Search found 130 matches

by Tyler Angtuaco 1G
Wed Mar 11, 2020 11:16 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Activation energies for multi-step reactions
Replies: 2
Views: 34

Activation energies for multi-step reactions

For a three step reaction, is there a way to determine which of the fast steps has the higher activation energy if we are not provided these values? Question 7.11 only provides us with three sets of reactions (which we have to assume which one is slow and which are fast based on the overall rate law...
by Tyler Angtuaco 1G
Wed Mar 11, 2020 9:08 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Effect of temperature 7D.7
Replies: 3
Views: 30

Re: Effect of temperature 7D.7

Raising the temperature for endothermic reactions will make the production of products more favorable (forward reaction). Conversely, raising the temperature for exothermic reactions makes the production of products less favorable (forward reaction). As for temperature's effect on rate constants, yo...
by Tyler Angtuaco 1G
Wed Mar 11, 2020 8:57 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Inferring Order
Replies: 2
Views: 26

Re: Inferring Order

You can infer order based on stoichiometric coefficients only during the individual steps of a reaction. You cannot for the overall reaction. For the overall reaction, you would need experimental data and use the method of initial rates.
by Tyler Angtuaco 1G
Wed Mar 11, 2020 8:55 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Derivation of Arrhenius Equation
Replies: 6
Views: 28

Re: Derivation of Arrhenius Equation

The Arrhenius equation can be re-written as ln k = -Ea/RT + ln A if you take its natural log. In this new form, you can compare the rate constants at two different temperatures using the equation you listed since subtracting lnk of one temperature and lnk of another cancels the term lnA.
by Tyler Angtuaco 1G
Wed Mar 11, 2020 8:48 am
Forum: General Rate Laws
Topic: Stoichiometric coefficients vs order
Replies: 4
Views: 26

Re: Stoichiometric coefficients vs order

They are the same as order for individual steps of a reaction, but not the overall reaction.
by Tyler Angtuaco 1G
Wed Mar 11, 2020 8:45 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: How to determine slow step?
Replies: 9
Views: 38

Re: How to determine slow step?

The slow step is denoted in the problem. It is also the step whose rate matches the overall rate law.
by Tyler Angtuaco 1G
Sun Mar 08, 2020 5:30 pm
Forum: Balancing Redox Reactions
Topic: Balancing a reaction
Replies: 5
Views: 23

Re: Balancing a reaction

Typically, you'll need to determine the oxidation and reduction half reactions. In each half reaction, balance all elements aside from H and O. Next, balance oxygens with water, then hydrogens with H+ ions. If the solution is alkaline/basic, balance H+ ions with OH- ions and combine them as water. T...
by Tyler Angtuaco 1G
Sun Mar 08, 2020 5:18 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 7
Views: 25

Re: Cell Diagrams

Both are fine since they are inert and allow the redox reactions to occur.
by Tyler Angtuaco 1G
Sun Mar 08, 2020 5:14 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Changes in Q
Replies: 3
Views: 46

Re: Changes in Q

Reducing the concentration of the reactant results in a higher Q value. Based on the Nernst equation, this would result in a lower cell potential.
by Tyler Angtuaco 1G
Sun Mar 08, 2020 5:06 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: How to determine Q
Replies: 4
Views: 24

Re: How to determine Q

Q is non-equilibrium ratio of products to reactants. So, you'll need to identify which species are the products and which ones are the reactants in the overall cell reaction.
by Tyler Angtuaco 1G
Sun Mar 08, 2020 5:01 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Using partial pressure in Q
Replies: 6
Views: 46

Re: Using partial pressure in Q

Yes it's fine to have different units as long as they cancel out. I think you would need to convert if you had a situation where three species were given in mol L^-1 and one given in bar.
by Tyler Angtuaco 1G
Sun Mar 01, 2020 6:12 pm
Forum: General Science Questions
Topic: Thermodynamics and Limiting Reactants
Replies: 1
Views: 30

Thermodynamics and Limiting Reactants

Question 5.55 part b reads, "A sample of graphite of mass 5.20 kg and 125 g of water were placed into a 10.0-L container and heated to 900 K. What are the equilibrium concentrations?" (In part a, we found the equilibrium constant using the equation delta g naught = -RT*lnK). The solutions ...
by Tyler Angtuaco 1G
Sat Feb 29, 2020 7:54 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.5b
Replies: 2
Views: 18

