## Search found 84 matches

- Thu Feb 18, 2021 4:24 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Textbook problem 4J7
- Replies:
**1** - Views:
**9**

### Textbook problem 4J7

Why is O2 gas included only in the calculation of entropy and not in those of enthalpy and Gibb's free energy?

- Wed Feb 17, 2021 4:51 pm
- Forum: Phase Changes & Related Calculations
- Topic: Textbook Problem 4B11
- Replies:
**2** - Views:
**10**

### Re: Textbook Problem 4B11

Just realized this wasn't even an assigned problem haha so nvm

- Wed Feb 17, 2021 4:37 pm
- Forum: Phase Changes & Related Calculations
- Topic: Textbook Problem 4B11
- Replies:
**2** - Views:
**10**

### Textbook Problem 4B11

I understand that during melting heat (+q) is absorbed and during condensation heat is released (-q), but how do we obtain positive/negative w values for these processes?

- Wed Feb 17, 2021 3:43 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Typo in answer key (4A.13)
- Replies:
**1** - Views:
**5**

### Re: Typo in answer key (4A.13)

Also I think a negative sign is omitted from the q value when it should be included.

- Wed Feb 17, 2021 3:42 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Typo in answer key (4A.13)
- Replies:
**1** - Views:
**5**

### Typo in answer key (4A.13)

I think there is a typo for this problem in the answer key that is not addressed in the Solution Manual Error Sheet. I believe the problem gives temperature in Celsius and the answer key puts these numbers in Kelvins without converting them. Let me know if you agree!

- Thu Feb 11, 2021 6:38 pm
- Forum: Phase Changes & Related Calculations
- Topic: Sapling Week 3/4 #9
- Replies:
**5** - Views:
**45**

### Sapling Week 3/4 #9

Struggling with this question. Is the entropy of the surroundings not just -139/298K? I keep getting the answer wrong.

- Thu Feb 11, 2021 5:38 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Sapling Week 3/4 #7
- Replies:
**1** - Views:
**13**

### Sapling Week 3/4 #7

How do you start by calculating delta H in this problem? We have been given so many equations and this problem is really overwhelming and I don't even know where to start.

- Sun Feb 07, 2021 11:44 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies:
**8753** - Views:
**1489580**

### Re: Post All Chemistry Jokes Here

Not my joke but vibes https://www.tiktok.com/@missalexbackgirl/video/6903968365593758982?_d=secCgYIASAHKAESMgow2VshK14H%2B8f2%2BXoK7byF6pp%2BFT0meOdlJC4AaLuFKS6Bem4UsorCk%2FEL7cjT613%2FGgA%3D&language=en&preview_pb=0&sec_user_id=MS4wLjABAAAA5mpJYMXAjlkmjPD8s_C7JED_IX-e8QsVkomWyPoqD_IZCka...

- Thu Jan 28, 2021 5:54 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Polyprotic acids and bases
- Replies:
**2** - Views:
**11**

### Polyprotic acids and bases

Will we need to know polyprotic acids and bases for the midterm tomorrow? I don't remember really going over them in lecture or talking about Ka1 and Ka2.

- Thu Jan 28, 2021 5:37 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook 6D15/17
- Replies:
**1** - Views:
**26**

### Textbook 6D15/17

For these problems, the given chemicals are different from those in the equilibrium equation. i.e. 16 (b) gives AlCl3 and the equation uses Al(H2O)6^3+ and 17 (a) gives NaCH3CO2 and the equation uses CH3CO2-

How do we know what parts to include?

How do we know what parts to include?

- Thu Jan 28, 2021 3:02 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Assuming x is negligible
- Replies:
**1** - Views:
**17**

### Assuming x is negligible

Textbook problem 6D5 for reference

How do we know when we can approximate that x is a negligible amount in the denominator? I.e. x^2/(0.057 - x) = x^2/0.057.

How do we know when we can approximate that x is a negligible amount in the denominator? I.e. x^2/(0.057 - x) = x^2/0.057.

- Thu Jan 28, 2021 2:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook 6D3 (a)
- Replies:
**2** - Views:
**14**

### Textbook 6D3 (a)

The denominator of the Ka in this problem is (0.10 - 0.06). Why is it this instead of just 0.10 because the question states that the concentration of HClO2 is 0.10?

