Search found 100 matches
- Sat Mar 13, 2021 11:00 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic Cell Diagrams vs. Electrolytic Cell Diagrams
- Replies: 1
- Views: 188
Galvanic Cell Diagrams vs. Electrolytic Cell Diagrams
Hello! I'm a bit confused about galvanic vs electrolytic cells. I am having trouble with the differences between their half-reactions and cell diagrams. Could someone please explain the major differences between the two? Thank you so much!
- Sat Mar 13, 2021 10:56 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Kinetics Outline
- Replies: 3
- Views: 379
Re: Kinetics Outline
Hi! Activation energy is the minimum amount of energy required for a reaction to occur. Free energy of activation is the difference in free energy (deltaG) between reactants and products. Hope this helps!
- Sat Mar 13, 2021 10:54 pm
- Forum: Calculating Work of Expansion
- Topic: when is change in internal energy 0
- Replies: 10
- Views: 1927
Re: when is change in internal energy 0
A general rule of thumb is that in an isolated system, the internal energy will equal zero. Just something helpful to think of when completing problems like these!
- Sat Mar 13, 2021 10:50 pm
- Forum: Zero Order Reactions
- Topic: Le Chatelier's principle
- Replies: 3
- Views: 425
Re: Le Chatelier's principle
Hi! This article goes in-depth about how Le Chatelier's principle will counteract changes in different factors of a system in order to reach equilibrium. Hope this helps! https://courses.lumenlearning.com/introchem/chapter/le-chateliers-principle/#:~:text=Le%20Chatelier's%20principle%20is%20an,achie...
- Sat Mar 13, 2021 10:42 pm
- Forum: Balancing Redox Reactions
- Topic: Tips for balancing a reaction with acidic/basic condition
- Replies: 12
- Views: 869
Re: Tips for balancing a reaction with acidic/basic condition
Hi! I think this video has a nice explanation and a pretty clear explanation with tips. Hope this helps! We love Professor Dave lol
https://www.youtube.com/watch?v=N6ivvu6xlog
https://www.youtube.com/watch?v=N6ivvu6xlog
- Mon Mar 08, 2021 12:32 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Gibbs Energy
- Replies: 20
- Views: 1170
Re: Gibbs Energy
\Delta G = \Delta H^{\circ} - T\Delta S^{\circ}, is the formula that directly relates Gibbs free energy to enthalpy and entropy. How can we find deltaS if its not given? delta S = (delta q) / T Hi! To find delta S, you can use the second law of thermodynamics: The change in entropy (delta S) is equ...
- Mon Mar 08, 2021 12:17 am
- Forum: Zero Order Reactions
- Topic: Equation with dt
- Replies: 6
- Views: 560
Re: Equation with dt
I was wondering about the same thing. I am pretty sure that it was mainly used for the derivation of the integrated rate laws.
- Mon Mar 08, 2021 12:11 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Non-spontaneous exothermic reaction
- Replies: 14
- Views: 4624
Re: Non-spontaneous exothermic reaction
An exothermic reaction can be non-spontaneous when the temperature is high and entropy is negative, as shown in the ∆G = ∆H-T∆S equation.
- Mon Mar 08, 2021 12:01 am
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Rust and Sea Water
- Replies: 8
- Views: 529
Re: Rust and Sea Water
Saltwater corrosion of metals happens faster than freshwater because of the increased presence of dissolved ions. These ions allow electrons to move faster on the metal, speeding up the formation of rust. Hope this helps!
- Sun Mar 07, 2021 11:54 pm
- Forum: *Free Energy of Activation vs Activation Energy
- Topic: Sapling #15 Wk.9-10
- Replies: 6
- Views: 14137
Re: Sapling #15 Wk.9-10
For this problem, I used the Arrhenius equation to calculate the activation energy but rearranged it to solve for Ea. Hope this helps!
- Fri Feb 26, 2021 4:00 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt bridge function
- Replies: 8
- Views: 640
Re: Salt bridge function
HI! I am a visual learner and this video helped me understand the function of the salt bridge. Hope this helps!
https://www.youtube.com/watch?v=BJzgnjg4Nok
https://www.youtube.com/watch?v=BJzgnjg4Nok
- Fri Feb 26, 2021 3:58 pm
- Forum: Van't Hoff Equation
- Topic: How deltaG affects product/reactant formation
- Replies: 6
- Views: 749
Re: How deltaG affects product/reactant formation
I was also confused about this and these explanations were super helpful. Thank you!!
