## Search found 70 matches

Thu Jan 21, 2021 1:01 am
Forum: Phase Changes & Related Calculations
Topic: The Energy of H bonds
Replies: 3
Views: 10

### Re: The Energy of H bonds

We primarily look at water when observing Hydrogen bonds. In the gas phase, molecules are in constant motion. Each gas molecule moves independently of the others, therefore, there are no hydrogen bonds forming. In liquids, the molecules slide past each other freely but move in relation to one anothe...
Sun Jan 17, 2021 11:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Combining chemical equations
Replies: 5
Views: 19

### Re: Combining chemical equations

There are a couple rules when dealing with equilibrium constants and combining equations. When you are adding two equations together, then you multiple the Ks together. When youre substracting one reaction from another, then you divide respectively. But remember when youre manipulating on equation t...
Sun Jan 17, 2021 11:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: reverse reactions
Replies: 2
Views: 21

### Re: reverse reactions

I think in general when calculating equilibrium compositions, you solve for K using the reaction as they have it written out for you. For #4 you just need to calculate Kp as [Pproduct]/[Preactants] using the ICE chart and use x to add up the total pressure
Sun Jan 17, 2021 11:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: reverse rxn equilibrium
Replies: 4
Views: 15

### Re: reverse rxn equilibrium

I assume the time that it takes for a reaction to reach equilibrium really depends on how much you perturb the system. So if you had a little vs a lot of reactant then it would take varying amounts of time to reach Equilibrium.
Sun Jan 10, 2021 9:00 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Removing product
Replies: 5
Views: 17

### Re: Removing product

K is the equilibrium constant, basically meaning the ratio of products to reactants. Now whenever something in the reaction is changed, the amounts of each thing will shift in a way that creates the same ratio as before(reaction will work to go back to K). So if the products in a reaction were sudde...
Sun Jan 10, 2021 8:42 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Effects of temperature
Replies: 6
Views: 23

### Re: Effects of temperature

Lavelle mentioned that we currently dont have the tools to solve this type of problem, but that we will be able to in the future units! I think understanding the trends is important right now and having a good understanding of that will prepare us for when we are presented with a more concrete probl...
Sun Jan 10, 2021 8:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K and pressure
Replies: 5
Views: 26

### Re: K and pressure

K, the equilibrium constant, is the ratio of products to reactants. Applying the Le Chateliers principle to a system that under goes a pressure change, that reaction will adjust to minimize the effects of said change. This means while the change in pressure does cause a change in concentration, the ...
Sun Dec 13, 2020 1:16 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity and Bond Angle
Replies: 2
Views: 13

### Re: Polarity and Bond Angle

So try an remember that bond angels depend on the structure of the molecule. Think of using the VSEPR notation to help you out! linear, AX2 (180), trigonal planar AX3 (120), tetrahedral AX4 (109.5), octahedral AX6(90, 120, 180) So now when we have molecules with lone pairs, say a molecule like a Ang...
Sun Dec 13, 2020 12:29 am
Forum: Octet Exceptions
Topic: Exceptions outside the ones we memorized
Replies: 6
Views: 60

### Re: Exceptions outside the ones we memorized

Many atoms that have access to the d orbital can have expanded octets. In general, we probably wont see any outside of the normal ones like P, Si, Cl, S, but basically any element beyond the third principle level is able to form expanded octets!
Sun Dec 13, 2020 12:23 am
Forum: Naming
Topic: Naming Coordination Number Textbook Problem
Replies: 3
Views: 24

### Re: Naming Coordination Number Textbook Problem

When we have ions bonded to a bracketed [] compound, the we take the charge of the full compound into consideration, not just the charge of the metal. For b, c calculate the charge of the compound (sulfato with a 2- and Cobalt with a 3+) which is an overall charge of +1, and we add subsequent Chlori...
Sun Dec 13, 2020 12:16 am
Forum: Identifying Acidic & Basic Salts
Topic: Textbook Fundamental J, 17
Replies: 2
Views: 31

### Re: Textbook Fundamental J, 17

So in most of these examples, the cation/anions connected to the acid/base are going to dissociate when placed in water! lone anions/cations are called specators, because they don't affect the pH of a solution (Na can neither steal or donate a H atom). For the first example, i honestly have no idea ...
Sat Dec 12, 2020 9:59 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Sapling 10
Replies: 6
Views: 43

