Search found 30 matches

by Tuong-Minh Tran 1C
Fri Mar 15, 2019 3:51 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Increasing volume
Replies: 3
Views: 181

Re: Increasing volume

Yes, K shifts to the side with more moles of gas when volume is increased.
by Tuong-Minh Tran 1C
Tue Mar 12, 2019 6:56 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Intermediates
Replies: 2
Views: 53

Re: Intermediates

You're basically correct. Because most chemical reactions go through multiple steps, intermediates are formed as initial products of the reactants, only to become the reactants of the final products.
by Tuong-Minh Tran 1C
Tue Mar 12, 2019 6:08 pm
Forum: First Order Reactions
Topic: using mass or conc in rate laws
Replies: 2
Views: 61

Re: using mass or conc in rate laws

Rate laws typically only use concentration. If a question gives or asks for the mass of a product or reactant, then you'll have to use the molar mass and volume of the substances involved to convert between mass and concentration.
by Tuong-Minh Tran 1C
Sun Mar 10, 2019 9:39 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Log version vs ln Version
Replies: 7
Views: 126

Re: Log version vs ln Version

It actually doesn't matter whether you use the log version or the ln version; the log version is an altered version of the ln version, so both should give the same result.
by Tuong-Minh Tran 1C
Sun Mar 10, 2019 9:37 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 12
Views: 225

Re: Test 2

Carissa Young 1K wrote:What happens if Gibbs free energy is zero exactly?


When Gibbs free energy is zero, that means that the reaction is at equilibrium.
by Tuong-Minh Tran 1C
Tue Mar 05, 2019 10:42 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Nerst Equation
Replies: 4
Views: 91

Re: Nerst Equation

The Nernst equation is generally used to solve for the cell potential of a galvanic cell. If a problem gives standard cell potentials of half-reactions as well as any information that can be used to solve for Q (the reaction quotient), such as the concentration/pressure of reactants and products, th...
by Tuong-Minh Tran 1C
Sat Mar 02, 2019 3:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: liquid and gaseous states in a cell diagram
Replies: 3
Views: 80

Re: liquid and gaseous states in a cell diagram

When you list substances with different states, you separate them with a line. The only time you use a comma is when they share the same state, such as if they're both aqueous. Like you said, electrodes should be on the outside. Another thing to keep in mind is that you should place the substance be...
by Tuong-Minh Tran 1C
Wed Feb 27, 2019 9:54 pm
Forum: Balancing Redox Reactions
Topic: Basic Solutions
Replies: 5
Views: 87

Re: Basic Solutions

For basic solutions, you generally want to place the OH- where there are less O atoms.

If you want to look for further clarification and have the 7th edition of the textbook, check out pages 541-543 and look at Example 6K.2.
by Tuong-Minh Tran 1C
Wed Feb 27, 2019 9:09 pm
Forum: Balancing Redox Reactions
Topic: Half Reactions in a Basic Solution
Replies: 4
Views: 89

Re: Half Reactions in a Basic Solution

You only add water to the same side of OH- temporarily to balance H on each side. In the end, you should only have H2O on one side. To clarify, you add OH- to the side that has less oxygen to balance out O on each side. However, that creates an excess of H on one side, which is why you add H2O on bo...
by Tuong-Minh Tran 1C
Sat Feb 23, 2019 8:16 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: How can a change in entropy be negative?
Replies: 3
Views: 66

Re: How can a change in entropy be negative?

A change in entropy can be negative if energy is able to escape the system. Technically, in the universe, entropy is always increasing, but if we only consider the earth as a system, then entropy can decrease.
by Tuong-Minh Tran 1C
Fri Feb 22, 2019 5:44 pm
Forum: Balancing Redox Reactions
Topic: Test 2 Material
Replies: 11
Views: 186

Re: Test 2 Material

What subjects should we focus on for test 2? I know that we have to study gibbs free energy and balancing redox reactions but what about entropy and enthalpy? The only thing I know for sure is that all the content covered during Week 7 will be on the test (e.g. Gibbs free energy and redox reactions...
by Tuong-Minh Tran 1C
Thu Feb 21, 2019 12:03 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Negative ∆G means spontaneous reaction?
Replies: 5
Views: 116

Re: Negative ∆G means spontaneous reaction?

