Search found 104 matches

by Ryan Narisma 4G
Mon Mar 09, 2020 11:18 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermal Irreversible Free Expansion
Replies: 3
Views: 82

Re: Isothermal Irreversible Free Expansion

Hi sarahforman_Dis2I! To answer your question, "free expansion" refers to the idea that there is no work done on the system or by the system. Thus, there is no interaction between the system and surroundings, so the delta S of the surroundings is zero. And because delta S(total) = delta S(...
by Ryan Narisma 4G
Mon Mar 09, 2020 11:10 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Reactant order
Replies: 4
Views: 54

Re: Reactant order

Hi vpena_1I! To answer your question, notice that whenever you change the concentration of the C, the rate of the reaction does not change. But between experiments 1 and 4 the concentration of A and B do not change while C changes, but the rate stays the same. C is thus zero order.In experiments 2 a...
by Ryan Narisma 4G
Mon Mar 09, 2020 10:55 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Pre-Equilibrium
Replies: 3
Views: 54

Re: Pre-Equilibrium

Hi Charisse Vu 1H! We use the pre-equilibrium approach because it makes it easier to relate the rates of the forward and reverse reaction in the elementary reaction that occurs before the slowest step. The steady state approximation involves the use of differential equations which make it harder for...
by Ryan Narisma 4G
Mon Mar 09, 2020 10:51 am
Forum: General Rate Laws
Topic: 7.23b
Replies: 1
Views: 78

Re: 7.23b

Hi Alicia Lin 2F! To answer your question, the overall rate law is determined by looking at the slowest step in the mechanism because the slowest step dictates how fast the reaction progresses. To clarify, the goal of the rate law is not to express it in terms of reactants and products but to expres...
by Ryan Narisma 4G
Mon Mar 09, 2020 10:46 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 7E.5
Replies: 1
Views: 43

Re: 7E.5

Hi Joseph Saba! To answer your question, a catalyst is a species that remains unchanged as the reaction progresses. In this mechanism we start out with OH- as a reactant but in the end we have a product OH-, so the species OH- was put in the reaction in step 1 only to be made as a product in step 2....
by Ryan Narisma 4G
Mon Mar 02, 2020 3:32 pm
Forum: Balancing Redox Reactions
Topic: 6K.5
Replies: 1
Views: 40

Re: 6K.5

Hi Rida Ismail 2E! Ozone is reduced because the oxidation number of oxygen changes from 0 to -2. If you take a look at the bromate ion (BrO3-) the oxidation number of the oxygen is -2. However the bromide ion changes from an oxidation number of -1 to +5, it oxidized to a really high positive number....
by Ryan Narisma 4G
Mon Mar 02, 2020 3:13 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6O.1 and 6O.3
Replies: 2
Views: 116

Re: 6O.1 and 6O.3

Hi! To answer your question, in an electrolytic cell you are trying to precipitate out metal solids from their ionic constituents through input of electrical energy in the solution. In this case we have Nickel (II) Sulfate, so the end goal is to reduce the nickel ion into nickel solid. Because the m...
by Ryan Narisma 4G
Mon Mar 02, 2020 3:02 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Hw 6.51
Replies: 1
Views: 27

Re: Hw 6.51

Hi Baoying Li 1B! In a galvanic cell, the electrons flow from anode to cathode (oxidation reaction to reduction reaction). As the electrons move from anode to cathode, there is a charge imbalance in the cells. To prevent this buildup of charge and keep the electrical current flowing, a salt bridge i...
by Ryan Narisma 4G
Mon Mar 02, 2020 2:57 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: HW Question 6N.23 Part A
Replies: 2
Views: 69

Re: HW Question 6N.23 Part A

Hi Fiona Latifi 1A! When something is below another metal in the elctrochemical series it means that the species that is below is better at reducing the metal that's above. Cathodic protection involves connecting the pipeline to something that's more strongly reducing—that is the metal that is more ...
by Ryan Narisma 4G
Mon Mar 02, 2020 2:49 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.7c HW
Replies: 1
Views: 50

Re: 6L.7c HW

Hi Hannah Lee 2F! To answer your first question, the reason why there is a line in between the two solids is to differentiate between the metal electrode used in the cell from the solid involved in the reaction. OH- is present in the diagram as the base, KOH. I think it's the in anode half reaction ...
by Ryan Narisma 4G
Thu Feb 27, 2020 11:54 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Problem 5.55
Replies: 1
Views: 38

Re: Problem 5.55

Hi Savannah Mance 4G! To answer your question, in this problem we are given the gibbs free energy values at 900K. From there we can calculate the gibbs free energy of the reaction at 900K. Once that is calculated, you can use the fact that: \Delta G ^{\circ} = -RT ln K. Isolate ln K and take the exp...
by Ryan Narisma 4G
Thu Feb 27, 2020 11:48 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M5a
Replies: 1
Views: 49

Re: 6M5a

Hi! To my understanding, in a cell diagram we must write all the species present in each of the half reactions, unless a particular species cancels out when combining the half-reactions together. In the NO 3 - /NO reaction, the H+ is a species which is interacting with the gases and the electrode; t...
by Ryan Narisma 4G
Thu Feb 27, 2020 11:42 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Homework 6L.7
Replies: 1
Views: 54