- Thu Jan 28, 2021 12:44 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook 6A21
- Replies:
**2** - Views:
**12**

### Textbook 6A21

This problem asks to find the OH and H3O concentrations for water at body temperature. Do we assume that water is completely neutral?

- Thu Jan 28, 2021 12:13 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook 6A19 (c)
- Replies:
**1** - Views:
**18**

### Textbook 6A19 (c)

This problem asks to find the OH- concentration based off of a H3O+ concentration of 3.1 mol/L. Why does the answer key convert 3.1 mol/L to 3.1 x 10^-3? It wasn't in mmol/L or anything so I'm confused.

- Wed Jan 27, 2021 4:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook 5J5 (d)
- Replies:
**2** - Views:
**10**

### Textbook 5J5 (d)

2HD(g) + H2(g) -> D2(g)

Why is there no change in the shift of this reaction after an increase in pressure if there are more mols of gas on the left side than the right?

Why is there no change in the shift of this reaction after an increase in pressure if there are more mols of gas on the left side than the right?

- Wed Jan 27, 2021 2:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook 5I23
- Replies:
**1** - Views:
**11**

### Textbook 5I23

This question states that 2.00 mol of CO2 and 3.00 mols of H2 were placed in a 10.0 L reaction vessel. Why does the answer key keep the initial values at 2 and 3 mols? Wouldn't it be 2/10 = 2.0 m/L and 3/10 = 3.0 m/L?

- Sat Jan 23, 2021 5:32 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong vs. weak acids and bases
- Replies:
**3** - Views:
**26**

### Strong vs. weak acids and bases

Will we just have to memorize which acids and bases are strong vs. weak for midterms/final or is there an easier way to identify them?

- Sat Jan 23, 2021 5:29 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Studying for Midterm #1
- Replies:
**63** - Views:
**181**

### Re: Studying for Midterm #1

Do the problems listed on the syllabus!!!! They are much more like midterm questions than the Sapling homework. Literally just do them all in a row its great practice if you don't know how to do some things and great review for the stuff you already know how to do!!

- Sat Jan 23, 2021 5:27 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling week 2 #9 and 10
- Replies:
**3** - Views:
**25**

### Sapling week 2 #9 and 10

I am confused about the rules for determining whether a predominate species is charged or neutral. Can someone explain this?

- Sat Jan 23, 2021 4:35 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling week 2 #6
- Replies:
**2** - Views:
**17**

### Sapling week 2 #6

I really have no idea where to even start with this problem, could someone explain how to sort these? Salts are very confusing for me.

- Sat Jan 23, 2021 4:08 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 2 #5
- Replies:
**1** - Views:
**17**

### Sapling Week 2 #5

Do you calculate percent protonated the same way that you would calculate percent ionized with pKa?

- Sun Jan 17, 2021 12:00 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 1 Question 5
- Replies:
**5** - Views:
**34**

### Re: Sapling Week 1 Question 5

Basically you want to create the equation that you're trying to find K for out of the other equations that have known K constants. If you attempt the question it the hint will give you some of the rules of how you need to change the K constants arithmetically. 2NH3(g)+3I2(g)↽−−⇀N2(g)+6HI(g) (equatio...

- Sun Jan 17, 2021 11:49 am
- Forum: Ideal Gases
- Topic: Gas for equilibrium equation
- Replies:
**8** - Views:
**38**

### Re: Gas for equilibrium equation

P indicates that we are using partial pressures to calculate an equilibrium constant instead of concentration.

- Sun Jan 17, 2021 11:47 am
- Forum: Ideal Gases
- Topic: Sampling hw #4
- Replies:
**16** - Views:
**176**

### Re: Sampling hw #4

I solved it with an ICE box the same way you would solve a Kc problem. PCl3 Cl2 PCl5 I 0 0 0.0400 C +x +x -x E +x +x 0.0400 - x Then plug this into Kp and set it equal to 325. Solve for x then add together the final pressures.

- Sat Jan 16, 2021 4:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Week 1 Sapling #5
- Replies:
**2** - Views:
**52**

### Week 1 Sapling #5

This problem deals with combining different equations to match the equation you need and using the product of their respective equilibrium constants to find the Kc for the equation in question. I understand how to do the math for this problem, but I don't understand how this concept works. Can someo...

- Sat Jan 16, 2021 3:58 pm
- Forum: Ideal Gases
- Topic: Kc vs. Kp
- Replies:
**31** - Views:
**117**

### Kc vs. Kp

Do we solve for Kp in the same way that we solve for Kc? Do we need to convert between pressure and concentration if the equation is all gases?