- Fri Feb 26, 2021 3:52 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Bomb Calorimeter
- Replies: 14
- Views: 4851
Re: Bomb Calorimeter
Hi! Since a bomb calorimeter is an isolated system (no energy or matter is being lost/gained), it is a perfect system. Hope this helps!
- Fri Feb 26, 2021 3:50 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Relationship between E naught and spontaneity
- Replies: 8
- Views: 1171
Re: Relationship between E naught and spontaneity
Hi! When E naught is positive, the redox reaction is favorable so you can deduce it is spontaneous. When E naught is negative, the reaction is not favorable so you can deduce it is not spontaneous. Hope this helps!
- Fri Feb 26, 2021 3:44 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: difference between E and Eº
- Replies: 7
- Views: 539
Re: difference between E and Eº
Hi! I also had this question and this link had a nice explanation in addition to the ones above. Hope this helps!
https://socratic.org/questions/what-is- ... ochemistry
https://socratic.org/questions/what-is- ... ochemistry
- Sun Feb 21, 2021 3:38 pm
- Forum: Calculating Work of Expansion
- Topic: Negative vs Positive Work
- Replies: 13
- Views: 813
Re: Negative vs Positive Work
Work is positive if the system is being compressed. Work is being done on the system. Work is negative if the system is being expanded. Work is being done by the system.
- Sun Feb 21, 2021 3:34 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: delta U=0
- Replies: 17
- Views: 2701
Re: delta U=0
Since the temperature is held constant, the change in energy is zero. The heat absorbed by the gas equals the work done by the ideal gas on its surroundings. Enthalpy change is also equal to zero because the change in energy zero and the pressure and volume is constant. Hope this helps!
- Sun Feb 21, 2021 3:29 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Stable vs Unstable Gibbs Free Energy
- Replies: 16
- Views: 2606
Re: Stable vs Unstable Gibbs Free Energy
If the free energy of the formation of a compound is negative, this means that in the reaction for the formation of the compound, the elements (reactants) will tend to combine to form the compound (products). When free energy is positive, the elements are favored in the reaction, so the compound wil...
- Sun Feb 21, 2021 3:23 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Spontaneous Reduction
- Replies: 9
- Views: 576
Re: Spontaneous Reduction
- A redox reaction is spontaneous if the standard electrode potential for the redox reaction, Eo(redox reaction), is positive. If Eo(redox reaction) is positive, the reaction will proceed in the forward direction (spontaneous). - If Eo(redox reaction) is negative (Eo(redox reaction) < 0), the reacti...
- Wed Feb 17, 2021 11:54 am
- Forum: Phase Changes & Related Calculations
- Topic: Melting of Ice in Heat equations
- Replies: 2
- Views: 413
Melting of Ice in Heat equations
I have a question relating to the following two questions: 4C.11 How much heat is needed to convert 80.0 g of ice at 0.0 8C into liquid water at 20.0 8C (see Tables 4A.2 and 4C.1)? 4C.13 An ice cube of mass 50.0 g at 0.0 8C is added to a glass containing 400.0 g of water at 45.0 8C. What is the fina...
- Sat Feb 13, 2021 12:39 pm
- Forum: Calculating Work of Expansion
- Topic: Positive vs. Negative Work
- Replies: 22
- Views: 946
Re: Positive vs. Negative Work
Yes, your reasoning is correct! Good job :)
Negative work indicates that the system is doing work whereas positive work indicates that work is being done on the system.
Negative work indicates that the system is doing work whereas positive work indicates that work is being done on the system.
- Sat Feb 13, 2021 12:37 pm
- Forum: Calculating Work of Expansion
- Topic: Work
- Replies: 6
- Views: 406
Re: Work
Reversible pathway: a slow series of steps and work done on the reversible pathway is greater than irreversible work because the external pressure is nearly equal to the system's pressure. Irreversible pathway: a quick series of steps. Takes less work because the system is pushing against low extern...
- Sat Feb 13, 2021 12:30 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Residual entropy
- Replies: 4
- Views: 604
Re: Residual entropy
The post that Allan included in his comment is very helpful and I also used it to understand this problem when I was confused. To add, entropy is higher for molecules with more possible orientations for each atom.
- Sat Feb 13, 2021 12:23 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isothermal Reactions
- Replies: 26
- Views: 1334
Re: Isothermal Reactions
Since the temperature remains constant in isothermal reactions, they are reversible.
- Sat Feb 13, 2021 12:21 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Gas Entropy
- Replies: 14
- Views: 911
Re: Gas Entropy
Yes, gas becomes more orderly when it liquifies. During the state change, the energy that is released into the surroundings increases the entropy of its surroundings. According to the second law of thermodynamics, the entropy of the universe is always increasing. Hope this helps!
