Search found 30 matches

by Eric Quach 1C
Tue Mar 12, 2019 11:14 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 1
Views: 58

Cell Diagram

Is there a difference in using a platinum electrode or a graphite (carbon) one?
by Eric Quach 1C
Tue Mar 12, 2019 11:11 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Equation
Replies: 1
Views: 41

Arrhenius Equation

Can someone explain what the A is in the Arrhenius Equation and why it's there?
by Eric Quach 1C
Tue Mar 12, 2019 11:10 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Molecularity
Replies: 5
Views: 105

Molecularity

Does molecularity only depend on the reactants? If there are multiple products does that affect molecularity?
by Eric Quach 1C
Fri Mar 08, 2019 8:33 pm
Forum: General Rate Laws
Topic: Third Order Reactions
Replies: 1
Views: 52

Third Order Reactions

Out of curiosity, what is the integrated rate law for a third order reaction?
by Eric Quach 1C
Fri Mar 08, 2019 8:29 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: n and significant figures
Replies: 5
Views: 271

Re: n and significant figures

Considering that it would make all of our answers have one sig fig, we would probably use the number that has next least number of sig figs. Also, we know the exact value for n, so it has "unlimited" sig figs in a sense.
by Eric Quach 1C
Fri Mar 08, 2019 8:26 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reaction Intermediates
Replies: 4
Views: 91

Re: Reaction Intermediates

AB would be an intermediate because if you sum up the elementary reactions for the overall reaction, AB is neither a product or reactant as it cancels out.
by Eric Quach 1C
Fri Mar 08, 2019 8:21 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow Step
Replies: 5
Views: 116

Re: Slow Step

Another way to put it would be that there is a bottleneck at the slow step. For example if there are 3 steps in a reaction and step 2 is the slow step, it doesn't matter if step 1 and 3 are almost instantaneous as step 2 must finish occurring before step 3 which completes the reaction.
by Eric Quach 1C
Fri Mar 08, 2019 8:18 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: k values
Replies: 4
Views: 130

Re: k values

k is the rate constant and is different for each reaction. the units for k vary depending on the order of the reaction. k can be found experimentally, but on the tests we will probably have to calculate it or solve for it.
by Eric Quach 1C
Fri Mar 08, 2019 8:15 pm
Forum: General Rate Laws
Topic: Order of a Reaction
Replies: 3
Views: 76

Re: Order of a Reaction

Adding on to the answers, to find the order one must plot the ln A, one over A, and just A (A being concentration of a reactant) against time to determine if it is first, second, or zero order. For the overall order, add the orders of each reactant to get the order for the entire reaction.
by Eric Quach 1C
Thu Feb 21, 2019 4:13 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Reduction Potentials
Replies: 3
Views: 78

Reduction Potentials

How are reduction potentials calculated?
by Eric Quach 1C
Thu Feb 21, 2019 4:10 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 3
Views: 68

Salt Bridge

I know that salt bridges are used to balance the charges to maintain the charges, but how exactly does a salt bridge do this?
by Eric Quach 1C
Thu Feb 21, 2019 4:04 pm
Forum: Balancing Redox Reactions
Topic: Oxidation States
Replies: 10
Views: 170

Re: Oxidation States

we don't have to memorize the oxidation states of metals, as they change depending on the compound. Just make sure to memorize the states for oxygen, the halogens, groups 1 and 2 and with that you can figure out the oxidation states of the metals.
by Eric Quach 1C
Thu Feb 14, 2019 10:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp equilibrium constant
Replies: 6
Views: 169

Re: Kp equilibrium constant

when its kp, the only thing to make sure about units is that they are all in units of pressure and the same unit of pressure. The units all cancel out in the end, making kp not have a unit.
by Eric Quach 1C
Thu Feb 14, 2019 10:19 pm
Forum: Calculating Work of Expansion
Topic: Work without change in volume
Replies: 8
Views: 325

Re: Work without change in volume

as work is equal to -PdeltaV and there is no change in volume, the expression would equal zero and no work is done.
by Eric Quach 1C
Thu Feb 14, 2019 10:16 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Liquid and moles
Replies: 8
Views: 321

Re: Liquid and moles

the two moles of water are not part of the ice table or the equilibrium constant as water is a liquid. This means that the water is solvent and there's an excess of it.
by Eric Quach 1C
Thu Feb 07, 2019 11:02 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work
Replies: 3
Views: 92