- Sun Jan 10, 2021 7:46 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Q and K
- Replies:
**8** - Views:
**49**

### Q and K

How do we know when to use Q and when to use K?

- Sun Jan 10, 2021 7:44 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentrations
- Replies:
**9** - Views:
**26**

### Re: Concentrations

The concentrations of P and R should be given to you in the problem.

- Sun Jan 10, 2021 7:42 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Water
- Replies:
**28** - Views:
**133**

### Re: Water

Include it when it is in a gaseous state! Otherwise (when its a solid or liquid) don't include it :)

- Sun Jan 10, 2021 7:39 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Clarification of terminology
- Replies:
**15** - Views:
**126**

### Re: Clarification of terminology

Each of these phrases mean the same thing! However some textbooks/websites will also use the word "shift" in place of these and it means the same thing even though its a slightly misleading term, as Dr. Lavelle said in lecture.

- Sun Jan 10, 2021 7:34 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Homogeneous and Heterogeneous Equilibrium
- Replies:
**13** - Views:
**112**

### Re: Homogeneous and Heterogeneous Equilibrium

Yes you would look at the overall reaction! Even though solids and liquids are omitted from the K expression, they are still used to determine whether the reaction is homogenous or heterogenous.

- Sat Dec 12, 2020 6:01 pm
- Forum: Lewis Structures
- Topic: SO2 Lewis Structure
- Replies:
**3** - Views:
**25**

### SO2 Lewis Structure

I understand that having one oxygen with a single bond and one oxygen with a double bond results in the lowest formal charge, but why can't the sulfur atom just have an expanded octet so that it has one lone pair and has double bonds with both oxygens? Wouldn't that result in each atom having 0 form...

- Sat Dec 12, 2020 4:21 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Textbook problem 9C.9
- Replies:
**4** - Views:
**31**

### Re: Textbook problem 9C.9

Sorry the question asks what the coordination numbers are of the metal ions in the complexes!

- Sat Dec 12, 2020 4:21 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Textbook problem 9C.9
- Replies:
**4** - Views:
**31**

### Textbook problem 9C.9

I am just confused in general about this problem and don't really understand the answers. Any help is appreciated!

(a) [NiCl4]2−

(b) [Ag(NH3)2]+

(c) [PtCl2(en)2]2+

(d) [Cr(edta)]−

Answers:

a) 4

b) 2

c) 6

d) 6

(a) [NiCl4]2−

(b) [Ag(NH3)2]+

(c) [PtCl2(en)2]2+

(d) [Cr(edta)]−

Answers:

a) 4

b) 2

c) 6

d) 6

- Sat Dec 12, 2020 3:53 pm
- Forum: Naming
- Topic: Textbook problem 9C.3
- Replies:
**4** - Views:
**46**

### Textbook problem 9C.3

How do you determine the number of atoms that appear outside of the brackets? i.e. how would I know that there are 3 K atoms in problem a but only one chlorine atom in problem b? (a) potassium hexacyanidochromate(III) (b) pentaamminesulfatocobalt(III) chloride (c) tetraamminediaquacobalt(III) bromid...

- Sat Dec 12, 2020 3:23 pm
- Forum: Dipole Moments
- Topic: Hydrogen Bonding
- Replies:
**6** - Views:
**55**

### Hydrogen Bonding

How do you find the number of sites on a molecule that are capable of hydrogen bonding? I was looking at this question from the zoom review if it helps to understand the context. The DNA double helix structure was determined in 1953 and found to involve intermolecular H-bonding between DNA bases pre...

- Sat Dec 12, 2020 2:57 pm
- Forum: DeBroglie Equation
- Topic: Question from Zoom Review
- Replies:
**1** - Views:
**46**

### Question from Zoom Review

I was not able to catch prof's zoom review on Wednesday. Could someone explain why the answer to this question is e? Thanks! Which of the following experiments most directly supports de Broglie's hypothesis of the wave nature of matter? a. Alpha-particle scattering by a metal foil b. The photoelectr...

- Thu Dec 10, 2020 3:51 pm
- Forum: Bronsted Acids & Bases
- Topic: Textbook problem J.17
- Replies:
**3** - Views:
**31**

### Textbook problem J.17

Are we expected to know how to predict products of a chemical reaction? This question gives the chemical formulas of certain salts and says they are combined with water and asks to write the equations of the proton transfer. I don't even know where to start with it.

