Search found 85 matches

by JoshMoore2B
Sun Feb 21, 2021 11:15 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Favorable and Unfavorable
Replies: 4
Views: 19

Re: Favorable and Unfavorable

What is the difference between the favorable and unfavorable reactions in Electrochemistry? What sets them apart? Similar to thermodynamics, those reactions that are favorable in Electrochemistry are those that bring the reactants to their lowest energy states and their most stable. So, favorable r...
by JoshMoore2B
Sun Feb 21, 2021 11:13 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Reduction Potential
Replies: 1
Views: 6

Re: Reduction Potential

Why do different elements have different reduction potentials? Does it depend on certain properties? I am pretty sure it is based on how ready an element is to accept electrons, which makes those at the end of the transition metals, like gold, have high reduction potentials, because these metals ar...
by JoshMoore2B
Sun Feb 21, 2021 11:08 pm
Forum: Balancing Redox Reactions
Topic: "Leo" Oxidation Numbers
Replies: 26
Views: 66

Re: "Leo" Oxidation Numbers

Hello, I am a but lost on some of the material from last Wednesday's lecture when the notes state that a loss of electrons causes "'Leo' oxidation numbers" to increase. I was wondering if someone could explain what this term means or the significance of this term "leo" in descri...
by JoshMoore2B
Sun Feb 21, 2021 11:03 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Entropies of Solid Products vs. Solid Reactants?
Replies: 2
Views: 19

Re: Entropies of Solid Products vs. Solid Reactants?

The textbook problem 4H.11 asks you to find ∆S for reactions using the reactants' & products' standard molar entropies. For the reaction: 4KClO_{3(s)} \rightarrow 3KClO_{4(s)} + KCl_{(s)} ∆S° for the reaction = -36.81 J/(K•mol) We have to explain why the entropy is decre...
by JoshMoore2B
Sun Feb 21, 2021 11:01 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Standard Conditions
Replies: 8
Views: 19

Re: Standard Conditions

Hypothetically, if there was a question where deltaH and deltaS are given and you want to solve for deltaG, would you assume that T is 25 degrees C ? Actually, contrary to a previous poster, I think you would assume T is 25 degrees C, for the "standard state" of a material, not STP. This ...
by JoshMoore2B
Sat Feb 13, 2021 7:59 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Spontaneous reactions
Replies: 2
Views: 41

Re: Spontaneous reactions

Can someone Spontaneous as written above a certain temperature vs under a certain temperature and its relationship with delta s and delta h? This deals with finding out whether or not something is spontaneous based on delta G. If delta G is negative, the reaction is spontaneous, and if positive it ...
by JoshMoore2B
Sat Feb 13, 2021 7:53 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: difference in ΔG and ΔG⁰
Replies: 15
Views: 54

Re: difference in ΔG and ΔG⁰

this applies to ΔH, ΔH⁰, ΔS, and ΔS⁰ as well but I forgot the difference between ΔG and ΔG⁰ and I feel like it was too small of a detail that made me unable to find in my notes what the difference was (and it's been hanging in my head for a while lol). does anyone know? thanks! From my understandin...
by JoshMoore2B
Sat Feb 13, 2021 7:50 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Sapling Week 5/6 #18
Replies: 7
Views: 47

Re: Sapling Week 5/6 #18

For this question, I found ΔG∘r and I know that I need to use the equation ΔG∘r = -RT ln (K) to get the final answer, but I keep getting stuck on how to solve for K. I plugged in the respective values and tried to solve for K a few times, but none of my answers were correct. Could someone explain h...
by JoshMoore2B
Sat Feb 13, 2021 7:41 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: when K=1
Replies: 12
Views: 53

Re: when K=1

Monica Soliman 3F wrote:Prof in Friday's lecture talked about when k=1 the delta g =0 and he said it was not common. why is that?


For delta G = 0 and k=1, the free energy of the reactants and the products must be exactly equal. This is extremely precise, so it isn't very common.
by JoshMoore2B
Sat Feb 13, 2021 7:38 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: delta S dominates vs delta H dominates
Replies: 5
Views: 26

Re: delta S dominates vs delta H dominates

In class, we did that example of Br2 (l) --> Br2 (g). Part of the explanation said that when T > 333K that the delta S dominates but when T < 333K that delta H dominates. I was wondering if someone could explains what it means for these two terms to dominate? Thanks! When saying that delta H domina...
by JoshMoore2B
Sun Feb 07, 2021 10:34 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: State Functions
Replies: 4
Views: 25