Re: 6L.5b

I think the statement about the necessity for an inert electrode refers to situations when the original species is in the same solution as its oxidized or reduced form. That is because I2 cannot be the anode since I- ions are already producing it in the process of oxidation.
by Tyler Angtuaco 1G
Sat Feb 29, 2020 7:43 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6O.1
Replies: 1
Views: 25

Re: 6O.1

I assumed that Ni2+ ions would be reduced since it was present as an aqueous solution and not solid. I also considered the possibility of the SO4 2- ion to reduce, but I realized that the reduction reaction present in Appendix 2B mentions H2SO3 as a product, which is not mentioned in the question so...
by Tyler Angtuaco 1G
Sat Feb 29, 2020 7:07 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Solving Gibbs Free Energy Problems
Replies: 1
Views: 18

Re: Solving Gibbs Free Energy Problems

Yes, you can use the equation ∆G = ∆G° + RT ln Q since K is given. If K is not given, delta G naught or the equilibrium concentrations/pressures likely will be.
by Tyler Angtuaco 1G
Sat Feb 29, 2020 7:01 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N3
Replies: 1
Views: 39

Re: 6N3

Bot equations should work since the equation using log Q is derived from the equation with ln Q.
by Tyler Angtuaco 1G
Sat Feb 29, 2020 6:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L. 5 c)
Replies: 1
Views: 9

Re: 6L. 5 c)

Since HCl is a strong acid and is aqueous, you can imagine most if not all of the ions in the solution to be present as H+ and Cl- ions. Thus, you are analyzing the reduction of Cl2 to these Cl- ions and the oxidation of H2 into these H+ ions.
by Tyler Angtuaco 1G
Sat Feb 29, 2020 6:49 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: 6L.1b Ecellº
Replies: 1
Views: 17

Re: 6L.1b Ecellº

Your calculation should be correct based on the values given on Appendix 2B. I'm not sure either how they got -1.29V.
by Tyler Angtuaco 1G
Sat Feb 29, 2020 6:39 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagram order
Replies: 4
Views: 26

Re: Cell diagram order

No, the order of those two ions is not important.
by Tyler Angtuaco 1G
Sat Feb 22, 2020 12:39 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Max Potential
Replies: 2
Views: 14

Re: Max Potential

If you are referring the to the max cell potential, it is simply represented by E. This can be calculated using -work/charge or delta G = -nFE (or work = -nFE), where work is the max work that can be done from the transfer of charge.
by Tyler Angtuaco 1G
Sat Feb 22, 2020 12:28 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 5
Views: 27

Re: Salt Bridge

The negative ions of the salt balance the increasingly positive solution of the anode and the positive ions of the salt balance the increasingly negative solution of the cathode.
by Tyler Angtuaco 1G
Sat Feb 22, 2020 12:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Explanation of This Diagram
Replies: 1
Views: 26

Re: Explanation of This Diagram

Experiments on redox reactions usually involve the components presented in the picture you uploaded: two electrodes connected by a circuit and a salt bridge. The electrode on the left is usually the anode (electrode that includes the species being oxidized/losing electrons) and the electrode on the ...
by Tyler Angtuaco 1G
Sat Feb 22, 2020 11:56 am
Forum: Phase Changes & Related Calculations
Topic: delta G0 versus delta G
Replies: 15
Views: 85

Re: delta G0 versus delta G

Delta G naught is an intensive property (values are calculated at standard conditions), whereas delta G isn't. Using delta G naught helps observe a reaction in unstandard conditions.
by Tyler Angtuaco 1G
Sat Feb 22, 2020 11:53 am
Forum: Phase Changes & Related Calculations
Topic: Van't Hoff Eq
Replies: 8
Views: 77

Re: Van't Hoff Eq

We only need to know the application of it: observing how the equilibrium constant for a reaction is affected by temperature.
by Tyler Angtuaco 1G
Sat Feb 15, 2020 1:31 pm
Forum: Van't Hoff Equation
Topic: Equilibrium
Replies: 6
Views: 298

