## Search found 100 matches

Sun Mar 15, 2020 8:32 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Doing work vs work done
Replies: 8
Views: 153

### Doing work vs work done

For w, when is it positive? Is it when work is being done on the system or when the work is being done by the system?
Sun Mar 15, 2020 8:31 pm
Forum: Balancing Redox Reactions
Topic: Half rxns
Replies: 27
Views: 466

### Re: Half rxns

Balancing acidic reactions means adding H2O to balance oxygens, and H+ to balance hydrogen.
Balancing basic reactions means adding H2O to balance oxygens, and OH- to balance everything else.
Sun Mar 15, 2020 8:30 pm
Forum: Balancing Redox Reactions
Topic: Test 2 Return
Replies: 20
Views: 389

### Re: Test 2 Return

My TA put it in her mailbox and she posted the grades on my.ucla!
Sun Mar 15, 2020 8:28 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: E cell
Replies: 9
Views: 130

### Re: E cell

Ecell is the cell potential for the half reaction.
E standard cell is the overall cell potential (Ecathode - Eanode)
Sun Mar 15, 2020 8:27 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Battery
Replies: 8
Views: 153

### Re: Battery

A dead battery means that the reaction is at equilibrium, so Ecell and delta G is 0.
Thu Mar 05, 2020 12:43 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: lnQ vs logQ
Replies: 5
Views: 91

### lnQ vs logQ

When would you use E=E°-(RT/nF)lnQ vs E=E°-(0.05916V/n)logQ ?

Also, I understand that you can substitute RT/F for 0.025963 for the ln equation when its under standard condition - 25 degree celsius. Is this correct?
Wed Mar 04, 2020 3:57 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.5
Replies: 1
Views: 55

### 6M.5

In the cell diagram Hg|Hg2^2+||NO3-,H+|NO|Pt, the half reactions are like this: 3e- + NO3- -> NO (red potential: 0.96V) 2Hg -> Hg2^2+ + 2e- However, only the reduction potential of 2e- + Hg2^2+--> 2Hg is given (0.79V). Why don't we flip the sign since its supposed to be an oxidation reaction (0-->1+...
Wed Mar 04, 2020 3:04 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: N in Nernst Equation
Replies: 1
Views: 33

### N in Nernst Equation

How do you find N in the Nernst equation?
Wed Mar 04, 2020 2:57 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Ecell vs Ecell°
Replies: 2
Views: 35

### Ecell vs Ecell°

Whats the difference between Ecell and Ecell° ?
Under which conditions would you need to find Ecell and Ecell° 2 and which equations would you use?
Wed Mar 04, 2020 3:01 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.5
Replies: 2
Views: 47

### 6M.5

2NO3-(aq)+8H+ (aq)+6 Hg(l)-> 3Hg2^2+(aq)+2NO(g)+4H2O If the cell diagram is Hg(l)|Hg2^2+||NO3-(aq),H+(aq)|NO(g)|Pt(s), how do you find the cell potential? If I am correct, the cell potential of the cathode is 0.96V. How do you find the potential of the anode or Hg(l)/Hg2^2+(aq)? I cannot find it in ...
Wed Mar 04, 2020 1:22 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt(s)
Replies: 3
Views: 46

### Pt(s)

When and where would you add Pt(s) into the cell diagram? Could you give an example?
Wed Mar 04, 2020 1:21 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L 3 part c)
Replies: 2
Views: 59

### Re: 6L 3 part c)

They are both aqueous, so it's separated by a comma!
Sun Mar 01, 2020 12:51 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt bridges
Replies: 11
Views: 119

### Re: Salt bridges

The salt bridge allows for transfer of electron and charge from anode to cathode, balancing the charges between the half cells.
Sun Mar 01, 2020 12:46 am
Forum: Balancing Redox Reactions
Topic: When to add H+ or H20
Replies: 19
Views: 335

### Re: When to add H+ or H20

In acidic solution: You add H2O to balance the oxygen first, and H+ to balance the hydrogen.
In basic solution: You add OH- to balance the oxygen first, and H2O to balance the hydrogen.
Sun Mar 01, 2020 12:44 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Finding N
Replies: 6
Views: 120

### Finding N

How do you find n in -nFE?
Sun Mar 01, 2020 12:43 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Flipping the sign
Replies: 10
Views: 111