Re: State Functions

If both q and w are NOT state functions, then how is it that the change in internal energy is one? I can't seem to wrap my head around this haha I think this is because both q and w are the product of non-state functions, not necessarily non-state functions themselves. When used to find the change ...
by JoshMoore2B
Sun Feb 07, 2021 10:28 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Sapling #8 Week 4
Replies: 3
Views: 27

Re: Sapling #8 Week 4

could someone pls explain how to approach this problem? I'm not quite sure where to even start. A 0.617 mol sample of SO2(g), initially at 298 K and 1.00 atm, is held at constant pressure while enough heat is applied to raise the temperature of the gas by 16.5 K. Calculate the amount of heat q requ...
by JoshMoore2B
Sun Feb 07, 2021 10:23 pm
Forum: Calculating Work of Expansion
Topic: Internal Work
Replies: 1
Views: 12

Re: Internal Work

I am having a lot of issues understand the concept of internal work done on a system and how to calculate it. What is the difference between this and q and what is considered to be internal work vs q. Does anyone have a good way to explain/remember this? Change in internal energy (delta U) is the a...
by JoshMoore2B
Sun Feb 07, 2021 10:17 pm
Forum: Calculating Work of Expansion
Topic: Internal work and change in heat
Replies: 3
Views: 11

Re: Internal work and change in heat

While doing the homework and watching the lectures, I learned that, at a constant volume, the change in heat (q) is equal to the internal work done to a substance (deltaE/deltaU). Why is this? I am a little confused still on exactly why this is. Also, does this told true for substances under consta...
by JoshMoore2B
Sun Feb 07, 2021 10:13 pm
Forum: Calculating Work of Expansion
Topic: Sapling #18
Replies: 3
Views: 30

Re: Sapling #18

A 0.565 mol sample of NO2(g), initially at 298 K and 1.00 atm, is held at constant pressure while enough heat is applied to raise the temperature of the gas by 18.9 K. Calculate the amount of heat q required to bring about this temperature change, and find the corresponding total change in the inte...
by JoshMoore2B
Sun Jan 31, 2021 10:40 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Pressure
Replies: 7
Views: 89

Re: Pressure

Constant pressure doesn't mean no pressure! It just means that there is no change in final and initial pressure. It could be both 0 or a nonnegative number. Why a nonnegative number specifically? Technically, pressure can never be less than 0, and technically it can. It depends on what your referen...
by JoshMoore2B
Sun Jan 31, 2021 10:37 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy vs heat
Replies: 19
Views: 85

Re: Enthalpy vs heat

Lea Baskin Monk 1F wrote:What is the difference between heat and enthalpy? I understand that they are connected, but in what ways do they differ?


Heat is a measure of energy transfer, while enthalpy is the change in energy of the system.

So, in a way, heat is responsible for enthalpy.
by JoshMoore2B
Sun Jan 31, 2021 10:35 pm
Forum: Phase Changes & Related Calculations
Topic: What really is "heat"
Replies: 6
Views: 27

Re: What really is "heat"

This question may sound sort of odd but I'm really curious what the relation between the heat given off in a reaction and our perceived heat is. Like when we touch something and it burns us, why is that exactly? Is it because the molecules are excited and therefore may cause damage to our less exci...
by JoshMoore2B
Sun Jan 31, 2021 10:24 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Work
Replies: 7
Views: 30

Re: Work

Jiayi Wu 3J wrote:Can someone explain to me where does the negative sign for the work equation comes from?


I believe the sign is negative because, for an object to perform work, it must expend (or 'use' or 'lose') energy. So, the energy of the object goes down by the amount of work done.
by JoshMoore2B
Sun Jan 31, 2021 10:22 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Exothermic vs Extothermic
Replies: 13
Views: 43

Re: Exothermic vs Extothermic

When Lavelle was discussing about the calorimeter and said that because the temperature increased, it is exothermic and if the temperature were to decrease, the reaction is endothermic, how could he tell and differentiate? Why is it that when temp increases, it is exothermic? I think one aspect to ...
by JoshMoore2B
Sun Jan 24, 2021 11:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Clarification for Sampling #7
Replies: 10
Views: 47

Re: Clarification for Sampling #7

HClO is a weak acid ( ka=4.0×10−8 ) and so the salt NaClO acts as a weak base. What is the pH of a solution that is 0.085 M in NaClO at 25 °C? In this problem, is it because they ask specifically about NaClO that you have to find kb first to solve the problem? I used ka and it was wrong so I just w...
by JoshMoore2B
Sun Jan 24, 2021 10:58 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Charge of Predominant Species
Replies: 5
Views: 26