- Thu Dec 10, 2020 2:05 pm
- Forum: Naming
- Topic: Textbook Question 9C.1
- Replies:
**1** - Views:
**22**

### Textbook Question 9C.1

I am so confused as to how the book explains finding the oxidation number of metals in complex ions. The book explains it through this equation: (# metal atoms)(oxidation number of metal) + (# of ligands)(charge of each ligand) = charge of ion How do I use this? Or is there a more straightforward wa...

- Thu Dec 10, 2020 1:04 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Textbook Problem 2.E23 (part c)
- Replies:
**1** - Views:
**21**

### Textbook Problem 2.E23 (part c)

VSPER structure of IO2F2-

Why does the iodine have an extra lone pair when it already has an octet?

Why does the iodine have an extra lone pair when it already has an octet?

- Thu Dec 10, 2020 12:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Textbook Problem 2.E17 (part a)
- Replies:
**1** - Views:
**18**

### Textbook Problem 2.E17 (part a)

Why is it that O3 forms one single bond and one double bond with uneven lone pairs instead of having two double bonds to form a linear molecule?

- Wed Dec 09, 2020 6:05 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Seesaw vs. trigonal pyramidal
- Replies:
**22** - Views:
**161**

### Seesaw vs. trigonal pyramidal

Are seesaw and trigonal pyramidal the same shape? I am confused

- Wed Dec 09, 2020 5:57 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Textbook problem 2E.13
- Replies:
**1** - Views:
**7**

### Textbook problem 2E.13

Can someone explain part c of this problem? It asks for the VSEPR structure of IO3^-. Why is it trigonal pyramidal and where does the negative charge come from?

- Sun Dec 06, 2020 1:20 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ligand Types
- Replies:
**3** - Views:
**25**

### Ligand Types

I still don't really understand the whole mono/di/tri/poly dentate thing. What is the easiest way to identify types of ligands and determine which kind they are based on chemical formulas?

- Sun Dec 06, 2020 1:17 pm
- Forum: Naming
- Topic: Sapling Week 9 #5
- Replies:
**3** - Views:
**38**

### Sapling Week 9 #5

[Co(en)2(CO)2]Br

Are there any other abbreviations like (en) that we need to know/memorize the properties of for the final? I had no idea what this meant when first doing the problem and much less knew that it was a bidentate.

Are there any other abbreviations like (en) that we need to know/memorize the properties of for the final? I had no idea what this meant when first doing the problem and much less knew that it was a bidentate.

- Sun Dec 06, 2020 1:14 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Flashcards
- Replies:
**8** - Views:
**66**

### Re: Flashcards

Flashcards are always a good resource for memorizing stuff. I also find it really helpful to just do a bunch of naming problems in one sitting to help me get in the groove of naming compounds. Once I do enough problems its much easier to associate the different prefixes and ligand names and stuff to...

- Sun Dec 06, 2020 1:11 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Writing name for coordination compound
- Replies:
**3** - Views:
**51**

### Re: Writing name for coordination compound

Yes, the potassium in the beginning means it is outside the coordination sphere! It would be written outside of the brackets in the formula.

- Sun Dec 06, 2020 12:59 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pair Locations
- Replies:
**6** - Views:
**76**

### Re: Lone Pair Locations

Lone pairs have a lot of repulsion strength, meaning they want to be as far away as possible from other areas of electron density (i.e. bonds and other lone pairs). Think about the H2O molecule. The two lone pairs on oxygen "push" the other bonds away, resulting in the molecule's bent shape.

- Sun Nov 29, 2020 2:43 pm
- Forum: Hybridization
- Topic: Sapling #11
- Replies:
**19** - Views:
**132**

### Re: Sapling #11

Hi! To find the hybridization of the phosphorus atom, first count the number of atoms attached to it and the number of lone pairs it has. Then add these numbers together and use this chart to determine the hybridization. You'll notice that all the phosphorus atoms in this structure have the same amo...

- Sun Nov 29, 2020 2:37 pm
- Forum: Hybridization
- Topic: Sapling #20
- Replies:
**4** - Views:
**37**

### Re: Sapling #20

Type of bonds does not matter when determining hybridization, just regions of electron density. To determine the hybridization of As in this problem, count the number of atoms it is attached to (4 oxygens) and number of lone pairs it has (0). Add these numbers together and use this chart to determin...

