CHEMISTRY COMMUNITY

Jaira_Murphy_2D

Will we be told to make/ not make approximations? Or will we have to decide on our own?

Jaira_Murphy_2D

How can you tell if a reaction would be least likely to occur?

Jaira_Murphy_2D

This was posted earlier this week: "An activated complex is the the structure that occurs when the molecule is at the highest energy along the reaction path (ie the transition state at the top of that curve at Ea). You will not be asked to draw the structure on the exam."

Jaira_Murphy_2D

Part b) a catalyst is not consumed in the course of a reaction
True of False

The answer is True

I don't understand why the answer is true because when we are looking for a catalyst in a reaction mechanism aren't we supposed to look for a catalyst that is being consumed and then formed?

Jaira_Murphy_2D

The presence of a catalyst provides a reaction pathway in which the activation energy of a certain reaction is reduced from 125 kJ/mol to 75 kJ/mol. (a) By what factor does the rate of the reaction increase at 298 K, all other factors being equal? (b) By what factor would the rate change if the reac...

Jaira_Murphy_2D

I love chemistry community because everyone replies so fast!

Jaira_Murphy_2D

How can you tell if a reaction is endothermic or exothermic based off Arrhenius equation, or given Ea and k?

Jaira_Murphy_2D

If I'm given a reaction mechanism with 2 steps I can just combine products on one side and reactants on the other side and cancel out like terms to get the overall reaction? And for a reaction mechanism with 3 or more steps, I have to use the pre-equilibrium approach? Or, how do I know when to use t...

Jaira_Murphy_2D

15.35 The half-life for the second-order reaction of a substance A is 50.5 s when [A]0 0.84 molL. Calculate the time needed for the concentration of A to decrease to (a) one-sixteenth; (b) one-fourth; (c) one-fifth of its original value. Can someone please explain how to solve part (a)? I'm pretty s...

Jaira_Murphy_2D

Determine the rate constant for each of the following first-order reactions, in each case expressed for the rate of loss of A: (a) A --->B, given that the concentration of A decreases to one-half its initial value in 1000. s

How do you solve part a) for this question?

Jaira_Murphy_2D

Given a table of rates and concentrations, when you find the rate constant k, is it the same k for all of the other concentrations?

Jaira_Murphy_2D

What is the rate law if the reaction is in 1st order, but there are 2 reactants?

Jaira_Murphy_2D

After writing the corresponding cell reaction using the cell diagram how can you tell if the cell reaction is spontaneous as written?
(If the problem only tells you that the cell potential is positive)

Jaira_Murphy_2D

Can someone explain how to find n in Delta G = -nFE ?

Jaira_Murphy_2D

How will I know if I am balancing an acidic or basic redox reaction? Or will the problem specify which one it is?

Jaira_Murphy_2D

Can someone explain this from the learning outcomes: Understand why reaction free energy depends on pressure and the equilibrium constant

Jaira_Murphy_2D

yes, I think S tot for a reversible process is = to 0

Jaira_Murphy_2D

What does a non-spontaneous process need to become spontaneous?

Jaira_Murphy_2D

Can someone explain this from the textbook? "At constant temperature and pressure, the direction of spontaneous change is the direction of decreasing Gibbs free energy."

Jaira_Murphy_2D

When writing the K expression and there's a solid or liquid in the reaction, should I balance the whole equation first and then not include the solid or liquid in my K expression? Or ignore the solid or liquid from the beginning and balance my the equation without them?

Jaira_Murphy_2D

Since Professor has review sessions during his lectures next week, will he be presenting the same past exam questions in each lecture, or different ones?

Jaira_Murphy_2D

Can someone please explain the concept behind why Delta H is equal to q at constant pressure?

Jaira_Murphy_2D

Can someone explain how I know which equation to start with for Hess' Law?

Jaira_Murphy_2D

Can anyone explain and apply the concept of reaction enthalpies to a biological or organic example? I'm not really sure what the outline means by being able to do that.

Jaira_Murphy_2D

Heat Capacity is measurement of heat absorbed or released. Since temperature change is directly proportional to the heat added, with the heat capacity as the proportionality constant, we can use the heat capacity to convert the temperature change into energy.

Jaira_Murphy_2D

I'm not exactly sure how it was derived but I know that it means the Heat lost in a reaction is gained by the calorimeter -q= qcal (- heat required is = + calorimeter constant) I think it applies to when you are Calibrating the calorimeter: the heat capacity is measured by supplying a quantity of he...

Jaira_Murphy_2D

Open system: Opened to both heat and matter (Ex. a test tube with liquid inside without a lid) Closed system: Closed to matter, but open to heat (Ex. a test tube with a closed lid, sitting in hot water; the liquid inside the test tube cannot escape but it can get warmer.) Isolated system: Closed to ...

Jaira_Murphy_2D

A State Property being independent of its path just means that how the system attained that state doesn't matter. For example how fast or slow the change happened doesn't matter, only its actual initial and final state matter. The value only depends on its current state not how it got there.

Jaira_Murphy_2D

Kc is just referring to calculating the eq of given concentrations and Kp refers to calculating the eq of given pressures.

Jaira_Murphy_2D

Is the reaction quotient unit-less as well?

Jaira_Murphy_2D

Can someone please explain to me why it’s necessary to balance a reaction equation when calculating Kc? I don’t understand why it mattters if concentration changes dont affect Kc.

CHEMISTRY COMMUNITY

Search found 31 matches

Approximations

Collision theory

Re: 15.85 6th Edition

HW problem 15.73

HW problem 15.67

Re: Exothermic vs Endothermic

Exothermic vs Endothermic

Overall Rate Law

solving for time elapsed

Re: 15.23 A) Determining rate constant

Reaction Rate

Rate law with 2 reactants

Spontaneous cell reaction

Finding n in Delta G = -nFE

Acidic Vs. Basic Redox Rxn

Re: Gibbs Free Energy Meaning

Re: irreversible v reversible

Non-spontaneous and spontaneous processes

Re: Spontaneity

Solids and Liquids in K expression

Dr. Lavelle's In-class Review Sessions

Delta H and q

Re: Hess' Law Confirmation

Biological Example

Re: heat capacity

Re: q(cal)= -q

Re: closed vs isolated system

Re: State Property

Re: Equilibrium constant

Re: reaction quotient [ENDORSED]

Calculating Kc