## Search found 93 matches

Thu Jan 21, 2021 7:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: textbook 6.A.19
Replies: 4
Views: 12

### Re: textbook 6.A.19

Hi! So remember that [H3O+][OH-]=Kw. You are given hydronium concentrations. In order to find the concentration of hydroxide you divide 3.1 mol/L from your kw (1.00*10^-14). Your answer should be 3.2*10^-15 mol/L. I hope this helps!
Wed Jan 20, 2021 12:11 am
Forum: Ideal Gases
Topic: 5I.3
Replies: 4
Views: 22

### Re: 5I.3

Hi! I don't think you would need to use PV= nRT. You would look at the Table and find that your Kc is 160 and then input the concentrations of [HI] and [I2] in the equilibrium constant equation to solve for x which is [H2].
Tue Jan 19, 2021 8:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: given Kb
Replies: 3
Views: 17

### Re: given Kb

Ka is the equilibrium constant for acids and acids produce hydronium and remember pH is -log(H3O+). If you leave Kb then you would find the concentration of your hydroxide reactant and then convert to pOH and then subtract your pOH from 14 to find your pH. I believe just changing the kb to ka is jus...
Mon Jan 18, 2021 12:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6D13: calculating pH
Replies: 4
Views: 35

### Re: 6D13: calculating pH

Yes! You answered this question correctly! I think we need the ka values to solve for pH as when you use the ka we are finding the concentration of hydronium which is needed when calculating the pH (-log[H3O+]). I hope this helps!
Sat Jan 16, 2021 11:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Week 2 Sapling #5
Replies: 1
Views: 19

### Re: Week 2 Sapling #5

Hi! So number 5 is a little tricky as you are only given the pH and Kb but not the initial concentration. You start by first subtracting the pH from 14 to find your pOH then do 10^-pOH to get your concentration of OH-. Then you need to find your initial concentration of B so you know that your x is ...
Sat Jan 16, 2021 3:21 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6D.13 - Can I look up the Ka and Kb values needed?
Replies: 1
Views: 12

### Re: 6D.13 - Can I look up the Ka and Kb values needed?

You would need the ka and kb values to find the pH so what I did was I referred back to the tables in 6C and 6D. Sometimes you would be given the pKa or pKb but to get the ka you would just set the pka to 10^-pka. I hope this helps!
Sat Jan 16, 2021 3:19 pm
Forum: Calculating the pH of Salt Solutions
Topic: textbook 6d.13
Replies: 1
Views: 7

### Re: textbook 6d.13

They are getting the pH by either finding the pKa or the Ka from the tables in 6C or 6D. They then set there ice table and continue solving for x. If you like I can post my calculations if you want a visual of how to solve for x and find the pH.
Fri Jan 15, 2021 1:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When x is negligible in Equilibrium constant
Replies: 34
Views: 98

### Re: When x is negligible in Equilibrium constant

The equilibrium constant has to be smaller than 10^-3 in order for the x to be negligible. But try to double check by using the 5 percent rule!! Which is when your x has to be less than 5 percent of your initial concentration!!
Fri Jan 15, 2021 1:47 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook problem 5I.27c
Replies: 3
Views: 26

### Re: Textbook problem 5I.27c

You solved for the X but now you have to enter 0.07 to the E in your ice table.
[PCl3]: 6-0.071 = 5.929
[Cl2]: 1-0.071 = 0.929
[PCl5]: 3 + 0.071 = 3.071
Wed Jan 13, 2021 9:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibrium Part 3 Post-Module Assessment #20
Replies: 3
Views: 23

### Re: Chemical Equilibrium Part 3 Post-Module Assessment #20

Okay! I tried doing that, but I still got the incorrect concentration for SO3. I'm sorry for the late response bur your x in the end should equal to about 4.94*10^-6 so to find the concentration of SO3 you would multiply that by 2 since there are two moles of SO3 in the reaction. Your SO3 in the en...
Wed Jan 13, 2021 8:51 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: 6.A.21
Replies: 4
Views: 30

### Re: 6.A.21

You would use the Kw given in the problem because you only use neutral water's Kw when the temperature is at 25 degrees Celsius. To find the concentrations for hydronium and hydroxide you would take the square root of the given Kw.
Wed Jan 13, 2021 8:47 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Textbook problem 5J5 (d)
Replies: 2
Views: 24

### Re: Textbook problem 5J5 (d)

Hi! I think you read the question wrong because it says 2HD (g) ⇌ H2 (g) + D2(g). So there will be no change because there are two moles on the reactants and two moles on the products.
Wed Jan 13, 2021 10:40 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook Problem 5I.33
Replies: 3
Views: 13