- Sun Nov 29, 2020 2:34 pm
- Forum: Hybridization
- Topic: Long Pairs/Double & Triple Bonds
- Replies:
**9** - Views:
**60**

### Re: Long Pairs/Double & Triple Bonds

Type of bond does not matter when determining hybridization, but lone pairs do! To determine the hybridization of an atom, count the number of atoms that are attached to it (bond type does not matter) and the number of lone pairs it has. Then add these numbers together (i.e. 3 atoms attached + 1 lon...

- Sun Nov 29, 2020 2:30 pm
- Forum: Hybridization
- Topic: hybridization of phosphorus (Sapling Q.11)
- Replies:
**21** - Views:
**126**

### Re: hybridization of phosphorus (Sapling Q.11)

The phosphorus atom has a sp3 hybridization because it has three regions of electron density (the double bond only counts as one region). I find it helpful to count the number of atoms is attached to the atom in question (in this case 4) and add the number of lone pairs on the atom in question (in t...

- Sun Nov 29, 2020 2:18 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Tips for VSEPR
- Replies:
**6** - Views:
**63**

### Tips for VSEPR

Does anyone have an easy way to remember/determine molecular geometry? Like is there a chart anywhere that shows basic bonds/lewis structures and how they relate to the molecules 3D shape?

- Sun Nov 22, 2020 12:23 pm
- Forum: Hybridization
- Topic: General question about hybridization
- Replies:
**3** - Views:
**15**

### General question about hybridization

I was really confused during lecture when Dr. Lavelle started talking about hybridization. Could someone explain it in a simpler way and also explain when/why it occurs?

- Sun Nov 22, 2020 12:17 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Overlapping Orbitals
- Replies:
**3** - Views:
**18**

### Overlapping Orbitals

What does it mean when orbitals overlap or interact in sigma and pi bonds? And how do we know that a molecule has a sigma or pi bond?

- Sun Nov 22, 2020 12:12 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies:
**8753** - Views:
**1489580**

### Re: Post All Chemistry Jokes Here

I ain't never seen two resonance structures with all the bonds in the same place. It's always one of em gotta be different.

- Tue Nov 17, 2020 3:22 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Textbook Problem 2A.3
- Replies:
**1** - Views:
**14**

### Textbook Problem 2A.3

The electron configuration for the V4+ ion and Fe3+ ions are listed in the answer key as [Ar] and [Ar]3d104s2, respectively. How is this true? I thought that V4+ would be [Ar]3d1 as it loses 4 electrons, and Fe3+ would be [Ar]3d5 because it loses 3 electrons. I am so confused. Not sure if its a typo...

- Tue Nov 17, 2020 2:49 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Textbook Problem 1E.25 d
- Replies:
**2** - Views:
**30**

### Textbook Problem 1E.25 d

This problem asks for the electron configuration of Cu, Ag, and Au.

Why is the answer (n-1)d10(n)s1 instead of (n-1)d9s2 ?

Why is the answer (n-1)d10(n)s1 instead of (n-1)d9s2 ?

- Sun Nov 15, 2020 3:37 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: What is effective nuclear charge?
- Replies:
**1** - Views:
**15**

### What is effective nuclear charge?

This term is mentioned in the textbook homework but I don't remember going over it during lecture.

- Sun Nov 15, 2020 2:34 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Textbook problem 1D.1
- Replies:
**3** - Views:
**37**

### Textbook problem 1D.1

This problem's answer states that both energy and atomic radius are functions of n. Were we ever given this as an equation/function or is this just a principle we should know?

- Sun Nov 15, 2020 2:06 pm
- Forum: Dipole Moments
- Topic: Sapling Week 5/6 #17
- Replies:
**2** - Views:
**14**

### Sapling Week 5/6 #17

How do you know if a molecule only exhibits dispersion forces? I.e. how do you figure out if it exhibits hydrogen bonding, dipole-dipole, etc. Do I need to draw out each molecule?

- Sun Nov 15, 2020 1:47 pm
- Forum: Coordinate Covalent Bonds
- Topic: Sapling Week 5/6 #13
- Replies:
**5** - Views:
**45**

### Re: Sapling Week 5/6 #13

There are 8. In addition to the 4 Hydrogen bonds that can be formed from the hydrogen atoms bonded to nitrogen, nitrogen has one pair of unpaired electrons and can form a hydrogen bond from that pair. Because there are two nitrogen atoms, 2 hydrogen bonds can be formed. Oxygen has two pairs of unpa...