- Sun Feb 07, 2021 1:41 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Positive vs Negative Heat Capacities
- Replies: 3
- Views: 141
Re: Positive vs Negative Heat Capacities
Yes I'm pretty sure, heat capacity always has a positive value since it is the amount of energy (heat) required to raise the temperature of the system. Hope this helps!
- Sun Feb 07, 2021 1:37 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: constant pressure in open beaker
- Replies: 8
- Views: 412
Re: constant pressure in open beaker
Since the surrounding system (the universe) is so large, changes in pressure in the open system would not have a significant effect on the system. As stated above, the example of putting a bucket of water in the ocean.
- Sun Feb 07, 2021 1:34 pm
- Forum: Phase Changes & Related Calculations
- Topic: Boiling water
- Replies: 25
- Views: 3120
Re: Boiling water
In the phase change from liquid water to water vapor, the breaking of hydrogen bonds allows the phase change to occur. The strength of hydrogen bonds explains why water has a high boiling point since H-bonds are difficult to break.
- Sun Feb 07, 2021 1:31 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong vs Weak acid/Bases
- Replies: 10
- Views: 551
Re: Strong vs Weak acid/Bases
Since weak acids and bases don't dissociate completely, ICE tables allow us to organize the information so we can determine how much they do dissociate.
- Sun Feb 07, 2021 1:24 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Friday's Lecture
- Replies: 8
- Views: 370
Re: Friday's Lecture
If delta U is 0 then q=-w. This concept stems from the first law of thermodynamics.
- Sun Jan 31, 2021 11:51 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: R Constant
- Replies: 91
- Views: 7513
Re: R Constant
Selecting the correct R constant can be determined by the units used in the calculations. It's super helpful to keep track of units through your calculations so you can choose the right R constant. Hope this helps!
- Sun Jan 31, 2021 11:48 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Property
- Replies: 11
- Views: 562
Re: State Property
Heat is not a state function because it depends on the path taken (as explained in the hiking example Dr. Lavelle used in the lectures) rather than just the initial and final conditions. Hope this helps!
- Sun Jan 31, 2021 11:42 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy vs heat
- Replies: 31
- Views: 2681
Re: Enthalpy vs heat
Heat is a transfer of energy due to a temperature difference. Enthalpy is the change in the amount of heat in a system at constant pressure. Remember that for these terms, you can only use heat and enthalpy interchangeably if there is no work being done to the system. Hope this helps!
- Sun Jan 31, 2021 11:40 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeters
- Replies: 15
- Views: 639
Re: Calorimeters
I think it'll definitely be helpful to have a strong understanding of calorimeters and for the most part, have the diagram memorized. Hannah's explanation above about the bathtub is a great trick to use!
- Thu Jan 28, 2021 9:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Outline 2-the pH of salt solutions
- Replies: 2
- Views: 110
Outline 2-the pH of salt solutions
I am a bit confused about what the difference is between these statements that are in outline 2. Can someone please explain the difference between the pH of salt solutions vs the pH of a weak acid and its salt? I'm hoping that by explaining the pH of a weak acid and its salt that the third question ...
- Sun Jan 24, 2021 4:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Box Polynomials
- Replies: 10
- Views: 499
Re: ICE Box Polynomials
I don't think we would have to solve for such values of x because they would be extremely small and therefore insignificant. Hope this helps!
- Sun Jan 24, 2021 4:17 pm
- Forum: Phase Changes & Related Calculations
- Topic: Define Phase Change
- Replies: 78
- Views: 5734
Re: Define Phase Change
A phase change occurs when a substance is either heated or cooled and changes from one state to another. For example, when a solid is heated it may change phases to liquid or gas. The reverse can also occur when a change in pressure or temperature causes a change from gas to liquid or solid. Hope th...
- Sun Jan 24, 2021 4:10 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: [B]formal
- Replies: 5
- Views: 365
Re: [B]formal
To find the formal concentration of B, find the sum of [B] and [BH+]. Hope this helps!
- Sun Jan 24, 2021 3:57 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Ionization Constant of water
- Replies: 4
- Views: 255
Re: Ionization Constant of water
Kw is super important when calculating Ka and Kb. If given either Ka or Kb, you can manipulate the formula Kw=Ka*Kb to solve for the unknown. Also, the value of Kw explains why the sum of pH and pOH is 14. Hope this helps!
- Sun Jan 24, 2021 3:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Difference between K and Kc
- Replies: 13
- Views: 691
Re: Difference between K and Kc
K is the equilibrium constant. Kc and Kp specific if the equilibrium constant is in regards to concentration or pressure. Hope this helps!