### Re: Textbook Problem 5I.33

Hi! You would not use ammonium carbamate at all! And yes you would convert 17.4 mg of CO2 to moles of CO2 and then divide by liters to get your molarity. When making your ice table you should note that CO2 would be +x and NH3 would be +2x (2 because of the coefficient of NH3). So, because the Molari...
Sat Jan 09, 2021 2:50 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Focus 5.I.13
Replies: 1
Views: 23

### Re: Focus 5.I.13

For part b you replace Cl with F. Your reaction should be F2(g) 2F(g). The molarity for F2 is the same as the molarity for Cl2 (1*10^-3). You then set up your ice table: F2(g). 2F(g) I. 1*10^-3. 0 C. -x. +2x E (1*10^-3 -x). 2x Then set your equilibrium constant equation 1.2*10-4 (K) = (2x)^2/(1*10^-...
Sat Jan 09, 2021 2:41 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibrium Part 3 Post-Module Assessment #20
Replies: 3
Views: 23

### Re: Chemical Equilibrium Part 3 Post-Module Assessment #20

In the beginning of the module post-assessment they had a for SO2 b for O2 and c for SO3. These are not variables we have to solve. Just multiply two times your x value to find the concentration of SO3.
Sat Jan 09, 2021 2:32 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook question 5I.17
Replies: 2
Views: 7

### Re: Textbook question 5I.17

You know x is small because of the equilibrium constant. If the equilibrium constant is small (less than 10^-3) then the x must be very small. If we subtract a very small x then we will approximate the term to essentially stay the same. I hope this helps!!
Sat Jan 09, 2021 2:25 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: terminology
Replies: 11
Views: 44

### Re: terminology

Hi! A forward reaction is when the reactants are forming products and the reverse reaction is when products form reactants. For a reaction to "favor" or "lie" or "shift" towards products it means the products are the most stable and will proceed towards it (also known a...
Fri Jan 08, 2021 5:52 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 1 HW #4
Replies: 6
Views: 71

### Re: Sapling Week 1 HW #4

Pertaining to a comment above, how does one go about using the reverse reaction to solve. Have we learned that in lecture and when do you know that it is okay to do this? They gave an equilibrium constant so to do the reverse reaction you would solve 1/K. Then switch the reaction to the reverse: PC...
Thu Jan 07, 2021 11:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 1 HW #4
Replies: 6
Views: 71

### Re: Sapling Week 1 HW #4

Pertaining to a comment above, how does one go about using the reverse reaction to solve. Have we learned that in lecture and when do you know that it is okay to do this? They gave an equilibrium constant so to do the reverse reaction you would solve 1/K. Then switch the reaction to the reverse: PC...
Wed Jan 06, 2021 11:44 pm
Forum: Administrative Questions and Class Announcements
Topic: Sapling Assignments
Replies: 26
Views: 133

### Re: Sapling Assignments

I believe those assignments are optional just focus on the weekly sapling assignments, he usually has the sapling assignment that is assigned for the week on ccle :)
Sun Dec 13, 2020 3:27 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 8
Views: 62

### Re: Ligands

A coordination compound can have multiple type of ligands so for example Myoglobin can have 4 NH3 and an oxygen and an amino acid (pyridine).
Sun Dec 13, 2020 12:01 am
Forum: Naming
Topic: Naming Coordination Number Textbook Problem
Replies: 3
Views: 24

### Re: Naming Coordination Number Textbook Problem

So Cl does not have a subscript of three because the sulfato has a charge of -2 and the chlorine has a charge of -1 making it have an overall charge of -3 but the oxidation state of Cobalt (+3) cancels the charges out. For part c NH3 does not have a charge and neither does water so the bromine has t...
Sat Dec 12, 2020 3:03 pm
Forum: Conjugate Acids & Bases
Topic: sapling question 14
Replies: 7
Views: 55

### Re: sapling question 14

If the pH is lower than the pka then it will be neutral, this is because the solution is more acidic than the actual acidity of the weak acid. Therefore, the acid will protonate and keep its proton. If the pH is bigger than the pKa, the solution is more basic so the weak acid will deprotonate and g...
Sat Dec 12, 2020 2:56 pm
Forum: Trends in The Periodic Table
Topic: How to Determine Polarity
Replies: 3
Views: 23

