Search found 88 matches

by Simrah_Ahmed1J
Sun Feb 21, 2021 9:42 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Reversible vs Irreversible Entropy Calculation
Replies: 4
Views: 16

Re: Reversible vs Irreversible Entropy Calculation

For ΔS...

reversible(isothermal): there is a change in V, no change in T
ΔS= n*R*ln(V2/V1)

irreversible: there is a change in T, no change in V
ΔS= n*Cv*ln(T2/T1)
by Simrah_Ahmed1J
Sun Feb 21, 2021 9:38 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Different Gas Constants
Replies: 9
Views: 36

Re: Different Gas Constants

Yeah, so the units for R can be many different things such as J/K·mol, L·atm/K·mol, L·bar/K·mol, and L·Torr/K·mol. But they all generally expressed in some type of units of pressure x volume (energy) per temperature increment per mole. (The values as shown on the equation sheet on the class website ...
by Simrah_Ahmed1J
Sun Feb 21, 2021 9:32 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Sapling #8
Replies: 3
Views: 13

Re: Sapling #8

Yeah, I think where this is confusing is that you do use the ΔS=C p *ln(T2/T1), but since it asks for the molar entropies so its just put like putting n=1 when calculating the entropy of heating the water and cooling the vapor. But also, for the entropy of vaporization you don't have to do any calcu...
by Simrah_Ahmed1J
Sun Feb 21, 2021 9:25 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter Calibration
Replies: 4
Views: 19

Re: Calorimeter Calibration

I'm not certain this is what you're asking but if you're talking about finding the heat capacity of the calorimeter?? the equation is Ccal= q/ΔT, and you can use other equations to find q.
by Simrah_Ahmed1J
Sun Feb 21, 2021 8:59 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 6
Views: 22

Re: Van't Hoff Equation

So basically you are finding K 2 and already have all the other values: 1. solve right side of equation: ln K 2 /K 1 = - (ΔH o /R)[1/T 2 - 1/T 1 ] now you have: ln K 2 /K 1 = x 2. raise whatever you got on the right side of the equation to e to get rid of the natural log now you have: K 2 /K 1 = e x...
by Simrah_Ahmed1J
Sun Feb 21, 2021 8:46 pm
Forum: Balancing Redox Reactions
Topic: Oxidation numbers
Replies: 4
Views: 24

Re: Oxidation numbers

Yeah I think you can follow the general trend of the groups, like alkali metals and such. Also, although our class periodic table doesn't have them I think there are periodic tables with all the oxidation numbers that you can look up to reference if you just want to visualize or get used to them or ...
by Simrah_Ahmed1J
Sun Feb 21, 2021 8:36 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: pH meter
Replies: 11
Views: 120

Re: pH meter

So basically, the pH scale is a measure the concentration of H+ ions in solution, and an acid is a compound that gives H+ ions, the strength/acidity of a solution is therefore correlated to how much H+ is in the substance. So the numbers on the pH scale represent a different level of concentration o...
by Simrah_Ahmed1J
Sun Feb 21, 2021 7:53 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Work in a Constant Volume
Replies: 13
Views: 34

Re: Work in a Constant Volume

Mathematically, it is from the w=PΔV equation. But the way to think about it, in general, is that because that no work of expansion is done (like when it comes to solids and liquids), the volume of the reactants and products is equal. That's why there is no change in volume when there is no work!
by Simrah_Ahmed1J
Sun Feb 21, 2021 7:46 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter Values
Replies: 3
Views: 12

Re: Calorimeter Values

We can assume a calorimeter has constant pressure and usually constant volume as well because you're assuming it is a bomb calorimeter. It's the heat/temperature that changes inside the calorimeter as the reaction progresses, so that's why we use the Ccal= q/ΔT equation.
by Simrah_Ahmed1J
Wed Feb 10, 2021 7:41 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Kelvin conversion
Replies: 40
Views: 105

Kelvin conversion

Hey, I was wondering if anyone can recall a specific kelvin conversion number we're supposed to use for conversions because I don't know how accurate the number has to be like down to a certain decimal place or if it doesn't really matter.
by Simrah_Ahmed1J
Sun Feb 07, 2021 8:41 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Friday's Lecture
Replies: 8
Views: 54

Re: Friday's Lecture

I think that we can figure out whatever we need to know from the equations, like in this case we know that ΔU= q + w, so in the case we know ΔU(change in internal energy)=0, then we know that q = -w.
by Simrah_Ahmed1J
Sun Feb 07, 2021 8:32 pm
Forum: Calculating Work of Expansion
Topic: Work of Expansion
Replies: 2
Views: 15

