Search found 38 matches

by Alexa Tabakian 1A
Mon Mar 11, 2019 8:56 pm
Forum: First Order Reactions
Topic: 15.31 6th Edition
Replies: 3
Views: 37

Re: 15.31 6th Edition

Make sure the order of the reaction corresponds to the right half-life equation.
by Alexa Tabakian 1A
Mon Mar 11, 2019 8:55 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Equation.
Replies: 4
Views: 56

Re: Arrhenius Equation.

You use this equation when you either have activation energy or need to find it.
by Alexa Tabakian 1A
Mon Mar 11, 2019 8:55 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 15.89
Replies: 1
Views: 22

15.89

How would you draw a reaction profile for the reaction? Do we need to know how to do this?
by Alexa Tabakian 1A
Tue Mar 05, 2019 2:26 pm
Forum: First Order Reactions
Topic: Integrating
Replies: 3
Views: 40

Re: Integrating

You should know how to get from the first equation to the last equation. Both of these will be given, but you should know how the last equation is derived from the first equation.
by Alexa Tabakian 1A
Tue Mar 05, 2019 2:24 pm
Forum: Phase Changes & Related Calculations
Topic: Steam vs Boiling Water
Replies: 8
Views: 199

Re: Steam vs Boiling Water

Steam has a higher enthalpy because it takes more energy and heat to keep it as a gas. Therefore, it causes worse burns.
by Alexa Tabakian 1A
Tue Mar 05, 2019 2:21 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Zero, First, and Second Order reactions
Replies: 2
Views: 48

Re: Zero, First, and Second Order reactions

Yes, it is a second order reaction because the exponents that you multiply by in the rate equation add up to 2.
by Alexa Tabakian 1A
Wed Feb 27, 2019 1:25 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Entropy of Fusion
Replies: 3
Views: 61

Re: Entropy of Fusion

Yes, delta S can be both positive and negative.
by Alexa Tabakian 1A
Wed Feb 27, 2019 1:23 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: flipping the sign of Ecell
Replies: 5
Views: 85

Re: flipping the sign of Ecell

All E cell values are reduction values. You can either flip the sign for oxidation or use the formula Ecell= Eright-Eleft
by Alexa Tabakian 1A
Wed Feb 27, 2019 1:22 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G at boiling point
Replies: 2
Views: 67

Re: Delta G at boiling point

It is 0 because water vaporizes at 100 degrees, therefore, the system is technically in equilibrium because the question asks for the delta g of vaporization.
by Alexa Tabakian 1A
Sat Feb 23, 2019 4:13 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 1
Views: 36

Cell Diagrams

On some of the homework solutions, they add a completely random element to the cell diagrams. For example, on 14.15, the cell diagram shows KOH, however there is no KOH in the solution. Can someone please explain?
by Alexa Tabakian 1A
Thu Feb 21, 2019 3:10 pm
Forum: Balancing Redox Reactions
Topic: Finding Charge
Replies: 3
Views: 66

Re: Finding Charge

Use the charges from the periodic table! Hope this helps!
by Alexa Tabakian 1A
Tue Feb 19, 2019 10:06 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.81
Replies: 2
Views: 55

9.81

Which is the thermodynamically more stable iron oxide in air, Fe3O4(s) or Fe2O3(s)? Justify your selection.

How do you know, is it based on the molecular mass?
by Alexa Tabakian 1A
Tue Feb 19, 2019 9:46 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.69 in Sixth Edition
Replies: 1
Views: 49

9.69 in Sixth Edition

What amount (in moles) of ATP could be formed if all the Gibbs free energy released in the oxidation of 3.00 mol NADH were used to generate ATP?

I do not know how to approach this problem given just three equations and delta G. Can anyone help me out?
by Alexa Tabakian 1A
Tue Feb 12, 2019 8:04 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: When is delta S = 0?
Replies: 3
Views: 312

Re: When is delta S = 0?

delta S equals zero when the reaction is reversible because entropy is a state function. When the process is reversible, it starts and ends in the same place making entropy equal to zero.
by Alexa Tabakian 1A
Tue Feb 12, 2019 8:02 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Std Enthalpy of Formations
Replies: 1
Views: 33

Re: Std Enthalpy of Formations

Their heat of formation is zero because they are in their most stable state, that is why they are not included.
by Alexa Tabakian 1A
Tue Feb 12, 2019 8:01 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Extensive vs Intensive
Replies: 1
Views: 39

Re: Extensive vs Intensive

Heat capacity is extensive because it depends on the number of particles you have. Specific heat capacity and molar heat capacity are intensive because it is uniform for all molecules. For example, the specific heat of water is always 4.184 J/G x C and it does not matter how much water you have.
by Alexa Tabakian 1A
Sat Feb 09, 2019 2:52 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: 9.35 Sixth Edition
Replies: 2
Views: 50

Re: 9.35 Sixth Edition

The book says container A has the most entropy, then C, then B.
by Alexa Tabakian 1A
Sat Feb 09, 2019 2:30 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: 9.35 Sixth Edition
Replies: 2
Views: 50

9.35 Sixth Edition

Container A is filled with 1.0 mol of the atoms of an ideal monatomic gas. Container B has 1.0 mol of atoms bound together as diatomic molecules that are not vibrationally active. Container C has 1.0 mol of atoms bound together as diatomic molecules that are vibrationally active. How do you determin...
by Alexa Tabakian 1A
Fri Feb 08, 2019 11:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Reaction Enthalpies
Replies: 2
Views: 49

