CHEMISTRY COMMUNITY

IreneSeo3F

Can someone explain why the concentration of the reactants and products remain the same when inert gas is added?

IreneSeo3F

When calculating the final concentration of NO2 for #10:
is the initial concentration for NO2=3.17 and N2O4=.422?

IreneSeo3F

Hello. For Week 1's Sapling #9, can someone help with the steps to calculate the final concentration of NO?

IreneSeo3F

Is the composition of the reaction mixture the concentration of the compounds at equilibrium?

IreneSeo3F

Hi. When given the Kp value and initial pressure of the product, how do you calculate total pressure?

IreneSeo3F

You would use first and third reactions.
Cube Ka because you multiply the coefficients by 3 to get 3H2+3I2->6HI. Then take the inverse of Kc because you need the inverse reaction to get 2NH3->N2+3H2. Then you multiply those values to determine final K.
Hope this helped!

IreneSeo3F

For week 1's sapling #3, how do I set up the equation for the equilibrium constant?

IreneSeo3F

How is pressure and partial pressure different?

IreneSeo3F

For Week 1's sapling #2, how do I calculate the moles of SO2?

IreneSeo3F

Hi! If a reaction starts with higher pressure, why is Kc not affected?

IreneSeo3F

How do you calculate the average bond length in a molecule when given the bond length of each atom?

IreneSeo3F

Hi. I was kind of confused about pKa. What exactly is pKa, and if pKa is higher, does that mean the acid is strong?

IreneSeo3F

In the Marshmallow Final Review, #41D, can someone explain why thymine only forms 6 hydrogen bonds?

IreneSeo3F

Hi. I thought if the pH is greater than pKa, than the predominant species would be charged. Can someone explain why it would be neutral? Thank you!

IreneSeo3F

On sapling #11, can someone explain why HClO is more acidic than HIO? Wouldn't HIO be more acidic because I has greater radius?

IreneSeo3F

Hi! I simply count the number of the ligands and that gives you the coordination number.

IreneSeo3F

en contributes 2, and Cl contributes 2; therefore, the coordination number is 4.

IreneSeo3F

Hi! Is a complex ion different from a coordination compound? If they are, can someone explain how they are different?

IreneSeo3F

How is the rule different when determining the geometry of a coordination compound? For sapling #3, why does a complex with coordination # 4 have two different geometries?

IreneSeo3F

When naming a coordination compound, how do I know which species come first? How do I determine the order?

IreneSeo3F

According to the solution, the pi bonds in C=C are perpendicular to one another in H2CCCH2 molecules, while pi bonds in terminal C=C bonds are parallel to one another in even number of C molecules. Thus, H atoms are coplanar when there are even number of C atoms.

IreneSeo3F

I think bonds are stronger when pi bonds are present rather than only sigma bond being present since the strength of bond order is triple bond>double bond>single bond.

IreneSeo3F

Hi, on sapling 20, why is the AsO43- ion nonpolar? How are the dipoles canceled?

IreneSeo3F

Hi, I am still confused on understanding the concept of hybridization. Does anyone know how to simply determine the hybridization of an atom?

IreneSeo3F

Hi, can someone explain how XeF2 molecule is linear? Thanks.

IreneSeo3F

Some molecules have net charge of 0 but do not have completed octets. A molecule that has a lone pair, whether negatively charged or not, can become a lewis base and donate its electron pair to the species that can accept the electron pair. For example, group 13 elements need 5 electrons to complete...

IreneSeo3F

First ionization energy is the energy needed to remove the outermost electron from an atom so it should be the outermost orbital! Second ionization energy is always greater than the first because the electron is more tightly held.

IreneSeo3F

I think polarizability means the tendency of its electron density to be distorted. For example, when you compare Br2 to I2, I2 is has higher polarizability than Br2 because its electrons are not as tightly held, therefore its electron density is easily distorted.

IreneSeo3F

Hi! If the molecule is symmetrical, can you assume that it's nonpolar? How do you determine if a molecule is polar or nonpolar?

IreneSeo3F

Hi! For #1 on sapling, why is the shape of the carbonate ion different from the sulfite ion? I can't really tell the difference.

IreneSeo3F

Hi! I'm having difficulty with problem 13 in sapling assignment.
The problem asks:
what is the maximum theoretical number of water molecules that one urea molecule can hydrogen bond with?
How can I solve this?

IreneSeo3F

Lewis acids are electron acceptor and lewis bases are electron donor. When you look at their chemical structure, the acid should be able to accept an electron pair while the base should be able to donate an electron pair.

IreneSeo3F

As more shells are added, they are more distant from the nucleus, therefore the radius of an atom increases when transitioning from a lower orbital to a higher orbital!

IreneSeo3F

Is london dispersion force is always present in all molecules? If it does, why?

