CHEMISTRY COMMUNITY

Nhi Vo 3A

Arrange the following substances in order of increasing standard molar entropy:
CHF3(g), CF4(g), CH3F(g), CH2F2(g)

The answer was CH3F (g) < CH2F2 (g) < CHF3 (g) < CF4 (g), but I don't understand why CF4 was placed last while CH3F is placed first. Is molar entropy not based on polarity?

Nhi Vo 3A

How do we know when to add the Pt(s) in our cell diagrams?

Nhi Vo 3A

I was wondering if electrophilic aromatic substitution and nucleophilic substitution reaction were similar or how are they different from each other?

Nhi Vo 3A

Thanks!!

Nhi Vo 3A

If given a proposed mechanism and the rate, how can you tell which step in the mechanism is likely to be the rate determining step?

Nhi Vo 3A

(CH3)2CHCH(CH2CH3)2

I get confuse when the compound is written like this. If possible, can you draw its line structure please. Thank you

Nhi Vo 3A

Step 1: O3 + NO --> NO2 + O2
Step 2: NO2 + O --> NO + O2

What is the catalyst in this reaction? How can you tell?

Nhi Vo 3A

The proposed two step mechanism for a reaction is H2AH2A + B --> BH^+ + HA^- and its reverse, both of which are fast, followed by HA^- + B --> BH ^+ + A^2-, which is slow.

Find the rate law with HA^- treated as the intermediate and write the equation for the overall reaction.

Nhi Vo 3A

Calculate the change in molar entropy of an ideal gas when it is compressed isothermally to 1/3 its initial volume.

Nhi Vo 3A

The reaction taking place in the silver cell used in some cameras and wristwatches in Ag2O(s) + Zn(s) --> 2Ag(s) + ZnO(s), and the cell potential when new is +1.6V. What is the reaction Gibbs free energy?

Nhi Vo 3A

Calculate the final temperature and the change in internal energy when 500. J of energy is transferred as heat to 0.900 mol Ne (g) at 298 K and 1.00 atm
a) at constant volume
b) at constant pressure
Treat the gas as ideal.

Nhi Vo 3A

Suppose that 1.00 kJ of energy is transferred as heat to oxygen in a cylinder fitted with a piston; the external pressure is 2.00 atm. The oxygen expands from 1.00 L to 3.00 L against this constant pressure. Calculate w and internal energy (delta U) for the entire process by treating the O2 as an id...

Nhi Vo 3A

A calorimeter was calibrated by mixing two aqueous solutions together, each of volume 0.100L. The heat output of the reaction that took place was known to be 4.16kJ, and the temperature of the calorimeter rose by 3.24 degrees C. Calculate the heat capacity of this calorimeter when it contains 0.200 ...

Nhi Vo 3A

A cylinder of volume 2.00 L contains 1.00 mol He (g) immersed in a constant-temperature water bath held at 30 degrees Celsius. Which process does more work on the surroundings, allowing the gas to expand isothermally to 4.00 L against a constant external pressure of 1.00 atm or allowing it to expand...

Nhi Vo 3A

Which anion is larger O ^- or S ^ 2- ?

Give two reasons why.

Nhi Vo 3A

What is the subshell notation and the total number of orbitals having the quantum numbers n=3, l=2, for a given element?

I got subshell notation to be 3d and total number of orbitals to be 10, why is this wrong?

Nhi Vo 3A

The photoelectric experiment became known as the photoelectric effect. What was the major conceptual change as a result of this experiment?

Nhi Vo 3A

Dibromobis(ethylenediamine)cobalt(III)sulfate

Nhi Vo 3A

From textbook self test 17.3B: Name the compound [CoBr(NH3)5]SO4

Write the formula of tetraamminediaquachromium(III)bromide

Thank you!

Nhi Vo 3A

Give the valence-shell electron configurations and bond orders for CO and CO+. Which has a stronger bond?

Nhi Vo 3A

Is there a way to present VSEPR theory without having to deal with Lewis structures?

Nhi Vo 3A

Why is the shape of ethyne linear when there three bonds instead of 2 like in BeCl2 ?

Nhi Vo 3A

Why does the lewis structure for XeF2 have Xe with three lone pairs instead of just two to complete an octet?

Nhi Vo 3A

Ohhhh okay that makes sense...I kept thinking it was L . oops :D

Nhi Vo 3A

In the Quiz 2 Preparation number 1: For each pair of compounds below, circle the compound that contains bonds with greater ionic character:

the last option states: AgF or Agl

what is Agl?