Re: Work of Expansion

I think it is work of expansion because as the quote says "the external pressure" is what is being increased, so if the gas outside the piston is expanding it is doing work on the piston and making it move in.
by Simrah_Ahmed1J
Sun Feb 07, 2021 8:27 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity of Calorimeter
Replies: 7
Views: 40

Re: Heat Capacity of Calorimeter

Its basically to say that the q=mcΔT equation doesn't depend on mass anymore so you can just solve with q=cΔT
by Simrah_Ahmed1J
Sun Feb 07, 2021 8:02 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Increase in Entropy
Replies: 5
Views: 20

Re: Increase in Entropy

Yes, because q is heat entering the system, so if then q is positive then more heat is entering the system, heat entering the system is more energy in the system, more energy increases entropy, so a positive q would suggest an increase in entropy.
by Simrah_Ahmed1J
Sun Feb 07, 2021 7:53 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U in relation to q
Replies: 5
Views: 30

Re: Delta U in relation to q

I think that we can figure out whatever we need to know from the equations, like in this case we know that ΔU= q when the volume is constant from the equation ΔU= q + w, because using the equation w= -P(ΔV), when the system has constant volume because ΔV=0 and since q is the heat input(ΔH), then w=0...
by Simrah_Ahmed1J
Mon Feb 01, 2021 12:03 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Textbook question
Replies: 3
Views: 21

Re: Textbook question

You would look at their k equilibrium ratios, a diatomic molecule is more stable if it divides into products less and remains in reactants, in other words, k is higher.
by Simrah_Ahmed1J
Sun Jan 31, 2021 11:59 pm
Forum: Phase Changes & Related Calculations
Topic: endothermic/exothermic
Replies: 43
Views: 161

Re: endothermic/exothermic

you can think about it intuitively, like with water: vaporization is liquid to vapor- liquid needs to absorb heat energy to vaporize and become a vapor -> endothermic melting/fusion is solid to liquid- a solid needs to melt or absorb energy to become a liquid -> endothermic sublimination is solid to...
by Simrah_Ahmed1J
Sun Jan 31, 2021 11:40 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Sapling week 3 #6
Replies: 12
Views: 106

Re: Sapling week 3 #6

The answer is -4 x bond energy of C-H because the C-H bonds are the ones being formed in the reaction, CH 4 is the product. So since you find ΔH o rxn with bond enthalpies by the equation: ΣH o (bonds broken) - ΣH o (bonds formed), we don't consider the bonds broken because the reactants are pure el...
by Simrah_Ahmed1J
Sun Jan 31, 2021 11:33 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Tips to drawing out molecules to determine enthalpy changes.
Replies: 8
Views: 49

Re: Tips to drawing out molecules to determine enthalpy changes.

It differs for different equations of course, but I think one big thing you have to pay attention to when drawing out molecules to determine enthalpy changes is C-H bonds, because sometimes there is longer chains or other specific shapes so you have to keep track of the many C-H bonds that are break...
by Simrah_Ahmed1J
Sun Jan 24, 2021 11:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sig Figs 5I.33
Replies: 3
Views: 28

Re: Sig Figs 5I.33

I really don't know how important worrying about sig figs is for the exam and stuff but like for example with this specific problem you obviously had to convert from mg and g to moles, and because of that you might have used a different periodic table with different accuracies of molar mass, and eve...
by Simrah_Ahmed1J
Sun Jan 24, 2021 10:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook 5I.17
Replies: 1
Views: 18

Re: Textbook 5I.17

Hey, you might want to check your set up for the equilibrium equation, because I found was x = 1.8 x 10 -4 , which gave me the correct answer for the problem. My set up was: K c = 1.00 x 10 -5 = [NO 2 ] 2 /[N 2 ]*[O 2 ] = (2x) 2 /(0.114-x)*(0.114*x) (and this was before approximating x=0 and substit...
by Simrah_Ahmed1J
Sun Jan 24, 2021 10:43 pm
Forum: Ideal Gases
Topic: Acids & Bases
Replies: 6
Views: 47

Re: Acids & Bases

To put it simply, a salt will be basic if it contains the cation part of a strong base. For example, Na 2 S is a basic salt because it has Na, which is in NaOH which is a strong base. A salt will be acidic if it contains the anion part of a strong acid. For example, NH 4 ClO 4 is an acidic salt beca...
by Simrah_Ahmed1J
Sun Jan 24, 2021 10:28 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Percent ionization
Replies: 10
Views: 71

