## Search found 60 matches

Sun Jan 17, 2021 11:54 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature
Replies: 38
Views: 94

### Re: Temperature

Because k does change when there's a change in temperature, products are favored during an endothermic reaction and reactants are favored during an exothermic reaction.
Sun Jan 17, 2021 11:50 pm
Forum: Student Social/Study Group
Topic: Comfort Movies
Replies: 108
Views: 240

### Re: Comfort Movies

I love Studi Ghibli movies! The animation and soundtrack are stunning.
Sun Jan 17, 2021 11:44 pm
Forum: Ideal Gases
Topic: PV=nRT
Replies: 72
Views: 441

### Re: PV=nRT

For PV=nRT,
P stands for pressure
V for volume
n for amount of moles
R for the gas constant, equaling 8.314 J/mol·K
T for temperature
Sun Jan 17, 2021 11:42 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q > K, Q< K
Replies: 25
Views: 75

### Re: Q > K, Q< K

When Q<K, there's not enough products and when Q>K, there's too few reactants. This means that Q<K would shift towards the right and Q>K would shift towards the left.
Sun Jan 17, 2021 11:20 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: q vs k
Replies: 62
Views: 162

### Re: q vs k

The Q value will always come back to equal K. Once the two values are equivalent, it means that the reaction is at equilibrium.
Sun Jan 10, 2021 11:59 pm
Forum: Ideal Gases
Topic: Units for Pressure
Replies: 41
Views: 815

### Re: Units for Pressure

Pressure units should be in atm!
Sun Jan 10, 2021 11:51 pm
Forum: Ideal Gases
Topic: Units of Temperature
Replies: 82
Views: 287

### Re: Units of Temperature

It should be Kelvin because the gas constant is given in J/mol·K units.
Sun Jan 10, 2021 11:47 pm
Forum: Ideal Gases
Topic: Gas constant R
Replies: 26
Views: 98

### Re: Gas constant R

The constant is universal, so the value will always remain consistent, equaling 8.3144598 J/mol·K.
Sun Jan 10, 2021 11:40 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Using Kc Vs Kp
Replies: 22
Views: 245

### Re: Using Kc Vs Kp

Susanna Givan 2B wrote:Is there any main difference in terms of how you solve K for Kc versus Kp?

When calculating Kc, I believe you can use the [P]/[R] equation. You can also use PV=nRT when converting between Kc and Kp.
Sun Jan 10, 2021 11:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs. Q
Replies: 53
Views: 159

### Re: K vs. Q

They are both calculated using the same method ([P]/[R]), but Q represents the reaction at any time while K represents the reaction at equilibrium.
Tue Dec 15, 2020 11:27 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Formulas
Replies: 4
Views: 34

### Re: Empirical Formulas

If you're given elements in values of grams, first convert it to moles. You would then divide each molar value by the smallest of the values calculated. Round to the nearest whole number or multiple the divided value by a whole number until you can easily round to the nearest whole number. (Ex: 1.31...
Tue Dec 15, 2020 11:19 pm
Forum: Resonance Structures
Topic: Valence Electrons [ENDORSED]
Replies: 43
Views: 256

### Re: Valence Electrons[ENDORSED]

You can use the group number to determine how many valence electrons are present in an element. For example, elements in group 1 have one valence electron while elements in group 6 have six. In regards to elements in the d-block, you could use electron configurations to derive the number of valence ...
Tue Dec 15, 2020 11:12 pm
Forum: Lewis Acids & Bases
Topic: Acids & Bases
Replies: 9
Views: 77

### Re: Acids & Bases

There are two possible definitions:
Lewis acid- a species that accepts an electron pair
Lewis base- donates an electron pair
Bronsted acid- a proton donor
Bronsted base- accepts a proton
They mean the same thing, it's just a matter of preference.
Tue Dec 15, 2020 11:04 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi Bonds
Replies: 21
Views: 157