Re: Homework 6L.7

Hi Victoria Zheng--2F! I answered this question in a previous post but I'm happy to explain it again! Firstly, if you take a look at the back of the textbook in Appendix 2B you can find all the standard potentials of a variety of reactions. In 7(a), the question is asking for the cell diagram and th...
by Ryan Narisma 4G
Thu Feb 27, 2020 11:37 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.7(a)
Replies: 1
Views: 52

Re: 6L.7(a)

Hi Althea Zhao 1B! To answer your question, if you take a look at the back of the textbook in Appendix 2B you can find all the standard potentials of common reactions. In 7(a), the question is asking for the cell diagram and the cell potential of the solubility of silver bromide. If you look in the ...
by Ryan Narisma 4G
Thu Feb 27, 2020 11:31 am
Forum: Balancing Redox Reactions
Topic: Homework L3 part d
Replies: 1
Views: 44

Re: Homework L3 part d

Hi MaryBanh_2K! To help answer your question, first of all this question is a little tricky since the anode in the cell diagram has species which have no atoms in common. Due to this lack of overlap we have to take into account that H+ is in solution—meaning that it is dissolved in water which gives...
by Ryan Narisma 4G
Thu Feb 27, 2020 11:17 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Midterm 3B
Replies: 1
Views: 111

Re: Midterm 3B

Hi! To answer your question, the question does take into account of the amount of moles of strong acid and strong base reacting, and you are definitely correct! Now that you've discerned which reactions have the maximum amount of moles, pay close attention to the the other changing variable: the vol...
by Ryan Narisma 4G
Tue Feb 18, 2020 11:01 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free naught
Replies: 2
Views: 49

Re: Gibbs Free naught

Hi! To answer your question, the \Delta G = \Delta G ^{\circ} + RT ln Q equation represents the gibbs free energy dependence on the concentrations/partial pressures of the products and the reactants at a certain instance in the reaction. If the reaction quotient is greater than the value of K at a g...
by Ryan Narisma 4G
Tue Feb 18, 2020 10:43 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 5G.17
Replies: 2
Views: 28

Re: 5G.17

Hi Junwei Sun 4I! To answer your question, because the reaction quotient value is greater than the value of K at this temperature, the reaction will proceed to form more reactants (I 2 gas). The graph is depicting this instance. As time progresses, the reaction will start to form more I 2 , hence th...
by Ryan Narisma 4G
Tue Feb 18, 2020 10:37 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Spontaneous
Replies: 10
Views: 230

Re: Spontaneous

Hi Ian Morris 3C! To answer your question, when the Gibbs free energy value is less than 0 (a negative value), the reaction will be spontaneous. However, spontaneity does not correlate with the time it takes for the reaction to complete. I hope this helps!
by Ryan Narisma 4G
Tue Feb 18, 2020 10:35 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Adiabatic systems
Replies: 3
Views: 84

Re: Adiabatic systems

Hi Ian Morris 3C! Yes! You are correct! In an adiabatic system, there is no heat transfer between the system and surroundings, so heat can't be added or released to/by the system. Thus, q will always be 0. I hope this helps!
by Ryan Narisma 4G
Tue Feb 18, 2020 10:34 pm
Forum: Balancing Redox Reactions
Topic: 6K.1
Replies: 1
Views: 23

Re: 6K.1

Hi ayushibanerjee06! To answer your question, when we refer to oxidation numbers we are referring to the oxidation number of a single atom of the element in question. You are correct in stating that the total oxidation number that the carbons have combined have a +4 charge; however, because there ar...
by Ryan Narisma 4G
Tue Feb 11, 2020 4:05 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4D.3
Replies: 1
Views: 43

Re: 4D.3

Hello RRahimtoola1I! To answer your question, part B involves calculating both q and w. Because this reaction is in a bomb calorimeter, the volume stays constant and with volume constant you don't have work! All you have to do is calculate q given the heat capacity of the calorimeter! You would then...
by Ryan Narisma 4G
Tue Feb 11, 2020 4:01 pm
Forum: Phase Changes & Related Calculations
Topic: 4.5 Time
Replies: 1
Views: 41

Re: 4.5 Time

Hello! In this problem, the 0.5 hours comes from the fact that it takes 30 minutes for liquid water at 0 C to raise the temperature to 5 C. I hope this helps!
by Ryan Narisma 4G
Tue Feb 11, 2020 3:57 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: weird residual entropy formula from class
Replies: 1
Views: 33

Re: weird residual entropy formula from class

Hello Emily Vainberg 1D! To answer your question, the equation that you wrote in your notes is specifically for 1 mol of a species that has two possible microstates. If you were to plug these conditions in the boltzmann equation (S = kB ln W) you'd get S = kB ln 2^(1 mol = 6.022 x 10^23 particles). ...
by Ryan Narisma 4G
Tue Feb 11, 2020 3:52 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Homework 4G.3
Replies: 2
Views: 33

Re: Homework 4G.3

Hi! To answer your question, when we talk about which molecule has more positional or residual entropy we have to take into account of how many microstates the molecule can take because molecules that have more microstates will have more positional entropy. When comparing these two molecules it is h...
by Ryan Narisma 4G
Tue Feb 11, 2020 3:13 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4I.5
Replies: 1
Views: 41