- Mon Jan 18, 2021 12:38 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: endothermic vs exothermic
- Replies: 16
- Views: 814
Re: endothermic vs exothermic
Endothermic reactions require heat to occur. Exothermic reactions release heat. These changes are denoted by changes in enthalpy. Hope this helps!
- Mon Jan 18, 2021 12:32 am
- Forum: Calculating the pH of Salt Solutions
- Topic: pH 1-14
- Replies: 4
- Views: 468
Re: pH 1-14
n short, it is possible to have pH outside of this range but it will be extremely concentrated, resulting in a virtually meaningless pH value. The exception of pH falling in the 1-14 scale can be caused by lowering the concentration of H20 (if not obeying the assumption that water does not have a va...
- Mon Jan 18, 2021 12:24 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: equilibrium shifts: left of right?
- Replies: 13
- Views: 729
Re: equilibrium shifts: left of right?
In order to maintain equilibrium between the products and reactants, if there is an addition to one side of the reaction, the equation will shift to the opposing side in order to maintain equilibrium.
- Mon Jan 18, 2021 12:22 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Ka and Kb relationship
- Replies: 5
- Views: 233
Re: Ka and Kb relationship
Given the equation Kw= Ka*Kb, you can see the relationship between Ka and Kb. Since Ka and Kb are on the same side of the equation, an increase in either Ka or Kb will cause an inverse reaction to the opposing constant.
- Mon Jan 18, 2021 12:19 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Ka vs. Kb
- Replies: 30
- Views: 5430
Re: Ka vs. Kb
Ka is the acidity constant and will be used when working with acids. Kb is the base dissociation constant and will be used when working with bases. The larger the Ka value, the stronger the acid. The larger the Kb value, the stronger the base. Hope this helps!
- Sun Jan 10, 2021 3:28 pm
- Forum: Ideal Gases
- Topic: Difference between real and ideal gas
- Replies: 10
- Views: 1195
Re: Difference between real and ideal gas
Here's a table I find super helpful when looking at the difference between real and ideal gas. Hope this helps!
- Sun Jan 10, 2021 3:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: solids and liquids in k expression
- Replies: 4
- Views: 289
Re: solids and liquids in k expression
Since they are not dissolved in a solvent, solids have no concentration (molL-1). Liquids are not included because their effective concentrations do not change in a reaction. Hope this helps!
- Sun Jan 10, 2021 3:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Stability of reactants vs products
- Replies: 5
- Views: 624
Re: Stability of reactants vs products
If Kc subscript is very large, ~1000 or more, you will have mostly product species present at equilibrium. If Kc is very small, ~0.001 or less, you will have mostly reactant species present at equilibrium. If Kc subscript is in between 0.001 and 1000, you will have a significant concentration of bot...
- Sun Jan 10, 2021 3:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: increasing total pressure in equilibria
- Replies: 11
- Views: 510
Re: increasing total pressure in equilibria
If the pressure in a system increases or the volume decreases, the equilibrium will shift to favor the side of the reaction that involves fewer moles of gas. In contrast, if the volume of a system increases or the pressure decreases, the production of additional moles of gas will be favored. Hope th...
- Sun Jan 10, 2021 3:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentration
- Replies: 12
- Views: 745
Re: Concentration
Since concentration has moles/liter as its units, you cannot have a negative value. Hope this helps!
- Wed Dec 16, 2020 10:42 pm
- Forum: Lewis Acids & Bases
- Topic: Lewis vs Bronsted
- Replies: 20
- Views: 1251
Re: Lewis vs Bronsted
Bronsted acids donate H+ ions. Bronsted bases accept H+ ions. Lewis acids accept an electron pair. Lewis bases donate an electron pair. Think: bronsted=H+ AND Lewis=electrons. Hope this helps a bit!
- Wed Dec 16, 2020 10:39 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Organic vs Inorganic
- Replies: 5
- Views: 613
Re: Organic vs Inorganic
Organic molecules have carbon-hydrogen bonds. Inorganic molecules do not contain carbon-hydrogen bonds. While carbon can still appear in inorganic molecules, such as in carbon dioxide, it lacks the additional hydrogens that make it organic.
- Wed Dec 16, 2020 10:37 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Strong acid / base ion
- Replies: 8
- Views: 502
Re: Strong acid / base ion
The ions in the strong acid and base will completely dissociate and the solution will then be neutral.