### Re: Sigma and Pi Bonds

You're right as in a single bond only contains a sigma bond while a double bond contains both a sigma and a pi bond. However, I don't think you can refer to a double bond solely as a pi bond because both sigma and pi bonds are present in a double bond.
Tue Dec 15, 2020 10:59 pm
Forum: Electronegativity
Topic: Periodic Table Trend
Replies: 37
Views: 387

### Re: Periodic Table Trend

Ionization energy decreases down a group and increases across a period. Because electronegativity is calculated using ionization energy, electronegativity follows the same periodic trend.
Tue Dec 15, 2020 10:53 pm
Forum: Naming
Topic: Cobalt vs Cobaltate
Replies: 12
Views: 75

### Re: Cobalt vs Cobaltate

It's because the ion has a negative charge. You add -ate to the end to signify this distinction in the compound name.
Fri Dec 11, 2020 7:12 pm
Forum: Calculating the pH of Salt Solutions
Topic: Hard Water vs. Soft Water
Replies: 9
Views: 63

### Re: Hard Water vs. Soft Water

Based on the lecture, water that feels soapy is alkaline due to 'soft' salts. Hard water feels soapy, making it alkaline. Therefore, soft water would be acidic.
Fri Dec 11, 2020 6:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 6
Views: 37

### Re: Bond Angles

It depends if lone pairs are present. Because lone-lone pair repulsion strength is strongest compared to lone-bonding and bonding-bonding pairs, we know they require more space, thereby making the bond angle slightly smaller than 109.5. However, we aren't expected to calculate the exact value of the...
Sun Dec 06, 2020 6:03 pm
Forum: Naming
Topic: Helpful Videos for Naming
Replies: 22
Views: 123

### Re: Helpful Videos for Naming

Thank you so much! These are definitely really helpful.
Sun Dec 06, 2020 6:01 pm
Forum: Hybridization
Topic: Pi Bonds Cannot Rotate
Replies: 23
Views: 162

### Re: Pi Bonds Cannot Rotate

When rotating, would the pi bond break because it is no longer parallel? Correct! Pi bonds don't allow atoms to rotate, so if the atom is no longer parallel, there is no pi bond. This is because pi bonds have electron densities on each side of the internuclear axis, preventing the bond to exist if ...
Sun Dec 06, 2020 5:55 pm
Forum: Student Social/Study Group
Topic: Studying for Final Exam
Replies: 57
Views: 358

### Re: Studying for Final Exam

Definitely reviewing the textbook problems! Also going over the bullet points in the outlines Dr. Lavelle provided so you know exactly what content is covered. The week 10 review sessions should be super helpful as well!
Sun Dec 06, 2020 5:48 pm
Forum: Hybridization
Topic: Good video about hybridization
Replies: 7
Views: 54

### Re: Good video about hybridization

Thank you! This is definitely one of my weaker subjects so this helps a lot!
Sun Dec 06, 2020 5:47 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligand definition
Replies: 7
Views: 48

### Re: Ligand definition

The only thing I would add is that ligands must have at least one lone pair and when directly attached to the central ion, it makes the coordination sphere. You definition works because it's how Dr. Lavelle explained them during lecture and I don't think he would use a different definition for the f...
Tue Nov 24, 2020 2:07 pm
Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
Topic: ionic liquids
Replies: 7
Views: 92

### Re: ionic liquids

It is salt in the liquid state. The solidification of ionic liquids take place at lower temperatures.
Tue Nov 24, 2020 2:01 pm
Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
Topic: determining viscosity
Replies: 11
Views: 98

### Re: determining viscosity

Conceptually, you can determine how high a liquid viscosity is by noticing how easily the substance moves. If it moves slower, you know it has a higher viscosity compared to something that moves relatively easy, like water.
Tue Nov 24, 2020 1:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: memorization
Replies: 12
Views: 114

### Re: memorization

Madison Wong 1G wrote:I use this as a reference for VSEPR and the shape/bond angles. Hope this helps!
https://ds055uzetaobb.cloudfront.net/im ... 091b2c.png