### Re: Sapling 10

For the bases, Sr(OH)2 and KOH, we can tell the Sr(OH)2 would be a stronger base because it contributes two OH- to a solution, compared to one by KOH.
NH3 is normally a very weak base.
For the acids HbrO and HclO4, the HClO4 is a strong acid with a much higher pH than the HbrO.
hope this helps!
Sat Dec 12, 2020 9:54 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: pKa and pH
Replies: 2
Views: 21

### pKa and pH

Im kind of confused on the relationship that pKa has in terms of pH. I know it is for weak acids, but what kind of calculaions might I need to be aware of?
Sat Dec 12, 2020 9:14 pm
Forum: Naming
Topic: "ferrate"
Replies: 8
Views: 64

### Re: "ferrate"

Lavelle said we should be able to recognize the ligand names and nomenclature. Iron involve in coordination compounds are always Ferrate, but in normal compounds, they are normally just iron.
Mon Dec 07, 2020 9:13 pm
Forum: Administrative Questions and Class Announcements
Topic: Ebook/Textbook problems
Replies: 9
Views: 82

### Ebook/Textbook problems

So I am trying to study for the final and complete the textbook problems but they are... not showing up? I will have some part of the question and then it will give options like a) b) c) but they arent completely blank. I've tried different browsers/ restarting / and have had this problem since yest...
Sun Dec 06, 2020 9:57 pm
Forum: Bronsted Acids & Bases
Topic: Strong & Weak Acid
Replies: 6
Views: 45

### Re: Strong & Weak Acid

Yes! You will need a periodic table in front of you as well! There are two general rules when it comes to measuring acidity of a compound: 1 - Longer bonds are weaker bonds, so the longer/weaker a bond is between the Hydrogen and other atom, the stronger the acidity! (This is because the strong acid...
Sun Dec 06, 2020 9:52 pm
Forum: Administrative Questions and Class Announcements
Topic: CCLE Lectures
Replies: 9
Views: 62

### CCLE Lectures

In anyone else having trouble accessing the lectures on CCLE? I haven't been able to watch Friday's lecture since I started trying to this morning and I was hoping it would be fixed by now.... Also would like to note that the UCLA VPN/ reloading / restarting didn't help me at all so must be a CCLE i...
Sun Dec 06, 2020 9:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook 2E15B
Replies: 3
Views: 25

### Re: Textbook 2E15B

Yes but actually calculating bond angles are beyond the scope of this class so most of the time, we just state that the angles are approximations
Sun Dec 06, 2020 9:09 pm
Forum: Amphoteric Compounds
Topic: 6A.17 Question
Replies: 3
Views: 30

### Re: 6A.17 Question

Acids are primarily : nonmetal-oxides
Bases are primarily : metal-oxides
- simple molecules containing Nitrogen are normally basic
Amphoteric : Metalloid-oxides including (but not limited to) Be, Sb, Sn, Al, Ga, Pb
- H2O is also amphoteric
Sun Dec 06, 2020 9:05 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Determining Oxidation Numbers
Replies: 6
Views: 30

### Re: Determining Oxidation Numbers

When trying to find the charge of a metal in a complex that you are unfamiliar with, it is best to calculate the formal charge of each atom respectively. Then do the equation [overall charge] - [sum of all formal charges] = the oxidation number (charge) of the atom you need. For example, finding the...
Sun Dec 06, 2020 8:59 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 4
Views: 27

### Re: Coordination Number

An en ligand is neutral and the edta ligand has a 4- charge. My TA mentioned that we should memorize these and the ones on the paper that Lavell posted on his website! He may provide teh charge but It is always better to be at least familiarized and more prepared for the final. [url]https://lavelle....
Sun Dec 06, 2020 8:54 pm
Forum: Student Social/Study Group
Topic: Thoughts on Switching Majors?
Replies: 30
Views: 236

### Re: Thoughts on Switching Majors?

Just a reminder for freshman as well, the first two years of a bio major are meant to "weed out" people. But don't let that get to you, especially if you have not finished the LS7 series!!!! It is definitely difficult and meant to basically introduce you to every possible biology concept u...
Sun Dec 06, 2020 8:47 pm
Forum: Naming
Topic: Homework Problem 9C.1
Replies: 4
Views: 32

### Re: Homework Problem 9C.1

Cyanido and cyano are actually the same. They both denote CN- Ligand bound to the transition metal. Lavelle mentioned in lecture that there is actually a new way of naming complexes and that either work (but i would stick to his way, which is cyano). Here is a link from the website that Lavelle ment...
Sun Dec 06, 2020 8:42 pm
Forum: Naming
Topic: Number after Metal
Replies: 9
Views: 66