### Flipping the sign

When would you flip the sign in a half reaction? Do you flip the sign of the given reduction potential is the reaction is oxidation?
Sun Mar 01, 2020 12:41 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Where to find Ecell values
Replies: 15
Views: 192

### Re: Where to find Ecell values

Appendix 2B or just google it!
Sun Feb 23, 2020 5:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: chemistry community posts
Replies: 12
Views: 84

### Re: chemistry community posts

I think it's 5 posts per week by Sunday night (every week of the quarter).
Sun Feb 23, 2020 5:02 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Half reactions
Replies: 13
Views: 157

### Half reactions

What are half reactions?
Sun Feb 23, 2020 5:02 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: salt bridge
Replies: 10
Views: 133

### Re: salt bridge

A salt bridge neutralizes the charges of the half cells by allowing for ion transfer.
Sun Feb 23, 2020 5:01 pm
Forum: Balancing Redox Reactions
Topic: Balancing redox reactions
Replies: 5
Views: 66

### Balancing redox reactions

Can someone outline the steps of balancing a redox reaction?
Sun Feb 23, 2020 5:00 pm
Forum: Balancing Redox Reactions
Topic: Oxidation number of H
Replies: 6
Views: 85

### Re: Oxidation number of H

Most of the time H has a charge of +1. However, when its bonded to a cation or a metal, it will have a charge of -1.
Thu Feb 13, 2020 9:56 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: deltaSrev/T
Replies: 2
Views: 35

### deltaSrev/T

When would you use the equation deltaSrev/T? And does this only work for reversible reactions?
Thu Feb 13, 2020 9:54 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: S vs Stotal
Replies: 7
Views: 121

### S vs Stotal

What is the difference between delta S and delta S total?
Thu Feb 13, 2020 9:53 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Boltzmann Formula
Replies: 3
Views: 55

### Re: Boltzmann Formula

Yes! S=kBlnW, and W= degeneracy aka (# of orientations/positions)^(# of atoms/ molecules).
Thu Feb 13, 2020 9:51 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: entropy of surr vs entropy of system vs total entropy
Replies: 3
Views: 148

### entropy of surr vs entropy of system vs total entropy

What's the difference between the entropy of the surrounding, system, and total entropy? And how would you find these values in isothermal reversible and irreversible expansions?
Thu Feb 13, 2020 9:44 am
Forum: Ideal Gases
Topic: STP
Replies: 7
Views: 169

### Re: STP

You should check the constants list and if it explicitly states that it's at STP and not 298K!
Thu Feb 06, 2020 4:26 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: U vs H
Replies: 15
Views: 317

### U vs H

What's the difference between delta U and delta H?
Wed Feb 05, 2020 5:19 pm
Forum: Phase Changes & Related Calculations
Topic: 4B.5
Replies: 7
Views: 114

### 4B.5

An ideal gas in a cylinder was placed in a heater and gained 5.50 kJ of energy as heat. If the cylinder increased in volume from 345 mL to 1846 mL against an atmospheric pressure of 750. Torr during this process, what is the change in internal energy of the gas in the cylinder? Which equation would ...
Wed Feb 05, 2020 5:03 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work done on or by the system
Replies: 4
Views: 66

### Work done on or by the system

How do you know if the work is done on or by the system? Which one would be negative and which one would be positive?
Wed Feb 05, 2020 5:01 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Change in Internal Energy
Replies: 4
Views: 1874

### Re: Change in Internal Energy

Because q and w are both in kilojoules, you don't need to do anything with the units!
Wed Feb 05, 2020 4:47 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A.13
Replies: 1
Views: 55

### 4A.13

A constant-volume calorimeter was calibrated by carrying out a reaction known to release 3.50 kJ of heat in 0.200 L of solution in the calorimeter (q 5 23.50 kJ), resulting in a temperature rise of 7.32 8C. In a subsequent experiment, 100.0 mL of 0.200MHBr(aq) and 100.0 mL of 0.200M KOH(aq) were mix...
Tue Jan 28, 2020 10:22 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: pKa and pKb
Replies: 17
Views: 215

### Re: pKa and pKb

pKa = -logKa
pKb = -logKb

pka + pkb = 14
Tue Jan 28, 2020 10:21 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Using Kc Vs Kp
Replies: 18
Views: 220

### Re: Using Kc Vs Kp

You use Kc when given concentrations, and Kp when given partial pressures.
Tue Jan 28, 2020 10:15 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE BOX
Replies: 27
Views: 265