A spontaneous reaction occurs when a system releases energy and moves into a lower energy state. ∆G is the change in Gibbs free energy; the reason why it is negative in a spontaneous reaction is because it means that the system is releasing energy into its surroundings and thus loses free energy.
by Tuong-Minh Tran 1C
Fri Feb 15, 2019 8:44 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Lecture Notes
Replies: 1
Views: 44

Re: Lecture Notes

Here you go.
by Tuong-Minh Tran 1C
Fri Feb 15, 2019 8:26 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: deltaS=nRln(V2/V1) vs. deltaS=Cln(T2/T1)
Replies: 1
Views: 128

Re: deltaS=nRln(V2/V1) vs. deltaS=Cln(T2/T1)

We already know that dS=dq(rev)/T. The C comes from the fact that it is related to dq(rev): dq(rev)=CdT. Through substitution, we get dS=CdT/T. With that, we can take the integral of the equation, which gives us ΔS=Cln(T2/T1). If you're still confused, you can look up the process on pg. 300 in Secti...
by Tuong-Minh Tran 1C
Fri Feb 15, 2019 8:04 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Clausius inequality
Replies: 1
Views: 55

Re: Clausius inequality

From page 324 of the 7th edition textbook: "If q(rev) in the definition of entropy ΔS=q(rev)/T is replaced by the smaller quantity q(irrev), then ΔS>q(irrev)/T. In general, the Clausius inequality is ΔS≥q/T." The Clausius inequality actually takes both the possibility of a reversible or ir...
by Tuong-Minh Tran 1C
Fri Feb 08, 2019 4:20 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: State Function
Replies: 3
Views: 75

Re: State Function

The internal change in energy ΔU is defined as a state function because its value is not dependent on the path taken to it - only the end result matters. The variables q and w, on the other hand, are not state functions because their values do depend on the path taken. It is perfectly legitimate for...
by Tuong-Minh Tran 1C
Thu Feb 07, 2019 3:48 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Calorimeter and Heat
Replies: 1
Views: 59

Re: Calorimeter and Heat

The entire idea of a calorimeter is that it can measure the change in heat of a system while influencing the change as little as possible (its purpose is to observe a process, not interrupt it). Thus, whatever heat is gained or lost by the calorimeter is the same as the heat gained or lost by the sy...
by Tuong-Minh Tran 1C
Thu Feb 07, 2019 1:17 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.11 when to use Cvln(T2/T1) vs nRln(T2/T1)
Replies: 2
Views: 61

Re: 4F.11 when to use Cvln(T2/T1) vs nRln(T2/T1)

In the end, it shouldn't matter which equation you use to find the change in entropy. I believe that ΔS=nR ln(T2/T1) was used over ΔS=Cv ln(T2/T1) simply because it you can derive the number of moles (using PV=nRT) more easily than trying to find the heat capacity. If you can find the heat capacity,...
by Tuong-Minh Tran 1C
Thu Jan 31, 2019 10:05 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Angles
Replies: 5
Views: 98

Re: Bond Angles

In enthalpy, the energy released by an exergonic reaction is represented by a negative value (since enegy in the system is lost), while the energy required to perform an endergonic reaction is represented by a positive value (because energy is added to the system). It happens to be that the formatio...
by Tuong-Minh Tran 1C
Thu Jan 31, 2019 10:01 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 2
Views: 56

Re: Bond Enthalpies

You would look at the total of all of the bonds: the three C=C bonds and three C-C bonds, for instance. This is definitely one way to find enthalpy. Also keep in mind that in real life, any molecules with multiple types of bonds result in resonance hybrids. Thus, if the bond enthalpy of a resonant ...
by Tuong-Minh Tran 1C
Wed Jan 30, 2019 10:03 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW Problem 4A.9
Replies: 3
Views: 62