Re: Reaction Enthalpies

I noticed the problems in the book have a distinct way they would prefer you to solve them. For example, to use the version where you break down the different reactions, the book gives you the equations. Hope this helps!
by Alexa Tabakian 1A
Fri Feb 08, 2019 11:56 pm
Forum: Calculating Work of Expansion
Topic: Which P to use? 6th edition, 8.27
Replies: 3
Views: 69

Re: Which P to use? 6th edition, 8.27

Yes, the pressure you would use to find n is 1.79 atm.
by Alexa Tabakian 1A
Fri Feb 08, 2019 11:51 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Work Equations
Replies: 2
Views: 56

Re: Work Equations

There is w=-PdeltaV, w=nRTln(V2/V1), and w=nRTln(P1/P2)
The first one would be used for constant pressure and irreversible reactions. The second and third ones would be used in isothermic reversible expansions.
by Alexa Tabakian 1A
Fri Feb 08, 2019 11:49 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: w=-PdeltaV
Replies: 6
Views: 100

Re: w=-PdeltaV

The first one is for reversible expansion, and the second one is for irreversible expansion.
by Alexa Tabakian 1A
Sat Feb 02, 2019 9:29 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 8.31 Sixth Edition
Replies: 2
Views: 50

8.31 Sixth Edition

Calculate the heat released by 5.025 g of Kr at .400 atm as it cools from 97.6 to 25.0 C at (a) a constant pressure and (b) constant volume.

I tried looking this up in the book and it wants to us to use fractions and stuff like that. Is there another way we learned how to do it in class?
by Alexa Tabakian 1A
Thu Jan 31, 2019 5:13 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 6th Edition, 8.9
Replies: 1
Views: 59

Re: 6th Edition, 8.9

You still use the 101.325 J to convert from L x atm to Joules. You should get -150.97 Joules for work and then convert it to kJ which is -.15 kJ, this is work. You then add work and q which is 5.5 kJ. Your final answer should be 5.35 kJ.
by Alexa Tabakian 1A
Wed Jan 30, 2019 6:10 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Decreasing volume and chemical equilibrium
Replies: 8
Views: 142

Re: Decreasing volume and chemical equilibrium

When volume is decreased at equilibrium, the reaction will shift to the side with less moles. It also depends on how Q relates to K.
by Alexa Tabakian 1A
Tue Jan 29, 2019 12:51 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.99 in Sixth Edition
Replies: 1
Views: 22

8.99 in Sixth Edition

How would we go about finding the final temperature of HCl if the initial temperature is 25 degrees Celsius? What do you do with the volume and molarity you are given?
by Alexa Tabakian 1A
Tue Jan 29, 2019 11:34 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeters
Replies: 3
Views: 59

Re: Calorimeters

We talked about it in lecture, so I'm assuming we need to know how to solve problems.
by Alexa Tabakian 1A
Fri Jan 25, 2019 8:42 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.3 6th Edition
Replies: 1
Views: 35

8.3 6th Edition

I have no idea how to approach this problem. If somebody could please explain how to solve how much work is done, I would really appreciate it.
by Alexa Tabakian 1A
Wed Jan 23, 2019 4:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: How to know when to use partial pressure or molar concentrations?
Replies: 4
Views: 83

Re: How to know when to use partial pressure or molar concentrations?

If they give Kp, convert it to atm or bar, but if it gives Kc leave it in terms of the molar concentration.
by Alexa Tabakian 1A
Wed Jan 23, 2019 4:37 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Acids and Bases
Replies: 6
Views: 93

Re: Acids and Bases

You can also tell if it is an acid or base based on the equation. If it gives off OH-, then it is a base, and if it gives off H3O+, it is an acid.
by Alexa Tabakian 1A
Wed Jan 16, 2019 8:40 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 7th Edition 5J.1
Replies: 3
Views: 49

Re: 7th Edition 5J.1

The concentration of H2 would increase because there is now more CO that is available to react. Also, the concentration of H2 would increase in order to keep the equilibrium constant the same.
by Alexa Tabakian 1A
Wed Jan 16, 2019 8:39 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Acid and Base Equilibria
Replies: 7
Views: 106

Re: Acid and Base Equilibria

A weak acid has a higher pH. A pH of 7 is neutral, so the weaker the base, the closer to 7 it gets.
by Alexa Tabakian 1A
Mon Jan 14, 2019 9:13 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 12.23 in sixth edition
Replies: 1
Views: 48

12.23 in sixth edition

I'm confused on how to set up the equation to get H30+ if we are only given one number which is Kw. Can someone please explain?
by Alexa Tabakian 1A
Sat Jan 12, 2019 5:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE tables
Replies: 2
Views: 33

Re: ICE tables

When the coefficient is not equal to one you would simply add the coefficient in front of the x. For example if you had 2H2 you would subtract or add 2x.
by Alexa Tabakian 1A
Wed Jan 09, 2019 9:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Kp
Replies: 2
Views: 24

Re: Calculating Kp

I believe you use the units that are given and you just use a constant that corresponds to the units that are given.
by Alexa Tabakian 1A
Wed Jan 09, 2019 5:13 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 11.41 in 6th edition
Replies: 1
Views: 38

11.41 in 6th edition

I was wondering how to set up the ICE table for this reaction. Do we have to convert into mol/L? Also do we assume that we start with no NH3 or CO2?
by Alexa Tabakian 1A
Tue Jan 08, 2019 4:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentrations of products/reactants
Replies: 6
Views: 80

Re: Concentrations of products/reactants

Q would be anything other than equilibrium, and K is the equilibrium.
by Alexa Tabakian 1A
Tue Jan 08, 2019 11:23 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.37 6th Edition
Replies: 3
Views: 69

11.37 6th Edition

I was wondering if anyone could explain how to find the partial pressures of N2, H2, and NH3 when only given that K=41. Do we have to involve constants from a table?

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