Nhi Vo 3A

Will questions like what if the hybridization of the central atom in a molecule or what are the hybrid orbitals be on the the upcoming quiz?

Nhi Vo 3A

Using molecular orbital theory, state why He2 not a stable molecule?

Thank you!

Nhi Vo 3A

That really helps, thank you!

Nhi Vo 3A

What is the difference between electron affinity and electronegativity?

They seem similar to me.

Nhi Vo 3A

Thank you!

Nhi Vo 3A

2.13 Describe the orientation of the lobes of the px, py, and pz orbitals with respect to the cartesian axes.

Nhi Vo 3A

Thank you!

Nhi Vo 3A

Xylitol, a sugar substitute, has a mass composition of C 39.43%, O 52.58%, H 7.88%, and a molar mass of 152.15 g/mol. What is its molecular formula? I found the moles for C, O, and H which are 3.283 mol C, 3.286 mol O, and 7.817 mol H. When I divided everything by 3.283, I got C: 1, H: 2.378, and O ...

Nhi Vo 3A

Write a balanced equation for the combustion of CH3OH.

Would the product of any combustion reaction have water and CO2?

Nhi Vo 3A

1. In photoelectric experiments, typically what part of the electromagnetic spectrum is the incoming light? Is the answer ultraviolet? 2. Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 105 m.s-1. The work function for sodium is 150.6 kJ.mol-1. Calculate the ener...

Nhi Vo 3A

Thank you! Your explanation was very clear.

Nhi Vo 3A

#10 in workbook: An excited hydrogen atom emits light with a frequency of 1.14 x 10^14 Hz to reach the energy level for which n=4. In what principle quantum level did the electron begin? The worked out solution uses the equation deltaE= hv to find energy. My confusion is how do I know when the equat...

Nhi Vo 3A

In a second experiment a shorter wavelength light source is used resulting in ejected electrons with a kinetic energy of 4.200 x 10-19J. What is the energy of this incident light? What is the wavelength of this incident light? What is the difference between the kinetic energy and just the energy of ...

Nhi Vo 3A

When the energy per photon is equal to the energy required to remove an electron, what is this energy called? Is the answer threshold energy? Also, if long wavelength light is not ejecting electrons from a metal surface will increasing the intensity of the light result in electrons being ejected? Th...

Nhi Vo 3A

1.69 : In a recent suspense film, two secret agents must penetrate a criminal's stronghold monitored by a lithium photomultiplier cell that is continually bathed in light from a laser. If the beam of light is broken, an alarm sounds. The agents want to use a handheld laser to illuminate the cell whi...

Nhi Vo 3A

1.65 : The energy required to break a C-C bond in a molecule is 348 kJ/mol. Will visible light be able to break this bond? If yes, what is the color of the light? If not, what type of electromagnetic radiation will be suitable?

Also, how do I convert from kj/mol to just joules?

Thank you

Nhi Vo 3A

1.57 : Lines in the Balmer series of the hydrogen spectrum are observed at 656.3, 486.1, 434.0, and 410.2 nm. What is the wavelength of the next line in the series?

Nhi Vo 3A

Thank you!

Nhi Vo 3A

Question : Self Test 1.5 A in the textbook :

The work function of zinc is 363 eV. What is the longest wavelength of electromagnetic radiation that could electrons from zinc?

How do I solve this?

Nhi Vo 3A

For quizzes, are we allowed to use the periodic table and formula sheet that came along with the course reader?

Nhi Vo 3A

Okay that makes sense. Thank you!

Nhi Vo 3A

Thank you!

Nhi Vo 3A

L.39. A 1.50-g sample of metallic tin was placed in a 26.45-g crucible and heated until all the tin had reacted with the oxygen in air to form an oxide. The crucible and product together were found to weigh 28.35 g. a). What is the empirical formula of the oxide? b). Write the name of the oxide. I f...

Nhi Vo 3A

For some reason, my question was like that. Thank you for your help!

Nhi Vo 3A

H.13. When nitrogen and oxygen gases react in the hot exhaust environment of an automobile engine, nitric oxide gas, NO, is formed. After it escapes into the atmosphere with the other gas on a solution of sodium sulfide, Na2S, in alcohol, which, in turn, is made by the reaction of hydrogen sulfide g...

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