CHEMISTRY COMMUNITY

ShravanPatel2B

Do we cancel out the intermediates when dealing with the elementary reactions then if they do not appear in the final reaction?

ShravanPatel2B

This can also be used to solve for the values of k inside of the Ln equation.

ShravanPatel2B

How does this concept apply to solving problems in this class? Is there some way to account for this process?

ShravanPatel2B

Which conditions have to be present to change the type of catalyst

ShravanPatel2B

What is the difference between order and molecularity. Does molecularity have to do more with elementary reactions?

ShravanPatel2B

Termonuclear reactions and above are uncommon because all of the present molecules have to simultaneously collide with each other with enough energy and the correct organization in order to produce a reaction.

ShravanPatel2B

Changing the concentration of one solution in the cell will increase the voltage potential of the cell because you are putting the system further out of equilibrium. Because the concentration in only one side of the cell has changed, the concentration gradient across both sides of the cell increases.

ShravanPatel2B

Problem 7.11 was useful in undestanding the different concepts surrounding rate laws, especially trying to understand how to determine the slow step

ShravanPatel2B

I do not believe we will be tested on the process specifically but as you said fully understanding this process makes it much easier to understand the concept presented and also how the equations work and how the different parts of the equation react when manipulated.

ShravanPatel2B

The Individual orders of the reactants are added up to produce the overall order of the reaction.

ShravanPatel2B

Yes the equation must be balanced because this can affect the concentration of products and reactants which would affect the value of K when calculated.

ShravanPatel2B

The potential outcome of a reaction is usually influenced by the rate of product formation which are kinetic factors

ShravanPatel2B

Is it required to know these different electrodes and what their functions could be for any sort of conceptual questions or solving problems in general.

ShravanPatel2B

Will knowing the electrochemical series and the chart be important or will any necessary information be provided by the problem?

ShravanPatel2B

When given multiple chemical equations how do we determine in which one the values for delta h and delta g are the most similar. This relates to problem 6b in the midterm. Thanks

ShravanPatel2B

What rules for natural logs are used when solving these equations where we solve for a missing PH or concentration? Im struggling with following the solution manual. Thanks!

ShravanPatel2B

How would we solve problems involving a bomb calorimeter when there are conditions like the volume being constant?

ShravanPatel2B

Can someone explain the effects of manipulating the cathode and anode in the Ln Q portion of the nernst equation?

ShravanPatel2B

The Nernst equation can be used to approximate the potential of an ion with some charge across a membrane.

ShravanPatel2B

It would be Reduction/Oxidation so it would be cathode/anode for ln Q

ShravanPatel2B

This is correct there is a typo

ShravanPatel2B

A catalyst would speed up the rates of the reverse and forward reactions in part a. But however Catalysts have no effect on the delta H of a reaction because it does not affect thermodynamics.

ShravanPatel2B

When writing cell diagrams how do we know what type of electrode to add to either anode or cathode. There are Platinum electrodes and sometimes carbon is written in the form C(gr)? what is the explanation behind this?

ShravanPatel2B

Definitely understand how to derive the equations as it aids in understanding their function and just to visualize how the different components interact with each other. This can aid with conceptual questions as well as solving questions.

ShravanPatel2B

Temperature can have an affect on the value of the equilibrium constant. This problem was also on the midterm i believe.

ShravanPatel2B

Can the units of the rate constant in a rate law be used to identify the order of the reaction? Also would the units of the rate constant be different in in a rate law of species with different order?

ShravanPatel2B

To find the unique rate of a reaction, you take the rate (of any product or reactant) and divide by the stoichiometric coefficient of that chosen species

ShravanPatel2B

I usually assume that the reaction is irreversible unless stated that it is reversible in the problem.

ShravanPatel2B

you would multiply .44 by 3 because there are 3 moles of oxygen in the chemical equation

ShravanPatel2B

Yes it would be a third order. But we should be focusing on 0,1,2 orders so until bimolecular.

ShravanPatel2B

The Gibbs free energy of the system is a state function because it is defined in terms of thermodynamic properties that are state functions. Such as entropy and enthalpy.

ShravanPatel2B

This is because in each case one of the values of temperature or pressure are being kept constant. Depending on this you would use the constant heat capacities 5/2 R or 3/2 R in your equation when solving to take into account the constant pressure or temperature

ShravanPatel2B

The Van't Hoff equation relates the change in the equilibrium constant, K, of a chemical reaction to the change in temperature given the standard enthalpy change.

This equation can be used to analyze the relationship between K and the change in temperature.

ShravanPatel2B

to find the overall reaction you would add the reactions and cancel any terms that appear on both sides. 2AC + B ---> A2 + 2C The intermediate would be AB because it is formed in the first step and consumed in the second step. This is intermediate because it doesn't actually appear as part of the ov...

ShravanPatel2B

When solving phase change problems on our exam are we required to show a heating curve associated with it?

