## Search found 103 matches

Wed Mar 11, 2020 11:13 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Units
Replies: 8
Views: 124

### Re: Units

the units for rate will always be M/s while rate constant can be M/w (0 order), 1/s (first order), or 1/Ms (second order)
Wed Mar 11, 2020 11:08 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts and Reaction Pathways
Replies: 6
Views: 41

### Re: Catalysts and Reaction Pathways

it helps if you look at the graph for the reaction profile. a catalyst would lower the activation energy for the whole graph so the new forward pathway and new reverse pathway look the same and both are at a lower Ea than before.
Wed Mar 11, 2020 10:50 am
Forum: Zero Order Reactions
Topic: 7.21 HW
Replies: 2
Views: 32

### Re: 7.21 HW

for (g) zeroth order, the half life against [A] can be written as function t = [A]/2k where 1/2k would be the slope between the two variables. I think we are assuming that [A] would be essentially the initial concentration for (h) second order, the half life against [A] can be written as function t ...
Wed Mar 11, 2020 10:46 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Pre-Equil Approach
Replies: 2
Views: 54

### Re: Pre-Equil Approach

this method would be useful in the situation where the slow step rate law (which we assume to determine the overall rate law) includes an intermediate. Since we do not want intermediates in the overall rate law, we can use the pre-equilibrium approach to substitute out the intermediate
Wed Mar 11, 2020 10:44 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 7.23
Replies: 2
Views: 32

### Re: 7.23

the answer should be ClO- + I- --> IO- + Cl-
what answer are you referring to?
Wed Mar 04, 2020 4:42 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6K.3
Replies: 1
Views: 34

### Re: 6K.3

I think the problem should be
reaction of chlorine in water:
Cl2(g) --> HClO(aq) + 2Cl-

because that is the only way Cl can be reduced and oxidized
Wed Mar 04, 2020 4:40 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.5
Replies: 1
Views: 28

### Re: 6M.5

i'm pretty sure you would have to calculate Ecell in order to know
Wed Mar 04, 2020 4:39 pm
Forum: Balancing Redox Reactions
Topic: Homework Problem 6K.1
Replies: 3
Views: 58

### Re: Homework Problem 6K.1

the balanced reduction reaction is missing a 6e- on the left side in order to balance the charges. so the oxidation reaction is multiplied by 3 so that the 2e- can balance with the 6e- from the reduction
Wed Mar 04, 2020 3:44 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.15
Replies: 1
Views: 57

### Re: 6N.15

usually the compartment with the lower concentration is the anode. This is because the lower concentration compartment would want more ions and in order to get more ions, it would have to donate electrons and oxidize the metal (Ni(s) --> Ni2+)
Wed Mar 04, 2020 3:41 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.3 part c
Replies: 2
Views: 52

### Re: 6N.3 part c

To find the cell potential using Nernst Equation, you will need to first find the standard cell potential for that system by writing out the half reactions of the anode and cathode and calculating from the appendix of standard reduction potentials. You will also need the value of reaction quotient Q...
Sat Feb 29, 2020 9:10 am
Forum: Balancing Redox Reactions
Topic: 6K. 5d
Replies: 1
Views: 51

### Re: 6K. 5d

P4 ---> PH3 balance P: P4 ---> 4PH3 balance H: 12H2O + P4 ---> 4PH3 + 12OH- balance charge: 12 H2O + P4 + 12e- ---> 4PH3 + 12OH- the H2O and OH- are added at the same time to balance H. because the left side needed 12 H, you can add 12 H2O and 12 OH- on the opposite side to balance the H.
Thu Feb 27, 2020 5:41 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L3d
Replies: 1
Views: 21

### 6L3d

Can someone explain the steps to take in writing the half reactions for cell diagram Pt(s)|O2(g)|H+(aq)||OH-(aq)|O2(g)|Pt(s) ?
What do you do when the two substances in anode or cathode are not the same? How do you go about this?
Thu Feb 27, 2020 4:05 pm
Forum: Balancing Redox Reactions
Topic: 6k3d
Replies: 3
Views: 31