### Re: ICE BOX

x is too small if it's < 10^-3.
Tue Jan 28, 2020 9:53 am
Forum: Ideal Gases
Topic: Ideal Gas
Replies: 4
Views: 59

### Ideal Gas

What does it mean for a gas to be ideal / act ideally?
Tue Jan 28, 2020 9:52 am
Forum: Ideal Gases
Topic: R Constant
Replies: 26
Views: 357

### Re: R Constant

Look at the units you have and match it with the R constant's units!
Thu Jan 23, 2020 3:54 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Shifting Forward or Reverse
Replies: 7
Views: 45

### Shifting Forward or Reverse

When you reduce a reactant, why does the equilibrium shift in the reverse direction?
Thu Jan 23, 2020 3:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Kp
Replies: 6
Views: 73

### Calculating Kp

Can you calculate Kp if you are not given the individual partial pressures? ICE table is only for concentration right?
Thu Jan 23, 2020 3:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.1
Replies: 1
Views: 27

### 5I.1

At 500. K, the equilibrium constant for the reaction Cl2(g)+ Br2(g)--> 2 BrCl(g) is Kc 5 0.031. If the equilibrium composition is 0.495M Cl2 and 0.145M BrCl, what is the equilibrium molar concentration of Br2?
Thu Jan 23, 2020 3:38 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle
Replies: 19
Views: 259

### Re: Le Chatelier's Principle

You use the Principle any time a change is made to the reaction at equilibrium. The reaction will shift to minimize the effect of the change due to Le Chatelier's Principle.
Thu Jan 23, 2020 3:35 pm
Forum: Ideal Gases
Topic: Kc vs Kp
Replies: 43
Views: 569

### Re: Kc vs Kp

You calculate Kc if given concentration. Kp if partial pressures are given.
Tue Jan 14, 2020 12:20 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q=K
Replies: 14
Views: 155

### Re: Q=K

Q can be calculated at any point during the reaction, including the equilibrium point. Thus, if Q = K, that means that the reaction is at equilibrium.
Tue Jan 14, 2020 12:19 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: What is this?
Replies: 23
Views: 674

### Re: What is this?

Le Chatelier's principle states that a system in equilibrium will shift right / forward or left / backwards in response to a change in pressure, temperature, volume, concentrations etc. in order to minimize its effects on the reaction. The reaction will shift in order to keep a "balance".
Tue Jan 14, 2020 12:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Table
Replies: 8
Views: 97

### ICE Table

Can you use ICE tables to calculate partial pressures for gases as well?
Tue Jan 14, 2020 12:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Hw for next week
Replies: 19
Views: 204

### Re: Hw for next week

I don't think it matters that much as long as the topics are relevant! Practicing acid and bases would be helpful though.
Tue Jan 14, 2020 12:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.1
Replies: 3
Views: 57

### 5I.1

At 500. K, the equilibrium constant for the reaction Cl2(g) Br2(g) ∆ 2 BrCl(g) is Kc 0.031. If the equilibrium composition is 0.495 mol L 1 Cl2 and 0.145 mol L 1 BrCl, what is the equilibrium concentration of Br2?
Thu Jan 09, 2020 3:16 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q
Replies: 10
Views: 101

### Re: Q

Yes. You calculate it the same way as K, except the reaction is simply not at equilibrium.
Thu Jan 09, 2020 3:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K expression
Replies: 6
Views: 66

### Re: K expression

Solids and liquids don't have concentrations nor partial pressures.
Thu Jan 09, 2020 3:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q vs K
Replies: 7
Views: 51

### Q vs K

What's the difference between Q and K?
Thu Jan 09, 2020 3:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q
Replies: 4
Views: 38

### Re: Q

Q is used at any point of the reaction, while K is calculated when the rxn is at equilibrium.
If Q<K, then the forward reaction will proceed (to make more products).
If Q> K, then the reverse reaction will proceed.
Thu Jan 09, 2020 3:13 pm
Forum: Ideal Gases
Topic: K value
Replies: 14
Views: 150

### Re: K value

Large K value (K>10^3) means that there are more products @ eq and that the "equilibrium sits to the right."
Small K value (K<10^-3) means that there are more reactants @ eq and that the "equilibrium sits to the left."
Thu Jan 09, 2020 3:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units
Replies: 4
Views: 45