- Wed Dec 16, 2020 10:35 pm
- Forum: General Science Questions
- Topic: atomic radius
- Replies: 7
- Views: 5947
Re: atomic radius
Both ions have their outermost electrons located on the same energy level, but they do not have the same ionic radius. The number of protons each species has in its nucleus varies. Potassium, which has an atomic number equal to 19, has 19 protons in its nucleus. Chlorine has 17. In the case of the p...
- Wed Dec 16, 2020 10:31 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Difference between pH and pOH
- Replies: 12
- Views: 1204
Re: Difference between pH and pOH
Kb and pKb relate to bases. A large Kb value indicates the high level of dissociation of a strong base. A lower pKb value indicates a stronger base. Kb is the base dissociation constant, while pKb is the -log of the constant. These values account for hydroxide ion concentration. pH tells us the conc...
- Wed Dec 16, 2020 10:26 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric vs Amphiprotic
- Replies: 7
- Views: 531
Re: Amphoteric vs Amphiprotic
An amphiprotic substance is one that donates hydrogen ions (protons) and also accepts them. Amphoteric means that they have reactions as both acids and bases.Hope this helps!
- Wed Dec 16, 2020 10:25 pm
- Forum: Naming
- Topic: Dentate Naming and Lewis Structures
- Replies: 3
- Views: 338
Re: Dentate Naming and Lewis Structures
To see if a ligand is a bidentate, tridentate, or hexadentate, you look to see how many lone pairs there are on the different atoms. The best way to see this is by drawing a lewis structure. For example, a bidentate would have two lone pairs, each on different atoms. Hope this helps!
- Wed Dec 16, 2020 10:21 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Tetrahedral molecular shape
- Replies: 10
- Views: 1849
Re: Tetrahedral molecular shape
The angle 109.5 degrees is obtained when all four pairs of outer electrons repel each other equally. The bond angles in tetrahedral structures are less than 109.5° because of the stronger repulsion by their lone pairs of electrons.
- Wed Dec 16, 2020 10:18 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Recognizing ligand binding sites
- Replies: 5
- Views: 518
Re: Recognizing ligand binding sites
As explained in the posts above, the number of lone pairs on an atom that can be donated will affect the number of possible ligand binding sites.
- Wed Dec 16, 2020 10:14 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability of anions
- Replies: 6
- Views: 1035
Re: Polarizability of anions
I think the rules for comparing polarizability will help with this and similar questions: The greater the number of electrons, the less control the nuclear charge has on charge distribution, and thus the increased polarizability of the atom. The greater the distance of electrons from nuclear charge,...
- Sun Dec 06, 2020 11:59 am
- Forum: Naming
- Topic: Monodentates and Polydentates
- Replies: 8
- Views: 655
Re: Monodentates and Polydentates
The term "monodentate" refers to the ligand binding to the center through only one atom. Some examples of monodentate ligands are chloride ions, water, hydroxide ions, and ammonia. Bidentate ligands have two donor atoms which allow them to bind to a central metal atom or ion at two points....
- Sun Dec 06, 2020 11:55 am
- Forum: Naming
- Topic: Coordination Compound vs complex ion
- Replies: 4
- Views: 3116
Re: Coordination Compound vs complex ion
A coordination complex is the product of a Lewis acid-base reaction in which neutral molecules or anions (called ligands) bond to a central metal atom (or ion) by coordinate covalent bonds. Compounds that contain a coordination complex are called coordination compounds. Coordination compounds and co...
- Sun Dec 06, 2020 11:40 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: sapling q 7
- Replies: 3
- Views: 480
Re: sapling q 7
Here's the set of rules I typically consult to determine that. Hope this helps! - If the salt's anion is the conjugate base of a strong acid, then its solution will be neutral. - If the salt's anion is the conjugate base of a weak acid, then its solution will be basic. - If the salt's cation is the ...
- Sun Dec 06, 2020 11:34 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Energy levels
- Replies: 5
- Views: 487
Re: Energy levels
Though context would suggest which is better to use, both formulas should produce the same result. There was probably an error in your calculation! Hope this helps.
- Sun Dec 06, 2020 11:28 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: pH Strengths
- Replies: 3
- Views: 251
Re: pH Strengths
The pH scale is logarithmic and as a result, each whole pH value below 7 is ten times more acidic than the next higher value. For example, pH 4 is ten times more acidic than pH 5 and 100 times (10 times 10) more acidic than pH 6. The same holds true for pH values above 7, each of which is ten times ...
- Sun Nov 29, 2020 2:40 pm
- Forum: Lewis Structures
- Topic: Tips on drawing Lewis structures
- Replies: 21
- Views: 2345
Re: Tips on drawing Lewis structures
Hi! Here are the general steps I follow when drawing lewis structures. First, determine the total number of valence electrons in a molecule. Second, draw a skeleton for the molecule which connects all atoms using only signal bonds. Third, arrange the remaining electrons to fill as many octets as pos...