Re: Equilibrium

It helps us observe how the equilibrium ratio between products and reactants differs for a reaction conducted at different temperatures.
by Tyler Angtuaco 1G
Sat Feb 15, 2020 1:27 pm
Forum: Van't Hoff Equation
Topic: When to apply the Van't Hoff Equation
Replies: 5
Views: 273

Re: When to apply the Van't Hoff Equation

You'll use the van't hoff equation when you're observing a reaction conducted at two different temperatures and their respective equilibrium constants.
by Tyler Angtuaco 1G
Sat Feb 15, 2020 1:25 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G and spontaneity
Replies: 4
Views: 38

Re: Delta G and spontaneity

Yes since a spontaneous reaction is one that will likely occur on its own without intervention. Thus, products will likely form since the reaction is likely to proceed.
by Tyler Angtuaco 1G
Sat Feb 15, 2020 1:17 pm
Forum: Calculating the pH of Salt Solutions
Topic: How do you know if something is a salt solution?
Replies: 5
Views: 55

Re: How do you know if something is a salt solution?

A salt solution would just be a salt plus water. The method to find pH would vary depending on what's given to you. But, you know that buffer solutions are created from a weak acid and its salt, which gives you more clues about a given reaction. Sometimes, you'll also be given Ka or Kb, which you ca...
by Tyler Angtuaco 1G
Sat Feb 15, 2020 1:13 pm
Forum: Van't Hoff Equation
Topic: Equation
Replies: 5
Views: 29

Re: Equation

It allows us to observe the relationship between the equilibrium constant and temperature.
by Tyler Angtuaco 1G
Sat Feb 15, 2020 1:11 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: Boltzmann Equation
Replies: 10
Views: 59

Re: Boltzmann Equation

If you are referring to S = kB*ln(W), it is used to calculate residual entropy.
by Tyler Angtuaco 1G
Sat Feb 15, 2020 1:09 pm
Forum: Van't Hoff Equation
Topic: Constant
Replies: 3
Views: 25

Re: Constant

I would guess the 8.314 J·K-1·mol-1 since enthalpy is in joules and temperature is in kelvin. The units would then cancel, which makes sense because the equilibrium constant has no units.
by Tyler Angtuaco 1G
Sat Feb 08, 2020 3:50 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Using Cv,m and Cp,m
Replies: 2
Views: 27

Re: Using Cv,m and Cp,m

The v and p just indicate that it is specific heat at a constant volume or constant pressure. I can't think of a situation where you would need to convert between the two or be extra wary which one the table is giving you. Usually, if you need specific heat, just refer to what the table gives you. Y...
by Tyler Angtuaco 1G
Fri Feb 07, 2020 8:52 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hf and Hc
Replies: 3
Views: 28

Hf and Hc

Question 4D 15 lists values I assumed was heat of formation, but labels them H with subscript c. What does this symbol mean and is it correct to assume it means the same as heat of formation?
by Tyler Angtuaco 1G
Fri Feb 07, 2020 8:48 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: H=q
Replies: 4
Views: 27

H=q

Why is it safe to assume that delta H = heat (delta H = q) for chemical reactions even if the question does not specify that pressure is constant?
by Tyler Angtuaco 1G
Fri Feb 07, 2020 8:36 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units for heat of reaction
Replies: 9
Views: 53

Units for heat of reaction

If you are given the heat of reaction in kJ but want to express it in terms of a reactant or product, is it correct to write "kJ per mole of said reactant or product?" Or is this an invalid statement?
by Tyler Angtuaco 1G
Fri Feb 07, 2020 7:48 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Question 4D9
Replies: 1
Views: 27

Question 4D9

The enthalpy of reaction is -13168 kJ per mole. The solutions manual divides this value by four (using stoichiometric ratios) to put this in terms of TNT, whose enthalpy density is what we are trying to find. If we are just using stoichiometric ratios to find this value in terms of TNT, why do we co...
by Tyler Angtuaco 1G
Thu Jan 30, 2020 10:55 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 4A.7
Replies: 3
Views: 25

Re: 4A.7

Yes, just add the heat supplied to the copper kettle and the heat supplied to the water to find part a. For part b, divide the heat that is supplied to the water by the total heat supplied to the system.
by Tyler Angtuaco 1G
Thu Jan 30, 2020 10:49 am
Forum: Calculating Work of Expansion
Topic: reversible and irreversible
Replies: 2
Views: 16

