CHEMISTRY COMMUNITY

Michelle Chernyak 1J

Because these topics were gone over after the midterm, will electrochem and kinetics make up a bigger part of the final?

Michelle Chernyak 1J

Because the system returns to its original internal energy, the overall deltaU of the reaction is 0. That means whatever deltaU we calculated in the first step we have to do the reverse of in the second step in order for them to cancel out and go back to 0.

Michelle Chernyak 1J

Can someone explain to me how raising the temperature will affect the rate constant?

Michelle Chernyak 1J

Help! I'm really confused with this problem. I feel like i need to solve for k of the first reaction and then use that to solve for the activation energy of the second but I don't even know if that's right. Also, when they say that all other factors are equal, do they mean to each or to their values...

Michelle Chernyak 1J

Because we are combining two equations, we now have 2 equilibrium constants, each with a different set of products over a different set of reactants. It would be impossible to add the two equilibrium constants together without altering the reaction (simple math; you'd have to bring it to a common de...

Michelle Chernyak 1J

if a molecule is not at the proper orientation when a collision happens, then the reaction will not occur

Michelle Chernyak 1J

i don't think the number itself can be a negative number, but k will be negative when it is the slope of a zero order or first order reaction.

Michelle Chernyak 1J

nope, just the ones on the syllabus!

Michelle Chernyak 1J

Michelle Chernyak 1J

When the two reactions are combined, Cl- is a product and I- is a reactant. Because we do not include solids or liquids when calculating the equilibrium quotient, Q= [Cl-]/[I-]

Michelle Chernyak 1J

Molecularity is only used to describe elementary reactions

Michelle Chernyak 1J

It depends. I think sometimes we will need to figure out the components on our own.

Michelle Chernyak 1J

standard potentials occur at 1 bar and when the substances in question are at their most stable states

Michelle Chernyak 1J

When it comes to voltaic cells, an input of energy/electric current is necessary in order for the reaction to occur. Because of this, a large negative cell potential would require a large input of energy.

Michelle Chernyak 1J

Because they have low activation energies, these reactions only require a small energy input in order to occur, therefore increasing the temperature would not make that big of a difference. This is because the reaction is already close to happening and therefore does not need a huge input so there w...

Michelle Chernyak 1J

Have you ever heard of the saying that a team is only as strong as its weakest link? Well basically its the same type of situation. Even if there are faster steps in the reaction, the slowest step is the one that governs the reaction because the rate of the reaction must accommodate for that step as...

Michelle Chernyak 1J

Yes you are correct. There s no work being done as a gas expands in a volume because there is no opposing force.

Michelle Chernyak 1J

Specific heat capacity is the amount of energy it requires to raise 1 g of a substance by 1 degree of temperature while heat capacity is the amount of energy it requires to raise the given amount 1 degree of temperature. Specific heat is an intensive property, meaning that regardless of the amount p...

Michelle Chernyak 1J

It is favorable for a substance to be at its most stable state, therefore when a substance reaches that, it is going to want to maintain that most stable state. This means that it wont spontaneously progress in either direction, it will just stay in its current form.

Hope that helps!

Michelle Chernyak 1J

w=-PdeltaV applies to the work done in a irreversible expansion and yes both irreversible and reversible processes do expansion work, there are just two different equations used to solve for w.

Michelle Chernyak 1J

Thermal energy is q while the heat required to raise a substance to a certain temperature is the specific heat capacity. Based off of this, the first is asking for q in q=mCdeltaT and the second is asking for the C.

Michelle Chernyak 1J

delta S total is the total entropy change that occurs during a reaction, while delta G is the total change in gibbs free energy that dictates if the reaction is spontaneous or not. In order to solve for delta G, we can often use delta S in the equation, delta G= deltaH -Tdelta S

Michelle Chernyak 1J

When it says a reaction is thermodynamically favored, it is referring to just the enthalpy or the free energy?

Michelle Chernyak 1J

Because all of the function in deltaG= deltaH -TdeltaS are state functions, does that mean that free energy is a state function as well?

Michelle Chernyak 1J

What carries more weight when determining if a reaction is spontaneous, the enthaply of the reaction (if it is endothermic or exothermic) or the entropy of the reaction? Or do they carry the same weight?

Michelle Chernyak 1J

This question maybe really stupid but is it possible to just subtract the enthalpies of formation of the products from the enthapies of formation of the reactants when doing a combustion problem?

Michelle Chernyak 1J

Why do you subtract products minus reactants for enthalpies of formation but do reactants minus products for bond enthalpies?

Michelle Chernyak 1J

Hi, I'm struggling with the set up for this question (8.41). I thought I knew how to do it, ( I set -q_ice=q_water) but my answer is off by a little bit. Can anyone help out please?

Michelle Chernyak 1J

The question (8.39) is "how much heat is needed to convert 80.0 g of ice at 0.0C into liquid water at 20.0C?"

I understand how to do the problem but I don't understand why we need to employ the specific heat capacity of liquid water rather than ice. Can someone please explain that to me?

Michelle Chernyak 1J

In today's lecture, Dr. Lavelle stated that in the isothermal reversible reaction, the gas expanding against the vacuum is exerting work. This confused me because I thought that with a vacuum, there is no opposing force, therefore work cannot be done because work= opposing force X distance. Can some...

Michelle Chernyak 1J

Why does a change in volume at constant pressure result in a negative work?

Michelle Chernyak 1J

In the book, it seems as though they sometimes use Celsius and kelvin interchangeably without applying a conversion when referring to heat capacities. Why is that?

Michelle Chernyak 1J

When there are two substances present in a calorimeter or the calorimeter is made up of a certain material, how do we know which specific heat capacity to use?

CHEMISTRY COMMUNITY

Search found 33 matches

what is going to be on the final? [ENDORSED]

Re: Midterm #5

Temperature and rate constants

Catalysis 15.69

Re: Multiplying Equilibrium Constants

Re: Collision Cross Section

Re: Rate law constant

Re: Chapters in Final Exam

Re: Half life

Re: Test 2 Q8

Re: Molecularity

Re: Elementary Reactions

Re: Standard Potential

Re: 14.25

Re: Activation Energy and Temperature Dependence of Rates

Re: Slowest Elementary Step

Re: Work

Re: State Properties

Re: Why are standard free energies of formation zero for elements in their stablest form?

Re: Gibb's Energy and Work

Re: heat vs thermal energy [ENDORSED]

Re: delta S total and delta G

thermodynamically favored

state functions

enthalpy and entropy when it comes to spontaneous reactions

combustion

Bond enthalpies vs. enthalpy of formation

Homework question 8.41

Question regarding 8.39 homework question

Question about today's lecture 1/24/18

Work in relation to pressure and volume

Celsius vs Kelvin with heat capacities [ENDORSED]

Specific Heat capacity