Re: Percent ionization

Does anyone know of a good YouTube video that explains percent ionization? I sort of understood how Lavelle explained it but I need more examples. This is good for understanding the concept: https://www.youtube.com/watch?v=6s7ZQBzAvV4 This is good for examples: https://www.youtube.com/watch?v=5JUA3...
by Simrah_Ahmed1J
Sun Jan 24, 2021 8:48 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Week 2 Sapling 5
Replies: 5
Views: 50

Re: Week 2 Sapling 5

There might be different ways of doing it, but this is how I did it:
by Simrah_Ahmed1J
Sun Jan 17, 2021 11:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: quadratic formula values
Replies: 13
Views: 79

Re: quadratic formula values

If you've solved the equation right and there's two positive x values as a result, there should be one x value that is greater even than the initial concentration itself, and we know that would have to be wrong because if we're using it as a change we cant have the equilibrium concentration be negat...
by Simrah_Ahmed1J
Sun Jan 17, 2021 11:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Initial Concentrations
Replies: 7
Views: 47

Re: Initial Concentrations

Im assuming you're talking about week one sapling problem 10, but basically for this problem you obviously have calculate the k value from the given equilibrium concentrations, then it asks you to calculate the equilibrium concentrations of the two when 1 mol of NO 2 is added after the system is alr...
by Simrah_Ahmed1J
Sun Jan 17, 2021 11:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook Problem 5I.27
Replies: 1
Views: 23

Re: Textbook Problem 5I.27

The way I did it was that: I: [PCl 3 ]= 3.00 mol/0.500 L = 6.00, [Cl 2 ]= 0.500 mol/0.500 L = 1.00, [PCl 5 ]= 1.500 mol/0.500 L = 3.00 C: [PCl 3 ] - x, [Cl 2 ] -x, [PCl 5 ] +x E: [PCl 3 ]= 6.00 - x, [Cl 2 ]= 1.00 - x, [PCl 5 ]= 3.00 + x so my equilibrium setup was K = (3.00 + x)/ ((6.00 - x)*(1.00 -...
by Simrah_Ahmed1J
Wed Jan 13, 2021 6:10 pm
Forum: Ideal Gases
Topic: Gas constant
Replies: 9
Views: 71

Re: Gas constant

Yeah, so the R is used in the ideal gas law equation PV=nRT, because while PV is proportional to nT, it is the R value that makes the whole ideal gas equation true and helpful for calculations. Now the units for R can be many different things such as J/K·mol, L·atm/K·mol, L·bar/K·mol, and L·Torr/K·m...
by Simrah_Ahmed1J
Wed Jan 13, 2021 6:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Temperature & K for Acids and Bases
Replies: 4
Views: 33

Re: Temperature & K for Acids and Bases

K does change based on temperature, as we learned, endothermic reactions go further towards products with higher temperatures and exothermic reactions go towards reactants with higher temperatures. I think we use this specific K value at this specific temperature 25 o C, because its a kind of standa...
by Simrah_Ahmed1J
Sun Jan 10, 2021 1:22 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Textbook problem 5J.5
Replies: 3
Views: 32

Textbook problem 5J.5

Can someone explain the reasoning for this problem? I understand that the reaction will proceed in the direction with less moles of gas to even it out based on Le Chateliers, but overall the concept and wording is confusing me and I'm finding it hard to relate pressure and volume.
by Simrah_Ahmed1J
Sun Jan 10, 2021 1:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Thermodynamically more stable-5I.13
Replies: 1
Views: 26

Re: Thermodynamically more stable-5I.13

In a simple way of saying, it is about which compound is more likely to dissociate more, or go to reactant more. Since the F 2 reaction has a higher K value, the ratio of the concentration of its products to its reactants are more than Cl 2 , which means the F 2 molecule is less stable because it wi...
by Simrah_Ahmed1J
Sun Jan 10, 2021 1:03 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Endothermic and Exothermic Reactions
Replies: 6
Views: 52

Re: Endothermic and Exothermic Reactions

To put it simply, it is based on the energy level of the reactants and products. This is why we measure it with enthalpy (H) which is related to heat energy. The attached drawings of graphs is from my notes on one of the lectures, it might help make sense of the idea. So basically, a reaction is exo...
by Simrah_Ahmed1J
Sun Jan 10, 2021 12:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Equilibrium Concentrations
Replies: 10
Views: 75

Re: Calculating Equilibrium Concentrations

Yes, so because substances as solids and liquids don't really change very much in molar concentration in a reaction, we don't use them to calculate K at all, so therefore we do not need to pay attention to them in our ICE chart bc they're not going to be used in our K equation anyway.
by Simrah_Ahmed1J
Thu Jan 07, 2021 9:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: R value
Replies: 5
Views: 72