- Sun Nov 29, 2020 2:33 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: sigma vs pi bonds
- Replies: 33
- Views: 2214
Re: sigma vs pi bonds
Sigma and pi bonds are chemical covalent bonds. Sigma and pi bonds are formed by the overlap of atomic orbitals. Sigma bonds are formed by end-to-end overlapping and Pi bonds are when the lobe of one atomic orbital overlaps another. Generally, sigma bonds are stronger than pi bonds because sigma bon...
- Sun Nov 29, 2020 2:26 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Seesaw and T-shapes
- Replies: 4
- Views: 816
Re: Seesaw and T-shapes
The seesaw shape maximizes the bond angles of the single lone pair and the other atoms in the molecule. The lone pair is in an equatorial position offering 120 and 90 degree bond angles, compared to only 90 degree bond angles if placed at the axial position. The T shaped structure minimizes the rema...
- Sun Nov 29, 2020 2:22 pm
- Forum: Lewis Structures
- Topic: Molecular Shapes
- Replies: 5
- Views: 801
Re: Molecular Shapes
In case you still needed an in-depth explanation as well as diagrams and images, here's a super helpful link that I used for studying!
https://study.com/academy/lesson/molecu ... mples.html
https://study.com/academy/lesson/molecu ... mples.html
- Sun Nov 29, 2020 2:14 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: delocalized pi bond
- Replies: 8
- Views: 541
Re: delocalized pi bond
Localized electrons exhibit normal behavior, a localized lone pair remains close to one atom, and a localized bond pair travels between two atoms. Resonance hybrids necessarily contain some "abnormal" electrons. In a delocalized pi bond, instead of sticking near one atom, it visits two ato...
- Sun Nov 15, 2020 11:20 am
- Forum: Octet Exceptions
- Topic: How does sulfur have up to 12 valence electrons
- Replies: 3
- Views: 2687
Re: How does sulfur have up to 12 valence electrons
Sulfur has one more electron pair in its 3s subshell so it can undergo excitation and place the electron in another empty 3d orbital. Now sulfur has 6 unpaired electrons which means it can form 6 covalent bonds to give a total of 12 electrons around its valence shell. Hope this helps with understand...
- Sun Nov 15, 2020 11:11 am
- Forum: Lewis Structures
- Topic: Nitrite vs Nitrate
- Replies: 17
- Views: 1347
Re: Nitrite vs Nitrate
I'm more of a visual learner and this video does a great job explaining nomenclature. Even though we don't need to memorize a lot of these structures, I think it's helpful to understand the reasoning behind the names.
https://www.youtube.com/watch?v=peguZTUTgHI
Hope this helps!
https://www.youtube.com/watch?v=peguZTUTgHI
Hope this helps!
- Sun Nov 15, 2020 11:04 am
- Forum: Trends in The Periodic Table
- Topic: Trends on the Period Table
- Replies: 8
- Views: 614
Re: Trends on the Period Table
This link is super helpful for understanding and visualizing the periodic table trends. There are definitions as well as diagrams of periodic tables with arrows indicating the trends across the table. Hope this helps! https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Modules_and_Websites_(...
- Sun Nov 15, 2020 11:01 am
- Forum: Ionic & Covalent Bonds
- Topic: Hydrogen and Covalent Bonds
- Replies: 3
- Views: 13417
Re: Hydrogen and Covalent Bonds
Hydrogen bonds are weaker than covalent bonds because hydrogen bonds do not involve a formal electron exchange. The formal electron exchange strengthens the bond. In comparison, hydrogen bonds are weaker than covalent and ionic bonds but stronger than most Van der Waals forces.
Hope this helps!
Hope this helps!
- Sun Nov 15, 2020 10:52 am
- Forum: Lewis Structures
- Topic: Lewis Acid and Base Reactions (Sapling Week 5/6 #6)
- Replies: 4
- Views: 223
Re: Lewis Acid and Base Reactions (Sapling Week 5/6 #6)
For shortcuts, I typically consider the following: Lewis Acids: cations, an atom/ion/molecule with an incomplete octet, molecules where the central atom can have more than 8 valence shell electrons, and molecules that have multiple bonds between atoms of different electronegativity. Lewis Bases: ani...