Re: 4I.5

Hello Jason Wu 1E! To answer your question, I would start off by finding the equilibrium temperature at which both masses of water will congregate. Then I would use the fact that delta S is equal to nCv ln (T2/T1). Using the temperature changes, and the molar heat capacity of water to calculate the ...
by Ryan Narisma 4G
Tue Feb 04, 2020 4:34 pm
Forum: Calculating Work of Expansion
Topic: 4B.13 part a
Replies: 1
Views: 26

Re: 4B.13 part a

Hi Maya Gollamudi 1G! To answer your question, you would use the work equation for irreversible expansion because the expansion occurs at constant pressure. I hope this helps!
by Ryan Narisma 4G
Tue Feb 04, 2020 4:32 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 4A. 13)
Replies: 2
Views: 33

Re: 4A. 13)

Hi Michael Du 1E! The given value is the temperature change that the calorimeter experienced when the 3.50 kJ of heat was added to the calorimeter containing 200 mL of solution. Because the temperature change is the same as if it was in Celsius or Kelvin, you can interchange the units. Take for exam...
by Ryan Narisma 4G
Tue Feb 04, 2020 4:23 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4D.7
Replies: 1
Views: 29

Re: 4D.7

Hi eduardomorales5! To answer your question, firstly because the chemical reaction produces gas we must take into account of not only the enthalpy change but also the work of expansion done by the system to calculate the change in internal energy. So to calculate enthalpy change, use the given that ...
by Ryan Narisma 4G
Tue Feb 04, 2020 4:15 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.1a
Replies: 4
Views: 49

Re: 4F.1a

Hi Amy Xiao 1I! To answer your question, the question is asking for the rate at which entropy is generated. Rate is typically some value per unit of time. For example, we have MPH, the rate of how far you're traveling (miles) per unit of time (hour). Because we want the rate of entropy generated, we...
by Ryan Narisma 4G
Tue Feb 04, 2020 4:08 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Temperature in Second Law
Replies: 2
Views: 24

Temperature in Second Law

Does the temperature have to be in Kelvin when calculating entropy or can I just leave it as Celsius? Thank you!
by Ryan Narisma 4G
Mon Jan 27, 2020 8:51 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4C.13
Replies: 3
Views: 43

Re: 4C.13

Hello Alicia Lin 2F! First of all, you are correct in setting the equations equal to each other. Did you take into account of the heat required to change the solid water (ice) to liquid water? Because there is an ice cube in the water, reaching the equilibrium temperature requires the heat required ...
by Ryan Narisma 4G
Mon Jan 27, 2020 8:47 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Stirrer in Calorimeter?
Replies: 3
Views: 21

Stirrer in Calorimeter?

Hello, why is there a stirrer in both the coffee/polystyrene cup calorimeter and the bomb calorimeter? What is the stirrer's function? Thank you in advanced!
by Ryan Narisma 4G
Mon Jan 27, 2020 8:43 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy of sublimation?
Replies: 8
Views: 63

Enthalpy of sublimation?

Will we ever need to calculate the enthalpy of sublimation or use this value in any of our calculations? If so, how do you perform calculations using enthalpy of sublimation? Thank you!
by Ryan Narisma 4G
Mon Jan 27, 2020 8:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibria
Replies: 4
Views: 32

Re: Chemical Equilibria

Hi to answer the second part of the post. At equilibrium the concentrations of both the reactants and products will stay the same (in other words, the concentration of the products and the reactants will not change). I hope this helps!
by Ryan Narisma 4G
Mon Jan 27, 2020 8:28 pm
Forum: Phase Changes & Related Calculations
Topic: #4C11
Replies: 2
Views: 36

Re: #4C11

Hi! The molar heat of vaporization can be found on page 268 in the 7th edition of the textbook (table 4C.1). It also has heat of fusion and boiling/melting points! I hope this helps!
by Ryan Narisma 4G
Tue Jan 21, 2020 11:06 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6.A.23
Replies: 1
Views: 24

Re: 6.A.23

Hi! The reason why Barium Hydroxide, Ba(OH)2, does not have a Kb value is because the species is a strong base. Strong bases completely dissociate in their constituent "ions" of Ba2+ and OH-. Because all of the Ba(OH)2 dissociate, then the concentration for Barium hydroxide would be the sa...
by Ryan Narisma 4G
Tue Jan 21, 2020 11:02 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: van't hoff's equation
Replies: 3
Views: 37

Re: van't hoff's equation

Hi! I think we don't need to know the equation because it deals with thermodynamics and this test focuses on equilibrium and acid/base equilibria. I hope I'm right.
by Ryan Narisma 4G
Tue Jan 21, 2020 11:00 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: exothermic reactions
Replies: 19
Views: 189

Re: exothermic reactions

Hello! When you are given that the reaction is exothermic, then the reaction produces heat. In this case you can think of the addition of heat (whether endothermic or exothermic) as a product or a reactant in the reaction. You would essentially treat heat like you would with concentrations. If heat ...
by Ryan Narisma 4G
Tue Jan 21, 2020 10:57 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: help with hw problem
Replies: 1
Views: 24