Re: Charge of Predominant Species

The way I think about it, if the pKa is smaller than the pH, then the acid in question can contribute to making the solution more acidic, so the species in which the H+ is lost is the predominant species. if the pKa is larger than pH, then the acid likely will not contribute to making the solution ...
by JoshMoore2B
Sun Jan 24, 2021 10:55 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Spectator Ions
Replies: 6
Views: 37

Re: Spectator Ions

Hey guys! On question six of the sapling homework #2, it used the term spectator ion in the explanation of the answer, and I was wondering if anyone could explain what that term means? Thank you! Spectator ions are those ions that, because of their chemical properties, aren't strong enough to inter...
by JoshMoore2B
Sun Jan 24, 2021 10:52 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Percent ionization
Replies: 10
Views: 59

Re: Percent ionization

What does the percent ionization tell us? Why is it important? % ionization tells us how much of our substance (let's say an acid that we'll call HA) is ionized or not (so whether it is HA or A-). It is important because it is a direct indication of the strength of the acid or base in solution, and...
by JoshMoore2B
Sun Jan 24, 2021 10:48 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Sapling 9
Replies: 10
Views: 67

Re: Sapling 9

Why is the predominant species neutral if the pH value is less than the pKa value? Think of it this way: pKa is a measure of a strength of an acid. When pH goes below pKa (that is, the acidity of the solution becomes stronger than the pKa), then the pKa won't be able to "compete" with the...
by JoshMoore2B
Sun Jan 17, 2021 6:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Box
Replies: 3
Views: 36

Re: ICE Box

How do we find the difference in molar concentration using molar ratio? I know he did something with it in the third module, but is there a rule that explains how to convert the molar ratios in the empirical formula to find the difference? In the ICE box, the molar ratio ends up being the ratio of ...
by JoshMoore2B
Sun Jan 17, 2021 6:02 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Kw equation
Replies: 9
Views: 81

Re: Kw equation

Is there a simpler way to explain Kw and how the 10^14 comes into play? I haven't seen this mentioned yet completely, but Kw is the product of Ka and Kb in water. Ka = 1.0 x 10^-7 in water, and Kb = 1.0 x 10^-7 in water. This is why water is considered neutral, because Ka = Kb. Multiplying both (Ka...
by JoshMoore2B
Sun Jan 17, 2021 5:51 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Post Assessment Question 15 Part 4
Replies: 3
Views: 14

Re: Post Assessment Question 15 Part 4

15. The photosynthesis reaction, 6 CO2(g) + 6 H2O(l) ⇌ C6H12O6(aq) + 6 O2(g), is endothermic. What effect will the following changes have on the equilibrium composition. a) The partial pressure of CO2 is increased. b) The partial pressure of CO2 is decreased. Hey guys! I was wondering if anyone cou...
by JoshMoore2B
Sun Jan 17, 2021 5:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pure Liquids (Solutes)
Replies: 7
Views: 18

Re: Pure Liquids (Solutes)

Other than H20, are there any other solutes of pure liquids that we should know? If we don't need to memorize it, how can you tell something will be a pure liquid or solute and insignificant to the calculations? I believe we don't need to know which compounds are pure liquids or pure solids for thi...
by JoshMoore2B
Sun Jan 17, 2021 5:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 1 and 2 #9
Replies: 5
Views: 31

Re: Sapling Week 1 and 2 #9

At equilibrium, the concentrations in this system were found to be [N2]=[O2]=0.100 M and [NO]=0.500 M. N2(g)+O2(g)↽−−⇀2NO(g) If more NO is added, bringing its concentration to 0.800 M, what will the final concentration of NO be after equilibrium is re‑established? Could someone help me with this sa...
by JoshMoore2B
Sun Jan 10, 2021 9:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 10^3-10^-3
Replies: 2
Views: 20

Re: 10^3-10^-3

So if K is between 10^3 or 10^-3 does this mean that the reaction just slightly favors products or reactants or does it mean that is doesn't favor either? By sheer technicality, it would slightly favor either side. However, in a much more practical sense, it is understood that it doesn't favor eith...
by JoshMoore2B
Sun Jan 10, 2021 9:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K=1
Replies: 8
Views: 72

Re: K=1

I remember in the lecture that Dr. Lavelle said K=1 was rare. Why is it rare? I get that it means that neither R or P is favored since it is in the range of 10^-3 and 10^3. But why is that specific value rare? Might not be important but I'm curious I think most others have brought up good, accurate...
by JoshMoore2B
Sun Jan 10, 2021 9:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Temperature for Concentrations
Replies: 3
Views: 31

Re: Temperature for Concentrations

Why is the ratio of products to reactants temperature-dependent? The ratio of products to reactants temperature-dependent because the temperature can affect the amount of energy available for a reaction. Let's say in a given reaction, it takes more activation energy to move in reverse than to move ...
by JoshMoore2B
Sun Jan 10, 2021 9:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids and Concentration
Replies: 8
Views: 58

Re: Solids and Concentration

Talia Leano 2H wrote:Why don't solids have a concentration?