Re: R value

Yeah, so the R value in this case is a constant is the universal gas constant , which is used in the ideal gas law equation PV=nRT, because while PV is proportional to nT, it is the R value that makes the whole ideal gas equation true and helpful for calculations. Now the units for R can be many dif...
by Simrah_Ahmed1J
Wed Dec 16, 2020 11:20 pm
Forum: General Science Questions
Topic: atomic radius
Replies: 7
Views: 66

Re: atomic radius

When you are comparing 2 ions that have the same electron configuration, you are obviously not considering the energy level as a factor in ionic/atomic radius because they have the same electron configuration. So then you can think about it in terms of "pulling power" or attraction of the ...
by Simrah_Ahmed1J
Wed Dec 16, 2020 11:14 pm
Forum: *Titrations & Titration Calculations
Topic: Titration Curves
Replies: 2
Views: 45

Re: Titration Curves

Titration curves basically show the different volumes of an acid, or the titrant , being added to to the concentration of base in the solution. In a graph, you have volume of acid on the x-axis and pH on the y-axis. The significance of the stoichiometric point is that it shows the amount of added ti...
by Simrah_Ahmed1J
Wed Dec 16, 2020 11:01 pm
Forum: Student Social/Study Group
Topic: Existing 14B Groupme
Replies: 4
Views: 51

Re: Existing 14B Groupme

Hey!
here's the link to the groupme:
https://groupme.com/join_group/62288203/dSSkobMS
by Simrah_Ahmed1J
Wed Dec 16, 2020 10:23 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Tetrahedral molecular shape
Replies: 10
Views: 100

Re: Tetrahedral molecular shape

Yeah, so basically you have to remember to think about it in 3-D, there are multiple planes so that means there is more than 360 o . In tetrahedrals there are 4 bonds exerting equal repulsions on each other, and then spreading out in a way that reduces the repulsions the most, with 109.5 o between t...
by Simrah_Ahmed1J
Wed Dec 16, 2020 9:25 pm
Forum: Naming
Topic: ONO vs. NO2
Replies: 9
Views: 132

Re: ONO vs. NO2

I think that when you see molecules are written like that (ONO) even when it can be written in the more common way or normal way (N2O) it is an indication of the layout of the actual structure.
by Simrah_Ahmed1J
Wed Dec 16, 2020 9:20 pm
Forum: Student Social/Study Group
Topic: 14B Groupme
Replies: 12
Views: 127

Re: 14B Groupme

Hey you guys!
here's the groupme link:
https://groupme.com/join_group/62288203/dSSkobMS
by Simrah_Ahmed1J
Wed Dec 16, 2020 9:13 pm
Forum: Lewis Structures
Topic: Maximum electrons in expanded octet
Replies: 2
Views: 36

Re: Maximum electrons in expanded octet

I believe that basically the amount of that the valence shell can hold influences whether or not the element can have an expanded octet. So like with your example of iodine, it can make more than 4 bonds because it has its valence electrons in the 4th energy level, and so then it has access to the e...
by Simrah_Ahmed1J
Wed Dec 16, 2020 2:18 pm
Forum: Identifying Acidic & Basic Salts
Topic: Strong acid / base ion
Replies: 8
Views: 65

Re: Strong acid / base ion

Yes, I think the ions of strong acids and bases will stay dissociated in the solution because of the way they interact with H+ and OH- from H2O.
by Simrah_Ahmed1J
Wed Dec 16, 2020 2:03 pm
Forum: Lewis Structures
Topic: Transition Metals Lewis Structures
Replies: 3
Views: 28

Re: Transition Metals Lewis Structures

I'm not sure of the exact rules for determining how many valence electrons the transition metals can have, but I think that the transition metals can violate the octet rule quite often by using their d orbitals for bonding, so can often have more than 4 bonds as the central atom.
by Simrah_Ahmed1J
Wed Dec 16, 2020 1:57 pm
Forum: Conjugate Acids & Bases
Topic: Bronsted Conjugates vs Lewis Conjugates
Replies: 1
Views: 26

Re: Bronsted Conjugates vs Lewis Conjugates

I believe that with a Bronsted acid, its conjugate base will be the molecule that is similar to it but with one less proton (H + ), and therefore for a Bronsted base, its conjugate acid will be the molecule that is similar to it, but with one more proton (H + ). Whereas with a Lewis acid, its conjug...
by Simrah_Ahmed1J
Sun Dec 13, 2020 9:58 am
Forum: Bronsted Acids & Bases
Topic: Amphoteric substances
Replies: 3
Views: 42