### Re: Units

[concentration].
(pressure) for when there are subscripts / coefficients before the products or reactants.
K values don't have units because they cancel out, from what I know.
Thu Dec 05, 2019 10:39 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: H2CO3 vs H2GeO3 [ENDORSED]
Replies: 3
Views: 78

### H2CO3 vs H2GeO3[ENDORSED]

Why is H2CO3 more acidic than H2GeO3 (besides the fact that carbonic acid is a known strong acid)?
Thu Dec 05, 2019 10:35 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: HBrO2 vs HClO2
Replies: 1
Views: 79

### HBrO2 vs HClO2

Why is HClO2 more acidic than HBrO2? I initially thought HBrO2 was more acidic as it has a larger atomic radius (negative charge more dispersed --> more stable ... etc). However, Cl is more electronegative than Br, which makes it more acidic. When would you look at atomic radius vs electronegativity?
Thu Dec 05, 2019 10:06 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: # of Oxygens and Acidity
Replies: 1
Views: 41

### # of Oxygens and Acidity

Section 6C.4 of the textbook says that the greater the number of oxygens attached to the central atom (or the greater the oxidation number), the stronger the acid. Why?

Thanks :)
Thu Dec 05, 2019 9:55 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Resonance and Acidity
Replies: 2
Views: 67

### Resonance and Acidity

Why is it that when the conjugate base of an acid has more electronegative atoms, it is more acidic?
Thu Dec 05, 2019 6:51 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Lewis Acid
Replies: 4
Views: 221

### Lewis Acid

Question 6A.13

Draw the Lewis structure or symbol for each of the following species and identify each one as a Lewis acid or Lewis base

Why are Ag+ and BF3 lewis acids? How do you determine this through drawing the lewis structure?
Tue Nov 26, 2019 11:51 pm
Forum: Hybridization
Topic: PCl6
Replies: 3
Views: 95

### PCl6

Why is the hybridization of P in PCl6 sp3d2?
Sun Nov 24, 2019 3:29 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: How to draw dipoles
Replies: 7
Views: 124

### How to draw dipoles

How do you figure out which direction to draw your dipoles in a lewis structure?
Sun Nov 24, 2019 3:27 pm
Forum: Resonance Structures
Topic: Resonance structures
Replies: 15
Views: 360

### Re: Resonance structures

Resonance structures are different ways that the Lewis structure can be drawn. For example, one structure might have a double bond on an atom while another has a double bond on another atom. Both would work thus they are resonance structures.
Sun Nov 24, 2019 3:23 pm
Forum: Dipole Moments
Topic: Melting points
Replies: 15
Views: 408

### Re: Melting points

Intermolecular forces are the significant factors affect melting points! The stronger/ more intermolecular forces, the higher the melting/boiling points.
Sun Nov 24, 2019 3:21 pm
Forum: Sigma & Pi Bonds
Topic: Sigma & Pi Bonds
Replies: 9
Views: 158

### Sigma & Pi Bonds

Why are sigma bonds are generally stronger than pi bonds? What is their difference?
Tue Nov 19, 2019 5:52 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Drawing dipoles
Replies: 3
Views: 56

### Drawing dipoles

In a molecule, do you draw the arrow/ dipole towards the δ- charge or the δ+ charge?
Fri Nov 15, 2019 4:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: vsepr formula
Replies: 3
Views: 47

### Re: vsepr formula

A is the central atom, so it's always 1.
X is the number of atoms bonded to the central atom.
E represents the number of lone pairs
Fri Nov 15, 2019 4:11 pm
Forum: Bond Lengths & Energies
Topic: Bond lengths in molecules
Replies: 7
Views: 82

### Re: Bond lengths in molecules

Triple bond strength > double bond > single bond.

Think of having one rope being pulled vs two ropes - the one with the two ropes is stronger thus shorter!
Fri Nov 15, 2019 4:09 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Week 7 Homework
Replies: 2
Views: 124

### Re: Week 7 Homework

3F! Honestly anything is fine, as long as it is close to what we are learning in class.
Fri Nov 15, 2019 4:07 pm
Forum: Resonance Structures
Topic: Best Resonance Structure
Replies: 5
Views: 228

### Best Resonance Structure

Why's the best / most stable resonance structure the one with the least formal charge?
Fri Nov 15, 2019 4:06 pm
Forum: Dipole Moments
Topic: London forces
Replies: 9
Views: 107