### Re: Number after Metal

In order to find the number that comes after a metal when naming compounds, you must first understand that it is the oxidation number! This basically means the charge on the metal atom, in most cases, they will provide the complex charge and you must calculate the formal charges of all the atoms wit...
Sun Nov 29, 2020 11:44 pm
Forum: Student Social/Study Group
Topic: Molecule Modeling tool
Replies: 4
Views: 40

### Molecule Modeling tool

This is a cool Chemistry tool that my friend showed me because I was having a hard time with the visualization of molecules and 3D structures. I just wanted to place it here to help people out with their studying and homework as we tackle the last weeks of Chem 14A!!! You can search or draw any mole...
Sun Nov 29, 2020 11:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: finding the shape of a molecule
Replies: 6
Views: 33

### Re: finding the shape of a molecule

The most stable lewis structure is what you should use as a template for figuring out the shape/structure of a molecule. I have a hard time visualizing 3D models as well so I use this cool website that you can search any structure up and it provides you with a 3D model to interact with! This was hel...
Sun Nov 29, 2020 11:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Remembering Bond Degrees
Replies: 7
Views: 73

### Re: Remembering Bond Degrees

https://molview.org/?cid=962 I depend a lot on visualization and structures to understand molecules so I sometimes use this cool website. It lets you search any molecule and then displays the lewis structure and most importantly, the 3D model that you can interact with. This also helps with equator...
Sun Nov 29, 2020 11:26 pm
Forum: Hybridization
Topic: How to simply determine hybridization
Replies: 27
Views: 185

### Re: How to simply determine hybridization

Here is a helpful little way to remember, but I believe it is also realllyyyy important to understand why the hybridization occurs rather then memorize the numbers. https://d3i71xaburhd42.cloudfront.net/ac73a46dc482862c4baa12b73f648f3dd3fa5989/28-Table1-1.png The attachments ^ means the number of bo...
Sun Nov 29, 2020 11:23 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Ring structure
Replies: 2
Views: 12

### Re: Ring structure

This is a little look into organic chemistry, so when working with Carbon, it super important to remember that they tend to form ring structures! The Carbons joinn together in cyclic rings and the Hydrogens are bonded to each Carbon, but not involved in the ring structure!
Sun Nov 29, 2020 11:18 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 7
Views: 57

### Re: Resonance Structures

Structures must be resonant structures if the delocalized electrons are in equivalent positions across all structures. It is helpful to make sure that the number of bonding pairs and lone pairs of electrons are equal. The overall formal charge must be equal as well.
Sun Nov 29, 2020 11:14 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Delocalized pi bond?
Replies: 4
Views: 40

### Re: Delocalized pi bond?

So generally speaking, pi bonds are the second bonding pair in a double bond. When we encounter structures that have resonance (multiple structures with bonds in different but equivalent positions), then we see delocalized pi bonds. Think of them as an extra bonding pair of electrons that doesn't st...
Sun Nov 29, 2020 11:03 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Delocalized vs localized
Replies: 12
Views: 82

### Re: Delocalized vs localized

Localized electrons are electrons that are involved in bonding with other atoms. We encounter delocalized electrons when we are looking at molecules that have resonance structures. If the pair of electrons can be involved in bonds in different but equal positions, then they are delocalized
Sun Nov 29, 2020 10:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Equatorial and Axial
Replies: 2
Views: 8

### Equatorial and Axial

The sapling provided some help on equatorial vs axial but I still do not understand how we might form a 3D structure of a molecule without knowing beforehand how many atoms are in each plane?
Sun Nov 22, 2020 11:42 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Lectures through Thanksgiving
Replies: 7
Views: 68

### Re: Lectures through Thanksgiving

Considering we had class on the school holiday, its a safe bet to except a lecture!! Im sure TA's will send ou8t a email if your discussion is on thursday or friday so keep an eye out for that!
Sun Nov 22, 2020 11:41 pm
Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
Topic: Viscosity/Surface Tension
Replies: 7
Views: 206

### Re: Viscosity/Surface Tension

Viscosity and Surface tension are directly related to one another; increase viscosity then the surface tension increases. This is due to the intermolecular forces between molecules. Take a look at water! Water has surface tension that stems from hydrogen bonding between H20 molecules, this means tha...
Sun Nov 22, 2020 11:36 pm
Forum: Hybridization
Topic: Electron Configuration
Replies: 2
Views: 28