### 6k3d

this redox reaction in acidic solution is Cl2 --> HClO + Cl2 where Cl2 is reducing and oxidizing agent. Is the reaction suppose to be Cl2 --> HClO + Cl- ?
Wed Feb 26, 2020 4:10 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Test 2
Replies: 2
Views: 41

### Re: Test 2

I believe it is Focus 5G.3, 5G.4, 5J.3 so problems 5G: 13, 15, 17, 19, 21; 5J: 11, 13, 15; and 5.55, 5.61
Wed Feb 26, 2020 4:09 pm
Forum: Balancing Redox Reactions
Topic: oxidation numbers
Replies: 3
Views: 64

### Re: oxidation numbers

in redox reactions, we usually always assume that Oxygen will have an oxidation number of 2-. using this information, you can then calculate the oxidation numbers of other elements in the same compound. for example Cr2O7(2-) has 7 oxygens which means 14 negative charges. since the overall charge is ...
Wed Feb 19, 2020 5:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: midterm Q4
Replies: 4
Views: 93

### Re: midterm Q4

The way i think of it is that the drug has a pKa of 10.89 and the "solution" it's in is pH 1.7 which is more acidic that the drug itself. because of that the drug will less likely give off protons and will act more like a base in the acidic surroundings.
Wed Feb 19, 2020 5:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: midterm 3C
Replies: 4
Views: 68

### Re: midterm 3C

yes exactly, because NH4Cl is in a solution, it will dissociate into NH4+ and Cl- and NH4+ acts as an acid
Wed Feb 19, 2020 5:28 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: midterm Q1A
Replies: 7
Views: 77

### Re: midterm Q1A

in the question, it states that the reaction is exothermic so if the temperature increases, the reverse reaction would be favored and K will decrease.
Wed Feb 19, 2020 4:57 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy
Replies: 2
Views: 42

### Re: Gibbs Free Energy

if the change in gibbs free energy is positive, it does not necessarily mean that delta H (enthalpy) is positive or negative because it also takes into account temperature and entropy. a reaction is endothermic if delta H is positive and exothermic if delta H is negative.
Wed Feb 19, 2020 4:56 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs free energy
Replies: 4
Views: 54

### Re: Gibbs free energy

if Gibbs free energy of the products is greater than that of the reactants, then for the forward reaction, there is an increase in free energy and delta G would be positive, implying that this forward reaction is unspontaneous
Thu Feb 13, 2020 2:04 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy Change over the Course of Thermodynamic Processes
Replies: 3
Views: 39

### Re: Entropy Change over the Course of Thermodynamic Processes

hm i calculated the entropy change for each step too but when i added it together it was pretty close to 0. I think it should still be the same result (change in S = 0) so maybe it was just a small calculation error.
Thu Feb 13, 2020 1:45 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4.17E: Calculating enthalpy change vs. assuming delta U = 0
Replies: 2
Views: 55

### Re: 4.17E: Calculating enthalpy change vs. assuming delta U = 0

i think constant temperature does not necessarily mean that internal energy is 0, for example, phase changes have an input of heat (q) but still stay at constant temperatures.
Mon Feb 10, 2020 5:56 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4C.3b
Replies: 1
Views: 31

### 4C.3b

how do you calculate the enthalpy at constant volume?
Mon Feb 10, 2020 5:32 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: definitions
Replies: 1
Views: 41

### definitions

two questions
does an isothermal reaction necessarily mean it is reversible?
and separately, does an isolated system necessarily mean the volume is constant?
Mon Feb 10, 2020 10:32 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: isolated system
Replies: 7
Views: 166

### isolated system

is an isolated system neccessarily q=0 and w=0?
Sat Feb 08, 2020 8:55 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: phase change entropy
Replies: 3
Views: 60

### phase change entropy

for the entropy change of a phase change, we use the fact that q(reversible)/T is the same as (change in enthalpy)/T. Why can we assume that q(reversible) = change in enthalpy of phase change? I thought that q at constant P = change in enthalpy but reversible reactions do not have a constant pressur...
Sat Feb 08, 2020 6:54 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: irreversible and reversible
Replies: 3
Views: 61

### irreversible and reversible

In the lecture, Professor Lavelle mentioned a graph to visually look at irreversible and reversible pathways. I think he mentioned that temperature is constant along the reversible and temperature changes along the irreversible. Why is this the case?
Thu Feb 06, 2020 11:48 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Delta H and qp
Replies: 8
Views: 55