Solids aren't considered to have a concentration in terms of calculating equilibrium because they cancel out on both sides of the equation, or they don't have an effect on the equilibrium state of a reaction.
by JoshMoore2B
Sun Jan 10, 2021 9:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentration vs Pressure
Replies: 9
Views: 45

Re: Concentration vs Pressure

Conceptually, are concentration and pressure basically the same thing, just for different states? Pressure is just used for gas, but they are the same when calculating? Not necessarily. With PV = nRT, we can see that pressure is dependent on a few things beyond just moles, whereas concentration is ...
by JoshMoore2B
Sat Dec 12, 2020 6:59 pm
Forum: Bronsted Acids & Bases
Topic: determining cations or anions
Replies: 4
Views: 43

Re: determining cations or anions

are we supposed to know how to do problems like J17a (in the textbook) on the final? I am very confused about how this would be solved :/ In each of the following salts, either the cation or the anion is a weak acid or a weak base in water. Write the chemical equation for the proton transfer reacti...
by JoshMoore2B
Sat Dec 12, 2020 6:51 pm
Forum: Lewis Acids & Bases
Topic: Acid vs. Base
Replies: 3
Views: 61

Re: Acid vs. Base

Hi, I am a little confused as to how to tell if a compound is an acid or a base just by looking at it. From my general understanding, you can use either the Bronsted or the Lewis definition of an acid or base: Bronsted: Acids are proton donors while Bases are proton acceptors Lewis: Acids are elect...
by JoshMoore2B
Sat Dec 12, 2020 6:45 pm
Forum: Amphoteric Compounds
Topic: Recognizing Amphoteric Substances
Replies: 8
Views: 73

Re: Recognizing Amphoteric Substances

Can someone please walk me through how to recognize or determine if a substance is amphoteric? Amphoteric compounds are ones that can act as both an acid or a base depending on the situation. So, as someone above said, a great way to determine if something is amphoteric is to see if it can accept a...
by JoshMoore2B
Sat Dec 12, 2020 6:40 pm
Forum: Air Pollution & Acid Rain
Topic: Why does acid rain exist
Replies: 13
Views: 179

Re: Why does acid rain exist

Why does acid rain exist. Is it because of air pollution, and what can be down about it? Acid rain exists because of chemical reactions that release compounds like CO2, SO2, and NO2 into the atmosphere. These react with water in the atmosphere to form acidic compounds like H2CO3, which might then c...
by JoshMoore2B
Sat Dec 12, 2020 6:36 pm
Forum: Identifying Acidic & Basic Salts
Topic: Why are spectator ions of a salt related to strong acids/bases?
Replies: 2
Views: 45

Re: Why are spectator ions of a salt related to strong acids/bases?

I understand why ions of weak acids and bases can make the solutions more alkaline/acidic when interacting with water but I don't get why ions of strong acids/bases don't? What is the reason these strong acid/base ions don't act like the ions of weak acids/bases? This has to do with the favorabilit...
by JoshMoore2B
Sun Dec 06, 2020 6:02 pm
Forum: Biological Examples
Topic: Most abundant coordination compound question
Replies: 2
Views: 38

Re: Most abundant coordination compound question

What is the most abundant coordination compound found on Earth? I can't find a direct answer for this, however my best guess would be heme. Heme is largely conserved across most species on the planet because of how functionally optimized it is, and because it is so essential to life and abundant in...
by JoshMoore2B
Sun Dec 06, 2020 5:58 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number Vs. Oxidation Sates Question
Replies: 3
Views: 37

Re: Coordination Number Vs. Oxidation Sates Question

What is the difference between coordination numbers and oxidation states? The main issue between them is that the oxidation state has only to do with charge. What this means is that if uncharged compounds bind to the transition metal, then the coordination number will go up, but no the oxidation st...
by JoshMoore2B
Sun Dec 06, 2020 5:50 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: polydentate ligands
Replies: 3
Views: 33

Re: polydentate ligands

How do we determine if a ligand is a polydentate? Does it correlate to the number of lone pairs - like would a ligand with 2 lone pairs be bidentate? Or do we just memorize which ligands are polydentate? I believe you are correct in saying that it correlates to the number of lone pairs. If you draw...
by JoshMoore2B
Sun Dec 06, 2020 5:48 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligand definition
Replies: 7
Views: 51