Re: Work

Yep if work is done by the system to the surrounding then the work is negative. If work is done by the surroundings on the system then work is positive. It's similar to q where if heat is released to the surroundings then q is negative. However, if the system gains heat, then q is positive.
by Eric Quach 1C
Thu Feb 07, 2019 10:59 pm
Forum: Calculating Work of Expansion
Topic: Integral Expression for Work
Replies: 4
Views: 97

Re: Integral Expression for Work

I think we just need to know how to apply it. The integral was used to help explain how the formula w=-PdeltaV was derived.
by Eric Quach 1C
Thu Feb 07, 2019 10:55 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Units for Entropy
Replies: 3
Views: 96

Units for Entropy

The units commonly used for entropy is J/K but I don't quite understand why it's like that. Is the unit supposed to show change in energy per kelvin?
by Eric Quach 1C
Sun Feb 03, 2019 7:13 pm
Forum: Phase Changes & Related Calculations
Topic: Work by expansion
Replies: 3
Views: 75

Re: Work by expansion

use the conversion 1L*atm=101.33 J and use dimensional analysis to convert
by Eric Quach 1C
Sun Feb 03, 2019 7:07 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: finding W
Replies: 6
Views: 109

Re: finding W

Yep the formulas give the same answer. I think Dr.Lavelle was just using the integral to show how the P delta V formula was derived.
by Eric Quach 1C
Sun Feb 03, 2019 7:05 pm
Forum: Phase Changes & Related Calculations
Topic: Compression Work
Replies: 3
Views: 81

Compression Work

If a piston is compressing then is work being done to the system or is the system doing work on the surrounding? What does this mean for negative and positive values of work?
by Eric Quach 1C
Thu Jan 24, 2019 7:42 pm
Forum: Phase Changes & Related Calculations
Topic: Change in Enthalpy
Replies: 3
Views: 55

Change in Enthalpy

Is the change in enthalpy from water as a liquid to gas positive and negative? Why?
by Eric Quach 1C
Thu Jan 24, 2019 7:41 pm
Forum: Phase Changes & Related Calculations
Topic: Reversible and Irreversible Process
Replies: 3
Views: 71

Re: Reversible and Irreversible Process

Reversible reactions have a two way arrow in a chemical reaction, while irreversible ones will have a one-way arrow.
by Eric Quach 1C
Thu Jan 24, 2019 7:37 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy and States
Replies: 8
Views: 140

Re: Enthalpy and States

State of matter does affect enthalpy. The value of enthalpy between liquid water and vapor will be different.
by Eric Quach 1C
Wed Jan 16, 2019 11:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentration
Replies: 4
Views: 106

Re: Concentration

K is the equilibrium constant and represents the ratio of products to reactants at equilibrium. While Q is the reaction quotient and is the ratio of products to reactants at a certain point in time (can be before or at equilibrium). Remember if Q does not equal K that means the reaction is not at eq...
by Eric Quach 1C
Wed Jan 16, 2019 11:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pH
Replies: 5
Views: 101

Re: pH

To find pH simply take the -log{H30+}.
by Eric Quach 1C
Wed Jan 16, 2019 12:13 am
Forum: Ideal Gases
Topic: Using Kc or Kp
Replies: 13
Views: 194

Re: Using Kc or Kp

Typically, Kp is used for when they give you partial pressures which means it will typically be used with problems that contain gases in the products or reactants. Kc is used with concentration values and are typically used in problems with aqueous solutions. However, if a problem gives you the conc...
by Eric Quach 1C
Wed Jan 09, 2019 7:41 pm
Forum: Ideal Gases
Topic: ideal gas constant
Replies: 4
Views: 86

Re: ideal gas constant

The value of R used is dependent upon the unit of pressure used.
For example if atmosphere is the unit of pressure used then 0.08206 is the R value. However, if torr is the unit of pressure used then use the R value of 62.36.
by Eric Quach 1C
Wed Jan 09, 2019 7:37 pm
Forum: Ideal Gases
Topic: Value of K
Replies: 6
Views: 110

Value of K

What does it mean when K is larger than 1 and smaller than 1?
by Eric Quach 1C
Tue Jan 08, 2019 5:39 pm
Forum: Ideal Gases
Topic: Equilibrium Constants
Replies: 4
Views: 107

Equilibrium Constants

For the equilibrium constant K, how does changing the coefficients in the chemical reaction affect K?
For example, how does doubling each coefficient change the value of K?

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