### Re: Delta H and qp

you can assume they are equal when the pressure is constant. im not completely sure why but i think by definition, enthalpy is the change in heat at constant pressure
Thu Feb 06, 2020 11:46 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.23 homework help
Replies: 4
Views: 46

### Re: 4D.23 homework help

using the standard enthalpy of formation for NO, and knowing that the standard enthalpy of formation for O2 is 0, you can first find the standard enthalpy of formation of NO2 by also taking into account the enthalpy change of the reaction. using this new found NO2 standard enthalpy of formation, you...
Thu Feb 06, 2020 8:57 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Free energy
Replies: 6
Views: 121

### Re: Free energy

i think it is deltaG = standard G + RTlnQ
Sun Feb 02, 2020 6:21 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Cp and Cv
Replies: 1
Views: 22

### Cp and Cv

why is the Cp of constant pressure 5/2 times the ideal gas constant? and why is Cv of constant volume 3/2 of the ideal gas constant? like why do we know that
Sun Feb 02, 2020 6:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka approximation
Replies: 6
Views: 51

### Re: Ka approximation

you can check if your approximation was valid by calculating the percent deprotonation and seeing if it is less than 5%
Wed Jan 29, 2020 11:37 am
Forum: Administrative Questions and Class Announcements
Topic: 14A Final Pickup
Replies: 3
Views: 61

### Re: 14A Final Pickup

it was week 3 in young hall 3034
Wed Jan 29, 2020 10:39 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constants
Replies: 2
Views: 34

### Re: Equilibrium Constants

Ka is the acid dissociation constant and Kb is the base dissociation constant.
Tue Jan 28, 2020 10:30 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Delta T
Replies: 4
Views: 40

### Re: Delta T

an exothermic reaction will release heat which will raise the temperature of the surroundings and an endothermic reaction will therefore do the opposite
Fri Jan 24, 2020 8:18 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy
Replies: 2
Views: 27

### Re: Enthalpy

yes i believe it is the same delta H used in gibbs free energy.
Thu Jan 23, 2020 5:50 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5.61f
Replies: 5
Views: 43

### 5.61f

when you add H2O to the reaction 6CO2 + 6 H2O (l) <--> C6H12O6 + 6O2, since it is a liquid, it technically doesn't affect the reaction so there will be no shift. but would it change the concentrations of the other molecules if they were (aq) instead of (g)?
Thu Jan 23, 2020 4:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: sig figs
Replies: 2
Views: 18

### sig figs

when we're considering sigfigs, should we include the equilibrium constant sig figs as well even though it is a constant?
Wed Jan 22, 2020 8:58 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: polyprotic acids
Replies: 3
Views: 39

### polyprotic acids

when calculating the H+ concentration of a polyprotic acid (ex: H2SO4) would you calculate the H+ concentration of each separate reaction and then add it together or would you treat as one system and write the second equation based on the results of the first one?
Wed Jan 22, 2020 8:55 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6E3
Replies: 2
Views: 47

### 6E3

I know that when K is less than 10^-3 it is considered to be insignificant to the initial concentration but how would you determine whether Ka2 is negligible compared to Ka1?
Fri Jan 17, 2020 3:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW Problem 6D. 3
Replies: 1
Views: 23

### Re: HW Problem 6D. 3

I think it would be the equilibrium concentration since the final concentration of H3O+ is used to calculate pH
Fri Jan 17, 2020 3:12 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: 6A.21
Replies: 2
Views: 87

### Re: 6A.21

because the autoprotolysis reaction is when H2O donates a proton to another H2O molecule. To form H3O+ requires H2O to lose a proton and become OH-
Wed Jan 15, 2020 5:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6A19 part c
Replies: 5
Views: 56

### Re: 6A19 part c

Do you mean (1.0x10^-14)/3.1? Because I'm not sure where you got the 3.2x10^-14
Wed Jan 15, 2020 3:45 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Textbook question 6B.11
Replies: 2
Views: 21