### Re: How to Determine Polarity

A bond is polar if there is an unequal share of electrons, causing a dipole moment. Just look at which element is more electronegative and you can infer that one end will have a partial positive charge and the other end will have partial negative charge! Attached below is an example! I hope this hel...
Sat Dec 12, 2020 2:53 pm
Forum: Hybridization
Topic: Lone Pairs & Hybridization
Replies: 6
Views: 42

### Re: Lone Pairs & Hybridization

Yes lone pairs do affect hybridization. For example if your Oxygen has three lone pairs and one bonding pair then your hybridization would be sp3. Attached below are more examples! I hope this helps and good luck studying!!
Sat Dec 12, 2020 2:47 pm
Forum: Conjugate Acids & Bases
Topic: sapling question 14
Replies: 7
Views: 55

### Re: sapling question 14

If the pH is lower than the pka then it will be neutral, this is because the solution is more acidic than the actual acidity of the weak acid. Therefore, the acid will protonate and keep its proton. If the pH is bigger than the pKa, the solution is more basic so the weak acid will deprotonate and gi...
Fri Dec 11, 2020 10:36 am
Forum: Bond Lengths & Energies
Topic: Difference between bond multiplicity and bond order
Replies: 2
Views: 27

### Re: Difference between bond multiplicity and bond order

Hi! So the strength of a bond can be measured by its dissociation energy so the stronger the bond the greater the dissociation energy. Also bond strength increases as multiplicity increases, which is single, double, and tripe bonds. A triple is stronger than a double which is stronger than a single....
Wed Dec 09, 2020 9:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle Question
Replies: 2
Views: 18

### Re: Bond Angle Question

Hi! So bond angles vary so although AX3E has four regions of electron density, and has an electron arrangement of tetrahedral it's molecular shape is trigonal pyramidal so the bond angles would not be 109.5 (bond angle for tetrahedral) because the lone pair has higher repulsion and pushes the bonded...
Mon Dec 07, 2020 12:32 am
Forum: Naming
Topic: coordination compounds with aqua
Replies: 12
Views: 62

### Re: coordination compounds with aqua

Either is correct but I believe OH2 is preferred as the Oxygen is the atom bonding with the central metal atom.
Sun Dec 06, 2020 11:34 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 4
Views: 36

### Re: Coordination Number

The coordination number would be 4 because the en is bidentate and can form two bonds and the two chlorines form two bonds so you will have a total of 4 bonds, giving you a coordination number of 4.
Sun Dec 06, 2020 9:35 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Finding Coordination Number
Replies: 7
Views: 16

### Re: Finding Coordination Number

The coordination number would be 6 because you have 5 ammine ligands and 1 sulfato ligand bonded to the central metal atom.
Sun Dec 06, 2020 8:46 pm
Forum: Naming
Topic: Homework Problem 9C.1
Replies: 4
Views: 32

### Re: Homework Problem 9C.1

Cyano and cyanido are the same thing. Cyanido is the New IUPAC Name convention but either one is correct :)
Sun Dec 06, 2020 8:06 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Identifying Ligands
Replies: 3
Views: 16

### Re: Identifying Ligands

Ligands are inside the brackets/coordination sphere. For example, in [AlCl4]-, the ligands are the chlorines so there would be four ligands bonded to the central atom and as a result your coordination number would be 4. A great way to identify these ligands is by memorizing the sheet Lavelle has on ...
Sun Dec 06, 2020 3:29 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number Question
Replies: 12
Views: 119

### Re: Coordination Number Question

You can determine the coordination number by counting the number of bonds connected to the metal central atom (the ligands inside the brackets). In this case the coordination number of this molecule would be 6 because there are four ammine ligands and 2 Bromines in the brackets which means the ligan...
Sun Dec 06, 2020 3:22 am
Forum: Naming
Topic: [Co(NH3) 3Cl3]
Replies: 2
Views: 31

### Re: [Co(NH3) 3Cl3]

The charge for Cobalt is +3 because there are three chlorines which all have a -1 charge and the three NH3 do not have a charge. Therefore, to balance the charge you would need Cobalt to have a +3 charge. I hope this helps!
Fri Dec 04, 2020 7:50 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 3
Views: 14

### Re: Coordination Number

To determine the coordination number of a coordinate compound you count the bonds connected to the central atom. For example the coordination number in [Fe(CN)6] is 6 as there are 6 ligands connected to the central transition metal atom. I hope this helps! Thank you, this makes a lot of sense! For ...
Fri Dec 04, 2020 7:43 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate Ligands
Replies: 3
Views: 28