Thank you for the chart! It's super helpful.
Tue Nov 24, 2020 1:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Final Exam Date
Replies: 21
Views: 219

### Re: Final Exam Date

Most likely it'll be the date posted on myUCLA especially since you take account of the final exam dates when choosing classes so exam times don't overlap.
Tue Nov 24, 2020 1:45 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: What is bond order?
Replies: 8
Views: 108

### Re: What is bond order?

It's basically the number of present bonds between atoms. One bond equates to a bond order of one, a double bond equates to a bond order of two, and a triple bond between two atoms equates to a bond order of three.
Sun Nov 15, 2020 9:47 pm
Forum: Resonance Structures
Topic: Sapling 9
Replies: 5
Views: 50

### Re: Sapling 9

The structure with the charge closest to zero because it's the most stable.
Sun Nov 15, 2020 9:43 pm
Forum: Coordinate Covalent Bonds
Topic: Hydrogen bonds
Replies: 19
Views: 125

### Re: Hydrogen bonds

Hydrogen bonding is a result of a hydrogen atom bonding to a very electronegative atom (F, N, O). Hydrogen would be unable to form a hydrogen bond with carbon because their electronegativity values are too close/similar.
Sun Nov 15, 2020 9:38 pm
Forum: Resonance Structures
Topic: resonance structures
Replies: 10
Views: 45

### Re: resonance structures

It would be the structure with the charge closest to zero. This is because it's the closest to an octet, which is the most stable structure.
Sun Nov 15, 2020 9:35 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: Van der Waals vs London Dispersion
Replies: 10
Views: 39

### Re: Van der Waals vs London Dispersion

Yes, they are interchangeable. Van der Waals is just another name for London dispersion forces.
Sun Nov 15, 2020 9:29 pm
Forum: Electronegativity
Topic: determining electronegativity
Replies: 31
Views: 253

### Re: determining electronegativity

It also helps to use the periodic trends. Electronegativity is calculated using ionization energy and electron affinity, so if ionization energy and electron affinity are high, then the atom will also have a high electronegativity. You can figure out the ionization energy and electron affinity by us...
Sun Nov 15, 2020 9:20 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?

It helps to look at the electronegativity! You would need to calculate the difference in electronegativities. If the electronegativity difference between the bonded atoms is less than 0.5, then the bond is nonpoplar. If the difference is between 0.5 and about 1.9, then the bond is polar.
Sun Nov 08, 2020 7:44 pm
Forum: Ionic & Covalent Bonds
Topic: Identifying Ionic and Covalent Bonds
Replies: 10
Views: 39

### Re: Identifying Ionic and Covalent Bonds

As mentioned above, ionic bonds are bonds between a nonmetal and a metal whereas a covalent bond is between a nonmetal and another nonmetal. You can usually distinguish between the two by using the periodic table to classify if the specified element is a nonmetal or metal!
Sun Nov 08, 2020 7:28 pm
Forum: Ionic & Covalent Bonds
Topic: Size of Bonds
Replies: 28
Views: 99

### Re: Size of Bonds

It's because single bonds share fewer electrons between two atoms so the attraction between the electrons and the nucleus is less than a double or triple bond because they have more electrons, thereby making the bond length shorter.
Sun Nov 08, 2020 7:17 pm
Forum: Coordinate Covalent Bonds
Topic: Definition
Replies: 17
Views: 233

### Re: Definition

A coordinate covalent bond is when two electrons from the same atom form a covalent bond.
Sun Nov 08, 2020 6:25 pm
Forum: Ionic & Covalent Bonds
Topic: Sapling #1
Replies: 3
Views: 16

### Re: Sapling #1

I think it's the way you positioned the elements around carbon. The two hydrogens should be on the top and on the right and the oxygen should be on the left. Other than that, everything else is correct. Hope that helps!
Sun Nov 08, 2020 6:16 pm
Forum: Lewis Structures
Topic: Lone Pairs Question
Replies: 22
Views: 119

### Re: Lone Pairs Question

Lone pairs are the electrons that aren't bonded or shared with another atom.
Sun Nov 01, 2020 7:22 pm
Forum: Quantum Numbers and The H-Atom
Topic: Nodal Planes
Replies: 10
Views: 70

### Re: Nodal Planes

Melanie Krahn 1C wrote:Where are nodal planes found and what are the possible exceptions?