- Thu Nov 05, 2020 2:23 pm
- Forum: Ionic & Covalent Bonds
- Topic: Electron Affinity
- Replies: 5
- Views: 184
Re: Electron Affinity
Fluorine is a small atom with a small amount of space available in its 2p orbital. Because of this, any new electron trying to attach to fluorine experiences lower electron affinity from the electrons already living in the element's 2p orbital. Since chlorine's outermost orbital is a 3p orbital, the...
- Thu Nov 05, 2020 2:21 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 1
- Replies: 5
- Views: 164
Re: Midterm 1
Some of the larger questions gave partial credit for some of the multiple-choice answers. Since partial credit was given, we had decimals in our final scores!
- Thu Nov 05, 2020 2:18 pm
- Forum: Lewis Structures
- Topic: Chemical Formulas
- Replies: 8
- Views: 367
Re: Chemical Formulas
I think as long as you have the common ones memorized, you should be fine! So far, that has been what my TA and Lavelle have said. Just be sure to double-check with your TA just in case!
- Thu Nov 05, 2020 2:14 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Scores
- Replies: 28
- Views: 1327
Re: Midterm Scores
The grades are posted on both CCLE and under grades and exams on MyUCLA!
- Thu Nov 05, 2020 2:13 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 1
- Replies: 9
- Views: 416
Re: Midterm 1
The grades are posted on both CCLE and under grades and exams on MyUCLA.
- Sun Nov 01, 2020 6:20 pm
- Forum: Octet Exceptions
- Topic: Other Exceptions
- Replies: 4
- Views: 253
Re: Other Exceptions
Yes, they are exceptions to the octet rule. I would assume he may mention it in the future or your TA will mention that during discussion. Hope this helped!
- Sun Nov 01, 2020 6:19 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Week 2,3,4 Sapling HW
- Replies: 5
- Views: 421
Re: Week 2,3,4 Sapling HW
If you still need some help, I would recommend using the value of R that Dr. Lavelle includes on his formula sheet: 3.28984*10^15 Hz. Hope this helped!
- Sun Nov 01, 2020 6:15 pm
- Forum: Photoelectric Effect
- Topic: Lyman Series
- Replies: 30
- Views: 1350
Re: Lyman Series
If the problem mentions the Lyman Series, there should be an n=1 somewhere in the equation. The Lyman series is in the ultraviolet while the Balmer series is in the visible and the Paschen, Brackett, Pfund, and Humphreys series are in the infrared.
Hope this helped!
Hope this helped!
- Sun Nov 01, 2020 6:13 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: ml atomic number
- Replies: 2
- Views: 140
Re: ml atomic number
Hi! The Ml atomic number specifies the orientation in space of an orbital of given energy (n) and shape (l). This number divides the subshell into individual orbitals which hold the electrons; there are 2l+1 orbitals in each subshell. Thus the s subshell has only one orbital, the p subshell has thre...
- Sun Nov 01, 2020 6:10 pm
- Forum: DeBroglie Equation
- Topic: Avogadro's Number
- Replies: 21
- Views: 1729
Re: Avogadro's Number
Hello! The answers above are super helpful, but I'm definitely a visual learner so I found a youtube video that explains super clearly! Hope this helps.
https://www.youtube.com/watch?v=M5q_YMN4CtY
https://www.youtube.com/watch?v=M5q_YMN4CtY
- Sun Oct 25, 2020 10:21 am
- Forum: Limiting Reactant Calculations
- Topic: Fundamental M.9
- Replies: 3
- Views: 690
Re: Fundamental M.9
First, you need to write the net ionic equation. In a net ionic equation, you do not need to include the spectator ions. So, in this case, you do not need to include NO3 and Na. That means, in the end, the net ionic equation, will be Cu2+ + 2(OH)- yields Cu(OH)2. In part b), you need to find the gra...
- Sun Oct 25, 2020 10:11 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Focus 1 Exercises: 1.3
- Replies: 2
- Views: 90
Re: Focus 1 Exercises: 1.3
Just be sure to convert the wavelength given in nanometers to meters since the constant c, the speed of light, is in meters.
- Sun Oct 25, 2020 10:08 am
- Forum: Limiting Reactant Calculations
- Topic: Actual yield
- Replies: 20
- Views: 925
Re: Actual yield
Given most of the practice problems in the textbook for this course, I would say they will give us the actual yield! If not, they would give you enough info (theoretical and percent yield) to be able to find it.
- Sun Oct 25, 2020 10:05 am
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Avogadro's #
- Replies: 33
- Views: 4251
Re: Avogadro's #
If you still need help, I find videos super helpful for things like these! This is a 3-minute video that is super easy to understand and really gives a detailed yet brief explanation! https://www.youtube.com/watch?v=jHbocq7n1Ew
- Sun Oct 25, 2020 10:01 am
- Forum: Empirical & Molecular Formulas
- Topic: Midterm - Chemical compund equations?