ShravanPatel2B

How does the collision model help to account for the temperature dependence of reactions?

ShravanPatel2B

What exactly does it mean to poison a catalyst? Does this play a role when solving problems or answering any questions conceptually?

ShravanPatel2B

What are some biological examples that have to do with chemical equilibrium? What exactly is meant by this in the course outline? Does it refer to problems that have to do with biological examples or do we need to be familiar with certain biological phenomena?

ShravanPatel2B

How is the equilibrium constant related to the forward and reverse rate constants of the
elementary reactions contributing to an overall reaction?

ShravanPatel2B

similar to the midterm problem when given the values for delta g you can you use the products minus reactants equation but when given values for enthalpy and entropy you should be prompted to use the second equation to solve for delta g.

ShravanPatel2B

What is a good explanation of an adiabatic system to be applied when faced in problems dealing with entropy?

ShravanPatel2B

you would determine overall order by adding up the orders of the individual species in the rate law. in this case it would be 5. A is in first order and B and C are in second order.

ShravanPatel2B

When writing cell diagrams from a given reaction when do we separate species with a comma? is this due to the species being in the same phase? If this is true would you also separate products and reactants in the same phase with a comma as well?

ShravanPatel2B

When do we know to add an inert electrode such as Pt to our cell diagrams when doing exercises such as 6l.5 part D. Thanks!

ShravanPatel2B

When writing half reactions can you only reverse the anode when it is required to cancel out electrons?

ShravanPatel2B

In question 6l.1 from the assigned homework problems how is the value of "n" determined when solving for the standard reaction gibbs free energy?

ShravanPatel2B

In this question does cl2 act as both the oxidizing agent and the reducing agent?

ShravanPatel2B

An oxidizing agent gains electrons and is reduced in a chemical reaction. A reducing agent, loses electrons and is oxidized in a chemical reaction.

ShravanPatel2B

When balancing redox reactions is it smart to begin with finding the oxidation states of each individual species or is there a method to quicker identify which species are being reduced and oxidized?

ShravanPatel2B

When doing problems or when we encounter a galvanic cell on our test do we always assume that the anode is on the left and that the cathode is on the right?

ShravanPatel2B

For lewis structures you should always work towards the lowest possible over all charge of the compound. but if it is an ion you should match the charges and if oxygens are present any negative charges are better on oxygen as it is more accepting of a negative charge due to its higher electronegativ...

ShravanPatel2B

Strong acid = weak conjugate base
weak acid = strong conjugate base

Strong base = weak conjugate acid
weak base = strong conjugate acid

ShravanPatel2B

When doing these problems make sure to find out the concentration of H30+ ions or OH- ions depending on whether you are starting with an acid or base. Then take the -log( ). that will give you either the pH or the pOH which can then be used to find the other value by subtracting from 14

ShravanPatel2B

In this problem the CH3COOH donates the H at the end to NH3 which makes NH3 the Bronstad base and the resulting conjugate acid NH4+ the conjugate acid to it

ShravanPatel2B

Add -ate to the end of the metal when naming when the overall charge is negative. Also take into the account that some metals utilize their latin names such as iron which would be ferrous but when negative ferrate

ShravanPatel2B

the coordination number is found by observing how many ligands are attached to the central atom

ShravanPatel2B

Are there any unbonded electron pairs on the central atom?

If yes, then this molecule can act as a Lewis Base

Is the valence shell of the central atom filled?

If not, then this molecule can act as a Lewis Acid

ShravanPatel2B

pOH = -log(.077) = 1.11
pH = 14-1.11 = 12.9

hope this helps!

ShravanPatel2B

Uric acid would have 14 hydrogen bonding sites. You would take into account the number of hydrogens and the lone pairs on the N and O atoms

ShravanPatel2B

An amphoteric oxide is an oxide that can act as either an acid or base in a reaction to produce a salt and water. examples include aluminum oxide and zinc oxide

ShravanPatel2B

VSEPR gives us a 3D model of molecules and compounds. This allows us to predict the functions of the molecules since structure is related to function.

ShravanPatel2B

When the coordination compound has a negative charge we would usually add the suffix -ate to the Lewis Acid

ShravanPatel2B

cis molecules have geometry that does not cancel out which results in a polar arrangement. trans molecules are non polar

ShravanPatel2B

sigma bonds would be stronger because there is overlap in their orbitals

ShravanPatel2B

A strong base is one that totally dissociates in an aqueous solution and results in more Hydroxide ion concentration

ShravanPatel2B

it can act as either as an acid or base. depending on the definition of an acid or base

ShravanPatel2B

The polarity of a molecule affects the boiling point because molecules that are higher in polarity usually have more electrons and thus require more energy in order to reach the boiling point.