Re: help with hw problem

Hi! To answer your question, if the reaction quotient (Q) is equal to the equilibrium constant (K), then the reaction is at equilibrium. Otherwise, the reaction will proceed to the reactants (if Q>K) or will proceed to the products side (if Q<K). In this problem specifically you are calculating the ...
by Ryan Narisma 4G
Tue Jan 21, 2020 10:53 am
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: help with hw problem
Replies: 1
Views: 139

Re: help with hw problem

Hi! To answer your question, you would first convert all the millimolar quantities to molar quantities using the fact that 1 mol = 1000 millimoles. Then determine the concentration using the volume given. And then calculate the reaction quotient using those concentration. Remember that the reaction ...
by Ryan Narisma 4G
Tue Jan 14, 2020 1:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE charts on tests/exams
Replies: 8
Views: 67

ICE charts on tests/exams

Do we have to include the ICE chart in tests and exams or can we just write the equilibrium expression using the variables?
by Ryan Narisma 4G
Tue Jan 14, 2020 12:54 pm
Forum: Polyprotic Acids & Bases
Topic: 6E.1
Replies: 1
Views: 65

Re: 6E.1

Hi! I think we just need to know what they mean and we know of them to see the pattern that as you remove a proton (H+) the Ka decreases significantly. On exams and the final I'm sure Dr. Lavelle will provide us with the necessary acid constants. I hope this helps!
by Ryan Narisma 4G
Tue Jan 14, 2020 11:27 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Expansion
Replies: 5
Views: 36

Re: Expansion

Hi! To answer your question, yes increasing volume affects a reaction at equilibrium. It does not, however, affect the value of Keq as long as the system is under constant temperature as you expand volume. Expanding the volume changes the molar concentrations of the reactants and products by reducin...
by Ryan Narisma 4G
Tue Jan 14, 2020 11:16 am
Forum: Ideal Gases
Topic: Problem 5l.11
Replies: 2
Views: 43

Re: Problem 5l.11

Hi! To solve this problem, let's first convert he millimols (mmol) to regular moles so we have the correct molarity. Dividing each mole value by 10^3 gives us: 1.20x10^(-3) mol SO2, 5.0x10^(-4) mol O2, 1.0x10^(-4) mol SO3. Divide each value by the reaction vessel volume of 0.500 L (remember to conve...
by Ryan Narisma 4G
Mon Jan 13, 2020 11:29 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Autoprotolysis of water endo or exo?
Replies: 4
Views: 31

Autoprotolysis of water endo or exo?

Is the autoprotolysis of water an endothermic reaction or exothermic? The reaction forms an OH bond and is breaking an OH bond so is the change in enthalpy 0?
by Ryan Narisma 4G
Thu Jan 09, 2020 8:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: finding the equilibrium constant
Replies: 2
Views: 27

Re: finding the equilibrium constant

I think we should be able to use either if the problem does not specify Kc or Kp. I know that if a concentration is given we should use Kc and if a pressure is given we should use Kp but, I believe in gas phase, as illustrated in class, you can give equilibrium constants in either concentration or ...
by Ryan Narisma 4G
Thu Jan 09, 2020 8:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: How does the concentration change the equilibrium constant?
Replies: 2
Views: 29

Re: How does the concentration change the equilibrium constant?

Hi nicolely3B! You are correct in saying that the K doesn't change as long as it is the exact same reaction. In the practice problems, these reactions are not exactly the same. They differ by the stoichiometric coefficients used in the Keq expression. The original expression looks something like thi...
by Ryan Narisma 4G
Thu Jan 09, 2020 8:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Catalyst and Equilibrium
Replies: 2
Views: 18

Re: Catalyst and Equilibrium

Hi 805312064. Adding a catalyst to a reaction only speeds up the reaction in the forward and the reverse direction by lowering the activation energy and providing a different pathway to creating product/reactant. Catalysts do not change the concentrations of the products and reactants at equilibrium...
by Ryan Narisma 4G
Thu Jan 09, 2020 8:13 pm
Forum: Ideal Gases
Topic: How Plausible is Ideal Gas?
Replies: 1
Views: 31

Re: How Plausible is Ideal Gas?

Gases behave ideally in situations when they have perfectly inelastic conditions. Gas molecules in a container typically collide with each other and bump into each other frequently because they're rapidly moving through the volume. However, when gas molecules collide, they start to have intermolecul...
by Ryan Narisma 4G
Thu Jan 09, 2020 7:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ksp?
Replies: 2
Views: 28

Ksp?

Do we need to know the solubility-product constant (Ksp) in this course?
by Ryan Narisma 4G
Thu Dec 05, 2019 8:42 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Acidity and Resonance/Delocalization
Replies: 1
Views: 51

Re: Acidity and Resonance/Delocalization

Hi Lindsey Chheng 1H! To answer your question, acids will be strong in either of the two conditions: 1. The length of the H-A bond is longer and can be broken easily or 2. The resulting anion after the acid gives its H+ away is more stable. The first condition is pretty straightforward, Dr. Lavelle ...
by Ryan Narisma 4G
Thu Dec 05, 2019 8:31 pm
Forum: Bronsted Acids & Bases
Topic: Neutral/Negatively Charged Acid
Replies: 1
Views: 42

Re: Neutral/Negatively Charged Acid

Hi Lindsey Chheng 1H! To answer your question, when an acid is negatively charged, it will be in the "ionized" form (it will dissociate). The example Dr. Lavelle gave in class is when an acid is poured in a solution and the solution's pH is either greater than pKa or less than pKa. The sol...
by Ryan Narisma 4G
Thu Dec 05, 2019 8:18 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Lewis Acid
Replies: 4
Views: 186