### Re: Polydentate Ligands

You can tell if a ligand is polydentate if it has 2 or more binding sites. A great example of this is ethylenediamine which has two binding sites at the Nitrogens, it is considered to be bidentate! Another example is diethylenetriamine which has three binding sites as the molecule has three nitrogen...
Fri Dec 04, 2020 7:34 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 3
Views: 14

### Re: Coordination Number

To determine the coordination number of a coordinate compound you count the bonds connected to the central atom. For example the coordination number in [Fe(CN)6] is 6 as there are 6 ligands connected to the central transition metal atom. I hope this helps!
Thu Dec 03, 2020 9:49 pm
Forum: Lewis Acids & Bases
Topic: 6 strong acids
Replies: 4
Views: 48

### Re: 6 strong acids

I don't think he mentioned all of the strong acids yet but there a total of 7 strong acids:
Hydrochloric acid (HCl), Hydrobromic acid (HBr), Hydroiodic acid (HI), Perchloric acid (HClO4), Nitric acid (HNO3), Periodic acid (HIO4), Sulfuric Acid (H2SO4), Chloric Acid (HClO3)
Thu Dec 03, 2020 4:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook Problem 2E.1
Replies: 2
Views: 17

### Re: Textbook Problem 2E.1

Hi! So a molecule can be linear and have lone pairs. A great example is I3- it has five domains of electron density, 2 bond pairs, 3 lone pairs, and has a linear shape (180 degrees bond angles). I hope this helps!!
Thu Dec 03, 2020 4:37 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Acid strength and bond length
Replies: 11
Views: 87

### Re: Acid strength and bond length

Hi! So the longer the bond (weaker bonds) = stronger acids. For a strong acid you want the bond to break easily so it can easily give off its proton. And in HBr the Bromine is much bigger than the chlorine in HCl therefore the bond would be longer (weaker bond) and is a much stronger acid than HCl. ...
Sun Nov 29, 2020 3:57 am
Forum: Lewis Structures
Topic: Tips on drawing Lewis structures
Replies: 20
Views: 142

### Re: Tips on drawing Lewis structures

Hi! So I like to calculate how many valence electrons I should have and then count the electrons again to make sure that I have drawn the lewis structure correctly. Also calculate the formal charges and remember you want the most stable/less charged structure. However, if you do have a charge like l...
Sun Nov 29, 2020 3:04 am
Forum: Determining Molecular Shape (VSEPR)
Topic: sapling #12
Replies: 13
Views: 88

### Re: sapling #12

Hi! So remember that Carbon has four valence electrons and since it is not in the third period it cannot form an expanded octet, it will form four bonds. Therefore, you would have three hydrogens bonded to it and then bond oxygen and bond that oxygen with hydrogen, forming a hydroxyl group. I hope t...
Sun Nov 29, 2020 2:58 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: isoelectronic
Replies: 12
Views: 82

### Re: isoelectronic

Isoelectronic is when atoms and ions have the same number of electrons. However, this does not imply they have the same chemical or physical properties because they have different nuclear charges. I hope this helps!!
Sat Nov 28, 2020 5:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape vs Polarity
Replies: 11
Views: 72

### Re: Shape vs Polarity

You determine the shape by the atoms bonded and not lone pairs. However if you have 4 regions of electron density and three atoms bonded and 1 lone pairs the shape would not be trigonal planar but it would be trigonal pyramidal. I would suggest memorizing AXnEn because the VSEPR formula determines t...
Fri Nov 27, 2020 4:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape Sheet
Replies: 7
Views: 81

### Re: Shape Sheet

Hi! This worksheet is pretty helpful!
https://www.angelo.edu/faculty/kboudrea ... _VSEPR.pdf
Wed Nov 25, 2020 1:24 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Reason why lone pairs decrease bond angle
Replies: 7
Views: 45

### Re: Reason why lone pairs decrease bond angle

Hi! So lone pairs have the greatest repulsion and they occupy a larger volume so they will push the bonding pairs down and slightly distort the bond angles by forcing the bond pairs together slightly. I hope this helps!!
Thu Nov 19, 2020 10:36 pm
Forum: Bond Lengths & Energies
Topic: 2D #13a
Replies: 3
Views: 35

### Re: 2D #13a

Hi! So bond strength increases as the multiplicity of a bond increases. In CO you have a triple bond, CO2 you have a double bond and CO32- you have a mixture of double and single bonds. Single Bonds has weaker bond strength/longer bonds than double which is also less than triple bonds. The question ...
Thu Nov 19, 2020 10:24 pm
Forum: Bond Lengths & Energies
Topic: Textbook Question 3F.15
Replies: 8
Views: 97

