CHEMISTRY COMMUNITY

Michael Lonsway 3O

For the answer attached, why isn't there a trans- before the naming? There's a double bond with opposite priority groups on both sides so why didn't the book include trans?

Michael Lonsway 3O

What range (in volts) does a voltmeter need to have to measure PH in the range of 1 to 14 at 25 degrees Celsius if the voltage is zero when PH=7?

How can we relate PH to the equations we've used for electrochem and solve this problem?

Michael Lonsway 3O

For this problem I'm confused on why we divide by 30.5kj for part a and divide by 30.5kj for part b as well. I was hoping someone could explain this problem in simple terms too.

Michael Lonsway 3O

How can we derive the integrated rate laws for zero, first, and second order reactions? In the 2014 final exam question 4 asked to derive a second order reaction with A as a reactant so how could we derive this?

Michael Lonsway 3O

For part c of this problem how do we get n=6? I looked at the reaction and it didn't look like there were 6 moles in the system.

Michael Lonsway 3O

How do we tell which substituent has the highest priority? What would it be in this example and how would you tell?

Michael Lonsway 3O

In the question below where do we start to number the carbon atoms? I'm not sure how to label the substituents in the cycloalkane since I don't know where we would start counting the carbon atoms.

Michael Lonsway 3O

For the electrophilic addition reaction of hydrogen bromide, HBr, to propene, CH3CHCH2, producing 2-bromopropane, CH3CHBrCH3, write the rate laws for each elementary step and the overall rate law. Explain your answer for the overall rate law. How can we determine which step is the slow step to creat...

Michael Lonsway 3O

How do we tell if a compound is a nucleophile or electrophile? There's a list of common ones on pg 81 of the course reader so should we only memorize those ones or is there a way to tell which type it is?

Michael Lonsway 3O

For the pre-equilibrium approach example why is there a 2 in front of the reaction constant? Is it because 2 products (2NO2 ) are formed? Also, is the intermediate only present in the rate law if the first reaction is fast and the second reaction is slow?

Michael Lonsway 3O

Are there any problems in the hw (or course reader) that show the three methods being used in one problem? I haven't been able to find any so far.

Michael Lonsway 3O

What's the difference between the pre-equilibrium approach and steady-state approach? The course reader states that they give the same result but I'm confused with which method goes to which approach. Also, how would the direct computation method relate to these two approaches?

Michael Lonsway 3O

The rate constant for the reaction A ---> B is 25 /min at 298k and 35 /min at 350k. Calculate the value of the rate constant at 770k. Give your answer in /min. I used a form of the Arrhenius equation to solve this and only got activation energy. What units are activation energy in and how can I find...

Michael Lonsway 3O

What's the difference between E and Ecell° as well as G and deltaG°? I know that they're used in the same formulas but I'm wondering under what conditions they'd change. I'm also wondering the names for each of the symbols since I know that there is Gibbs free energy and cell potential but I don't k...

Michael Lonsway 3O

Calculate the standard Gibbs free energy for the following cell reactions:
a) 2Ce+4 + 3I- ----> 2Ce+3 + I3-, Ecell=+1.08V

I know we used deltaG= -nFE but how do we find n? I thought we need to be given the number of electrons in the reaction.

Michael Lonsway 3O

Balance the skeletal equation by using oxidation and reduction half-reactions. All the reactions take place in basic solution. Identify the oxidizing agent and reducing agent in each reaction. d)Reaction of elemental phosphorus to form phosphine, PH3, a poisonous gas with the odor of decaying fish: ...

Michael Lonsway 3O

You need to solve this problem numerically but I was also wondering the concept behind when u, q, or w would be 0.

Michael Lonsway 3O

If 2.00 mol of an ideal gas at 300. K and 3.00 atm expands isothermally and reversible from 6.00L to 18.00L and has a final pressure of 1.20 atm, what is w, q, and delta U? The answer key said that delta U is 0 but would it still be 0 if we weren't working with an ideal gas? Also what initial condit...

Michael Lonsway 3O

A technician carries out the reaction 2SO2(g) + O2(g) --> 2SO3(g) at 25°C and 1.00 atm in a constant-pressure cylinder fitted with a piston. Initially, 0.0300 mol SO2 and 0.0300 mol O2 are present in the cylinder. The technician then adds a catalyst to initiate the reaction. a)Calculate the volume o...

Michael Lonsway 3O

Hydrochloric acid oxidizes zinc metal in a reaction that produces hydrogen gas and chloride ions. A piece of zinc metal of mass 8.5g is dropped in an apparatus containing 800.0mL of 0.500M HCL(aq). If the initial temperature of the hydrochloric acid solution is 25°C, what is the final temperature of...

Michael Lonsway 3O

I'm confused about the second part of the solution. I understand that we needed to find the enthalpy of formation of N2O5 but why is -169.2kJ not the final answer?

