO4, or would it include the 5 moles of H2O?
Sun Oct 06, 2019 1:11 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant Tips
Replies: 4
Views: 110

### Re: Limiting Reactant Tips

One trick I learned was to calculate the amount in moles of each reactant. Then, divide by that reactant's coefficient that is given in the balanced equation. The reactant with the lower ratio is the limiting reactant.
Sun Oct 06, 2019 1:08 pm
Forum: Empirical & Molecular Formulas
Topic: What decimal place to round to when taking masses from the Periodic Table?
Replies: 19
Views: 657

### Re: What decimal place to round to when taking masses from the Periodic Table?

A student asked Professor Lavelle this same question in lecture on Friday. He said he uses all the decimal places, and waits to round until the final answer.
Sun Oct 06, 2019 1:05 pm
Forum: Molarity, Solutions, Dilutions
Topic: G. 13
Replies: 5
Views: 125

### Re: G. 13

You would first find the molarity of the new solution using the equation M1V1=M2V2, then using the equation Molarity = (Moles)/(Volume) find the moles in 100mL.