### Re: Textbook question 6B.11

for part b, you want to use the concentration of the original solution (answer to part aii) which is the concentration of OH- of the original solution. Using this information, you can use the OH- concentration to find the mols of OH- in that 200mL solution. using the mols of OH-, you can convert it ...
Wed Jan 15, 2020 3:42 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Textbook question 6B.11
Replies: 2
Views: 21

### Re: Textbook question 6B.11

In order to find the original solution's concentration of OH-, use the diluted concentration that you found in part ai) and find how many mols of OH- are really in the diluted solution. Then use this number of mols of OH- and divide it by 5.00mL to find the original concentration. This works because...
Sat Jan 11, 2020 11:05 am
Forum: Ideal Gases
Topic: Solids and liquids [ENDORSED]
Replies: 6
Views: 72

### Re: Solids and liquids[ENDORSED]

you can think of liquids as solvents like H2O. molecules of a solvent can technically react but the vast majority of the solvent will stay a solvent which means there is no significant change in concentration. since there is not significant change, including the concentration of liquid would just ca...
Fri Jan 10, 2020 5:02 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.35
Replies: 1
Views: 27

### 5.35

for 5.35, there is a graph with compounds A, B, and C and you are asked to write a balanced equation for the reaction. How would you know the stoichiometric coefficients of A, B, C? Thanks!
Thu Jan 09, 2020 8:02 pm
Forum: Ideal Gases
Topic: Understanding equilibrium
Replies: 2
Views: 25

### Re: Understanding equilibrium

In equilibrium, forward and reverse reactions are always occurring. There is always reactants changing into products and products changing into reactants. Equilibrium just says that these forward and reverse reactions are at the same rate!
Thu Jan 09, 2020 7:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating K 5I.33
Replies: 2
Views: 26

### Re: Calculating K 5I.33

yes you would have to convert mass to moles and then convert to mol/L
Tue Jan 07, 2020 10:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibrium Part 2 Post Module #12
Replies: 2
Views: 35

### Re: Chemical Equilibrium Part 2 Post Module #12

I did exactly what you did but I got 0.000416? Maybe just a calculation error because it should work
Fri Dec 06, 2019 5:06 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: HF
Replies: 4
Views: 153

### Re: HF

because F is so electronegative, it pulls electrons harder and the bond between H and F is stronger and so HF doesn't lose protons (H+) as easily.
Tue Dec 03, 2019 3:04 pm
Forum: Identifying Acidic & Basic Salts
Topic: Cl- and NaCl
Replies: 2
Views: 44

### Re: Cl- and NaCl

Because Cl- is a stable ion. When HCl dissociates, Cl- is a stable anion and a really weak conjugate base to the strong acid.
Tue Dec 03, 2019 3:02 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 9C5 (b)
Replies: 1
Views: 27

### 9C5 (b)

for CO3(2-) our TA mentioned that it is polydentate and can be either monodentate or bidentate because of the resonance structure but I'm still confused about how exactly it can be both. can someone explain a little more about how you can tell
Tue Dec 03, 2019 3:00 pm
Forum: Amphoteric Compounds
Topic: Textbook 6A.17
Replies: 3
Views: 103

### Re: Textbook 6A.17

most amphoteric oxides align with the metalloid diagonal. For example c and d are amphoteric because As and Bi are metalloids
Mon Dec 02, 2019 8:38 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH sigfigs
Replies: 3
Views: 44

### pH sigfigs

hi how do we know how many sigfigs to use with calculated pH
Tue Nov 26, 2019 6:16 pm
Forum: Biological Examples
Topic: vitamin b12
Replies: 3
Views: 54

### vitamin b12

what do we need to know about the structure and biological function of vitamin b12?
Tue Nov 26, 2019 5:33 pm
Forum: Biological Examples
Topic: cisplatin
Replies: 3
Views: 46

### cisplatin

is there anything else we need to know about cisplatin other than the fact that it binds with DNA to block DNA replication. does anyone know the more details to this biological example
Mon Nov 25, 2019 5:58 pm
Forum: Hybridization
Topic: Finding Hybrid Orbitals
Replies: 1
Views: 32