IreneSeo3F

Hi! In our sapling hw, a question mentions resonance hybrid. Can someone explain what resonance structure is?

IreneSeo3F

More bonds, shorter length due to stronger attraction!

IreneSeo3F

For the second part of the question, you would divide the total energy by the value you got for the work function. Total Energy (J) / Work Function (J/photon) = Number of electrons (photons)

IreneSeo3F

To find the mass of a single Fluorine molecule, you would multiply the molar mass of F by 2 and divide by the Avogadro's constant. And I did not have to use the temperature when solving this question, so I think it was just given.

IreneSeo3F

Hi! I'm having difficulty figuring out how to solve #25 on sapling. #25) The E.coli bacterium is about 1.6 micrometers long. Suppose you want to study it using photons of that wavelength or electrons having that de Brogile wavelength. What is the energy Ephoton of the photon? Which equation should I...

IreneSeo3F

Hi! Can someone explain the difference between electron affinity and ionization energy? Thank you!

IreneSeo3F

Hi!! While I was doing the sapling questions, I was just wondering if we have to memorize the quantum numbers for every subshell or there is a particular way to calculate/figure them out?

IreneSeo3F

I ordered my textbook in early October and received an email that it was shipped on October 8th. I still haven't received my tracking code nor my textbooks. I emailed the UCLA store, but I did not get any reply. And I just found out that my sapling free trial has ended and there is no way for me to ...

IreneSeo3F

Since we are learning the basics of atoms and their properties, I think orbitals are significant in the sense that we understand the wavelike behavior of electrons. Knowing more about orbitals allows us to specify properties of a specific element as well as the trend among periods and groups.

IreneSeo3F

Hi, the question on sapling asks why oxygen has lower first ionization energy than both nitrogen and fluorine.
Doesn't the first ionization energy increase as you move across a period? Can someone explain the reason of this?

IreneSeo3F

I always used the whole numbers from the calculator and rounded to correct sig figs at the end, but sometimes the question wants me to stick to the sig fig rules from the beginning. As far as I know, both of answers shouldn't be too different.

IreneSeo3F

I would suggest converting them to SI units so that you don't have to convert it every single time along the way. Whenever the wavelength is given in nm, I would convert it to m before using the equations like c=lambdav.

IreneSeo3F

Hi! 1)I would convert the wavelength from nm to m by multiplying 10^-9 so that you get 4.2x10^-7m. 2)Using the equation c=lambdav, you calculate the frequency, v=(3x10^8m/s/4.2x10^-7m)=7.1x10^14 s^-1. 3)Using the equation E=hv, E=(6.626x10^-34 Js)(7.1x10^14 s^-1)=4.7x10^-19 J/photon 4)(32 J/s)(2 s)=...

IreneSeo3F

Frequency and wavelength are inversely proportional to each other. The greater the frequency, the shorter the wavelength and vice versa. Also, frequency is directly proportional to energy.

IreneSeo3F

I am confused with number 5 on this week's sampling. The question asks: A liquid is exposed to infrared radiation with a wavelength of 5.68x10^-4cm. Assume that all the radiation is absorbed and converted to heat. How many photons are required for the liquid to absorb 17.97J of heat? How can I start...

IreneSeo3F

The SI unit for Energy is J(joule) and Joule = kgm^2s^-1. And yes the units are all the same in order for you to subtract from one another. If you are adding/subtracting something, the components must have the same unit!

IreneSeo3F

I am having difficulty with question 7 in the Sampling. The question is: how many photons with a wavelength of 889nm are needed to melt 451g of fusion. The enthalpy of fusion is given. What is enthalpy of fusion, and how can I approach this question?

IreneSeo3F

Hi. I am a little confused about the energy levels. Why do the gaps become smaller as the energy levels increase?

IreneSeo3F

Hi! The picture gives us skeletal structures. There is a carbon atom at each junction and at the end of each bond. Also, we assume that there are hydrogen atoms attached to the carbon atoms to make 4 bonds. Skeletal structures are difficult to understand at first, but once you understand, they allow...

IreneSeo3F

I planned to be a premed student, but I never had the opportunity to talk to a real med student. This advice really helped me and I feel so relieved. Thank you!

IreneSeo3F

To find the molecular formula, simply count the number of each element in the picture. After finding the molecular formula, you multiply the number of subscripts to the molar mass of each element and the sum is the molecular mass.

IreneSeo3F

6. South Korea

IreneSeo3F

Hello, everyone. This is my first time posting a question on chemistry community. I am having difficulties with the sampling question #9. The compound contains only C, H, and O and was experimentally found to have a molar mass of 110±10 g/mol . When a 1.000 g sample of caproic acid is burned in exce...

Search found 57 matches