Re: Lewis Acid

Hi vanessas0123! To answer your question, keep in mind the the Lewis definition of acids and bases involve who's giving and who's accepting lone pairs of electrons, which is totally different from the Bronsted definition that involves who's accepting and giving protons (H+). In the Lewis definition,...
by Ryan Narisma 4G
Thu Dec 05, 2019 8:12 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Pd exception
Replies: 1
Views: 130

Re: Pd exception

Hi Vincent Leong 1A! I think Dr. Lavelle has mentioned that we only need to worry about the exceptions of transition metals in the third row of the periodic table. In other words, just the Chromium and Copper exceptions. I hope this helps!
by Ryan Narisma 4G
Thu Dec 05, 2019 8:09 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted vs. Lewis Definitions
Replies: 2
Views: 34

Re: Bronsted vs. Lewis Definitions

Hi Althea Zhao 1B! To answer your question, no matter what definition you use, the acid will be an acid and the base will be a base. Take for instance, NH3. In the lewis definition, ammonia would be a base because it can donate its lone pair of electrons to form a bond with a H+ atom. In the bronste...
by Ryan Narisma 4G
Mon Nov 25, 2019 8:59 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: ETDA formula - acetate or acetic acid end?
Replies: 1
Views: 86

Re: ETDA formula - acetate or acetic acid end?

Hello Tiffany Chen 1K! To answer your question, ethylenediaminetetra acetato is the ligand that can bind to the transition metal because it has available lone pairs of electrons on the negatively charged oxygen atoms. However, when you're speaking about the ethylenediaminetetra acetic acid , the neg...
by Ryan Narisma 4G
Mon Nov 25, 2019 8:51 pm
Forum: Naming
Topic: naming complexes
Replies: 3
Views: 30

Re: naming complexes

Hi halle young 4A! To answer your question, typically the binding atom is the one that is named first in the ligand. Take for example ammonia. Ammonia will bind to a transition metal from the Nitrogen atom because the nitrogen atom has an available lone pair that can create a coordinate covalent bon...
by Ryan Narisma 4G
Mon Nov 25, 2019 8:43 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Prefixes
Replies: 1
Views: 43

Re: Prefixes

Hello Junwei Sun 4A! To answer your question, I think Dr. Lavelle mentioned two cases in which you would use the "bis-", "tris-", "tetrakis-"... etc. One would be if there is a "di-", "tri-", "tetra-"... etc. already in the ligand. Take for...
by Ryan Narisma 4G
Mon Nov 25, 2019 8:34 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Question on naming coordinate compound
Replies: 2
Views: 49

Re: Question on naming coordinate compound

I agree with I don't believe that ironate would be correct. From what I have understood based on the chart and textbook, ferrate seems to be the best choice for those examples. Technically, you're supposed to write "-ate" after the latin name of the element; however, because the latin name...
by Ryan Narisma 4G
Mon Nov 25, 2019 8:25 pm
Forum: Hybridization
Topic: Composition of each bond
Replies: 2
Views: 39

Re: Composition of each bond

Hello ariaterango_1A! I talked to my TA if we needed to know how to name the bonds in this way and he told me that all we need to know is how to identify whether a bond is a sigma or a pi bond. I hope this helps!
by Ryan Narisma 4G
Tue Nov 19, 2019 9:57 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: 3F.19
Replies: 5
Views: 102

Re: 3F.19

Hello Alexa Mugol 3I! To answer your question, diethyl ether is not capable of hydrogen bonding. When you draw the lewis structure of diethyl ether, the Oxygen atom is in the center of the diagram and is not connected to any hydrogens. If the oxygen were covalently bonded to a hydrogen, then diethyl...
by Ryan Narisma 4G
Tue Nov 19, 2019 9:41 pm
Forum: Sigma & Pi Bonds
Topic: Resonance Structures in 2F.3
Replies: 4
Views: 48

Re: Resonance Structures in 2F.3

Hello Alexa Mugol 3I! To answer your question, which resonance structure are you referring to? The lewis structure for SO2 would be S as central atom with a single bond between S and one of the Oxygens and a double bond between the S and the other Oxygen atom with a lone pair of electrons on the S a...
by Ryan Narisma 4G
Tue Nov 19, 2019 9:34 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: Boiling and Melting Points
Replies: 1
Views: 46

Re: Boiling and Melting Points

Hi Zoya Mulji 1F! To answer your question, first draw the lewis structure of the molecules in question. Then, determine the polarity of these molecules to check whether the dipoles cancel. Determine the strongest intermolecular force that this molecule can participate in. Finally, place the molecule...
by Ryan Narisma 4G
Tue Nov 19, 2019 9:30 pm
Forum: Lewis Structures
Topic: XeO2F2 Lewis Structure
Replies: 2
Views: 69

Re: XeO2F2 Lewis Structure

Hi Bryce Ramirez 1E! To answer your question, the reason why xenon has more than the 8 (octet) electrons is that the total number of valence electrons is greater than the number of octets that need to form. XeO2F2 has a total of 34 electrons, when you draw the lewis structure and add at least one bo...
by Ryan Narisma 4G
Tue Nov 19, 2019 4:33 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: CHF3 and CHI3
Replies: 1
Views: 32