ShravanPatel2B

You shouldn't disregard an intermolecular force when doing these problems because certain forces are stronger than others which can change your answer in different scenarios of different questions

ShravanPatel2B

This shouldn't be covered in this course, most likely in future classes like 14c or 14d

ShravanPatel2B

Can someone walk me through the shape and bond angle for (CH3)2 Be. Since Be would be the central atom and it only forms two bonds would the shape of the overall structure be based off of the Carbons or the Be that is in the middle?

Thanks!

ShravanPatel2B

Lone pairs have the greatest repulsion strength because they are the closest to eachother.

ShravanPatel2B

How exactly do we account for double and triple bonds in when getting the molecular shape?

ShravanPatel2B

This is because the lone pairs of electrons prefer to lie in the equatorial positions due to the fact that this causes less electron repulsions. This leaves the atoms in the T Shape.

ShravanPatel2B

Okay Thank You!

ShravanPatel2B

On this problem I got that the OCLO bong angle would be 120 degrees but why is it less than 120 degrees?
Is this due to the lone pairs on the oxygens pulling away from the central atom resulting in a smaller angle?

Thanks!

ShravanPatel2B

On our test or final will we have to give both the electron arrangement and the molecular shape or just the molecular shape?

Thanks!

ShravanPatel2B

yes they are the same thing.

ShravanPatel2B

l could be 11 -> 0 and ml would be 23 orbitals

ShravanPatel2B

Rules in regards to what?

ShravanPatel2B

Yes you would remove electrons first from the highest energy level. p -> s -> d -> f

ShravanPatel2B

usually an expanded octet can have 8 bonds

ShravanPatel2B

Can someone explain to me what we need to know about Radical and Biradical for the midterm. I did not understand what he went over in lecture? Do they have to do with drawing the lewis structures.

ShravanPatel2B

What are the main exceptions that we need to know for this class regarding drawing the structures? We talked about them in my section but I didn't understand what was exactly happening. If anyone could explain this to me it would be much appreciated.

Thanks!

ShravanPatel2B

The work function for chromium metal is 4.37 eV. What wavelength of radiation must be used to eject electrons with a velocity of 1.5 x 10^3 km*s^-1? Has anyone solved this problem, and if so what steps did you take to get to your answer? I used the formula kinetic energy = energy of photon - work fu...

ShravanPatel2B

why is the R negative in your equation?

ShravanPatel2B

I did a practice problem (which I will post here) but I am not sure whether I went about it the right way. If someone could please tell me if my answer and process is correct, it would be much appreciated. PROBLEM : An excited hydrogen atom emits light with frequency of 1.14 x 10^14 Hz to reach the ...

ShravanPatel2B

Thank you this makes a little more sense now!

ShravanPatel2B

The reason is because as the principle quantum number increases (n) the energy increases due to it being further from the nucleus

ShravanPatel2B

I am having trouble understanding the topic presented in Section 1D.4 having to do with the equation presented for finding the probability of an electron. If anyone could clarify this section for me it would be greatly appreciated.

Thanks!

ShravanPatel2B

I saw on an example online that for the electron configuration of some metals electrons are donated from the s block? I saw this specifically for silver and wanted to know how often this occurs and how much we should take this into consideration when doing our work.

Thanks

ShravanPatel2B

When writing out our electron configurations do we always follow the order of s,p,d,f? I have seen some answers in which the order is reversed. Are both ways correct, if not which one is?

Thanks!

ShravanPatel2B

This post is in reference to question number 1E5 Part d.

Is it true that the Z eff e would be less for p orbital electrons because they experience more shielding by the s orbital electrons?

ShravanPatel2B

1B.15 The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 3 103 km?s21. (a) What is the wavelength of the ejected electron? (b) No electrons are emitted from the surface of the metal until the frequency of the radiation reaches 2.50 3 1016 Hz. How much energy is re...

ShravanPatel2B

I was reading through the textbook and found one of the example questions under the de Broglie section and i am not sure if the answer I got is correct. The Question: Self-test 1B.4B Calculate the wavelength of a rifle bullet of mass 5.0 g traveling at twice the speed of sound (the speed of sound is...

ShravanPatel2B

There is a periodic table posted on the website

ShravanPatel2B

(Question Pasted Below) For my answer I got C. Im not sure whether or not my explanation for the answer is adequate or not. I said that since there is a decrease in the frequency the waves become longer and that causes the amplitude of the wave to decrease. Since the amplitude decreases it lowers th...

ShravanPatel2B

There is the same number of moles of Na, H, and O. This equation does abide by the law of conservation of mass because the mass is equal on both sides.

ShravanPatel2B

I read in the book that catalysts are just written on top of the arrow in the equation so thats what I did for my answer

ShravanPatel2B

Thank You!

ShravanPatel2B

I solved question G.17 but I am not sure if my answers are correct. (a) Determine the mass of anhydrous copper(II) sulfate that must be used to prepare 250 mL of 0.20 m CuSO4(aq). b) Determine the mass of CuSO4?5H2O that must be used to prepare 250 mL of 0.20 m CuSO4(aq). a) For part A I solved for ...

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