Re: reversible and irreversible

It's most helpful to consider what reversible and irreversible expansion is in the context of a system with a piston. Reversible expansion: If the external pressure and pressure of the system are pretty much equal, a slight increase in external pressure would cause the piston to move slightly in due...
by Tyler Angtuaco 1G
Thu Jan 30, 2020 10:01 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Strong acids and bases as gases
Replies: 4
Views: 33

Strong acids and bases as gases

Would a strong acid or strong base in gas form fully dissociate in the presence of water in gas form?
by Tyler Angtuaco 1G
Wed Jan 29, 2020 4:59 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: work equations
Replies: 5
Views: 44

Re: work equations

The second equation is likely referring to the work done on the system, which is why it is positive. The first one you mention is what will be used most for the problems in the thermodynamics section since our observations are typically made in reference to the system and the work it is doing.
by Tyler Angtuaco 1G
Wed Jan 29, 2020 4:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4A7
Replies: 4
Views: 36

Re: 4A7

The table for specific heat is provided earlier in the chapter.
by Tyler Angtuaco 1G
Wed Jan 29, 2020 4:46 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Including n or m in "q" Equation
Replies: 2
Views: 208

Re: Including n or m in "q" Equation

We wouldn't need n or m if we were only attempting to find the heat capacity of a substance in general. We would need it, however, if we were curious about the (specific) heat capacity of a sample of this substance.
by Tyler Angtuaco 1G
Wed Jan 29, 2020 4:38 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Delta T
Replies: 4
Views: 28

Re: Delta T

The final temperature of the system is less than the initial temperature of the system since the exothermic reaction caused the release of heat.
by Tyler Angtuaco 1G
Sun Jan 26, 2020 1:12 pm
Forum: Phase Changes & Related Calculations
Topic: Heat vs temperature
Replies: 6
Views: 48

Re: Heat vs temperature

I think this refers to the moment when a sample is about to change states of matter. If you observe a heat curve, you notice that when ice is melting into water or water is freezing into ice, temperature remains constant regardless of how much heat is added or lost. This is because the sample is abs...
by Tyler Angtuaco 1G
Sun Jan 26, 2020 12:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Exceptions to Hess's Law
Replies: 1
Views: 11

Re: Exceptions to Hess's Law

Probably only when your adding reactions that don't involve common molecules or elements, such as if one molecule or element is present in one reaction but not the other(s). This is likely the case since heat of formation will be different with molecules or elements of different bond energies. I don...
by Tyler Angtuaco 1G
Sun Jan 26, 2020 12:41 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Br2(l) --> 2Br(g)
Replies: 2
Views: 9

Re: Br2(l) --> 2Br(g)

You use the heat/enthalpy of vaporization since the reactant is being vaporized into gas. You use bond enthalpy since the bond in the diatomic molecule Br2 breaks, forming two bromine atoms in the reaction.
by Tyler Angtuaco 1G
Sun Jan 26, 2020 12:32 pm
Forum: Phase Changes & Related Calculations
Topic: Work
Replies: 3
Views: 40

Re: Work

Work is applicable to everything, but not everything in this course requires you to calculate it. A good majority of thermochemistry will revolve around enthalpy, change in enthalpy, and other concepts of energy change. You won't need to calculate work with the formula force times distance.
by Tyler Angtuaco 1G
Sun Jan 26, 2020 12:27 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpy vs. Standard Enthalpy of Formation
Replies: 2
Views: 18

Re: Bond Enthalpy vs. Standard Enthalpy of Formation

Bond enthalpy refers to the energy it takes to break a bond in any particular molecule, whereas standard enthalpy of formation is the enthalpy change produced from the formation of a product from its reactants. Keep in mind the standard enthalpy of formation is the enthalpy change for one mole of a ...
by Tyler Angtuaco 1G
Fri Jan 17, 2020 7:59 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Initial concentrations and molar ratios
Replies: 2
Views: 17

Initial concentrations and molar ratios

If you are given the initial concentration of one of two reactants in a reaction, is the only reason why we cannot use molar ratios to determine the initial concentration of the other reactant because of the possibility that one of them is a limiting reactant? Or are there more reasons to this?
by Tyler Angtuaco 1G
Fri Jan 17, 2020 7:53 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating concentrations on ideal scenarios
Replies: 1
Views: 15