### Re: London forces

There are london forces among all molecules due to the random movement of electrons!
Fri Nov 08, 2019 12:38 pm
Forum: Bond Lengths & Energies
Topic: Bond Lengths
Replies: 8
Views: 156

### Re: Bond Lengths

Double/triple bonds have a stronger attraction, thus they are shorter than single bonds!
Fri Nov 08, 2019 12:35 pm
Forum: Bond Lengths & Energies
Topic: Bond Lengths
Replies: 8
Views: 156

### Re: Bond Lengths

Double/triple bonds have a stronger attraction, thus they are shorter than single bonds!
Fri Nov 08, 2019 12:34 pm
Forum: Resonance Structures
Topic: Formal Charge Question
Replies: 16
Views: 373

### Re: Formal Charge Question

Sum up to the overall charge!
Fri Nov 08, 2019 12:34 pm
Forum: Sigma & Pi Bonds
Topic: Sigma & Pi Bonds
Replies: 5
Views: 98

### Sigma & Pi Bonds

What are sigma and pi bonds and what's the difference?
Fri Nov 08, 2019 12:32 pm
Forum: Ionic & Covalent Bonds
Topic: Ionization of Nitrogen vs Oxygen
Replies: 11
Views: 177

### Ionization of Nitrogen vs Oxygen

Why is the ionization energy of nitrogen higher than that of oxygen's? Doesn't IE increase from left to right on the periodic table?
Fri Nov 08, 2019 12:30 pm
Forum: Ionic & Covalent Bonds
Topic: Why is the ionization energy of nitrogen higher than that of oxygen's?
Replies: 11
Views: 215

### Re: Why is the ionization energy of nitrogen higher than that of oxygen's?

nitrogen is more stable, thus it takes more energy to remove an electron, compared to oxygen.
Thu Oct 31, 2019 12:48 pm
Forum: Electronegativity
Topic: Electronegativity vs. Electron Affinity
Replies: 7
Views: 96

### Re: Electronegativity vs. Electron Affinity

Electronegativity is the tendency of an atom to attract a bonding pair of electrons, while electron affinity is the amount of energy released when an electron is added to a neutral atom.
Thu Oct 31, 2019 12:46 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal change equation
Replies: 3
Views: 49

### Re: Formal change equation

I'm pretty sure the equation will not be provided on the front page of our test, but it might be helpful to memorize it. You could definitely complete lewis structure questions without using it though.
Thu Oct 31, 2019 12:40 pm
Forum: Ionic & Covalent Bonds
Topic: What is the Octet Rule?
Replies: 5
Views: 60

### Re: What is the Octet Rule?

The octet rules states that atoms prefer to have a full thus stable electron shell, which includes 8 electrons.This rules applies when drawing lewis structures!
Thu Oct 31, 2019 12:38 pm
Forum: Ionic & Covalent Bonds
Topic: Homework for Week 5
Replies: 8
Views: 85

### Re: Homework for Week 5

Probably on chemical bonds since that's the topic for this week!
Thu Oct 31, 2019 12:38 pm
Forum: Resonance Structures
Topic: Difference between Resonance and Lewis structures
Replies: 5
Views: 86

### Difference between Resonance and Lewis structures

What is the difference between resonance and lewis structures? When would you need to draw resonance structures?
Sun Oct 20, 2019 10:33 pm
Forum: Trends in The Periodic Table
Replies: 16
Views: 290

Atomic radii should be only measured /compared in the ground state
Sun Oct 20, 2019 10:15 pm
Forum: Einstein Equation
Topic: When do we use the Einstein Equation?
Replies: 14
Views: 425

### Re: When do we use the Einstein Equation?

It is used to solve for the energy of the photon. You also use it with the C=λν equation a lot.
Sun Oct 20, 2019 10:13 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration of Tungsten
Replies: 1
Views: 38

### Electron Configuration of Tungsten

Why is the electron configuration of tungsten [Xe]4f14 5d4 6s2?
Sun Oct 20, 2019 9:23 pm
Forum: Properties of Electrons
Topic: Mass of an Electron
Replies: 14
Views: 235

### Re: Mass of an Electron

It's a set mass! So are the masses of protons and neutrons.
Sun Oct 20, 2019 8:39 pm
Forum: Properties of Electrons
Topic: Energy of Electron
Replies: 3
Views: 81