### Re: Finding Hybrid Orbitals

yes for example in NH3, there are 3 bonds and one pair of lone electrons. This means NH3 will have 4 hybridized sp3 orbitals. one of the sp3 orbitals will have two paired electrons (which represent the lone pair) and the other 3 sp3 hybrid orbitals will have one unpaired electron in each (representi...
Mon Nov 25, 2019 5:55 pm
Forum: Hybridization
Topic: 2F.17
Replies: 1
Views: 29

### Re: 2F.17

if you think about it like sp2 is 33% s and 66% p and sp3 is 25% s and 75% p, then it makes more sense than an increase in s character means a decrease in p orbitals and the bond angles increase since there are less regions of electron density
Mon Nov 25, 2019 5:48 pm
Forum: Naming
Topic: OH2 naming
Replies: 4
Views: 45

### Re: OH2 naming

hydroxide would be OH
Mon Nov 18, 2019 7:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: dipole dipole
Replies: 5
Views: 57

### dipole dipole

what do we look for to determine if a dipole dipole is stronger than another dipole dipole force
Mon Nov 18, 2019 5:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: CHI3 and CHF3
Replies: 1
Views: 26

### CHI3 and CHF3

I understand why CHI3 has strong dipole dipole forces because Iodide is large and has more electrons making it more polarizable. Why does CHF3 not make hydrogen bonds even though it has lone pairs on F that can bond with H from another CHF3 molecule?
Mon Nov 18, 2019 3:16 pm
Forum: Hybridization
Topic: s character
Replies: 1
Views: 33

### s character

when the s character of a hybrid increases, the bond angle also increases inbetween the orbitals but why?
Mon Nov 18, 2019 2:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: seesaw
Replies: 1
Views: 25

### seesaw

In Dr. Lavelle's lecture he mentioned that AX4E is a seesaw because the lone pair will be on the equatorial plane and affect the two axial atoms and be more stable since the other option is having an axial lone pair that affects all three atoms on the equatorial plane. My question is wouldn't the eq...
Mon Nov 18, 2019 2:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: CH2Cl2 structure
Replies: 2
Views: 26

### CH2Cl2 structure

How do we know if the H attached to the C in CH2Cl2 will be opposite to each other or opposite to a Cl atom? Does it matter which one you choose or is one better than the other?
Mon Nov 18, 2019 2:37 pm
Forum: Hybridization
Topic: hybridization 1st number
Replies: 3
Views: 28

### hybridization 1st number

how do you know what number is in front of the hybridization numbers and when the question will ask for it versus just the hybrid orbital? for example the 2 in 2sp
Mon Nov 18, 2019 1:42 pm
Forum: Hybridization
Topic: Triple bonds hybridization
Replies: 1
Views: 34

### Re: Triple bonds hybridization

for hybridization we would usually look at the number of regions of electron density around the central atom and since C would have two regions of electron density (since a triple bond is considered one region) the hybridization would be sp
Sat Nov 16, 2019 12:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T-shape
Replies: 6
Views: 81

### Re: T-shape

He didn't talk about it in lecture but I think the T shape is when you have a central atom with 3 bonds and two lone pairs for example ClF3
Fri Nov 15, 2019 7:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Notation used in VSEPR
Replies: 8
Views: 105

### Re: Notation used in VSEPR

I don't think it's not completely necessary but it does help you categorize the different VSEPR shapes into number of bond electrons and lone electrons.
Fri Nov 15, 2019 7:32 pm
Forum: Sigma & Pi Bonds
Topic: Sigma And Pi Bond Concept Question
Replies: 2
Views: 38

### Re: Sigma And Pi Bond Concept Question

Pi bonds are formed by having a flat bond above or below the sigma bond, this pi bond is only stable in one orientation and if there is any rotation then this bond breaks
Wed Nov 13, 2019 9:09 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: Problem 3F.5
Replies: 3
Views: 62

### Re: Problem 3F.5

well i think for intermolecular forces we look at size because the larger atom means a bigger electron density which results in an easily distortable electron cloud. This leads to stronger dipole moments and stronger intermolecular forces. But for electronegativity, i think it plays more of a role i...
Tue Nov 12, 2019 9:56 pm
Forum: Dipole Moments
Topic: Why doesn't CH3CHO form a hydrogen bond?
Replies: 3
Views: 41