Michael Lonsway 3O

Calculate the standard enthalpy of formation of dinitrogen pentoxide from the following data, and from the standard enthalpy of formation of nitric oxide, NO (see Appendix 2A) 2NO(g) + O2(g) ---> 2NO2(g) Delta h= -114.1kJ 4NO2(g) + O2(g) ---> 2N2O5(g) Delta h = -110.2kJ I'm having trouble getting th...

Michael Lonsway 3O

Use the data provided in Appendix 2A to calculate the standard reaction enthalpy for the reaction of calcite with hydrochloric acid: 4HNO3(l) + 5N2H4(l) ----> 7N2(g) + 12H2O(l) The solution manual subtracted the standard enthalpy of products from reactants, however, it didn't include the standard en...

Michael Lonsway 3O

How would I calculate the final PH for both friend's?

Michael Lonsway 3O

I'm having trouble with part b) since I can't find the new H3O+ concentration. How would I calculate it?

Michael Lonsway 3O

Write the molecular-orbital valence electron-configuration of the CN radical and determine its bond order. Does the bond order match the type of bond in the Lewis structure? What does your calculated bond order suggest about the stability of the cyanide radical? The answer states that the bond order...

Michael Lonsway 3O

: This is the image given by the problem

Michael Lonsway 3O

Suppose that 25.0ml of .10M CH3COOH is titrated with .10M NAOH. a)What is the initial PH of the .10M CH3COOH solution? b) What is the PH after the addition of 10.0ml of .10M NAOH?c)What volume of .10M NaOH is required to reach halfway to the stoichiometric point? d) Calculate the PH at that halfway ...

Michael Lonsway 3O

There are only two ligands: the cyanide ligand, and the entire ring with its tail which we call "corrin-DMB." State each ligand's total charge.
*See diagram on page 260 for reference

Michael Lonsway 3O

List the following acids in order of increasing strength and explain why: F3O2H, H3O2H, Cl3O2H, H3C(CH3)2O2H

I'm also wondering how to determine what makes an acid strong. Is it based only on its ability to lose an H atom? How would you determine what makes a base strong too?

Michael Lonsway 3O

Consider the following reaction at 800k, for which you know kc=2.1x10^-3: I2(g)<-->I(g)
If you measure [I2] to be 3.18x10^-4M, calculate the equilibrium concentration of I for this experiment.

The answer is 8.2x10^-4M but I got a number much larger than that

Michael Lonsway 3O

This problem asks which statement is false and the answer was: Atoms or molecules with an even number of electrons are diamagnetic. I was wondering what this was false since I thought that atoms/molecules with an odd amount of electrons were paramagnetic while the ones with event electrons were diam...

Michael Lonsway 3O

During spontaneous fission uranium-235 emits a neutron with a mass of approximately 1.00866g/mol. If one of these neutrons has an energy of 4.84 Mev, what is its de Broglie wavelength? In your solution use E=p^2/2m and explicitly show that kinetic energy is related to momentum. I'm confused with wha...

Michael Lonsway 3O

For compounds is ionic character greater when the two elements are further apart or when they have greater ionic energy. For example, would K and Cl have greater ionic character than Mg and F? And would the same principle apply to polar character?

Michael Lonsway 3O

The problem states: Write the Lewis structure, including typical contributions to the resonance structure (where appropriate, allow for the possibility of octet exmpansion, including double bonds in different positions), for a) sulfite ion, b) hydrogen sulfite ion; perchlorate ion, d)nitrite ion. I'...

Michael Lonsway 3O

I was looking through chapter 2 and I'm wondering how can you tell if an element has gone through an excited state? I know that if an electron skips an orbital it can occur but I'm wondering how else it occurs and why does it happen.

Michael Lonsway 3O

Thanks for the help! I made Delta E negative since the problem states that energy is emitted and was able to get the right answer.

Michael Lonsway 3O

I put n=4 into n-initial and solved for n-final which allowed me to get n=6. I'm wondering why this worked because the problem asked for the quantum level where the electron began.

Michael Lonsway 3O

An excited hydrogen atom emits light with a frequency of 1.14x10^14 Hz to reach energy level for which n=4. In what principle quantum level did the electron begin?

I got n=3 but the answer is n=6. I used the different variations of the Rydberg equation and haven't been able get the right answer.

Michael Lonsway 3O

In the question section of chapter 1 #13 asks: Use the Rydberg formula for atomic hydrogen to calculate the wavelength for the transition from n = 4 to n = 2. b) What is the name given to the spectroscopic series to which this transition belongs? c) Use Table 1.1 to determine the region of the spect...

Michael Lonsway 3O

Thanks for the help! I got the wrong answer before since I forget to include 4pi when finding delta x.

Michael Lonsway 3O

Find the uncertainty in the position of a marble of mass 1.5g given that its speed is known to within +/- 0.55 m/s. Answer: Delta x= 3.2E-32m

Michael Lonsway 3O

In the fall workbook Fall 2015 quiz prep question 3 asks: Find the uncertainty in the position of a marble of mass 1.5g given that its speed is known to within + or - 0.55m/s. I used the uncertainty equation delta x= h/m*delta v and made sure to convert mass to kg and use 1.1 m/sec speed. I got a di...

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