### Re: Electron Configuration

So we have only written our electron configurations in "ground state" for our atoms in this class, and i think it is a safe bet that we wont go beyond that. But you can write your hybrid orbitals in electron configurations when filling it out for hybrid molecules!
Sun Nov 22, 2020 11:28 pm
Forum: Lewis Structures
Topic: Octet Rule
Replies: 17
Views: 133

### Re: Octet Rule

The octet rule would only be "broken" if an atom has more than 8 valence electrons filling its outer orbital. You most make sure you calculate the total electrons involved in a molecule and make sure to calculate the formal charge of each atom. As with every chemistry rule, there are many ...
Sun Nov 22, 2020 11:18 pm
Forum: Electronegativity
Topic: Polarity of Molecules
Replies: 7
Views: 59

### Re: Polarity of Molecules

You will always be provided with a Periodic table in which you can determine the charge difference between atoms. A higher charge difference between two atoms will mean the electrons in the covalent bond are not exactly equally shared. Using the Periodic table and charges from there, you should be a...
Sun Nov 22, 2020 11:12 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Ionic Bond and Covalent Character
Replies: 4
Views: 42

### Re: Ionic Bond and Covalent Character

Ionic bonds form between atoms with high electronegativity differences (a cation and anion), and is generally between metals and nonmetals. Covalent bonds generally form between two nonmetals, and the difference in electronegativity largely contributes to the ionic character of the covalent bond. In...
Sun Nov 22, 2020 11:07 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 25
Views: 133

### Re: Bond Angles

Lavelle mentioned in his lectures that it will be important to remember the NAMES for bond angles of different structures (i.e. Linear, Trigonal Planar, Octohedral). Be able to recognize these patterns among molecules and look at the textbook example problems that lavelle assigns!
Sun Nov 22, 2020 11:04 pm
Forum: General Science Questions
Topic: Finals
Replies: 39
Views: 373

### Re: Finals

The final date and time is on December 13th. from11:00am-1:30pm on a sunday! It is cumulative and my TA said it will reflect the two midterms so most likely multiple choice but plan for many more questions! It covers everything that we have learned and normally has homework/textbook problems on it s...
Sun Nov 22, 2020 11:01 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic and Covalent Bonds
Replies: 7
Views: 31

### Re: Ionic and Covalent Bonds

Look at what blocks and element types each atom belongs too. A general rule to follow is that ionic bonds form between atoms with high electronegativity differences, and is almost exclusively between cations and anions. This generally means the bond is between a metal and nonmetal. On the other hand...
Sun Nov 22, 2020 10:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: NO2- Bent Molecular Geometry
Replies: 7
Views: 56

### Re: NO2- Bent Molecular Geometry

Due to the lone pair on the Nitrogen, these elctrons have a much stronger repulsion to the bonded electrons between the Nitrogen and Oxygens. This stronger repulsion results in the angle you see in the structure, as the lone electron pair repels the Oxygens with a stronger force than they repel each...
Sat Nov 14, 2020 11:09 pm
Forum: Dipole Moments
Topic: Rod-shaped molecules
Replies: 6
Views: 52

### Re: Rod-shaped molecules

I believe it is due to the fact that rod shaped atoms have more surface area to interact with one another. The less distance and resulting more interaction between the two atoms creates a stronger dipole moment.
Sat Nov 14, 2020 11:07 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen bonding not in H2S
Replies: 3
Views: 17

### Hydrogen bonding not in H2S

Lavelle explained that Hydrogen bonding occurs in H2O but not H2S but I did not really understand why? H2S seems to fit the description of an H atom covalently bonded to an electronegative atom and close to the electronegative S in another H2S molecule would form a H bond (why does that not occur?)
Sat Nov 14, 2020 11:03 pm
Forum: Ionic & Covalent Bonds
Topic: Conceptual Question about Covalent Bonds
Replies: 1
Views: 23

### Re: Conceptual Question about Covalent Bonds

Lavelle is expanding on the previous knowledge that you learned in highschool, and this higher level chemistry often comes with many more exceptions! Oxygen often loans it's lone e- pair in something called coordinate covalent bonding (covered in the 11/04, Wednesday lecture). Hydrogen bonding can a...
Sat Nov 14, 2020 10:05 pm
Forum: Resonance Structures
Topic: Determining oxidation numbers?
Replies: 9
Views: 42