Re: Ligand definition

Hi guys, so I know a ligand is anything that attached to a transition metal and gives off a pair of electrons (correct me if I'm wrong), but would that be the formal definition of a ligand? Also, what would be the main importance of ligands? At its simplest, a ligand is something that bonds to a ce...
by JoshMoore2B
Sun Dec 06, 2020 5:43 pm
Forum: Naming
Topic: Anion Naming
Replies: 7
Views: 79

Re: Anion Naming

Hey guys! I just wanted to clarify something about naming anions that interact with coordination compounds. On Sapling, I had to name [Co(NH3)5Cl]Cl2. I understand how to name the coordination compound inside the brackets, but I was a little confused about how to name the anion outside the brackets...
by JoshMoore2B
Sun Nov 29, 2020 8:38 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: non polar bonds/polar molecules
Replies: 6
Views: 23

Re: non polar bonds/polar molecules

I’ve mainly seen examples of molecules that have polar bonds , but is overall a non polar molecule, are there examples of polar molecules having non polar bonds? Most people here gave a very straightforward answer, but I suppose I will go a little into the explanation. Essentially, polarity is meas...
by JoshMoore2B
Sun Nov 29, 2020 8:28 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angles
Replies: 7
Views: 47

Re: Bond angles

In terms of determining bond angles, do we just look at the geometrical shape and take into account any lone pairs? Or are there more factors? For the purpose of the final, for example, all we need to know for bond angles is the angle of the parent (i.e. tetrahedral having bond angles of 109.5 degr...
by JoshMoore2B
Sun Nov 29, 2020 8:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: ions
Replies: 8
Views: 86

Re: ions

Agustina Santa Cruz 2F wrote:If atoms in a molecule have a negative or positive charge, how would that affect the VSEPR theory?


Generally, this isn't something you need to worry about for VSEPR theory. VSEPR theory only deals with lone pairs and bonding regions.
by JoshMoore2B
Sun Nov 29, 2020 8:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: How do bonds affect shapes?
Replies: 11
Views: 90

Re: How do bonds affect shapes?

Sometimes I get the shapes of the molecules wrong. I usually go by how many atoms surround the central atoms, mainly because I am not sure how double and triple bonds affect the structure. Any tips/information that can help me? Thank you. Going by the amount of atoms around the central atoms is a g...
by JoshMoore2B
Sun Nov 29, 2020 8:01 pm
Forum: Hybridization
Topic: Counting for Hybridization
Replies: 2
Views: 34

Re: Counting for Hybridization

I understand that we count the number of bonding "groups" instead of individual bonds when determining hybridization, but can anyone explain why this is the case? It doesn't make sense to me intuitively that a double bond + single bond on a central atom would have the same hybridization a...
by JoshMoore2B
Sun Nov 22, 2020 6:33 pm
Forum: Hybridization
Topic: Hybrid Orbitals
Replies: 3
Views: 31

Re: Hybrid Orbitals

In friday lecture Dr. Lavelle discussed the mixing of s and p orbitals to create hybrids so certain atoms may form more bonds. I was wondering if such hybridization can occur all along the periodic table, as in between d and f orbitals potentially, or other variations as such? Are hybrid orbitals o...
by JoshMoore2B
Sun Nov 22, 2020 6:29 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs
Replies: 6
Views: 41

Re: Lone Pairs

In one of the lectures, Dr. Lavelle kept mentioning how lone pairs are "more diffuse" than bonding pairs. I was a little confused on this statement. Can someone further explain what he means by this? When Dr. Lavelle kept referring to lone pairs as "more diffuse" than bonding pa...
by JoshMoore2B
Sun Nov 22, 2020 6:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 21
Views: 126

Re: Bond Angles

How do you calculate/approximate bond angles in a given molecule? Thanks! I believe what you are asking here is for your own individual problem solving, so the best advice I can give is to memorize the bond angles between "parent" shapes as well as memorize that adding lone pairs decrease...
by JoshMoore2B
Sun Nov 22, 2020 6:21 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Stable Geometry
Replies: 2
Views: 19

Re: Stable Geometry

On one of the questions for Sapling, the solution mentioned that the most stable geometry is an arrangement that keeps the atoms or electrons bonded to the central atom as far apart as possible. Why is this true? Does it have something to do with electron-electron repulsion? Yes, this should have t...
by JoshMoore2B
Sun Nov 22, 2020 6:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Remembering Molecular Shapes
Replies: 4
Views: 32