Re: CHF3 and CHI3

Hi Jina Kwon! To answer your question, the reason why CHI3 has a higher boiling point than CHF3 is because of the difference in polarizability. The only difference between these two molecules is the bonded halogen: one has iodines and the other has fluorines. When you draw out the lewis structures o...
by Ryan Narisma 4G
Tue Nov 19, 2019 4:19 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: Nonpolar molecules
Replies: 1
Views: 29

Re: Nonpolar molecules

Hi Alvaro Chumpitaz 4D! Yes! Nonpolar molecules only exhibit london dispersion forces. This is because the dipole moments in the molecule cancel out; however, the molecule does attract other molecules. Because electrons are free to roam around the electron cloud, there are some moments that the elec...
by Ryan Narisma 4G
Tue Nov 19, 2019 4:12 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: effect of lone pairs on molecular angles
Replies: 1
Views: 22

Re: effect of lone pairs on molecular angles

Hello! The only thing we need to know about the effect of lone pairs on bond angles is that lone pairs decrease the known angle, and you've got it! There is no way to determine how much the angle decreases by using lewis structure alone. To actually find the degree to which the lone pair decreases t...
by Ryan Narisma 4G
Tue Nov 19, 2019 4:06 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: Boiling/melting points
Replies: 5
Views: 52

Re: Boiling/melting points

Hi! Molecules that have strong attractive forces with each other will have higher boiling points. This is because the stronger the attraction the more energy you need to break the intermolecular forces that hold these molecules together. Weaker intermolecular attractions, such as induced-dipole/indu...
by Ryan Narisma 4G
Tue Nov 19, 2019 4:03 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: H-bonding vs ion-dipole
Replies: 4
Views: 47

Re: H-bonding vs ion-dipole

Hi! To my understanding, ion-dipole forces would be stronger than hydrogen bonding interactions. This is because in ion-dipole forces, one of the attractive, participating molecules has a permanent electrical charge (the ion) that is attracted to another molecule that has a partial charge (polar mol...
by Ryan Narisma 4G
Fri Nov 15, 2019 8:01 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent or angular?
Replies: 2
Views: 50

Bent or angular?

In a previous chemistry I learned the shape "bent" instead of "angular". Is it ok if I name the shape "bent" instead of "angular" on a test or exam?
by Ryan Narisma 4G
Thu Nov 07, 2019 7:48 pm
Forum: Properties of Light
Topic: Work Function
Replies: 2
Views: 128

Re: Work Function

Hi! If you wanted to find the longest wavelength which can eject the electron from a metal surface, then you can definitely just use the work function energy. This is because you want the photon of light to equal the work function. Energy of the photon: E=hv. then you can use the relationship that C...
by Ryan Narisma 4G
Thu Nov 07, 2019 7:36 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: Question 3F 1
Replies: 1
Views: 25

Re: Question 3F 1

Hi Alexis Webb 1B! To answer your question. All species experience induced-dipole/induced-dipole attractions. This includes noble gas-noble gas, noble gas-nonpolar molecules, noble gas-polar molecules... etc. No matter whether the molecule is polar or nonpolar, or has a filled valence shell, every m...
by Ryan Narisma 4G
Thu Nov 07, 2019 7:23 pm
Forum: Bond Lengths & Energies
Topic: Lone pairs
Replies: 1
Views: 39

Re: Lone pairs

Hi! I think that having more sets of lone pairs greatly decreases the strength of the bond because the electron-electron repulsions that the species experiences is more than just having one or no repulsions. In page 100 in the textbook it says that "bond strength decreases as the number of lone...
by Ryan Narisma 4G
Thu Nov 07, 2019 7:04 pm
Forum: Lewis Structures
Topic: Radicals
Replies: 5
Views: 121

Re: Radicals

Hi LNgo 14A! I think it would make sense if the single electron was on the more electronegative atom. Because it's more electronegative, the atom will want to take as many electrons as possible and this single electron is no exception. I'm not sure, but I hope this helps explain it!
by Ryan Narisma 4G
Thu Nov 07, 2019 6:59 pm
Forum: Bond Lengths & Energies
Topic: Bond Dissociation Energies vs. Bond enthalpy
Replies: 2
Views: 32

Bond Dissociation Energies vs. Bond enthalpy

Hello! Are bond dissociation energies the same as bond enthalpies? Thank you!
by Ryan Narisma 4G
Fri Nov 01, 2019 8:54 pm
Forum: Bond Lengths & Energies
Topic: Bond length and strength
Replies: 3
Views: 43

Re: Bond length and strength

Hi Lauren Bui 1E! To answer your question, bond length and bond strength are inversely proportional—that is: if the bond length is longer, the bond strength is weaker and if the bond length is shorter, then the bond strength is stronger. Bond length corresponds to the internuclear distance between t...
by Ryan Narisma 4G
Fri Nov 01, 2019 8:44 pm
Forum: Lewis Structures
Topic: Determining lowest energy lewis structure
Replies: 2
Views: 28