### Re: Textbook Question 3F.15

AsF3 would have a higher boiling point than AsF5 because it is a polar molecule that has Dipole-Dipole and LDF. AsF5 only experiences LDF because all of the Fluorines are pulling it equally. Could you please walk me through how you realized that AsF5 is a polar molecule? Hey! Sorry AsF3 is the pola...
Thu Nov 19, 2020 10:11 pm
Forum: Electronegativity
Topic: Textbook problem 2d.5
Replies: 3
Views: 36

### Re: Textbook problem 2d.5

C and F would be more ionic because Fluorine is the most electronegative element by a lot. Fluorine has an electronegative value of 4 and Carbon has an electronegative value of 2.5 and Hydrogen has an electronegative value of 2.1. So HF would be more ionic because it has a greater electronegative di...
Thu Nov 19, 2020 4:09 pm
Forum: Dipole Moments
Topic: Textbook Question 3F.3
Replies: 2
Views: 42

### Re: Textbook Question 3F.3

The last one does not have dipole-dipole interactions because all of the Chlorines are pulling the Carbon equally. If you compare CCl4 to CHCl3, there is a hydrogen present that is making it dipole-dipole because there is not an equal pull as the chlorine atoms will pull the electrons to itself more...
Thu Nov 19, 2020 4:03 pm
Forum: Bond Lengths & Energies
Topic: Textbook Question 3F.15
Replies: 8
Views: 97

### Re: Textbook Question 3F.15

AsF3 would have a higher boiling point than AsF5 because it is a polar molecule that has Dipole-Dipole and LDF. AsF5 only experiences LDF because all of the Fluorines are pulling it equally.
Thu Nov 19, 2020 3:33 pm
Forum: Lewis Structures
Topic: Expanded Valence
Replies: 11
Views: 60

### Re: Expanded Valence

Expanded octets can only happen on elements in period 3 and up so if you the central atom of the lewis structure you are drawing is in period 3 or period 4, etc then it could have an expanded octet! I hope this helps :)
Sun Nov 15, 2020 9:13 pm
Forum: Lewis Structures
Topic: Bonding with Atoms in the D State
Replies: 4
Views: 13

### Re: Bonding with Atoms in the D State

Hi! Yes you are allowed to draw the lone pairs on the central atom. SO2 has 18 electrons and has no charge. Therefore, the Oxygens will develop a double bond with the Sulfur and have two lone pairs on it (because it needs to form an octet). You would then have two electrons left over so you will put...
Sun Nov 15, 2020 9:05 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: How do you determine whether something is polar or non-polar?
Replies: 3
Views: 14

### Re: How do you determine whether something is polar or non-polar?

Hi! I believe you can look at the symmetry (if there is an unequal pull then it is polar). Also, if a molecule has lone pairs it is usually polar. For example, AsF5 is non-polar as the fluorines are pulling on the Arsenic equally. However, AsF3 is polar because there is a lone pair on Arsenic. I hop...
Sat Nov 14, 2020 5:16 pm
Forum: Administrative Questions and Class Announcements
Topic: Solutions Manual
Replies: 1
Views: 17

### Re: Solutions Manual

If you go on sampling they have solutions to the textbook problems. Attached below is a pdf to the solutions in case you can't find it!
Sat Nov 14, 2020 5:15 pm
Forum: Octet Exceptions
Topic: Expanded Octets
Replies: 5
Views: 31

### Re: Expanded Octets

Expanded octets can happen for atoms in period 3 and below. This happens when you have a full octet on the atoms in the lewis dot structure but still have left over electrons. For example, BrF3 has an expanded octet. The fluorines have a complete octet and so does bromine but there are still left ov...
Sat Nov 14, 2020 1:43 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Order of Intermolecular Forces
Replies: 5
Views: 54

### Re: Order of Intermolecular Forces

Hi! So the order from weakest to strongest intermolecular forces are as follows: London Dispersion Forces < Dipole-Dipole < Hydrogen Bonding < Ion-Dipole The difference between dipole-dipole and dipole-induced dipole is dipole-dipole is present with polar molecules verses dipole-induced dipole (or L...
Sat Nov 14, 2020 1:35 am
Forum: Electronegativity
Topic: Periodic Table Trend
Replies: 37
Views: 387

### Re: Periodic Table Trend

The trend for electronegativity and ionization energy generally decreases down a group and increases across the periodic table from left to right. Ionization energy is the minimum energy needed to remove an electron and as you go down a group the shells increase so the electrons are further from the...
Sat Nov 14, 2020 1:20 am
Forum: Ionic & Covalent Bonds
Topic: London Dispersion Forces
Replies: 11
Views: 74