Re: Amphoteric substances

I think the best way to figure out which are oxides are amphoteric is whether they include a metalloid or something close to a mettaloid. I have attached a picture of what we were taught about amphoteric, acidic, and basic oxides in lecture, the red line that is drawn is around other oxides that can...
by Simrah_Ahmed1J
Sun Dec 13, 2020 9:49 am
Forum: Calculating the pH of Salt Solutions
Topic: Textbook problem 6B.3 part b
Replies: 2
Views: 45

Textbook problem 6B.3 part b

How would you use the information given to arrange a -log([H + ]) calculation in part b of this problem? 6B.3 A careless laboratory technician wants to prepare 200.0 mL of a 0.025 M HCl(aq) solution but uses a volumetric flask of volume 250.0 mL by mistake. (a) What would the pH of the desired solut...
by Simrah_Ahmed1J
Sun Dec 13, 2020 12:48 am
Forum: Bronsted Acids & Bases
Topic: Sapling #12
Replies: 6
Views: 66

Re: Sapling #12

Yeah, basically by Br having its electrons in bonds with electronegative O atoms, its electrons become more shared in that region and are not so close to the Br itself. Rather than there being less O bound to the Br, in that case are more lone pairs on Br, which help use more of that negative charge...
by Simrah_Ahmed1J
Sun Dec 13, 2020 12:31 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Atoms Outside of Coordination Sphere
Replies: 1
Views: 44

Re: Atoms Outside of Coordination Sphere

I believe theres always the cation in the coordination compound and the atoms outside of the bracket are the anions and/or the hydrates, so in that case they make a salt and they are ionically bonded. Because they are ionically bonded, they have completely transferred their electrons.
by Simrah_Ahmed1J
Sun Dec 13, 2020 12:16 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles for See-Saw and T-Shaped
Replies: 2
Views: 40

Re: Bond Angles for See-Saw and T-Shaped

Yes, I think you're partly right because the electrons that are the most delocalized and spread out are the lone pairs, which affect the shape a lot. But also overall the bonded electrons in that remaining space also need to have angles that help place them as far apart as possible, and the difficul...
by Simrah_Ahmed1J
Sun Dec 13, 2020 12:00 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: About electron configurations positive ions of elements in the 4p period (Based on Cu and Cr)
Replies: 2
Views: 29

About electron configurations positive ions of elements in the 4p period (Based on Cu and Cr)

So I know the exceptions of Cr and Cu in terms of filling order and how they "borrow" from the 4s electrons, but I'm wondering about when it comes to the positive ions of elements in 4p, such as Ga + , Ge 2+ , or even more positively charged versions of those atoms. When writing their elec...
by Simrah_Ahmed1J
Sat Dec 12, 2020 11:52 pm
Forum: Octet Exceptions
Topic: Exceptions outside the ones we memorized
Replies: 6
Views: 67

Exceptions outside the ones we memorized

I know we had to memorize that H, He, Li, and Be as able to have less than an octet, and P, S, and Cl as able to have more than an octect of electrons, but there are also other atoms besides those that come up regularly that are exceptions as well. What are some of them/the most important ones? just...
by Simrah_Ahmed1J
Thu Dec 10, 2020 10:57 pm
Forum: Hybridization
Topic: Question 18 Sapling Week7/8
Replies: 1
Views: 16

Re: Question 18 Sapling Week7/8

Yeah, this is a pretty confusing question, you definitely have to think of that question based on the questions before it, because they ask about hybridizations and bond angles and that's what might help you figure out this question. I have tried to draw out all the information in an image. Basicall...
by Simrah_Ahmed1J
Thu Dec 10, 2020 10:30 pm
Forum: Properties of Light
Topic: Is c always the speed of light?
Replies: 88
Views: 509

Re: Is c always the speed of light?

Yes, I think you can be completely sure to use c when you're talking about energy because it is in the form of photons and it is always light and therefore always has the speed c.
by Simrah_Ahmed1J
Wed Dec 09, 2020 10:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Predicting the shape of AsF5
Replies: 2
Views: 46

Re: Predicting the shape of AsF5

This shape can be a bit confusing because As was not one of the elements we learned to be able to have an expanded octet, but the trick is that since As is in the 3rd period, its valence electrons are in the p orbital of the 3rd energy level, and the 3d orbital is completely empty, which allows the ...
by Simrah_Ahmed1J
Sun Dec 06, 2020 4:28 pm
Forum: Identifying Acidic & Basic Salts
Topic: Concept of pH
Replies: 10
Views: 73