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

I think it does? Because the OH at the end has lone pairs and hydrogens will form H bonds with it right
Wed Nov 06, 2019 1:16 pm
Forum: Electronegativity
Topic: Karen's worksheet #12
Replies: 3
Views: 81

### Karen's worksheet #12

from most polar to least polar, the answer is MG-O, C-O, B-O, O-O but im confused on why C-O is considered more polar than B-O?
Tue Nov 05, 2019 3:23 pm
Forum: Lewis Structures
Topic: 2C3.c
Replies: 1
Views: 37

### 2C3.c

for chloric acid (HClO3) how would we know that the hydrogen is attached to the oxygen rather than the central atom chlorine in lewis structures?
Tue Nov 05, 2019 10:20 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Uncertainty Module Question
Replies: 2
Views: 65

### Re: Heisenberg Uncertainty Module Question

use the equation (uncertainty of momentum)(uncertainty of position) >= h/4pi
your uncertainty in position would be (5m)*2 = 10 m
the uncertainty of momentum can also be written as
uncertainty of momentum = mass * uncertainty of velocity
Tue Nov 05, 2019 10:17 am
Forum: Resonance Structures
Topic: Resonance Structure for 2B.15
Replies: 3
Views: 63

### Re: Resonance Structure for 2B.15

no because Nitrogen in that case would have exceeded the octet rule
Tue Nov 05, 2019 10:15 am
Forum: Lewis Structures
Topic: 2D13
Replies: 4
Views: 60

### 2D13

can someone explain why the lewis structure of so3 would have one double bond and two single bonds rather than just three double bonds? why is one better than the other?
Tue Oct 29, 2019 12:32 pm
Forum: Dipole Moments
Topic: van der waal
Replies: 4
Views: 87

### van der waal

how can we tell which molecules will have a greater dipole-dipole or London force? aka what factors contribute to the strength of dipole-dipole interactions?
Tue Oct 29, 2019 12:29 pm
Forum: Dipole Moments
Topic: 3F.5
Replies: 1
Views: 33

### 3F.5

for part C (which has higher melting point: CHI3 vs CHF3) wouldn't CHF3 have a higher melting point because of its possible hydrogen bonds?
Tue Oct 29, 2019 12:27 pm
Forum: Dipole Moments
Topic: intermolecular interactions
Replies: 2
Views: 56

### intermolecular interactions

how can one tell if a molecule will have certain intermolecular interactions (specifically how can you tell if it has dipole-dipole attractions)
Mon Oct 28, 2019 10:48 am
Forum: Lewis Structures
Topic: BrF3
Replies: 2
Views: 39

### Re: BrF3

Br shares electrons with 3 F and has two lone pairs of its own because it exceeds the octet rule
Mon Oct 28, 2019 10:47 am
Forum: General Science Questions
Topic: homework
Replies: 5
Views: 89

### homework

does anyone know if this week's homework is on the quantum stuff still or the chemical bonds or both
Thu Oct 24, 2019 12:18 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2nd electron
Replies: 4
Views: 51

### Re: 2nd electron

You can also think of it like once you remove the first electron, there are less total electrons which means less electron electron repulsion so the positive nuclear charge pulls harder on the remaining electrons
Mon Oct 21, 2019 10:00 pm
Forum: Properties of Electrons
Topic: Diffraction Patterns
Replies: 2
Views: 48

### Re: Diffraction Patterns

i think diffraction patterns are a result of waves interacting with each other
Mon Oct 21, 2019 5:51 pm
Forum: Properties of Light
Topic: 1B.15 --> c=λv vs. λ= h/mv
Replies: 2
Views: 49

### Re: 1B.15 --> c=λv vs. λ= h/mv

the v in c= λv represents the frequency not velocity
Mon Oct 21, 2019 5:50 pm
Forum: Photoelectric Effect
Topic: Module Assessment Question
Replies: 2
Views: 66

### Re: Module Assessment Question

the photoelectric experiments basically told us that energy is related to frequency so E = hv shows us this relationship. the work function and kinetic energy were parts of the photoelectric effect but they do not show us the relationship between E and frequency
Mon Oct 21, 2019 5:47 pm
Forum: Photoelectric Effect
Topic: Intensity of Light
Replies: 4
Views: 69