### Re: London Dispersion Forces

Hi! London Dispersion forces are the weakest intermolecular force. LDF is pretty much anything that interacts with each other. So hydrogen bonding has LDF, Dipole-Dipole has LDF. However, London dispersion forces are mainly in non-polar molecules. So for example, all hydrocarbons are only LDF becaus...
Sun Nov 08, 2020 1:05 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence Electrons vs. Outer Electrons
Replies: 4
Views: 35

### Re: Valence Electrons vs. Outer Electrons

Hi! So the inner or core electrons are the electrons from the previous noble gas in your electron configuration. Your outer electrons are your electrons in the highest energy level so you would look at the largest coefficient in your electron configuration. Lastly your valence electrons is the last ...
Sat Nov 07, 2020 2:42 am
Forum: Electronegativity
Topic: Periodic Trends
Replies: 9
Views: 40

### Re: Periodic Trends

Hi! So for the atomic radius a good way to remember the trend is thinking of a snowman. So the snowman get bigger as you go down and then imagine the snowman falling to the right. However, you should still be aware of the actual reason why the atomic radius increases going down (because energy level...
Fri Nov 06, 2020 10:27 pm
Forum: Student Social/Study Group
Topic: Blind sided by Midterm 1 memorization questions, How to study for memorization questions
Replies: 11
Views: 117

### Re: Blind sided by Midterm 1 memorization questions, How to study for memorization questions

Hi! For the memorization questions, I made flashcards but also made a study guide from the notes I took from the textbook and lectures. This helped me focus on the conceptuals and prevented me from getting stressed from all the notes in my notebook. Also, if you know something will be tested on like...
Wed Nov 04, 2020 7:01 pm
Forum: Resonance Structures
Topic: Resonance structures
Replies: 3
Views: 47

### Re: Resonance structures

Hi! I believe so. Lavelle said that electrons involved in resonance structures are delocalized and the real structure of that compound will have equal length bonds. In other words the real structure is the average or blending of the structures. I hope this makes sense!
Wed Nov 04, 2020 12:37 am
Forum: Trends in The Periodic Table
Topic: Effective nuclear charge
Replies: 4
Views: 21

### Re: Effective nuclear charge

Hi! So because the valence electrons are being shielded by inner electrons, it reduces the effective nuclear charge. So let's say we have fluorine and are calculating the effective nuclear charge we would subtract the two inner electrons from the number of protons fluorine has. The effective nuclear...
Sat Oct 31, 2020 11:44 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals and Electrons
Replies: 9
Views: 40

### Re: Orbitals and Electrons

Hi! There can only be two electrons in each orbital because of the Pauli Exclusion Principle!
Tue Oct 27, 2020 4:53 pm
Forum: *Shrodinger Equation
Topic: Delta V value
Replies: 5
Views: 64

### Re: Delta V value

Hi! So the textbook answer is wrong and Lavelle clarifies this through his Solution Manual Sheet on his website! You were supposed to double in this problem! I hope this helps!!
Tue Oct 27, 2020 4:50 pm
Forum: Einstein Equation
Topic: Sapling HW #6
Replies: 4
Views: 84

### Re: Sapling HW #6

Hi! Because you are trying to find the maximum number of electrons that could be ejected you would divide 6.07*10^-7 by the answer you got in part a (4.32*10^-19). I hope this helps!!
Mon Oct 26, 2020 10:28 pm
Forum: Empirical & Molecular Formulas
Topic: Limiting Reactant Calculations Module #22
Replies: 2
Views: 40

### Re: Limiting Reactant Calculations Module #22

Hi! So first step would be to balance your reaction! So you would put a three in front of AgCl. You identified that C6H9Cl3 was the limiting reactant so then you would multiply 0.004 mol times the moles of AgCl in the reaction which is three and then multiply by AgCl's molar mass which is 143.32g/mo...
Mon Oct 26, 2020 9:24 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty of Position of Electron 1/100xspeed of light
Replies: 2
Views: 27

### Re: Uncertainty of Position of Electron 1/100xspeed of light

Hi! Your work is correct maybe you just messed up when calculating. I like to make sure Planck's constant is always in parenthesis so maybe try that (6.626*10^-34)/4pi=(5.2728*10^-53)/(2.73*10^-24)=2.0*10^-11m. I hope this helps!
Sun Oct 25, 2020 2:14 pm
Forum: DeBroglie Equation
Topic: Detecting wavelike properties
Replies: 5
Views: 29

