## Search found 30 matches

Sun Mar 17, 2019 12:04 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Deriving Enthalpy Equations
Replies: 3
Views: 340

### Re: Deriving Enthalpy Equations

make sure you can switch equations around to find for something in particular within that equation. Thats always helpful.
Sat Mar 16, 2019 11:58 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: state functions
Replies: 4
Views: 307

### Re: state functions

A state function is a property whose value does not depend on the path taken to reach that specific value. Examples delta G , DELTA H, DELTA V, DELTA T. Path functions will be work and heat
Sat Mar 16, 2019 11:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K
Replies: 3
Views: 314

### Re: K

when calculating k the equation won't always be at a state of equilibrium, we have to find if it is by finding Q and comparing. if Q=k then its at equilibrium.
Sun Mar 10, 2019 10:27 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: rate determining
Replies: 3
Views: 112

### rate determining

In a multi step reaction, how do you figure out which step is the rate determining step?
Sun Mar 10, 2019 10:24 pm
Forum: Second Order Reactions
Topic: Temperature
Replies: 6
Views: 202

### Temperature

Does temperature affect the orders or just the rate constant?
Sun Mar 10, 2019 10:18 pm
Forum: Second Order Reactions
Topic: 2nd order
Replies: 4
Views: 174

### 2nd order

Can someone explain why a second order graph has a positive slope? Does this mean that the concentration is increasing?
Sun Mar 03, 2019 11:25 pm
Forum: General Rate Laws
Topic: rate laws
Replies: 1
Views: 100

### rate laws

Are catalysts always included in rate laws or only sometimes? And why?
Sun Mar 03, 2019 11:19 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Edition 6 14.25
Replies: 3
Views: 176

### Edition 6 14.25

Arrange the following metals in order of increasing
strength as reducing agents for species in aqueous solution:
(a) Cu, Zn, Cr, Fe

Sun Mar 03, 2019 11:15 pm
Forum: General Rate Laws
Topic: Edition 6 15.37
Replies: 1
Views: 82

### Edition 6 15.37

Sulfuryl chloride, SO2Cl2, decomposes by first-order kinetics, and k =2.81 x 10^-3 min^-1 at a certain temperature.
(a) Determine the half-life for the reaction

Can someone help me get started on this problem? Not really sure what to do.
Sun Feb 24, 2019 10:16 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: K>1
Replies: 2
Views: 89

### K>1

When will a reaction be K>1 ? I'm a little confused on this one. Thanks
Sun Feb 24, 2019 10:10 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: I2 (s)
Replies: 1
Views: 79

### I2 (s)

Why doesn't I2(s) produce electricity ?
Sun Feb 24, 2019 11:11 am
Forum: Balancing Redox Reactions
Topic: How do you balance a redox reaction
Replies: 4
Views: 142

### How do you balance a redox reaction

How do you balance the electrons of a redox reaction while balancing the moles as well?
Sun Feb 17, 2019 9:11 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: spontaneity
Replies: 3
Views: 128

### Re: spontaneity

Spontaneity just means that a chemical process can happen without a major outside force acting on the chemical reaction. There are two outside forces, I believe they are enthalpy and entropy.
Sun Feb 17, 2019 8:54 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Problem 115 ch 11 6th edition
Replies: 2
Views: 85

### Problem 115 ch 11 6th edition

11.115 The overall photosynthesis reaction is 6 CO2(g) + 6 H2O(l) -> C6H12O6(aq) + 6 O2(g), and Delta H = +2802 kJ. Suppose that the reaction is at equilibrium. State the effect that each of the following changes will have on the equilibrium composition (tends to shift toward the formation of reacta...
Sun Feb 17, 2019 8:40 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G
Replies: 3
Views: 135

### Delta G

Can someone clarify what exergonic and endergonic mean ? And how they relate to delta G. Thanks!
Sun Feb 10, 2019 12:50 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Enthalpy Equations
Replies: 1
Views: 114

### Re: Enthalpy Equations

3/2R is used for constant volume i believe and 5/2R is used for constant pressure.
Sun Feb 10, 2019 12:45 pm
Forum: Phase Changes & Related Calculations
Topic: Phase changes equations
Replies: 1
Views: 105