Re: HW Problem 4A.9

The most important concept to take into account here is that the energy it takes to heat up the water to its final temperature is equal to the amount of heat energy the copper loses. It can be portrayed as this: ΔH(copper)=-ΔH(water) After that, we refer to the general equation ΔH=m*C(specific)*ΔT a...
by Tuong-Minh Tran 1C
Thu Jan 24, 2019 7:57 pm
Forum: Phase Changes & Related Calculations
Topic: Change in Enthalpy
Replies: 3
Views: 45

Re: Change in Enthalpy

The enthalpy of water from liquid to gas is positive. Enthalpy is defined as the internal energy of a substance. In order for water to turn from a liquid to a gas, energy must be added into the system in order to excite the molecules enough to change from a liquid state to a gas state.
by Tuong-Minh Tran 1C
Wed Jan 23, 2019 11:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW Problem 6D. 17
Replies: 2
Views: 45

Re: HW Problem 6D. 17

Since the problem does not give you a K value, you have to derive it yourself. While Table 6D.1 does not have what you need, Table 6C.1 (page 461) does. To clarify: a) NaCH3CO2 is basically acetic acid with a sodium ion attached. Therefore, you refer to the Ka value of 1.8*10^-5 (pKa=4.75). b) Simil...
by Tuong-Minh Tran 1C
Mon Jan 21, 2019 10:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: listing strength of acids by their pKa/pKb values
Replies: 2
Views: 69

Re: listing strength of acids by their pKa/pKb values

In general, the lower the pKa, the stronger the acid will be. That means the acid with the highest pKa value will be the weakest in the list while the acid with the lowest pKa will be the strongest. The relationship between pKb and acidity strength is the opposite than that involving pKa: the lower ...
by Tuong-Minh Tran 1C
Sat Jan 19, 2019 5:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Determining when k is small or big
Replies: 2
Views: 47

Re: Determining when k is small or big

10^-3 and 10^3 serve as guidelines to determine whether a chemical equation strongly favors reactants or products. When the K value is between 10^-3 and 10^3, it just means that the equation does not favor reactants or products to such an extent that it is significant enough for people to acknowledg...
by Tuong-Minh Tran 1C
Sat Jan 19, 2019 5:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 10^-3 as a comparison
Replies: 2
Views: 36

Re: 10^-3 as a comparison

Basically, your assumption is correct. The equation does indeed favor products when K=2.0, but not really that strongly. 10^-3 and 10^3 are just arbitrary baselines that chemists established to alert them when an equation extremely favors reactants or products.
by Tuong-Minh Tran 1C
Sat Jan 19, 2019 5:22 pm
Forum: Student Social/Study Group
Topic: ICE Table
Replies: 6
Views: 100

Re: ICE Table

While trying to find equilibrium concentrations based on initial concentrations is definitely a factor in deciding whether to use an ICE table, there are also other points to consider. Most importantly, its best to make sure whether the acid or base on the reactants side is weak or strong. If the ac...
by Tuong-Minh Tran 1C
Sat Jan 12, 2019 1:22 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Change in pressure
Replies: 2
Views: 60

Re: Change in pressure

As the previous reply said, Q<K, so the reaction shifts to the right. To find the reason why, it's best to look back to the formula for K and Q: [P]/[R]. As you know, when Q is not equal to K, the reaction has not attained equilibrium yet. This means that the reaction will either proceed left or rig...
by Tuong-Minh Tran 1C
Sat Jan 12, 2019 1:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Table
Replies: 6
Views: 136

Re: ICE Table

Basically, yes; whenever you set up the ICE table, you start by assuming that the reaction hasn't taken place yet. Therefore, there won't be any products formed yet, so their initial concentrations are 0.
by Tuong-Minh Tran 1C
Wed Jan 09, 2019 9:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.9 Moles and Partial Pressure in Equilibrium
Replies: 1
Views: 30

Re: 5G.9 Moles and Partial Pressure in Equilibrium

When looking at the relationship between the number of moles and pressure, it's best to take a look at the ideal gas law: PV=nRT In the formula, n represents the number of moles of gas while P represents the pressure of the gas in the container. As shown, moles and pressure are directly proportional...

Go to advanced search