### Re: Detecting wavelike properties

Hi! 10^-38 is to small any numbers less that 10^-15 will not be detected :)
Sun Oct 25, 2020 2:37 am
Forum: *Shrodinger Equation
Topic: Schrodinger's Wave Function and Equation
Replies: 2
Views: 36

### Re: Schrodinger's Wave Function and Equation

Hi! I don't think we are expected to use the equation to make the calculations of the wave function and energy. However, in Saturday's workshop with Justin he stated that we should know the conceptual aspects of Schrodinger's wave function and how squaring the wave function represents the probabilit...
Sun Oct 25, 2020 1:04 am
Forum: Properties of Electrons
Topic: Experiments/conceptuals we need to know
Replies: 4
Views: 45

### Re: Experiments/conceptuals we need to know

Hi! The modules have a lot of conceptual problems that I think could be helpful to study! Also reviewing worksheets you have completed with the the UA's can help :)
Fri Oct 23, 2020 9:23 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: n1 and n2 in Rydberg Equation
Replies: 4
Views: 55

### Re: n1 and n2 in Rydberg Equation

Hi! Lavelle has a Solution manual error sheet on his website where he clarifies that it should be from n=3 to n=1 as energy is being emitted!
Fri Oct 23, 2020 6:24 pm
Forum: Properties of Light
Topic: Wavelength
Replies: 14
Views: 91

### Re: Wavelength

Hi! I believe it depends on what the question is asking. It will sometimes tell you to solve the wavelength (nm) so you would convert meters to nanometers at the end. For the midterm I would suggest looking at your answer options and seeing if it is in nm or meters then converting if needed! I hope ...
Fri Oct 16, 2020 2:31 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Module Question 18
Replies: 1
Views: 14

### Re: Module Question 18

Hi! For this problem I first multiplied 0.05 nm by 0.01 and then converted it to meters to get 5*10^-13. Then used the Heisenberg's Indeterminacy Equation: delta p times delta x = h/4pi. We know that P is mass times velocity so we have (9.11*10^-31kg * delta v)(5*10^-13)=h/4pi. You then divide the d...
Fri Oct 16, 2020 1:28 am
Forum: Photoelectric Effect
Topic: Workshop Problem
Replies: 5
Views: 29

### Re: Workshop Problem

Hi! So the energy of the incident light is equal to the sum of the kinetic energy and work function. The work function is given to you (9.83*10^-19J). So you solve for the kinetic energy which is 1/2mv^2. After plugging in your velocity into that equation you should add that plus the work function t...
Fri Oct 16, 2020 1:18 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Bohr Frequency Condition
Replies: 2
Views: 16

### Re: Bohr Frequency Condition

The Bohr Frequency Condition is if the frequency of the incoming light matches the energy difference between 2 electronic energy levels, then you will have absorption. Neils Bohr was discussing this in respect to Hydrogen. The Bohr Frequency only works for Hydrogen. I hope this helps :)
Thu Oct 15, 2020 10:32 pm
Forum: Photoelectric Effect
Topic: Mass of an object
Replies: 5
Views: 65

### Re: Mass of an object

Hi! So when having to do conversions I believe you have to have memorized the common SI prefixes. An example could be having to go from meter to nanometers, in every 1 nm there is 10^-9 m so that would be your conversion. I hope this helps!!
Thu Oct 15, 2020 10:26 pm
Forum: DeBroglie Equation
Topic: Wavelike Properties
Replies: 4
Views: 62

### Re: Wavelike Properties

In one of his video modules, Lavelle mentioned that all matter has particle and wavelike properties but only noticed for objects (like electrons) with small masses and high velocity! I hope this helps :)
Tue Oct 13, 2020 3:31 am
Forum: Limiting Reactant Calculations
Topic: Difference between limiting reactant and limiting reagent?
Replies: 14
Views: 109

### Re: Difference between limiting reactant and limiting reagent?

They are the same thing :)
Mon Oct 12, 2020 3:09 pm
Forum: Properties of Light
Topic: Lecture 5 "Quantized"
Replies: 3
Views: 35

### Re: Lecture 5 "Quantized"

I believe when he says "quantized" it means that they have to have certain values like n=1, n=2, n=3, etc. There is no in between. He also mentioned that when there is conditions it is quantized meaning there is discrete variables it is not continuous like in classical mechanics. I hope th...
Sat Oct 10, 2020 10:30 pm
Forum: Empirical & Molecular Formulas
Topic: F3 Part A (Textbook)
Replies: 6
Views: 47