Re: Concept of pH

So basically, the pH scale is simply a measure the concentration of H+ ions in solution, and an acid is a compound that gives H+ ions, the strength/acidity of a solution is therefore correlated to how much H+ is in the substance. So the numbers on the pH scale just represent a different level of con...
by Simrah_Ahmed1J
Sun Dec 06, 2020 4:03 pm
Forum: Lewis Acids & Bases
Topic: Acids vs Basis
Replies: 11
Views: 110

Re: Acids vs Basis

It depends on what kind of acid/base you're looking for but... Obviously, if you have the full equation it will be easiest to determine based on the way the H+ and OH- move. It also helps to look at whether or not the molecule is an ion with a positive charge, in this case the molecule can usually e...
by Simrah_Ahmed1J
Sun Dec 06, 2020 3:22 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecules with lone pairs
Replies: 5
Views: 86

Re: Molecules with lone pairs

Lone pairs are more repulsive than bonds because their charge density is spread out more, whereas electrons in a bonding pair are specifically held in a region right between the two bonded atoms. Because the electrons in the lone pair are able have their charge density more spread out, they repel ot...
by Simrah_Ahmed1J
Sun Dec 06, 2020 2:16 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Does pH indicate strength of an acid?
Replies: 26
Views: 178

Re: Does pH indicate strength of an acid?

Yeah you're right, since the pH scale is simply a measure the concentration of H+ ions in solution, and an acid is a compound that gives H+ ions, the strength/acidity of a solution is therefore correlated to how much H+ is in the substance. So the numbers on the pH scale just represent a different l...
by Simrah_Ahmed1J
Sun Dec 06, 2020 1:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular shape and polarity
Replies: 3
Views: 22

Re: Molecular shape and polarity

I get your line of thinking and it makes sense, because a lot of nonpolar molecules have no lone pairs on the central atom, those nonpolar molecules are usually in shapes we've learned such as tetrahedral, trigonal planar, trigonal bipyramidal, and octahedral, and usually the atoms bound to the cent...
by Simrah_Ahmed1J
Sun Nov 29, 2020 9:29 pm
Forum: Octet Exceptions
Topic: PCl5 expanded octet question
Replies: 6
Views: 50

Re: PCl5 expanded octet question

At least for 14A I believe we need to know the exceptions for expanded octets as being P, S, and Cl. Basically, these atoms can accommodate more than 8 electrons in their valence shell because they are atoms in period 3, so they have empty d-orbitals in their valence shell on n=3 which are open to a...
by Simrah_Ahmed1J
Sun Nov 29, 2020 9:25 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configuration exceptions
Replies: 1
Views: 36

Re: Electron configuration exceptions

For me, I always remember it by the fact that the d orbitals would prefer to have a half full or a completely full orbital for more stability, so that's why when it comes to Cr there is an exception because it is one away from a half full 3d orbital so it 'steals' one electron from the 4s orbital, m...
by Simrah_Ahmed1J
Sun Nov 29, 2020 6:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Cyclic Structures
Replies: 3
Views: 15

Re: Cyclic Structures

So when it comes to cyclic structures, the molecules are arranged with a ring, in most cases such as this one it involves a Carbon ring. So for this structure C 3 h 4 you arrange the Cs as a ring and the H around them with any double or triple bonds between the C atoms needed to ensure an octet for ...
by Simrah_Ahmed1J
Sun Nov 29, 2020 6:23 pm
Forum: Dipole Moments
Topic: Dipole moment definition/calculation [ENDORSED]
Replies: 3
Views: 47

Re: Dipole moment definition/calculation [ENDORSED]

The dipole moment describes the relationship between two different charges in space because like we learned they make an electric field. Whereas electronegativity is a measurement of how reactive an atom is, or how likely it is to bond with another atom, or how likely it is to attract a shared pair ...
by Simrah_Ahmed1J
Sun Nov 29, 2020 5:51 pm
Forum: Dipole Moments
Topic: Tetrahedral Atoms and Dipole Moments
Replies: 7
Views: 67

Re: Tetrahedral Atoms and Dipole Moments

Yes I think your right because you have to think about the individual dipole moments and then the net dipole moment for the molecule. So unless there are 4 of the same atoms around the central atom, there will always be a net dipole due to the differing forces since the different atoms have differen...
by Simrah_Ahmed1J
Sun Nov 29, 2020 4:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Axial vs Equatorial Bonds
Replies: 11
Views: 109

Re: Axial vs Equatorial Bonds

I makes more sense when you think of axial and equatorial bonds in terms of the 3-D arrangement of the molecule. The image I drew and attached might help you visualize its lay out. But yes, lone pairs are often in axial positions in order to minimize repulsions as you can see from many bent, pyramid...
by Simrah_Ahmed1J
Sun Nov 22, 2020 9:42 pm
Forum: Sigma & Pi Bonds
Topic: Sigma Bond Flexibility
Replies: 5
Views: 35