Calculating concentrations on ideal scenarios

In a chemical reaction involving two reactants and two products, is it possible to assume the equilibrium concentrations of all molecules in the reaction based solely on stoichiometric ratios if only the equilibrium concentration of one product is given and if you know there was a perfect amount of ...
by Tyler Angtuaco 1G
Fri Jan 17, 2020 7:50 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium concentration of products
Replies: 2
Views: 21

Equilibrium concentration of products

If given a balanced chemical reaction which produced two products, can you determine the equilibrium concentration of one product solely based on molar ratios if you are given the equilibrium concentration of the other product?
by Tyler Angtuaco 1G
Wed Jan 15, 2020 9:28 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Self Test 5I.3b
Replies: 4
Views: 25

Re: Self Test 5I.3b

I would assume that the pressure given is the initial pressure for HCl since the question does not explicitly state it is an equilibrium value, and also because the question seems to phrase it as if it just added HCl until there was enough for the desired reaction to occur. Next, I would construct a...
by Tyler Angtuaco 1G
Wed Jan 15, 2020 9:14 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE Tables
Replies: 4
Views: 38

Re: ICE Tables

If none of the equilibrium values are provided, use an ICE table to determine the equilibrium composition of a reaction. If one or more of the equilibrium values are provided, you can use stoichiometric ratios to determine the amount of change the initial amount of reactants or products experiences ...
by Tyler Angtuaco 1G
Wed Jan 15, 2020 9:09 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE tables
Replies: 4
Views: 23

Re: ICE tables

If the question does not state the values are at equilibrium, they are not. ICE tables are needed when the equilibrium values are not provided, but are not necessary if you know the equilibrium amount of one of the reactants or products. This is because you can use the stoichiometric ratios of the b...
by Tyler Angtuaco 1G
Wed Jan 15, 2020 9:00 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: pressure
Replies: 5
Views: 41

Re: pressure

Pressure happens to be one of the parameters that affects the rate of reactions. When pressure is altered, the reaction will proceed to the side with less moles of gas. This observation can be derived by first considering the inverse relationship between pressure and volume (which affects concentrat...
by Tyler Angtuaco 1G
Wed Jan 15, 2020 8:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka + Kb
Replies: 6
Views: 31

Re: Ka + Kb

This was in reference to the ionization constant for water, Kw, because the addition of both reactions in the example (the addition of water to ammonium and the addition of water to ammonia) resulted in the concentration of hydronium ions multiplied by the concentration of hydroxide ions (derived fr...
by Tyler Angtuaco 1G
Wed Jan 15, 2020 8:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1
Replies: 1
Views: 29

Test 1

What are we expected to know about ATP hydrolysis and osmotic pressure? These are listed on the chemical equilibrium outline, but I don't remember these being discussed in lecture.
by Tyler Angtuaco 1G
Wed Jan 15, 2020 10:40 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: calculating kP
Replies: 4
Views: 37

calculating kP

Are there certain units of pressure that need to be converted in order to use partial pressure values when calculating the equilibrium constant? Certainly, the equilibrium constant would be different if we were to use kilopascals instead of atmospheric pressure.
by Tyler Angtuaco 1G
Sat Jan 11, 2020 2:22 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic and endothermic reactions
Replies: 4
Views: 28

Exothermic and endothermic reactions

How will the reaction change if it is exothermic and heat is added (considering the fact that exothermic reactions release heat)? Conversely, how would it change if the reaction was endothermic and cooled (considering that endothermic reactions absorb heat)?
by Tyler Angtuaco 1G
Sat Jan 11, 2020 2:03 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Decreasing pressure by increasing volume [ENDORSED]
Replies: 4
Views: 33

Decreasing pressure by increasing volume [ENDORSED]

Dr. Lavelle established that increasing the pressure by decreasing volume results in the production of more products if there is more moles of gas on reactant side and more reactants if there are more moles of gas on product side. Will these trends be the same if we decrease pressure, such as if we ...
by Tyler Angtuaco 1G
Fri Jan 10, 2020 10:41 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Why does only Temp affect K?
Replies: 10
Views: 97

Re: Why does only Temp affect K?