- Sun Nov 15, 2020 1:34 pm
- Forum: Coordinate Covalent Bonds
- Topic: Sapling Week 5/6 #13
- Replies:
**5** - Views:
**45**

### Sapling Week 5/6 #13

I'm really confused about how to find how many water molecules can theoretically bond to a urea molecule. I thought it would be 4 since there are 4 hydrogen atoms bonded to the N atom, however this isn't the answer.

- Sun Nov 15, 2020 1:20 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Sapling Week 5/6 #9
- Replies:
**1** - Views:
**19**

### Sapling Week 5/6 #9

Can someone explain why the resonance structure with the 3+ Cl charge is most plausible based on the oxidation number? I don't quite understand why this is true.

- Sun Nov 08, 2020 12:20 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Sapling Assigning Formal Charges
- Replies:
**4** - Views:
**43**

### Re: Sapling Assigning Formal Charges

Both the periodic table valence electron number and the electron number from your Lewis structure are necessary to find formal charge! FC = V - (S/2 + L) V = valence electrons (from periodic table groups) S = shared electrons (from Lewis diagram; 1 bond = 2 shared electrons) L = lone pair electrons ...

- Sun Nov 08, 2020 12:11 pm
- Forum: Electronegativity
- Topic: Lewis Acids and Bases (Sapling #6)
- Replies:
**4** - Views:
**43**

### Lewis Acids and Bases (Sapling #6)

How do you know if a species is a Lewis acid or Lewis base? I thought I totally had it down after lecture but Sapling #6 took me like ten tries lol and I still don't quite understand what makes each one an acid or a base. Could someone explain this to me? Thank you! :) Acids: Na+, BCl3, SO3 Bases: S...

- Sun Nov 08, 2020 12:07 pm
- Forum: Lewis Structures
- Topic: Sapling #3
- Replies:
**10** - Views:
**88**

### Sapling #3

I am still struggling to understand how to draw Lewis structures that "minimize formal charge." What is the best way to approach these types of problems?

- Sun Nov 08, 2020 12:02 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Oxidation number?
- Replies:
**8** - Views:
**81**

### Oxidation number?

Maybe I'm just blanking but have we learned anything about oxidation numbers? They are mentioned in #9 in sapling and I'm not sure if we've gone over them already and I just didn't catch it or if they are coming up in lecture next week.

- Fri Nov 06, 2020 12:43 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: What do we use formal charges for?
- Replies:
**15** - Views:
**52**

### What do we use formal charges for?

I am comfortable with calculating formal charges and understand the equation, but I don't really understand what formal charges actually are and why/when we use them.

- Sun Oct 25, 2020 6:57 pm
- Forum: Properties of Light
- Topic: De Brogile Sapling HW Problem help
- Replies:
**7** - Views:
**82**

### Re: De Brogile Sapling HW Problem help

Hello! You can find the mass needed for the DeBroglie equation by using the molar mass of nitrogen and Avogadro's constant.

28.01 x 10^3 kg/mol / 6.022 x 10^23 mol^-1

Then use this answer for your mass in the equation! Hope this helped :)

28.01 x 10^3 kg/mol / 6.022 x 10^23 mol^-1

Then use this answer for your mass in the equation! Hope this helped :)

- Sun Oct 25, 2020 4:36 pm
- Forum: SI Units, Unit Conversions
- Topic: Textbook Practice Problem Answers
- Replies:
**4** - Views:
**56**

### Re: Textbook Practice Problem Answers

Sachi Sengupta 3B wrote:I know CCLE is down right now so if you logged into Sapling via that maybe it didn't load completely or something. I downloaded the answer key pdf beforehand so if you need it I can possible email it to you.

That would be amazing if you could!! My email is shannonmoore@g.ucla.edu

Thank you!! :)

- Sun Oct 25, 2020 4:15 pm
- Forum: SI Units, Unit Conversions
- Topic: Textbook Practice Problem Answers
- Replies:
**4** - Views:
**56**

### Textbook Practice Problem Answers

I'm not sure if this is just an issue with my textbook loading or something, but many of the problems in the odd number answer section of the textbook just have no answers written down whatsoever. I'd say about 50-75% of the numbers in the answers section are just completely blank. Is anyone else ha...