Re: Remembering Molecular Shapes

Does anyone have any tips for remembering molecular shapes? I looked up charts online and was just wondering if anybody has any advice! Hello! Memorization is something I'm actually quite a fan of, oddly enough. If you are super interested in strengthening your ability to memorize information for t...
by JoshMoore2B
Sun Nov 15, 2020 8:56 pm
Forum: Octet Exceptions
Topic: Phosphate
Replies: 7
Views: 55

Re: Phosphate

Why is phosphate an exception to the octet rule? It isn't that phosphate itself is an exception to the octet rule, but rather that the phosphorus in the phosphate acts as an exception to the octet rule to create the compound. This is because the phosphorus has access to the 3d orbital, and so it ca...
by JoshMoore2B
Sun Nov 15, 2020 8:53 pm
Forum: Bond Lengths & Energies
Topic: Bond Length & Strength Comparison
Replies: 3
Views: 28

Re: Bond Length & Strength Comparison

Hi everyone! I had a question regarding the comparison of bond lengths. I understand that single bonds are the longest and weakest in strength, while triple bonds are the shortest and strongest in strength. However, what would we do if we are asked to compare the bond length and strength in a situa...
by JoshMoore2B
Sun Nov 15, 2020 8:48 pm
Forum: Bond Lengths & Energies
Topic: Energies for interactions
Replies: 4
Views: 22

Re: Energies for interactions

When reviewing interactoins between ion-ion and ion-dipole interactions, where do the energies come from? I understand that, in an ion-ion example, the two are attracted to each other, but I don't undersatnd how that contributes to the negative energy (being released)? It is better not to think of ...
by JoshMoore2B
Sun Nov 15, 2020 8:43 pm
Forum: Bond Lengths & Energies
Topic: Bond Length
Replies: 5
Views: 44

Re: Bond Length

Is there a cutoff value for considering a bond overwhelmingly single-bonded or ample double-bonded? I believe that this is a pretty discretionary thing, so it is up to the individual. Generally, I would say something is overwhelmingly single- or double-bonded if the measured values for the bond len...
by JoshMoore2B
Sun Nov 15, 2020 8:36 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge and Ions
Replies: 7
Views: 83

Re: Formal Charge and Ions

I believe that the concept of formal charges only applies to covalent bonds. I wrote in my notes that the definition of formal charge is "gain or loss of electrons of an atom when forming a covalent bond." Thus, formal charge does not apply to ionic compounds. This also makes sense becaus...
by JoshMoore2B
Sun Nov 08, 2020 7:07 pm
Forum: Octet Exceptions
Topic: Group 13
Replies: 3
Views: 42

Re: Group 13

Are Group 13 elements always electron deficient or does it depend? Also, does electron deficient (the way that Dr. Lavelle uses it) mean that the atom/element can be without an octet? Some of the Group 13 elements can sometimes exist in compounds where they have 8 valence electrons, such as BF3NH3,...
by JoshMoore2B
Sun Nov 08, 2020 6:58 pm
Forum: Ionic & Covalent Bonds
Topic: Identifying Ionic and Covalent Bonds
Replies: 10
Views: 39

Re: Identifying Ionic and Covalent Bonds

When doing the sapling homework I came across a problem that asked me to identify certain bonds as either ionic or covalent. For ionic bonds, I know that these are formed when oppositely charged ions share electrons, and the more electronegative ion hogs the electrons, but I am a bit confused on ho...
by JoshMoore2B
Sun Nov 08, 2020 6:45 pm
Forum: Lewis Structures
Topic: Atom in the middle of a lewis structure
Replies: 7
Views: 43

Re: Atom in the middle of a lewis structure

When doing lewis structures, why is it that the atom with the lowest ionization energy goes in the middle? Others have explained why the atom with the lowest ionization energy goes in the middle in that it tends to make the most bonds. The logistics behind why the atom with the most bonds goes in t...
by JoshMoore2B
Sun Nov 08, 2020 6:40 pm
Forum: Ionic & Covalent Bonds
Topic: London dispersion forces
Replies: 12
Views: 56

Re: London dispersion forces

Can someone explain what London dispersion forces are? And how to differentiate between how strong the forces are? London dispersion forces are forces that exist, in essence, by chance. They occur because of the unpredictable movement of electrons. Due to the fact that the electrons move unpredicta...
by JoshMoore2B
Sun Nov 08, 2020 6:29 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen Bonds
Replies: 3
Views: 59