### Re: F3 Part A (Textbook)

Nitric Acid is a strong acid ( I don't know if he expects us to memorize it) but I know in AP Chem we had to memorize the 8 strong acids.
Sat Oct 10, 2020 10:27 pm
Forum: Molarity, Solutions, Dilutions
Topic: Fundamentals HW G.5
Replies: 2
Views: 26

### Re: Fundamentals HW G.5

Hey! So we are given the mass of Na2CO3 so we divide it by 105.991g to get the number of moles which should total to 0.02 and then we are given the volume which is 240mL but to find the molarity we need to convert mL to L so we divide it by 1000 to get Liters (0.25L). To calculate molarity you divid...
Tue Oct 06, 2020 9:08 pm
Forum: Limiting Reactant Calculations
Topic: maximum amount of products
Replies: 4
Views: 35

### Re: maximum amount of products

In the previous questions you determined that A is the limiting reactant, so to determine the amount of product that can be produced you focus on what A can produce. You do dimensional analysis and divide 2 mol of A from 3 mol C and should get 1.5 mol C as product. Let me know if you would like me t...
Tue Oct 06, 2020 8:58 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Moles produced
Replies: 3
Views: 41

### Re: Moles produced

Hi! So you are trying to find how many moles of CO2 are produced when 1Kg of CaCO3 is used so you start first by converting Kg to g. To do this you multiply 1kg by 1000. Then you find the number of moles by dividing 100.086g of CaCO3 from 1000g and you should get a total of 9.991 mol of CaCO3. Then ...
Tue Oct 06, 2020 8:47 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Fundamentals Review problems question
Replies: 5
Views: 38

### Re: Fundamentals Review problems question

Hi! You are correct the formula for magnesium sulfate is MgS04 and then heptahydrate would be 7H20. Hepta means 7 and hydrate refers to water (H20).
Tue Oct 06, 2020 8:11 pm
Forum: Empirical & Molecular Formulas
Topic: Sapling Question #9 find mass of carbon
Replies: 3
Views: 61

### Re: Sapling Question #9 find mass of carbon

Hi! So you are trying to determine the mass of C in CO2 so you would divide 44.009g CO2 from 2.275g CO2 and then you would determine that in 1 mole of CO2 there is only 1 mol of Carbon and in 1 mole of Carbon there is 12.011g. You should get a total of about 0.62089g C. You would repeat this process...
Tue Oct 06, 2020 8:02 pm
Forum: Limiting Reactant Calculations
Topic: Sapling Question #10
Replies: 9
Views: 132

### Re: Sapling Question #10

Hi! So you are correct!! In order to find the mass of 2-butanone you must multiply the density by 0.40mL and then to find the moles you must divide it by 72.1g. Because 2-butanone is your limiting reactant the number of moles for 3-methyl-3-hexanol will be the same number of moles you got for 2-buta...
Mon Oct 05, 2020 12:05 pm
Forum: Balancing Chemical Reactions
Topic: L.35
Replies: 9
Views: 113

### Re: L.35

Hi! There was a typo for this problem. It should have been typed Fe3Br8 + 4Na2CO3 --> 8NaBr+ 4CO2 + Fe3O4.
Mon Oct 05, 2020 11:20 am
Forum: Molarity, Solutions, Dilutions
Topic: Serial Dilutions
Replies: 4
Views: 69

### Re: Serial Dilutions

The number of moles would stay the same because of the Law conservation of Mass only the molarity and volume could be changed.
Sun Oct 04, 2020 10:43 pm
Forum: Limiting Reactant Calculations
Topic: Week 1 Sapling HW Chem 14A Problem 10
Replies: 10
Views: 198

### Re: Week 1 Sapling HW Chem 14A Problem 10

I don't think we're expected to know the molar mass of 2-butanone or 3-methyl-3-hexanol so I simply found the molar mass from the internet. As for molar ratios a good way to think of it is the product is determined from the limiting reactant so in this case because 6.18*10^-3 mol of 2-butanone was p...
Sun Oct 04, 2020 9:58 pm
Forum: Limiting Reactant Calculations
Topic: Week 1 Sapling HW Chem 14A Problem 10
Replies: 10
Views: 198

### Re: Week 1 Sapling HW Chem 14A Problem 10

Hi I thought the same way as you did! The first step would be to convert the given density for 2 butanone into grams so you would multiply the density (0.81 g/ml) by the given volume (0.55mL) to get 0.445g of 2 butanone. Then you would find the moles so divide 72.1g (the molar mass of butanone) from...