### Re: Determining oxidation numbers?

The oxidation number of an ion is synonymous with the charge on an ion. So Cl has an ionic charge of -1 and therefore an oxidation number of -1. Elements Cl, Br, and I have different oxidation numbers when bonded to F or O. In the case like ClF, the Cl oxidation number is +1 because F has a -1
Sat Nov 14, 2020 9:41 pm
Forum: Trends in The Periodic Table
Topic: Atomic size and trend
Replies: 5
Views: 42

### Re: Atomic size and trend

Here is a helpful graphic that is much easier to understand than my lengthy explanation!
Sat Nov 14, 2020 9:40 pm
Forum: Trends in The Periodic Table
Topic: Atomic size and trend
Replies: 5
Views: 42

### Re: Atomic size and trend

The protons and neutrons are clustered tightly in the center of an atom (the nucleus). Their masses contribute to most of the atom's atomic weight because electrons are much much smaller. However, electrons orbit the nucleus rather than cluster together. The bigger the nucleus (the more p+ and n), t...
Sat Nov 14, 2020 9:30 pm
Forum: Resonance Structures
Topic: Formal Charge influence on Resonance Structure
Replies: 4
Views: 18

### Re: Formal Charge influence on Resonance Structure

When dealing with molecules that have multiple potential structures (resonance structures), to find the most stable structure, you calculate the molecule formal charges. Choosing the molecule that has the smallest formal charge normally indicates which structure is most stable(and sometimes most oft...
Sat Nov 14, 2020 9:22 pm
Forum: Dipole Moments
Topic: Textbook discrepancy
Replies: 6
Views: 45

### Re: Textbook discrepancy

In lecture he denotes the arrow in dipole moments to point towards the atoms/molecule with the more negative charge. I believe that if you are able to discern the correct partial charges for atoms in a molecule, then that should be sufficient information for exams!
Thu Nov 12, 2020 11:32 pm
Forum: Coordinate Covalent Bonds
Topic: Hydrogen bonding
Replies: 15
Views: 112

### Hydrogen bonding

Is a Hydrogen bond considered a coordinate covalent bond, or a distinct other type of bonding that occurs?
Sun Nov 08, 2020 9:21 pm
Forum: Lewis Structures
Topic: Expanded octets in Lewis diagrams
Replies: 1
Views: 14

### Expanded octets in Lewis diagrams

I understand that some elements like Chlorine and Sulfur are able to expand their octets. Will we have to draw any Lewis dot structures with these expansions (what would the correct notation for that be), and how might we gauge whether an element will have an expanded octect??
Sun Nov 08, 2020 9:14 pm
Forum: Administrative Questions and Class Announcements
Topic: Taking Bio and Chem simultaneously
Replies: 26
Views: 114

### Re: Taking Bio and Chem simultaneously

The LS7 series can be very time consuming but the most relevant information for tests is always presented in lectures! Launchpad is an online course that you must complete before each class, but for the most part, it is an information dump that you simply have to sort through by tuning into the most...
Sun Nov 08, 2020 9:09 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm 2 Question Count
Replies: 17
Views: 106

### Re: Midterm 2 Question Count

My TA mentioned that the midterm would be a couple more questions but the total amount of points it is worth will be fairly close to midterm 1's points. Lavelle mentioned that the freebie question was likely a one time thing so I wouldn't expect something like that to show up on the second midterm.
Sun Nov 08, 2020 9:07 pm
Forum: Octet Exceptions
Topic: Expanded Octets
Replies: 6
Views: 27

### Re: Expanded Octets

Third period elements (like Cl and P etc) have an n=3 and 5 d-orbitals. This makes it possible for a select number of elements to expand their octets. Normally the energy of empty 3d-orbitals is higher than 4s orbital, but the difference can be so small that d orbitals acquire more electrons to expa...
Sun Nov 08, 2020 9:02 pm
Forum: Student Social/Study Group
Topic: Midterm 2
Replies: 28
Views: 164

### Re: Midterm 2

I found that the textbook problems were super helpful!! They often get more complex than examples on sapling or in lecture so it really solidifies your understanding of the concepts. Also going to multiple Peer learning workshops is very helpful!
Sun Nov 08, 2020 1:54 pm
Forum: Properties of Light
Topic: Equation clarifications
Replies: 4
Views: 43

