CHEMISTRY COMMUNITY

Chew 2H

For concentration cells with different concentration, why does the product has to have lesser concentration than the reactant when we write the overall reactions?

Chew 2H

Thank you! And if it wasn't a galvanic cell, and the overall E could be negative. how do we know which one to flip?

Chew 2H

In the second electrochem problem Lavelle went through today in lecture, why did we flip the E value for the second equation? Do we always flip the equation with a much more negative value?

Chew 2H

In lecture, Lavelle went through the 3 ways to to calculate reaction mechanism, Steady state, pre equilibrium and the "direct computation: solve for differential equations". What exactly is the "direct computation" approach. I'm kinda confused.

Chew 2H

Clarification:
When we write rate law based on order, we only include the intermediates if we're writing the rate law for the specific reaction (say step 1 or step 2) right? If it's the overall reactions, we always have to cancel out the intermediates?

Chew 2H

is there a way to numerically calculate k' from k without knowing the K?

Chew 2H

For 15.35 part a, the half life for the second order reaction of a substance A is 50.5s when [A]initial is 0.84M. it then asks us to calculate the time needed for the concentration of A to decrease to one sixteenth of its original value. For this question why can't we just multiply 50.5s by 4 like w...

Chew 2H

when we express the loss of one reactant corresponding to the coefficient of another reactant (like we did in 15.29) , does it only work for first order reactions?

Chew 2H

is half life an extensive or intensive property?

Chew 2H

There's also one using kPA/sec. Does anyone know how kPA relates to the rate of reactions?

Chew 2H

I've seen problems that uses k either from the value given in the textbook or by calculating it. how do we know when we calculate for it ourselves and when we simply use the table provided in the textbook?

Chew 2H

Could someone explain why there is a positive linear slope for the second order reaction while the slopes are both negative for zero order and first order? Wouldn't the positive slope mean that the concentration in increasing? I'm alittle confused

Chew 2H

Could someone help explain what exactly happens in the salt bridge as well as with what it does to the reaction? I'm not clear on how the ions gets transferred across it.

Chew 2H

i think this is referring to the external wire circuit. From what i know, salt bridges don't exist in Electrolytic cells.

Chew 2H

How much of Electrolysis are we supposed to know regarding the test this week?

Chew 2H

In the anode/cathode diagram we saw, is Anode always on the left side or can it be switched? If so, how would we know which is which?

Chew 2H

What exactly are monoatomic ideal gases? When finding the Cv of F2, would we use 3/2R or 5/2R?

Chew 2H

when do we use -PdeltaV and when do we use -nRTln(V2/V1) in calculating w? What's the difference between the two?

Chew 2H

In the equation that converts K to Kc, what does the "c" represent?

Chew 2H

I understand that going from solid to gas from reactant to product would lead to an increase in entropy. I also understand that increase in number of moles lead to an increase in entropy. But what happens when a reaction has an increase in the number of moles but also goes from gas to solid in the p...

Chew 2H

Could someone help with how to solve 9.15? I'm not sure where to start

Chew 2H

Would the values of deltaG be the same regardless of which method is being used to calculate it or is there one that is less accurate than others?

Chew 2H

Would the value of entropy differ based on bond strength as well? Would there be less entropy in a triple bond than in a single bond?

Chew 2H

In the lecture, Dr Lavelle went over the phase change problem from Br(l)--> Br(g). There, he talked about how deltaH + is a endothermic reaction that does not favor forward processes. I understand that deltaH + refers to reactions being spontaneous at high temperature but what did Dr Lavelle mean by...

Chew 2H

Because Heating capacity refers to the amount of temperature required to raise a certain substance by 1 degree celcius, lower heat capacity means higher rise in temperature over once heated. So on the heating curve, the temperature rises higher thus making the slope of the curve steeper.

Chew 2H

In the question Dr Lavelle showed us in lecture, Br2(l) --> 2Br(g), i understand that we have to add the enthalpy of vaporization with the bond enthalpies. But what would the enthalpy of vaporization be? is it the normal n*heat of vaporization or is there another way of it?

Chew 2H

Based on the deltaU=q+w equation, if a system is endothermic and q is positive, would the work always be negative? If not, when does it become positive?

Chew 2H

Do we need to know the born haber cycle for the test?

Chew 2H

So does that mean deltaU=q+w does not apply to an isolated system?

Chew 2H

Extensive properties depend on the amount of the substance so basically an example would be Heat Capacity (the amount of heat required to change the temp by 1 Degree celcius of a substance. But for intensive properties (which are much more useful), it would be things like specific heat capacity or m...

Chew 2H

Why again are bond enthalpies the least accurate? In exams, do we always try to use Hess Law unless told otherwise?

Chew 2H

In Hess Law, if we flip the equation product reactant-wise, do we take the reciprocal of the enthalpy value or multiply it by '-'?

Chew 2H

Endothermic reaction in a flask feels cool because endothermic reactions use up energy(heat) from the surrounding. Therefore the surroundings loses heat and cools down.

Chew 2H

In the Heating Curve shown in lecture today, how do we know kJ/mol values of each solid/liquid/gas phases depending on the temperatures? Will it always be given?

CHEMISTRY COMMUNITY

Search found 34 matches

Concentration cells

Re: E cell value

E cell value

Ways to approach reaction mechanism

Intermediates in Rate law

Re: K and K'

15.35

15.29

half life

Re: Units [ENDORSED]

When do we calculate for k

positive slope in second ordre graph

Salt Bridge

Re: 14.91 Electrolyte

electrolysis

Anode/ Cathode

Monoatomic Ideal Gases

different ways to calculate w

K to Kc equation

Predicting signs of entropy [ENDORSED]

9.15

Gibbs free energy which method is the most accurate? [ENDORSED]

Re: Entropy Change factors

Phase change question demonstrated in Lecture

Re: Heating Capacity from Heating Curve

enthalpy of phase change

Heat and Work relation

Born Haber

Re: Energy Change in an Isolated System

Re: Extensive vs. Intensive

Bong Enthalpy accuracy [ENDORSED]

Hess Law [ENDORSED]

Re: Reaction in a Flask

Heating Curve: How is the kJ calculated?