- Sun Oct 25, 2020 4:09 pm
- Forum: Significant Figures
- Topic: Midterm
- Replies:
**9** - Views:
**117**

### Re: Midterm

My TA said that there shouldn't be any problems on the midterm that have you choose between answers with two different sig figs. There might be some with differences in unit conversions, but not sig figs. Hope this helps :)

- Thu Oct 22, 2020 4:40 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Constant/Equation
- Replies:
**2** - Views:
**51**

### Rydberg Constant/Equation

In the Sapling homework for weeks 2/3/4, there were two different Rydberg's constants needed to solve different problems (numbers 8, 9 and 10). Also, there was an equation called the Rydberg equation for hydrogen that was needed, but I don't remember going over it during lecture. When do we know to ...

- Sun Oct 18, 2020 3:06 pm
- Forum: Properties of Light
- Topic: Example during lecture 6
- Replies:
**5** - Views:
**90**

### 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

- Sun Oct 18, 2020 3:01 pm
- Forum: Properties of Light
- Topic: Energy from shorter wavelength
- Replies:
**5** - Views:
**47**

### Re: Energy from shorter wavelength

Hi Anya :) ^^^Yes its the energy of the photon coming in from the outside light source. I don't think we've been given problems to find the kinetic energy of the electrons yet.

- Sun Oct 18, 2020 2:49 pm
- Forum: Properties of Light
- Topic: Word Problems
- Replies:
**7** - Views:
**34**

### Re: Word Problems

Units are usually the easiest thing to look at to differentiate the two! Frequency will be in Hertz and wavelength will be in nanometers :)

- Sun Oct 18, 2020 2:46 pm
- Forum: Student Social/Study Group
- Topic: How are you studying?
- Replies:
**203** - Views:
**1377**

### Re: How are you studying?

I think practice problems are the best way to study and are key to knowing how to approach problems from all angles. I think sometimes tests feel really difficult when questions come up that you know you've studied but you don't know how to solve them because you've never encountered that type of qu...

- Sun Oct 18, 2020 1:03 pm
- Forum: Photoelectric Effect
- Topic: Wave Properties of Electrons
- Replies:
**3** - Views:
**19**

### Wave Properties of Electrons

When we say that electrons have wave like properties, does this mean the electrons themselves are wave-like or that they are particles that move in a wave-like fashion?

- Sun Oct 11, 2020 9:47 pm
- Forum: Significant Figures
- Topic: SigFigs
- Replies:
**4** - Views:
**57**

### Re: SigFigs

I feel like I should know this by now but...when completing a chemistry problem, you round the to the least amount of significant figures in the problem right? Because the answer can't be more precise than the least precise value...? Yes!! The least number of sig figs in a number in the problem det...

- Sun Oct 11, 2020 9:44 pm
- Forum: Empirical & Molecular Formulas
- Topic: Difference In Formula Types
- Replies:
**4** - Views:
**27**

### Re: Difference In Formula Types

Also is it true that empirical formulas are just the most reduced form? Or do I need to do all the calculations every time to get a correct empirical formula?

- Sun Oct 11, 2020 9:36 pm
- Forum: Empirical & Molecular Formulas
- Topic: Difference In Formula Types
- Replies:
**4** - Views:
**27**

### Difference In Formula Types

What is the easiest way to think about the difference between chemical, molecular and empirical formulas? I feel like I know how to figure out each one but I don't really know what each one is used for and when/where to apply it.

- Sun Oct 11, 2020 9:30 pm
- Forum: Balancing Chemical Reactions
- Topic: Week 1 Sapling Homework #10
- Replies:
**4** - Views:
**59**

### Week 1 Sapling Homework #10

For the 2-butanone 1-bromopropane magnesium reaction, I googled each of the reactant/product formulas so I could have the reaction written out for my homework.

I was just wondering why the product has no bromine nor magnesium in it?

I was just wondering why the product has no bromine nor magnesium in it?

- Sun Oct 11, 2020 9:12 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Test Accuracy
- Replies:
**13** - Views:
**155**

### Test Accuracy

For questions with numerical answers on our midterms/final how exact are we expected to be in our answers?

i.e. rounding, sig figs, etc. Will there be specific directions on the test to get exact answers or will there be a certain amount of leniency?

i.e. rounding, sig figs, etc. Will there be specific directions on the test to get exact answers or will there be a certain amount of leniency?