Re: Determining lowest energy lewis structure

Hi Lauren Bui 1E! To answer your question, when drawing the lowest energy lewis structure try to arrange the bonds in such a way that all (if not then the majority) of the atoms to have a formal charge of 0. When all (or most) formal charges are 0, the lewis structure is said to be the most stable—i...
by Ryan Narisma 4G
Fri Nov 01, 2019 8:35 pm
Forum: Lewis Structures
Topic: central atom
Replies: 16
Views: 1434

Re: central atom

Hi Lauren Bui 1E! To answer your question, to decide which element is the central atom, check which element has the least electronegativity (electron pulling power). I hope this helps!
by Ryan Narisma 4G
Thu Oct 31, 2019 5:30 pm
Forum: Sigma & Pi Bonds
Topic: Difference between sigma and pi bonds
Replies: 4
Views: 65

Re: Difference between sigma and pi bonds

Hi Jina Kwon! To answer your question, the difference between sigma and pi bonds is in the orientation of the hybrid orbitals within the molecule. In sigma bonds, the overlap of the orbitals is in an end-to-end fashion and the electron density is located between the nuclei of the two bonded atoms. I...
by Ryan Narisma 4G
Thu Oct 31, 2019 5:22 pm
Forum: Electronegativity
Topic: electronegative
Replies: 6
Views: 116

Re: electronegative

Hi Jina Kwon! I am confused as to which type of bond you are talking about, but I will assume it's a covalent bond. If two elements are bonded covalently and one is more electronegative than the other, then the element that is more electronegative will be pulling the shared electrons to that element...
by Ryan Narisma 4G
Thu Oct 24, 2019 9:13 pm
Forum: Lewis Structures
Topic: Lewis Structures: Lone pairs as dots or lines?
Replies: 5
Views: 61

Lewis Structures: Lone pairs as dots or lines?

Hi, in lecture Dr. Lavelle indicated lone pairs of electrons as dots. On a test or midterm can we use lines to denote these lone pairs instead of two dots?
by Ryan Narisma 4G
Thu Oct 24, 2019 9:06 pm
Forum: Bond Lengths & Energies
Topic: Bond Length and Bond Order
Replies: 1
Views: 37

Bond Length and Bond Order

Hi, when comparing bond lengths between two different molecules/ions, can we use the bond order of the molecule to justify the sequence of bond lengths? For example, in problem 2D #13 Place the bond lengths in decreasing order: a) The CO bond in CO, CO2, CO3^2—. The C-O bond order in CO is 3; CO2 is...
by Ryan Narisma 4G
Thu Oct 24, 2019 8:51 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: noble gas notation
Replies: 2
Views: 83

Re: noble gas notation

Hi! Yes! The noble gas notation is just the shortcut way of writing electron configurations of atoms. As PranaviKolla3G mentioned, first find the element of which you want to find the electron configuration. Then, locate the immediate preceding noble gas. Write the noble gas element abbreviation in ...
by Ryan Narisma 4G
Thu Oct 24, 2019 8:43 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Orbital Box Diagram
Replies: 5
Views: 63

Re: Orbital Box Diagram

Hi Melvin Reputana 1L! When drawing the orbital diagrams I think Dr. Lavelle mentioned that you can use either the up arrow or down arrow as long as you are consistent. Take for example nitrogen. Nitrogen's (N) electron configuration is 1s^2 2s^2 2p^3. In the first two orbital diagrams (1s and 2s), ...
by Ryan Narisma 4G
Wed Oct 23, 2019 9:28 am
Forum: Trends in The Periodic Table
Topic: Ionization Energy [ENDORSED]
Replies: 3
Views: 73

Re: Ionization Energy [ENDORSED]

Hi SarahSteffen_LEC4! The Ionization Energy typically increases as you move across a period (from left to right) due to the increase in the effective nuclear charge of the atom (basically the number of protons). Keep in mind that whenever you're adding an electron across a period, the electron remai...
by Ryan Narisma 4G
Fri Oct 18, 2019 7:55 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configuration of Tungsten (W) compared to Chromium (Cr) [ENDORSED]
Replies: 2
Views: 210

Electron configuration of Tungsten (W) compared to Chromium (Cr) [ENDORSED]

Hi, in class I learned that there is an electron configuration exception for Chromium where the electron from the 4s-sublevel is added to the 3d-sublevel instead, which makes the configuration to be [Ar] 3d^5 4s^1. However, I was looking online and found that the electron configuration for Tungsten ...
by Ryan Narisma 4G
Wed Oct 16, 2019 11:04 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: General question 1B.27
Replies: 4
Views: 72

Re: General question 1B.27

Hi Simon Dionson 4I! So the uncertainty in velocity is given by a \pm 5.0 m/s. Let's say the velocity given was 10 m/s. Then velocity COULD be 15 m/s OR 5 m/s. The range (in statistics) of this is the uncertainty in velocity. So the uncertainty in velocity— \Delta v— is equal to 10 m/s. It is not 5....
by Ryan Narisma 4G
Wed Oct 16, 2019 10:54 pm
Forum: Photoelectric Effect
Topic: When energy is equal to work function
Replies: 9
Views: 214

Re: When energy is equal to work function

Hi Alvaro Chumpitaz 4D! I respectfully disagree with ishaa Diwakar 4E and the comment that "the electron would not be ejected from the metal". If the Energy of the photon of incoming light is EQUAL to the work function (Energy THRESHOLD) then the ELECTRON WILL BE EJECTED. This is true beca...
by Ryan Narisma 4G
Wed Oct 16, 2019 10:46 pm
Forum: Properties of Light
Topic: The units for each equation we're using?
Replies: 4
Views: 85

Re: The units for each equation we're using?