Nodal planes are regions where the probability of finding an electron is zero. Using Schrodinger's wave equation you're able to find where the planes are located.
Sun Nov 01, 2020 7:16 pm
Forum: Trends in The Periodic Table
Topic: Isoelectronic Ions
Replies: 5
Views: 17

### Re: Isoelectronic Ions

It's when two or more elements have the same amount of valence electrons. The Sapling question used N3-, O2-, F-, Na+, and Mg2+. Despite having a different amount of electrons in its neutral state, their ions make them all have 10 electrons, making them isoelectronic.
Sun Nov 01, 2020 7:07 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Sapling #24
Replies: 16
Views: 73

### Re: Sapling #24

It helps me to envision wrapping the wave into the circle. The wave should be continuous so if you were to connect the two ends, they'd flow seamlessly. One end of the wave would be above the line or x-axis and the other end of the wave should come up underneath the line or y-axis.
Sun Nov 01, 2020 7:00 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration For Calcium
Replies: 7
Views: 72

### Re: Electron Configuration For Calcium

It also really helps me to use the electron configuration tree. This way I'm able to visualize the order of the configurations on paper.
Sun Nov 01, 2020 6:55 pm
Forum: Quantum Numbers and The H-Atom
Topic: electrons in an atom
Replies: 2
Views: 23

### Re: electrons in an atom

L signifies the orbital type. So each energy level (n) specifies the size of the orbital and the angular momentum (l) signifies the shape of the orbital. If the atomic orbital is s, the value of l is 0. For p: l=1, for d: l=2, f: l=3, and so on so forth. Hope this helps!
Sun Oct 25, 2020 11:12 pm
Forum: Electronegativity
Topic: Noble Gases
Replies: 40
Views: 1750

### Re: Noble Gases

No, neon gases aren't included in electronegativity. This is because they've filled their valence shells so they don't need to attract electrons and electronegativity is the ability of an atom to gain an electron.
Sun Oct 25, 2020 11:07 pm
Forum: Properties of Light
Topic: Is c always the speed of light?
Replies: 88
Views: 457

### Re: Is c always the speed of light?

Since in class "c" has remained the constant for speed of light, I think it's safe to assume that whenever we'd encounter c in a problem/equation that it'd be used as a constant. I think Dr. Lavelle would've specified otherwise if that was the case!
Sun Oct 25, 2020 11:01 pm
Forum: Student Social/Study Group
Topic: Textbook sections on the midterm?
Replies: 3
Views: 36

### Re: Textbook sections on the midterm?

Do we have to know the material covered in 1C? It's not assigned as additional practice problems but I'm still unsure since it's before 1D.2.
Sun Oct 25, 2020 3:54 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation Confusion
Replies: 3
Views: 49

### Re: Rydberg Equation Confusion

It would be from final to initial! n1 being final and n2 being initial. Since the formula describes the change in energy from one energy level to another, you would subtract the the final by the initial to find the difference.
Sun Oct 25, 2020 3:47 pm
Forum: SI Units, Unit Conversions
Topic: Can someone explain Avogrado's #?
Replies: 8
Views: 91

### Re: Can someone explain Avogrado's #?

Because, Avogadro's number represents the number of atoms, ions, or molecules in one mole of a substance. Basically, one mole of a substance is equal to 6.02214x10^23 units of that substance. The units can be measured in either atoms, ions, or molecules - this would be decided based on what the ques...
Sun Oct 18, 2020 9:21 pm
Forum: Properties of Light
Topic: Chemistry Community Points
Replies: 10
Views: 86