Re: Sigma Bond Flexibility

Its basically because sigma bonds have more flexibility because the atoms are only interacting one way and so they can rotate around that one point, whereas the pi bonds are more complicated and more overarching and cannot be manipulated as well. This picture might help you visualize better how the ...
by Simrah_Ahmed1J
Sun Nov 22, 2020 9:02 pm
Forum: Bond Lengths & Energies
Topic: Melting Point
Replies: 12
Views: 119

Re: Melting Point

For molecules, those with stronger intermolecular forces have a higher melting point. Ionicly bonded crystals will have very high melting points, then hydrogen bonded molecules, then dipole-dipole, then weak London Disperson forces.
by Simrah_Ahmed1J
Sun Nov 22, 2020 8:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: linear shape?
Replies: 5
Views: 26

Re: linear shape?

Since shapes are based on electron repulsion and trying to balance out the space between election clouds, you will usually be able to tell whether a bond is linear if on both sides of the bonds their are equivalent. Almost always this is in regards to having the same exact things on either side of t...
by Simrah_Ahmed1J
Sun Nov 22, 2020 8:31 pm
Forum: Hybridization
Topic: sigma and pi bonds in triple bonds
Replies: 2
Views: 22

Re: sigma and pi bonds in triple bonds

Its basically based on the way the orbitals/electron clouds interact/connect in order to create the bonds, side by side for the sigma bonds and different protruding areas for pi bonds.
I tried to draw it to explain how it looks in the picture attached.
by Simrah_Ahmed1J
Sun Nov 22, 2020 8:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook Problem 2E. 19
Replies: 3
Views: 27

Re: Textbook Problem 2E. 19

Actually in this problem part b you have to take Be as the central atom because you're not seeing the whole molecule written as C 2 H 6 Be, but it is written (CH 3 ) 2 Be, so you are taking CH 3 as methyl group not as separate Carbons and Hydrogens. So you put aside the usual rule that you choose th...
by Simrah_Ahmed1J
Sun Nov 22, 2020 8:07 pm
Forum: Sigma & Pi Bonds
Topic: Pi bonds and Sigma bonds
Replies: 3
Views: 22

Re: Pi bonds and Sigma bonds

Sigma and pi bonds basically define the way the atoms are bonded together and the shape of the electron clouds when they make bonds. Single bonds only have a sigma bond, double bonds contain 1 sigma and 1 pi bond, and a triple bond contains 1 sigma and 2 pi bonds. I tried to draw the bonds to explai...
by Simrah_Ahmed1J
Sun Nov 22, 2020 7:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: memorizing molecular shapes
Replies: 3
Views: 13

Re: memorizing molecular shapes

I believe do have to memorize at least the ones covered in lecture, good for you if you learn more than that, but I do think the ones in lecture have to be memorized.
by Simrah_Ahmed1J
Sun Nov 22, 2020 7:44 pm
Forum: Lewis Structures
Topic: Focus 2 Exercise 7
Replies: 3
Views: 40

Re: Focus 2 Exercise 7

Yeah, again its really just counting up the number of electrons total available for the molecule, then seeing how many arrangements you can make with different types of bonds. Try to make some resonance structure with completely different arrangements for problems like this like with different amoun...
by Simrah_Ahmed1J
Sat Nov 14, 2020 1:51 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Electron Distortion and Polarizing Power Periodic Trend
Replies: 2
Views: 31

Re: Electron Distortion and Polarizing Power Periodic Trend

Yes I think you have some the right idea, I'm just going to address your question about the polarizing power , for a very strong polarizing power you want a very strong positive charge right, so you want the a lot of strength(attraction) from the nucleus and you want as high of a positive charge you...
by Simrah_Ahmed1J
Sat Nov 14, 2020 1:23 am
Forum: Lewis Structures
Topic: 2.7
Replies: 1
Views: 40

Re: 2.7

Yeah you probably had the right idea, I think the question is worded weirdly because it's sounding like it's only asking for you to draw the most important Lewis structure but then it also asks for all the resonance structures, I think that might be what's confusing you. But yes, based on formal cha...
by Simrah_Ahmed1J
Sat Nov 14, 2020 12:50 am
Forum: Electronegativity
Topic: Textbook 2D problem #7
Replies: 3
Views: 24