### Re: Equation clarifications

I also found that we often have to use the same two equations ( c=λv, E=hν) and move them around in different ways (hence the E=hc/λ) in order to find the necessary components to a problem. I find it helpful to write out what each variable represents and the units because then you know what informat...
Wed Nov 04, 2020 11:48 pm
Forum: Ionic & Covalent Bonds
Topic: Learning Outline 3
Replies: 6
Views: 67

### Re: Learning Outline 3

Crash course chemistry is also a great place to find the basic information very clearly explained with plenty of examples. Plus, the information is portrayed in a fun and engaging way!
Wed Nov 04, 2020 11:46 pm
Forum: Lewis Structures
Topic: Lewis structures and charges
Replies: 3
Views: 34

### Lewis structures and charges

Rewatching the lecture video from last Friday, i was trying to understand why we add/subtract the electrons from the charges when calculating the total valence electrons in each molecule. Where do those electrons come from and why do we count them in our structures.
Wed Oct 28, 2020 10:18 pm
Forum: Administrative Questions and Class Announcements
Topic: Sapling access code
Replies: 3
Views: 63

### Sapling access code

I ordered my textbook and access code on September 28 and then I got an email that it was shipped on Oct 8. My free trial just ended (great timing two days before midterm) and i still haven't received the access code. Is anyone experiencing similar problems/ have any idea what to do?
Sun Oct 25, 2020 10:22 pm
Forum: Properties of Light
Topic: Work function
Replies: 5
Views: 29

### Re: Work function

In what context or problem are you talking about? remember the "normal energy" is the amount of energy/light being exerted onto a metal in cases like the photoelectric experiment. The work function is the amount of energy required to eject an electron from the surface of a substance. There...
Sun Oct 25, 2020 10:17 pm
Forum: Properties of Light
Topic: Speed of light
Replies: 25
Views: 158

### Re: Speed of light

From friends that have taken Lavelle's classes before; The sig figs matter! Lavelle will give you options that give the same answer but with varying sigfigs to test your knowledge (and rounding ability for some reason lol). So make sure you use the exact values given on the constants and equations s...
Sun Oct 25, 2020 10:07 pm
Forum: Properties of Light
Topic: How are you guys studying for the midterm?
Replies: 19
Views: 125

### Re: How are you guys studying for the midterm?

The homework textbook problems are awesome practice for the midterm!! Everyone that i know that has taken this class told me that homework problems always show up on the exams (and Lavelle mentioned it as well), and the exam problems follow the same format as many homework problems. Making sure you ...
Thu Oct 15, 2020 12:20 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E23 Confused
Replies: 4
Views: 87

### Re: E23 Confused

We only look at the ratios between the same element when looking at the ratio of Cu and CuBr2. So there is 1 Cu : 1 Cu
Thu Oct 15, 2020 12:18 am
Forum: Empirical & Molecular Formulas
Topic: Rounding up Molar Ratios
Replies: 6
Views: 75

### Re: Rounding up Molar Ratios

In the audio visual lectures, Lavelle even rounded numbers as far as .2 off. I think a good rule of thumb though is anything more than .2 from a whole number should be further multiplied out to get the ratios.
Thu Oct 15, 2020 12:14 am
Forum: Balancing Chemical Reactions
Topic: Week 1 Sapling Homework #10
Replies: 4
Views: 58

### Re: Week 1 Sapling Homework #10

Given the structure of each molecule, you are also able to figure out the molecular formulas from them! A general rule of thumb is that each question that Lavelle gives should have all the information necessary to solve it (no google allowed during tests)! Each corner of the molecule will be a Carbo...
Thu Oct 15, 2020 12:08 am
Forum: Properties of Light
Topic: work function
Replies: 15
Views: 142

### Re: work function

Doing all the steps together (using parenthesis to separate and organize the problem) on a scientific calculator is ideal! And remember to not round your answers until the very end. You may find that with a phone calculator, it is much harder to keep track of complex equations, and often is not as a...
Sun Oct 11, 2020 12:15 am
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 133
Views: 17961

### Re: All students read this sig fig post[ENDORSED]

In my discussion class, my TA said that 0.500g is only 1 significant figure. I am pretty sure it was 3 significant figures, but I just wanted to double check here. The Sig figs sheet on Lavelle's website states that trailing zeros with a decimal point are counted as significant. Take a look at that...
Sun Oct 11, 2020 12:13 am
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 133
Views: 17961

### Re: All students read this sig fig post[ENDORSED]

Does Sapling homework normally take into account the sig figs? I had some problems submitting an answer with the correct rounding and took multiple tries.