Re: Hydrogen Bonds

How does the size and shape of a molecule limit the number of hydrogen bonds formed? I was thinking about this from the Sapling question about the Urea molecule. Generally, the only deciding factor for number of hydrogen bonds formed is the amount of polar bonds in a molecule. The more polar bonds ...
by JoshMoore2B
Sun Nov 01, 2020 4:09 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: [Ar]3d14s2 vs [Ar] Ar4s23d1
Replies: 3
Views: 28

Re: [Ar]3d14s2 vs [Ar] Ar4s23d1

I probably missed the explanation for this slide in lecture, but on the slide it says that the ground state electron for scandium is [Ar]3d 1 4s 2 and NOT [Ar]4s 2 3d 1 . However, I always recall writing it in the latter way. Could someone explain this to me please? I understand that the 4s shell i...
by JoshMoore2B
Sun Nov 01, 2020 4:04 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 2
Views: 47

Re: Electron Affinity

For electron affinity, why does a transition to a more stable state release energy? For example, Cl releases more energy than Al by gaining an electron while He absorbs the most energy by gaining an electron? Also in the calculations we did earlier in this unit (involving \Delta E= Efinal- Einitial...
by JoshMoore2B
Sun Nov 01, 2020 4:01 pm
Forum: Quantum Numbers and The H-Atom
Topic: Effective Nuclear Charge
Replies: 4
Views: 50

Re: Effective Nuclear Charge

I saw the term "Effective Nuclear Charge" used in the sapling homework, and realized it was something Dr. Lavelle talked about in lecture. I understand that inner electrons shield the outer electrons from the electrostatic charge of the positive nucleus, and are therefore held less tightl...
by JoshMoore2B
Sun Nov 01, 2020 3:50 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Energy of s, p, d, f states
Replies: 3
Views: 80

Re: Energy of s, p, d, f states

Why is it that the d-orbital has more energy than the s-orbital because the electrons in the d-orbital experience a lesser effective nuclear charge than electrons in the s-orbital? Why would a lower charge mean a greater potential energy? Essentially, the closer to the nucleus an electron is, the l...
by JoshMoore2B
Sun Nov 01, 2020 3:44 pm
Forum: Trends in The Periodic Table
Topic: ionic radius
Replies: 14
Views: 69

Re: ionic radius

Anions should have the largest ionic radius, because they have extra electrons. These extra electrons increases electron-electron repulsion, fill in shells, and overall increase the range at which the anion can interact with other objects. Generally, the radius of atoms or ions is determined by thei...
by JoshMoore2B
Fri Oct 23, 2020 3:40 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Impossible Model
Replies: 2
Views: 41

Re: Impossible Model

During the impossible model example given in class, we said that the diameter of the nucleus was equal to delta x? Can someone explain how that is? If we took the center of the nucleus as a known position, then the furthest the electron could be in 3-space is plus or minus the radius of the nucleus...
by JoshMoore2B
Fri Oct 23, 2020 3:37 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: h/4pi
Replies: 7
Views: 68

Re: h/4pi

If we know the value of h/Planck's constant as 6.626 x 10^-34 J*s and the value of pi rounded as 3.14, why is h/4pi always written if it is a constant? I believe another reason why h/4pi is always written out as opposed to some other, new constant (let's call it Q), is because h itself is a constan...
by JoshMoore2B
Fri Oct 23, 2020 3:32 pm
Forum: Properties of Light
Topic: Energy and intensity of light in both models
Replies: 4
Views: 55

Re: Energy and intensity of light in both models

Hi guys, I know that in the particle model of light, energy and intensity are different, but how about in the wave model of light? Is energy equal to intensity in the wave model? To better understand this, it is best to look at light in different ways: As a particle, as a stream , and as a wave. An...
by JoshMoore2B
Fri Oct 23, 2020 3:22 pm
Forum: Photoelectric Effect
Topic: Application
Replies: 5
Views: 44

Re: Application

does the photoelectric effect only apply to metal surfaces? Another way to explain this in a way you might have heard before that the other answers didn't quite touch on is that, in metals, electrons are allowed to move freely through the surface. This greater freedom of movement allows the photons...
by JoshMoore2B
Fri Oct 23, 2020 3:12 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty in velocity of proton in hydrogen atom
Replies: 2
Views: 35

Re: Uncertainty in velocity of proton in hydrogen atom

This caught my eye, so I decided to take a look. Using the values given to us from Wednesday's lecture, and using the indeterminacy equation, we have something like this: deltaV >= h/(4pi * deltaX * Mass_proton) or deltaV >= (6.63x10^-34 J*s)/((4pi)(1.7x10^-15m)(1.67x10^-27kg) which, when worked out...
by JoshMoore2B
Sun Oct 18, 2020 4:17 pm
Forum: Photoelectric Effect
Topic: What happens to absorbed photons?
Replies: 6
Views: 77

Re: What happens to absorbed photons?