- Replies: 7
- Views: 433
Re: Midterm - Chemical compund equations?
Like everyone said above, you should be ok for the first midterm. Once Dr. Lavelle goes over that topic in the lecture/your TA covers it, then it'll probably be expected for you to understand. Otherwise, I think just the well-known compounds are expected to be memorized! Good luck on the midterm!
- Sun Oct 18, 2020 12:15 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Can an electron stay in its excited state? [ENDORSED]
- Replies: 18
- Views: 1830
Re: Can an electron stay in its excited state? [ENDORSED]
Electrons do not stay in excited states for very long - they soon return to their ground states, emitting a photon with the same energy as the one that was absorbed.
- Sun Oct 18, 2020 12:13 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Test Accuracy
- Replies: 13
- Views: 842
Re: Test Accuracy
Hi! I believe Dr. Lavelle asked us to use the traditional sig fig rules - in the final answer, use the same number of sig figs as the smallest given value in the original problem. Hope this helped
- Tue Oct 13, 2020 1:48 pm
- Forum: Limiting Reactant Calculations
- Topic: Difference between limiting reactant and limiting reagent?
- Replies: 14
- Views: 2401
Re: Difference between limiting reactant and limiting reagent?
Limiting reagent and limiting reactant are the same thing! I think it's easiest to always call it the limiting reactant so you know which side - reactants vs products - the limiting compound will be found (hopefully that makes sense). Just keep in mind that if you see "limiting reagent" it...
- Tue Oct 13, 2020 1:41 pm
- Forum: Properties of Light
- Topic: video modules
- Replies: 10
- Views: 349
Re: video modules
I found that the modules are very helpful to do before each week's lectures. There are a series of objectives for each week that Dr. Lavelle sent us and you can look at them to see which video to do in preparation for the week!
- Tue Oct 13, 2020 1:38 pm
- Forum: Properties of Electrons
- Topic: Quanta vs Photons
- Replies: 4
- Views: 189
Re: Quanta vs Photons
Hi! Here is my understanding of each of them and their difference: A quantum is a packet of energy that may or may not be light energy. A photon is a packet of light energy. The different is that a photon is light energy, while quanta may not be light energy. To sum up: a quantum may not be a photon...
- Thu Oct 08, 2020 12:36 pm
- Forum: SI Units, Unit Conversions
- Topic: SI Base Unit Kg
- Replies: 5
- Views: 256
Re: SI Base Unit Kg
I would recommend using the units that the initial problem uses unless the problem states for you to change the units in your final answer. Hope this helps!
- Thu Oct 08, 2020 12:31 pm
- Forum: Properties of Light
- Topic: Converting wavelength to Angstrom
- Replies: 5
- Views: 908
Re: Converting wavelength to Angstrom
Not a dumb question at all!! An angstrom is a unit of length that represents 10^-10 meter. Typically, it is used as a unit for wavelengths or distances between atoms. Hope that helped!
- Thu Oct 08, 2020 12:22 pm
- Forum: Balancing Chemical Reactions
- Topic: States of Matter in Chemical Equations
- Replies: 13
- Views: 325
Re: States of Matter in Chemical Equations
Hello!
I would continue to write states of matter when balancing equations as I am pretty sure Dr. Lavelle uses the states of matter throughout his examples during lectures. Plus I'm sure it will be good practice for when we eventually take higher-level chemistry classes.
Hopefully that helps!
I would continue to write states of matter when balancing equations as I am pretty sure Dr. Lavelle uses the states of matter throughout his examples during lectures. Plus I'm sure it will be good practice for when we eventually take higher-level chemistry classes.
Hopefully that helps!
- Thu Oct 08, 2020 12:11 pm
- Forum: Empirical & Molecular Formulas
- Topic: Sapling Homework 1 Question 9
- Replies: 9
- Views: 767
Re: Sapling Homework 1 Question 9
I believe that the ± in "molar mass of 110±10 g/mol" means that the mean molar mass of the compound is 100g/mol, but can vary by one standard deviation (10g/mol). While completing the problem, use the mean value of molar mass.
- Thu Oct 08, 2020 11:47 am
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Sapling E.5
- Replies: 3
- Views: 470
Re: Sapling E.5
Hi! For part A, you need to convert the units of people to moles. You can do so by dividing the world's population (in people) by Avogadro's number (6.022*10^23). This will convert the population of the world to the units you would need for part B. Hoepfully that helps a bit!