### Re: Intensity of Light

because increasing the intensity is equivalent to increasing the number of photons but it doesn't change the energy each photon has. the energy each photon contains is what ejects the electron
Mon Oct 21, 2019 5:46 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: spins
Replies: 4
Views: 75

### Re: spins

+1/2 is spin up and +1/2 is spin down
Thu Oct 17, 2019 10:49 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: HW D13
Replies: 3
Views: 72

### Re: HW D13

well i think n is the shell number which is equivalent to how many energy levels an atom has so 6D would have n = 6 . since it is a d orbital, l = 2 i believe

l = 0; s orbital
l = 1; p orbital
l = 2; d orbital
Thu Oct 17, 2019 10:47 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Momentum
Replies: 7
Views: 134

### Re: Momentum

we only want the possible variance of the velocity. it does seem like it should be twice the number to cover the range but it's just suppose to be the +/- value, not sure why
Thu Oct 17, 2019 10:44 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Homework Question
Replies: 3
Views: 52

### Re: Homework Question

haha okay well then the indeterminacy would be just the ± 5.00 because that's what the measured amount is varied by? idk. i see what your saying but i think this is just how it is
Thu Oct 17, 2019 10:41 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Spin State
Replies: 17
Views: 148

### Re: Spin State

+1/2 refers to spin up and -1/2 refers to spin down because an electron can either be spin up or spin down. don't know how it would be determined tho
Thu Oct 17, 2019 10:37 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Homework Question
Replies: 3
Views: 52

### Re: Homework Question

do you mean the indeterminacy of velocity instead of the change in velocity?
Fri Oct 11, 2019 2:09 pm
Forum: Properties of Light
Topic: HW Problem A15
Replies: 2
Views: 35

### Re: HW Problem A15

if you derived En(final) - En(initial) it would do the same thing as the Rydberg equation since En = -hR/n^2. so technically you can do either and still get the same result!
Fri Oct 11, 2019 2:05 pm
Forum: DeBroglie Equation
Topic: When to use DeBroglie Equation
Replies: 16
Views: 286

### Re: When to use DeBroglie Equation

I think you only use it for the wavelength of particles with momentum. if you wanted to solve the wavelength of light, this equation would require you to know the momentum. the wavelength of light can be found by using c = wavelength*frequency instead.
Tue Oct 08, 2019 3:27 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: The relationship of precision between position and momentum
Replies: 3
Views: 46

### Re: The relationship of precision between position and momentum

I think the answer was the more precisely the position is determined, the less precisely the momentum is known and vise versa bc they are inversely related to each other
Mon Oct 07, 2019 11:29 am
Forum: Einstein Equation
Topic: Wavelengths
Replies: 5
Views: 122

### Re: Wavelengths

3.607 x 10^-19 J would be the threshold energy, the energy required to remove an electron use the known formulas E = hv and c=wavelength*v and rearrange them so it looks like E = hc/wavelength ---> wavelength = hc/E you can then get the wavelength with planks constant, speed of light constant, and t...
Mon Oct 07, 2019 11:21 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Finding Wavelength of Light
Replies: 3
Views: 81

### Re: Finding Wavelength of Light

You can use the formula

frequency = -R((1/(n1^2)) - (1/(n2^2))

where R is rydberg's constant, n1 would be 2 and n2 would be 1 for that electron transition

and then you can use that frequency to find the wavelength
Tue Oct 01, 2019 3:19 pm
Forum: Limiting Reactant Calculations
Topic: Another question on E9 but now on part b
Replies: 2
Views: 27

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

Use the molar mass of magnesium sulfate heptahydrate to find the mols of the compound and multiply by 11 (11 oxygen mols per mol of magnesium sulfate heptahydrate) and then multiply by avogadro's constant to get the number of oxygen atoms in the sample!
Tue Oct 01, 2019 3:17 pm
Forum: Limiting Reactant Calculations
Topic: Help on question M9
Replies: 1
Views: 37

### Re: Help on question M9

The Na is left out of the net ionic equation (Cu^2+ + 2OH- --> Cu(OH)2) but the hydroxide part of the molecule is what is included in the product.