So Professor Lavelle said that photons of the correct frequency can displace electrons if their frequency gives them enough energy to do so. However, what happens to the photons in the process? Do they just stick around with the atom? In such case, do any given atoms have neutrons, protons, electro...
by JoshMoore2B
Sun Oct 18, 2020 4:07 pm
Forum: Properties of Light
Topic: Example during lecture 6
Replies: 5
Views: 90

Re: Example during lecture 6

In the example problem prof went over during Friday's (10/16) lecture, he removed the negative sign from the -4.01 x 10^-19 J answer when plugging it in to the next equation. Could someone explain why he did that? I didn't quite understand Dylan gave a good answer, but I wanted to expand a little m...
by JoshMoore2B
Sun Oct 18, 2020 3:56 pm
Forum: Einstein Equation
Topic: HW problem 5
Replies: 6
Views: 105

Re: HW problem 5

How would I approach this problem? A liquid is exposed to infrared radiation with a wavelength of 9.74×10−4 cm. Assume that all the radiation is absorbed and converted to heat. How many photons are required for the liquid to absorb 32.74 J of heat? Do I need to use both E=hv and C=lambda(V)? Yes. I...
by JoshMoore2B
Thu Oct 15, 2020 9:43 pm
Forum: Properties of Light
Topic: When do you use the balmer or lydberg series?
Replies: 4
Views: 74

Re: When do you use the balmer or lydberg series?

I saw that someone answered this with a general answer, so I will augment that with numerical specifics (in the event that a question on the homework or the test provides you with a wavelength number and not the range). The Lyman series operates roughly from 122nm to 91 nm. The Balmer series operate...
by JoshMoore2B
Tue Oct 13, 2020 3:55 pm
Forum: Photoelectric Effect
Topic: Counting Photons Using the Photoelectric Effect
Replies: 1
Views: 28

Counting Photons Using the Photoelectric Effect

Let's say you were to recreate the photoelectric effect experiment with a detector that could count or calculate the number of electrons hitting its surface. Using this detector, wouldn't you then be logically able to calculate the number of photons emitted by your original light source (in a given ...
by JoshMoore2B
Sat Oct 10, 2020 8:38 pm
Forum: Limiting Reactant Calculations
Topic: Double Check my Understanding
Replies: 10
Views: 141

Re: Double Check my Understanding

You are indeed correct: when calculating the molar mass of a compound, you do not take into account the stoichiometric coefficient in front of the compound in the balanced chemical equation. A situation you would use the stoichiometric coefficient times the molar mass of a compound would be when you...
by JoshMoore2B
Sat Oct 10, 2020 7:57 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Preference on Scientific Notation
Replies: 13
Views: 169

Re: Preference on Scientific Notation

Is there a preference between the 1.0 x10^6 scientific notation and the shorthand 1.0 E6 notation? I personally would recommend using "1.0 x 10^6," since the shorthand notation with E seems to most commonly be associated with calculator provided/digital answers while the "1.0 x 10^6&...
by JoshMoore2B
Thu Oct 08, 2020 10:24 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical and Molecular Formula
Replies: 17
Views: 131

Re: Empirical and Molecular Formula

Yes. The empirical formula is the formula of a compound that simply shows the ratio of elements in the compound in simplest terms. For example, NH3 is the molecular formula for ammonia, but because NH3 also shows the ratio of elements in the compound in simplest terms (3 hydrogens for every nitrogen...
by JoshMoore2B
Thu Oct 08, 2020 10:04 pm
Forum: Molarity, Solutions, Dilutions
Topic: sapling number 6 (cont.)
Replies: 4
Views: 74

Re: sapling number 6 (cont.)

I've been over this equation a million times and keep getting it wrong, and was hoping someone could point out the error in my calculations or set up. I've attached a screenshot of my work for number 6 (which hopefully shows up). Thanks for all of the help and clarification from the previous post! ...
by JoshMoore2B
Thu Oct 08, 2020 9:41 pm
Forum: SI Units, Unit Conversions
Topic: #10 in the sapling
Replies: 6
Views: 87

Re: #10 in the sapling

for this problem, is the molar ratio 1:1? if so, how did you determine that for sure without being able to actually write out the chemical formula and balance it? For this question in particular, I believe that the diagram shows an organic chemical reaction, and in organic chemistry you will likely...

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