Just a speculation, but I would assume temperature affects the rate at which a reaction occurs, causing the equilibrium values of products and reactants to be different. This is because the temperature affects the viability of a reaction in the first place and thus the amount of products formed/reac...
by Tyler Angtuaco 1G
Fri Jan 10, 2020 10:38 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp vs Kc
Replies: 6
Views: 28

Re: Kp vs Kc

It should not matter unless the question is asked in a way where only pressure or concentration is calculable. However, if either are acceptable, it is best to use pressure if the states of matter are all gas, and concentration if they are all aqueous.
by Tyler Angtuaco 1G
Fri Jan 10, 2020 10:36 am
Forum: Administrative Questions and Class Announcements
Topic: Required number of responses for chem community
Replies: 7
Views: 43

Required number of responses for chem community

Is the required number of responses for Chemistry Community still 5 responses for Chem14B?
by Tyler Angtuaco 1G
Fri Jan 10, 2020 10:24 am
Forum: Ideal Gases
Topic: 5G1 true/false
Replies: 8
Views: 65

Re: 5G1 true/false

A higher initial amount of reactant would produce more product. The equilibrium values of the reactant and product will also be higher and the numerator and denominator of the equilibrium constant ratio will be proportional to those of a reaction with less reactant if both reactions occur under the ...
by Tyler Angtuaco 1G
Fri Jan 10, 2020 8:57 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating K
Replies: 6
Views: 42

Re: Calculating K

Kc is always the ratio of the equilibrium concentrations of the products to the reactants, so it would just be 1/(concentration of that reactant).
by Tyler Angtuaco 1G
Fri Jan 10, 2020 8:55 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Comparing K and Q
Replies: 6
Views: 40

Re: Comparing K and Q

When the equilibrium concentrations or pressures are not given, we need to calculate Q to determine whether the forward or reverse reaction is favored.
by Tyler Angtuaco 1G
Fri Jan 10, 2020 8:27 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q and speed of reaction
Replies: 5
Views: 37

Re: Q and speed of reaction

Q itself is just a calculation made from the current concentrations or pressures of products and reactants during some point of the reaction. Thus, it does not impact the speed of the reaction. However, you can make observations about the direction a reaction will proceed based on the comparison bet...
by Tyler Angtuaco 1G
Thu Jan 09, 2020 10:54 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Value of Kc and Kp
Replies: 6
Views: 37

Value of Kc and Kp

Will the value of the equilibrium constant be the same regardless if we calculate it using the equilibrium concentrations or the equilibrium pressures?
by Tyler Angtuaco 1G
Fri Dec 06, 2019 2:56 pm
Forum: Properties of Light
Topic: speed of light and protons
Replies: 3
Views: 69

speed of light and protons

Is it safe to assume that the speed of a proton is the same as the speed of light?
by Tyler Angtuaco 1G
Fri Dec 06, 2019 2:39 pm
Forum: Identifying Acidic & Basic Salts
Topic: Strong acids and strong bases
Replies: 1
Views: 25

Strong acids and strong bases

How do we determine if a solution is acidic or basic if the strong base and strong acid have different concentrations?
by Tyler Angtuaco 1G
Fri Dec 06, 2019 2:05 pm
Forum: Bronsted Acids & Bases
Topic: acetate functional group [ENDORSED]
Replies: 1
Views: 50

acetate functional group [ENDORSED]

What is the chemical significance of the acetate functional group?
by Tyler Angtuaco 1G
Fri Dec 06, 2019 1:56 pm
Forum: Biological Examples
Topic: Transition metals and enzymes [ENDORSED]
Replies: 1
Views: 461

Transition metals and enzymes [ENDORSED]

How do manganese, nickel, copper, and zinc aid enzyme function?
by Tyler Angtuaco 1G
Fri Dec 06, 2019 1:55 pm
Forum: Identifying Acidic & Basic Salts
Topic: Weak acid and weak base
Replies: 1
Views: 29

Weak acid and weak base

What results from the addition of a weak acid and weak base? Could a salt even be formed?
by Tyler Angtuaco 1G
Fri Nov 29, 2019 3:06 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Hemoglobin vs Myoglobin
Replies: 3
Views: 38

Hemoglobin vs Myoglobin

Can someone describe the difference between hemoglobin and myoglobin in terms of their chemical structures or chemical properties?
by Tyler Angtuaco 1G
Fri Nov 29, 2019 3:03 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Value of pH
Replies: 8
Views: 52