Re: Textbook 2D problem #7

I believe you are right about the electronegativities, Ba is much more electronegative than Mg, but Mg and Ba are both metals (in the alkaline earth metal group) and O is a nonmetal, typically the bonds formed between metals and nonmetals are ionic bondswhere a cation and an anion are present, in th...
by Simrah_Ahmed1J
Thu Nov 12, 2020 5:07 pm
Forum: Ionic & Covalent Bonds
Topic: Textbook Problem 2.A.15
Replies: 2
Views: 17

Re: Textbook Problem 2.A.15

Yes, you have to look at the ions and see whether a positive charge (losing an electron) or a negative charge (gaining an electron) would be most 'advantageous' in acquiring a full orbital. But I see how it could be confusing for some elements because like, for example, in the case of Carbon, it is ...
by Simrah_Ahmed1J
Thu Nov 12, 2020 4:40 pm
Forum: Lewis Structures
Topic: Oxygen and Hydrogen
Replies: 1
Views: 23

Re: Oxygen and Hydrogen

I'm not sure if this answers your entire question, but when your dealing with an OH (hydroxide ion) it should be the O which bonds with the other parts of the molecule because H of course only has one electron which is being used to bond with the O.
by Simrah_Ahmed1J
Thu Nov 12, 2020 2:32 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Definition of valence electrons
Replies: 2
Views: 20

Re: Definition of valence electrons

Yup that's correct, by definition the valence electrons are the ones in the outermost shell or the highest energy level. And yeah in terms of d orbitals they usually have a full s orbital on a higher energy level. That's why most of the time transition metals (in their ground state) have 2 valence e...
by Simrah_Ahmed1J
Thu Nov 12, 2020 2:25 pm
Forum: Trends in The Periodic Table
Topic: Ionization energy of Copper?
Replies: 2
Views: 28

Re: Ionization energy of Copper?

I think you have to be careful to think of ionization energy in terms of the electron configuration and which electrons are in the furthest energy level, or the outermost electrons and therefore the first to be removed. Actually what makes it a bit confusing is that I believe Copper is actually an e...
by Simrah_Ahmed1J
Sun Nov 08, 2020 10:09 pm
Forum: Ionic & Covalent Bonds
Topic: Sapling Question #3
Replies: 6
Views: 64

Re: Sapling Question #3

basically the same thing, thats just their way of telling you that phosphorus is an exception to the octet rule and can take on more than 8 valence electrons, and because it can take on more than 8 valence electrons, it can take on more than 4 bonds.
by Simrah_Ahmed1J
Sun Nov 08, 2020 10:06 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Effective Nuclear Charge
Replies: 2
Views: 17

Re: Effective Nuclear Charge

Effective nuclear charge is reliant on the power of the positive protons in the nucleus having an electrostatic attraction to the negative nature electrons. As atoms get larger, there are multiple factors that reduce the effective nuclear charge on the outer electrons such as them becoming much furt...
by Simrah_Ahmed1J
Sun Nov 08, 2020 9:58 pm
Forum: Lewis Structures
Topic: Valence Shell electrons
Replies: 2
Views: 44

Re: Valence Shell electrons

I believe that no matter how many electrons are in an atoms d and f orbitals, that does not account for how many electrons are in the atoms valence shell, the outermost valence shell is always consisting of the s and p orbitals. So for example, zinc has only 2 valence electrons, because those are th...
by Simrah_Ahmed1J
Sun Nov 08, 2020 9:53 pm
Forum: Lewis Structures
Topic: Lewis acids and bases
Replies: 10
Views: 76

Re: Lewis acids and bases

You need to determine which compound is gaining more electrons than its atoms originally are supposed to have, that one is the lewis acid, the other one by default has less than its atoms originally had and is therefore the lewis base
by Simrah_Ahmed1J
Sun Nov 08, 2020 9:51 pm
Forum: Lewis Structures
Topic: nitrate lewis structure
Replies: 7
Views: 65

Re: nitrate lewis structure

I believe it is because that is to many bonds for nitrogen, 10 instead of 8. That energy level would technically be favorable but not possible based on nitrogen bonding abilities
by Simrah_Ahmed1J
Sun Nov 08, 2020 9:47 pm
Forum: Ionic & Covalent Bonds
Topic: Electron Affinity
Replies: 8
Views: 69

Re: Electron Affinity

To put it simply, it is basically how likely the atom are to "want" another electron (it wants to have full orbital or valence shell of electrons to have a lower overall energy). That's why atoms that are closer to a full outer orbital/shell have a higher electron affinity because they are...
by Simrah_Ahmed1J
Sun Nov 08, 2020 9:38 pm
Forum: Ionic & Covalent Bonds
Topic: Sapling Question #3
Replies: 6
Views: 64

Re: Sapling Question #3

Well the trick is that phosporus is a bonding exception and it can form 5 bonds rather than just 4.

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