Hi KNguyen_3G! I'm a little confused as to what you mean by "equation"? Which equations specifically? The Heisenberg uncertainty, Schrodinger's equation, or the DeBroglie equation? Most of them have to do with frequency with units s ^{-1} (or Hz), lambda (or wavelength) with units of meter...
by Ryan Narisma 4G
Wed Oct 16, 2019 10:38 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals
Replies: 4
Views: 91

Re: Orbitals

Hi halle young 4A! To answer your question, a) 1 orbital b) 5 orbitals c) 3 orbitals d) 7 orbitals. First, let's note that quantum number "l" give us the SHAPE/TYPE of the orbital. The various types of orbitals are: s, p, d, f. In s there is 1 orbital; p has 3; d has 5; and f has 7. The nu...
by Ryan Narisma 4G
Wed Oct 16, 2019 10:29 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Numbers
Replies: 2
Views: 49

Re: Quantum Numbers

Hello, EthanPham_4D! To answer your question, I think Dr. Lavelle mentioned that the chemists/physicists experimentally figured out these quantum numbers and from this data they can figure out a pattern that related the each of the quantum numbers to each other. They derived the relationships based ...
by Ryan Narisma 4G
Tue Oct 08, 2019 9:18 pm
Forum: Properties of Light
Topic: What does n stand for in quantum
Replies: 4
Views: 97

Re: What does n stand for in quantum

Hi Ronak Naik! To answer your question, the "n" in the Balmer and Lyman series represents the principal energy levels or quantum numbers. Kind of like the electron shells you may have learned in high school chemistry and how far the electrons may be from the nucleus. I hope this helps!
by Ryan Narisma 4G
Tue Oct 08, 2019 9:08 pm
Forum: Molarity, Solutions, Dilutions
Topic: G. 23
Replies: 3
Views: 115

Re: G. 23

Hi Riya Sood 4C! I'm having trouble understanding what you mean by "multiply by 2 to account for the 2 chloride ions". But to solve this problem I would first determine the amount of chloride ions (in moles) that's in the solution. To do that I would use the molar masses of each NaCl and K...
by Ryan Narisma 4G
Tue Oct 08, 2019 9:01 pm
Forum: Properties of Light
Topic: Problem 1B, #15
Replies: 1
Views: 42

Re: Problem 1B, #15

Hi Megan Vu 1H! Before answering the question, I want to point out the fact that the frequency given is the the minimum frequency required to remove the electron from the surface of the metal—in other words the "threshold" frequency. Using this frequency we can calculate the incoming Energ...
by Ryan Narisma 4G
Tue Oct 08, 2019 8:53 pm
Forum: Properties of Light
Topic: Rays of the EM Spectrum
Replies: 2
Views: 63

Re: Rays of the EM Spectrum

Hi Alvaro Chumpitaz 4D! From what I recall during lecture, anything with a wavelength of shorter than visible light is harmful. Since UV radiation is known to cause some skin cancers, I would say anything with a shorter wavelength than UV can cause harm for organisms. Similarly, doctors avoid using ...
by Ryan Narisma 4G
Tue Oct 08, 2019 8:49 pm
Forum: Balancing Chemical Reactions
Topic: Chemical States
Replies: 3
Views: 93

Re: Chemical States

Hi Joanne Kang 3I! I agree with Alvaro Chumpitaz 4D that you should put the states if they're known and given in the problem. Sometimes, the states are kind of ambiguous. However there are some reactions for which we should know the states. Take for example combustion reactions. We know that a hydro...
by Ryan Narisma 4G
Tue Oct 01, 2019 10:14 pm
Forum: Empirical & Molecular Formulas
Topic: homework problem E9
Replies: 6
Views: 176

Re: homework problem E9

Hi there! So the compound at question is called Magnesium Sulfate Heptahydrate (MgSO _{4} \cdot 7H _{2} O). This specific salt is made of Magnesium (Mg ^{2+} ), Sulfate (SO _{4}^{2-} ), and water (H _{2} O) in a 1:1:7 ratio. In other words, to make Magnesium Sulfate Heptahydrate it must include 7 mo...
by Ryan Narisma 4G
Tue Oct 01, 2019 9:57 pm
Forum: Significant Figures
Topic: E1 Sig Figs
Replies: 4
Views: 96

Re: E1 Sig Figs

Hi Joanne Kang 3I! The quantity given is 1.00 mol Ag atoms. Remember that if there is a decimal point, you must count the significant figures from Left to Right. Once you start counting significant figures you must include any zeros after the decimal point as a significant figure. So for this proble...
by Ryan Narisma 4G
Sun Sep 29, 2019 11:18 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Is this the correct answer for question E3 in Fundamentals?
Replies: 3
Views: 349

Re: Is this the correct answer for question E3 in Fundamentals?

Hi KayleyW_3L! To answer your question, I think you would use the same method to determine how many atoms. In this problem, they used estimates for the molar masses just to model the difference in mass between the two different elements. I hope this helps!

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