Re: Value of pH

It can be, such as when the concentration of hydronium is greater than one, but is uncommon.
by Tyler Angtuaco 1G
Fri Nov 29, 2019 3:01 pm
Forum: Hybridization
Topic: Sigma and Pi bonds
Replies: 7
Views: 66

Re: Sigma and Pi bonds

Sigma bonds are the first bonds that form between atoms. Every consecutive bond (double, triple, etc) is a pi bond.
by Tyler Angtuaco 1G
Fri Nov 29, 2019 3:00 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Strength and Weakness
Replies: 12
Views: 352

Re: Strength and Weakness

For strong acids (no kA value provided), observe bond length. For weak acids, the stronger acid is the one with a higher kA value (concentration of the products divided by the concentration of the reactants).
by Tyler Angtuaco 1G
Fri Nov 29, 2019 2:58 pm
Forum: Lewis Acids & Bases
Topic: HCl vs HF
Replies: 19
Views: 118

Re: HCl vs HF

HCl has a longer bond between the two atoms, meaning that it is weaker and the H atom is easier to dissociate.
by Tyler Angtuaco 1G
Wed Nov 20, 2019 7:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: XA2E2
Replies: 9
Views: 68

Re: XA2E2

is AX3E also called bent AX3E would be trigonal pyramidal because there is a tetrahedral electron arrangement (bond angles of 109.5 degrees), but the lone pair reduces the bond angle because of repulsion. If you meant AX2E, yes, AX2E would be bent too. This is because there would be a trigonal plan...
by Tyler Angtuaco 1G
Wed Nov 20, 2019 7:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: XA2E2
Replies: 9
Views: 68

Re: XA2E2

Yes, it would be bent because electrons would position themselves on the same side of the atom rather than 180 degrees apart. This is due to the fact that lone pair - lone pair repulsion is strongest.
by Tyler Angtuaco 1G
Wed Nov 20, 2019 7:38 pm
Forum: Dipole Moments
Topic: Hydrogen Bonding
Replies: 17
Views: 245

Re: Hydrogen Bonding

yes
by Tyler Angtuaco 1G
Wed Nov 20, 2019 7:38 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2.63
Replies: 1
Views: 22

Re: 2.63

The image in the book does not include lone pairs, but to determine angle b, we have to consider the VSEPR shape of oxygen with the lone pairs in mind (lone pairs exist because of the octet rule). Keeping in mind that lone-pair to lone-pair repulsion is strongest, oxygen would have a tetrahedral ele...
by Tyler Angtuaco 1G
Wed Nov 20, 2019 7:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: lewis structure of organic compunds
Replies: 5
Views: 51

Re: lewis structure of organic compunds

The rules that help me the most are the octet rule, the expanded octet trend, and formal charge. Make sure each atom satisfies the octet rule before adding any left over electrons. If there are extra electrons, create multiple bonds or add lone pairs to atoms located in period 3 or below on the peri...
by Tyler Angtuaco 1G
Wed Nov 20, 2019 7:21 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: HCL vs NaCl
Replies: 6
Views: 55

Re: HCL vs NaCl

Ion-ion interactions are stronger than the dipole-dipole interactions of HCl, so it takes more energy (heat) to overcome ion-ion forces.
by Tyler Angtuaco 1G
Wed Nov 20, 2019 7:19 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: Boiling Points
Replies: 7
Views: 48

Re: Boiling Points

NO2- would have a bent molecular shape, preventing its dipoles from cancelling. N20 would be linear, causing its dipoles to cancel. Thus, NO2- has dipole-dipole interactions, which are stronger than the LDF that N20 only has.
by Tyler Angtuaco 1G
Wed Nov 20, 2019 7:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Octahedral
Replies: 6
Views: 49

Re: Octahedral

There is a total of eight sides if you draw two pyramids, each with four sides.
by Tyler Angtuaco 1G
Wed Nov 20, 2019 7:14 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Bond angles in Trigonal Bipyramidal
Replies: 4
Views: 32

Re: Bond angles in Trigonal Bipyramidal

Trigonal byprimadal electron arrangements have bond angles of 90, 120, and 180 degrees. Maybe you named the molecule by its electron arrangement rather than its molecular shape, which would differ since it only accounts for atoms and because its bond angles would be affected by lone pairs.
by Tyler Angtuaco 1G
Wed Nov 20, 2019 7:11 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: affect of size
Replies: 2
Views: 53