### Re: Chemistry Community Points

So technically, this reply comment wouldn't count? I just want to verify, I don't accidentally want to miss easy points for the class. Thank you. I believe this comment would count as a point. You're still technically helping another student with questions regarding the class. What would be the due...
Sun Oct 18, 2020 9:16 pm
Forum: *Black Body Radiation
Topic: Black Body Radiation
Replies: 13
Views: 96

### Re: Black Body Radiation

I think Dr. Lavelle mentioned it in the lectures more as an example rather than for us to know the concept. Since it's more a physics topic, we won't be covering it in gen chem.
Sun Oct 18, 2020 9:11 pm
Forum: Quantum Numbers and The H-Atom
Topic: Emitting a Photon
Replies: 9
Views: 54

### Re: Emitting a Photon

An electron would only emit a photon coming back to ground state rather than when it's on ground state because that signifies that the electron is back to its normal energy level, thereby finding no need to emit photons.
Sun Oct 18, 2020 8:54 pm
Forum: Administrative Questions and Class Announcements
Topic: 14A webpage password
Replies: 4
Views: 28

### Re: 14A webpage password

It's given in one of Dr. Lavelle's early emails before class started. I got the email on Sep. 25. Hope you find it!
Sun Oct 18, 2020 8:51 pm
Forum: Empirical & Molecular Formulas
Topic: F 25 empirical to molecular formula
Replies: 2
Views: 38

### Re: F 25 empirical to molecular formula

It helps me by thinking of it as a fraction. The molecular formula is just a multiple of the empirical formula's ratio. If you were working backwards, trying to find the empirical formula from the molecular formula, you'd need to find the least common denominator and divide each subscript by the sam...
Sun Oct 18, 2020 8:42 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1289

### Re: How are you studying?

Active recall is an excellent studying method! Combined with spaced repetition, you should be able to pass any test. Constantly re-exposing yourself to the material would be a game changer. It definitely takes some self discipline, though. A good method to help implement active recall is using corne...
Sun Oct 11, 2020 5:46 pm
Forum: Molarity, Solutions, Dilutions
Topic: Sapling HW Number 7
Replies: 12
Views: 129

### Re: Sapling HW Number 7

Because the problem gives the total mass of the mixture (718.0g) and the percent of calcium chloride (33.5%), you'd have to find how many grams is 33.5% of 718.0 g is equal to and then subtract that value from the total mass to find the mass of water used. However, I believe Sapling assigns differen...
Sun Oct 11, 2020 5:26 pm
Forum: Empirical & Molecular Formulas
Topic: Could someone help me solve this?
Replies: 2
Views: 38

### Re: Could someone help me solve this?

You'd have to use the equation: M(initial)V(initial)=M(final)V(final)
M(inital) = 0.20M
V(initial) = 40.0mL
M(final) = 1/5 dilution of 0.20M
V(final) = unknown
Hope this helps!
Thu Oct 08, 2020 5:35 pm
Forum: Significant Figures
Topic: Sapling HW #4
Replies: 31
Views: 324

### Re: Sapling HW #4

It's because there's no decimal placed after the numbers! 950000 only has two sig figs because of the trailing zeros. However, if a decimal were to be placed after 950000., then there would be 6 sig figs. Same goes for 80060. The two zeros count between the 8 and 6 because they're not trailing, unli...
Thu Oct 08, 2020 5:23 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Textbook question E.1
Replies: 7
Views: 86

### Re: Textbook question E.1

I only converted the answer to km because the textbook's final answer was in km.
Does anyone know why we're supposed to? I initially was going to leave it in m.
Thu Oct 08, 2020 5:18 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Textbook question E.1
Replies: 7
Views: 86

### Re: Textbook question E.1

Hey! I was struggling with this problem a bit too. First I converted the given amount of moles (1.00mol Ag) to atoms since the problem is asking for the creation of fibers one atom wide. Multiply 144pm by two because they give you the radius and you need the diameter (=288p^2m). Next, multiply the n...

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