### Phase changes equations

Hello, what are some of the phase changes equations we should know?
Sun Feb 10, 2019 12:13 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Delta S equations
Replies: 3
Views: 146

### Re: Delta S equations

delta S(surrounding)= q(surrounding)/T which gives us delta S (surrounding) = -nRln(V2/V1) because q(surr)=w and w= -nRTln(V2/V1)
Sat Feb 02, 2019 5:37 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: are systems always measured at equilibrium?
Replies: 2
Views: 70

### Re: are systems always measured at equilibrium?

We only assume that the temperature is unchanged when it is an isothermal process which means that the temperature is unchanged. Unless they tell you that the temperature is not constant than we use a different equation for the problem. And I'm not sure why the temperature is always assumed to be 25...
Sat Feb 02, 2019 5:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: bond enthalpy equations
Replies: 6
Views: 196

### bond enthalpy equations

What are the steps to help solve bond enthalpy equations? I'm having a hard time understanding.
Sat Feb 02, 2019 5:11 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Why are reaction enthalpies per mol?
Replies: 1
Views: 109

### Re: Why are reaction enthalpies per mol?

It is in kj per mol because we are calculating the heat and whether the reaction is endothermic or exothermic. So that "energy/heat" that is required to break or make a bond is in kj. Now it is kj per mole because at the end of the reaction we should add all the individual values of heat f...
Sun Jan 27, 2019 6:56 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Temperature
Replies: 7
Views: 243

### Re: Standard Temperature

298 Kelvin is also useful.
Sun Jan 27, 2019 6:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Preferable Method?
Replies: 3
Views: 104

### Re: Preferable Method?

Usually Hess's method is a little bit more accurate because you won't have to write down all the bond enthalpies in an equation and keep track of the enthalpy change. With Hess's method you can just add the equations together change the moles and reverse the equations when necessary and at the end a...
Sun Jan 27, 2019 6:33 pm
Forum: Administrative Questions and Class Announcements
Topic: thermo equations
Replies: 1
Views: 116

### Re: thermo equations

∆G° = ∆H° - T∆S°
∆G° = - RT ln K
∆G = ∆G° + RT ln Q
∆G=E$G= \sum \Delta G(Products)-\sum \Delta G(Reactants)$
w = - PdeltaV
Sun Jan 20, 2019 7:47 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium and Volume
Replies: 2
Views: 80

### Re: Equilibrium and Volume

If there is an increase in volume it will change equilibrium to the left favoring the reactants. If there is a decrease in volume equilibrium will shift to the part of the reaction that has less moles.This happens for gas phase reactions.
Sun Jan 20, 2019 7:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.3 6th edition
Replies: 3
Views: 112

### Re: 11.3 6th edition

That is a really good question! Usually we are supposed to balance the equation first before we do any other steps! In this case we were asked to only write the expression of K with no other calculations necessary, so maybe it was just practice to get us used to placing the coefficients where they b...
Sun Jan 20, 2019 7:13 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: ICE Table Calculations
Replies: 4
Views: 186

### Re: ICE Table Calculations

I believe so. Some homework problems have 2 or more species depending on the question.
Sun Jan 13, 2019 4:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: equations
Replies: 10
Views: 279

### Re: equations

We can use the model equation of aA+bB <=> cC +dD to guide us. I believe chemical equations are written this way. Reactants are on the left( A and B) because they react with each other to create products which are on the right of the equation (C and D). C and D are products and A and B are reactants...
Sun Jan 13, 2019 3:46 pm
Forum: Ideal Gases
Topic: Kc and Kp
Replies: 6
Views: 142

### Re: Kc and Kp

Yes you can use Kc when everything is in gas phase. It makes calculations easier, and you won't have to convert back and forth from Kp to Kc or Kc to Kp. And yes we would have to use pV=nRT to convert. Remember that concentration= n/V
Sun Jan 13, 2019 1:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc and Kp
Replies: 5
Views: 166

### Re: Kc and Kp

Dr. Lavelle said that we should do Kc because it is easier for us to solve based on concentration. It would be harder for us to solve Kp and covert. We should solve for Kp when it is asked of us in a question.