### Energy of Electron

This is just to clarify:

s orbital --> l = 0, n=1
p orbital --> l = 1, n= 2

so when electron moves from n=1 to n=2 the energy of the electron increases because it's absorbing energy instead of emitting energy (like when it moves down levels) right?
Thu Oct 17, 2019 2:50 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisengberg Uncertainty Equation Meaning
Replies: 7
Views: 104

### Heisengberg Uncertainty Equation Meaning

What does Heisenberg Uncertainty Equation measure and when would you use it?
Thu Oct 17, 2019 2:32 pm
Forum: DeBroglie Equation
Topic: DeBroglie Equation Use
Replies: 5
Views: 90

### DeBroglie Equation Use

Can someone explain when you would use DeBroglie's Equation and what it means?
Thu Oct 17, 2019 2:30 pm
Forum: Photoelectric Effect
Topic: Unit of measurements for E=hv
Replies: 6
Views: 84

### Re: Unit of measurements for E=hv

Yes! The units for E is joules but it's also joules per photon.
Thu Oct 17, 2019 2:25 pm
Topic: Will this concept be tested
Replies: 8
Views: 756

### Re: Will this concept be tested

It won't be tested! He is just going over the concept in class.
Thu Oct 17, 2019 1:28 am
Forum: Properties of Light
Topic: What are the units of hertz
Replies: 41
Views: 499

### Re: What are the units of hertz

Hz is unit for frequency, and it equals to 1 cycle / second.
Thu Oct 17, 2019 1:19 am
Forum: Photoelectric Effect
Topic: Photoelectric effect
Replies: 5
Views: 91

### Re: Photoelectric effect

They'll tell you the specific metal and give you the work function, or you will be able to calculate the work function for that specific metal.
Thu Oct 17, 2019 1:09 am
Forum: Properties of Light
Topic: Rydberg's Equation [ENDORSED]
Replies: 4
Views: 56

### Rydberg's Equation[ENDORSED]

Can someone explain when you would use Rydberg's Equation / what types of questions you use it in?
Thu Oct 17, 2019 1:03 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test 1 [ENDORSED]
Replies: 107
Views: 5192

### Re: Test 1[ENDORSED]

Kennedi3K wrote:Does anyone know when the scores for the test will be up ? Thanks!

You can see your test scores once your TA hands it back in discussion. I think you can also view it on CCLE!
Thu Oct 17, 2019 12:59 am
Forum: SI Units, Unit Conversions
Topic: Test 1
Replies: 2
Views: 77

### Re: Test 1

You get your test back the discussion the week after you take your test! At least that's what happened for my discussion.
Tue Oct 15, 2019 4:31 pm
Forum: Einstein Equation
Topic: 7th edition 1B.5
Replies: 5
Views: 238

### Re: 7th edition 1B.5

1eV (electronvolt) = 1.6022x10^-19J (joules), so 1keV (kilo-electronvolt) = 1.6022x10^-16J. The energy in the formula E=hv is in joules, so you need to convert first!
Fri Oct 04, 2019 12:45 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Replies: 9
Views: 188

Avogadro's number is 6.022 × 10^23 and it indicates the number of atoms or molecules in a mole of any substance!
Fri Oct 04, 2019 12:41 pm
Forum: Empirical & Molecular Formulas
Topic: What decimal place to round to when taking masses from the Periodic Table?
Replies: 19
Views: 438

### Re: What decimal place to round to when taking masses from the Periodic Table?

I usually use the full number the periodic table gives you in all my calculations, then use sig figs for the final answer.
Fri Oct 04, 2019 12:37 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Replies: 7
Views: 399

Avogadro's constant is 6.02x10^23, and you use it when you want to determine how many "formula units" (you might see this term in the textbook!) are in a mole. Most times it is used to calculate how many atoms / molecules are in a mole of substance.
Fri Oct 04, 2019 12:34 pm
Forum: Significant Figures
Topic: How does one read sig figs?
Replies: 3
Views: 90

### Re: How does one read sig figs?

Here are some examples, hope this helps:

567 = 3 sig figs
100264 = 6 sig figs
0.0034 = 2 sig figs
3.21002 = 6 sig figs
190000 = 2 sig figs
Fri Oct 04, 2019 12:29 pm
Forum: Significant Figures
Topic: Significant Figures
Replies: 6
Views: 96

### Re: Significant Figures

You should avoid rounding until the very end! Keep and use the exact values in your calculator while you're calculating, and round / use sig figs for the final answer.