Re: affect of size

Atoms with larger radii are more easily polarizable. In other words, the electrons of larger atoms are easier to pull away from the nucleus of the atom. Thus, the polarizability of atoms increases down a group because size increases down a group (more electrons occupy more energy shells) and the out...
by Tyler Angtuaco 1G
Wed Nov 20, 2019 6:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape of I3-
Replies: 3
Views: 20

Re: Shape of I3-

I3- would have a square pyramidal electron arrangement. If you picture the lone pairs of electrons being in the farthest positions away from each other (because repulsion of electron clouds between lone pairs are strongest), one would be on the axial atom (top of the pyramid), and two pairs would be...
by Tyler Angtuaco 1G
Wed Nov 20, 2019 6:38 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Radicals
Replies: 2
Views: 42

Radicals

How does a single electron compare to lone pairs in terms of repulsion? Assuming there was a molecule whose shape was square planar, with a lone pair on one axial position and a single electron on the other axial position, how would the bond angles differ from a molecule with the same shape but anot...
by Tyler Angtuaco 1G
Wed Nov 20, 2019 6:33 pm
Forum: Ionic & Covalent Bonds
Topic: CO2 and H20
Replies: 4
Views: 69

CO2 and H20

Which intermolecular forces arise between CO2 and H20, considering the fact CO2 is not a dipole? Can hydrogen bonds even form between the oxygen atoms of CO2 and the hydrogen atoms of H20?
by Tyler Angtuaco 1G
Wed Nov 13, 2019 10:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Axial vs Equatorial Lone Pairs
Replies: 2
Views: 44

Axial vs Equatorial Lone Pairs

Will electrons always occupy the equatorial position if given the option between that and the axial position?
by Tyler Angtuaco 1G
Wed Nov 13, 2019 1:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Hybridization
Replies: 1
Views: 27

Hybridization

Can someone explain the concept of overlapping orbitals and their effect on the strength of bonds?
by Tyler Angtuaco 1G
Wed Nov 13, 2019 1:02 pm
Forum: Administrative Questions and Class Announcements
Topic: Class grading
Replies: 12
Views: 217

Class grading

Does anyone know the grading scale for final grades in this class?
by Tyler Angtuaco 1G
Wed Nov 13, 2019 12:57 pm
Forum: Bond Lengths & Energies
Topic: Dipole-Dipole Forces
Replies: 3
Views: 45

Dipole-Dipole Forces

When polar molecules are separated, how do their opposite partial charges on each molecule "merge and cancel" as stated in the textbook?
by Tyler Angtuaco 1G
Wed Nov 13, 2019 12:53 pm
Forum: Ionic & Covalent Bonds
Topic: Bonding and Potential Energy
Replies: 1
Views: 41

Bonding and Potential Energy

Can someone explain the trends between IMF forces in bonding and potential energy?
by Tyler Angtuaco 1G
Wed Nov 13, 2019 12:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sigma vs. Pi Bonds
Replies: 2
Views: 32

Sigma vs. Pi Bonds

Can someone explain the difference between sigma and pi bonds in terms of their geometry and nodal planes?
by Tyler Angtuaco 1G
Wed Nov 13, 2019 12:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Topics on Outlines for Test 2
Replies: 3
Views: 36

Topics on Outlines for Test 2

Does anyone know which chapters from the book we will need to know for Test 2 based on Dr. Lavelle's outlines?
by Tyler Angtuaco 1G
Sun Nov 10, 2019 5:53 pm
Forum: Electronegativity
Topic: Electron Affinity and Electronegativity
Replies: 7
Views: 37

Re: Electron Affinity and Electronegativity

Electron affinity is a quantitative property of atoms which describes their likelihood of gaining an electron. Electronegativity, on the other hand, is a qualitative property that describes the pull an atom has on electrons.
by Tyler Angtuaco 1G
Sun Nov 10, 2019 5:51 pm
Forum: *Shrodinger Equation
Topic: Shrodinger Equation
Replies: 4
Views: 58

Re: Shrodinger Equation

It describes the wave qualities of an electron's orbital(s). It can be used to find electron probability density by squaring it.

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