CHEMISTRY COMMUNITY

Sean Tran 2K

Use Kelvin, as the gas constant R includes it.

Sean Tran 2K

Electrodes connect cells, while electrolytes are ions.

Sean Tran 2K

An enzyme is a biological catalyst that allows for reactions to proceed faster.

Sean Tran 2K

The way it is written does not matter, it just makes it more easily understandable.

Sean Tran 2K

Kinetics is not included in Test 2, only up to Electrochemistry.

Sean Tran 2K

Test 2 covers the last bit of Thermodynamics that wasn't on the midterm, as well as electrochemistry

Sean Tran 2K

273 K and 1atm under STP. It should be provided during tests.

Sean Tran 2K

G(not) represents standard Gibbs Free energy.

Sean Tran 2K

The test should cover the end of thermo, as well as electrochemistry.

Sean Tran 2K

The test will be week 9 in discussion

Sean Tran 2K

X is dropped when it is less than 10^-3 and the percent at the end is less than 5

Sean Tran 2K

If X is less than 10^-3

Sean Tran 2K

Partial pressure is based upon the pressures of the gases in a reaction.

Sean Tran 2K

Increasing pressure and decreasing volume increases concentration on the side with a greater amount of moles.

Sean Tran 2K

The value used is dependent on the units given.

Sean Tran 2K

Bomb calorimeters are isolated systems.

Sean Tran 2K

Q is heat transfer, while H is enthalpy.

Sean Tran 2K

Yes, include H2O as a gas, but not liquid.

Sean Tran 2K

Negative delta H shows a release of energy, being exothermic

Sean Tran 2K

You can change heat, mass, or do work on the system.

Sean Tran 2K

K is changed by change in temperature.

Sean Tran 2K

The gas constant needed will be based on the units of pressure. The constants should be on the formula sheets during tests.

Sean Tran 2K

Increasing heat in an exothermic reaction favors the reactants.

Sean Tran 2K

Increasing temperature in an endothermic reaction would favor the forward reaction.

Sean Tran 2K

In an exothermic reaction, decreasing the temperature will favor the formation of products, while increasing temperature would favor formation of reactants.

Sean Tran 2K

Due to K being a ratio, it does not have units.

Sean Tran 2K

Is there a certain significance to homogeneous and heterogeneous equilibrium? Or do we just need to know what they are?

Sean Tran 2K

It is correct that solids and liquids are omitted from equilibrium constant concentrations. Aqueous solutions are included in the calculations.

Sean Tran 2K

When there are gases, use Kp to show partial pressure, and when there are aqueous solutions, use Kc to show molarity.

Sean Tran 2K

Q and K are both calculated similarly, but Q can be calculated at any time during the reaction and can be compared with K to determine the direction in which the reaction is favored.

Sean Tran 2K

The coordination number of a central atom on a molecule refers to the number of bonds on it.

Sean Tran 2K

I thought the only thing regarding the structure of cisplatin we needed to remember was what side the Cl atoms were on.

Sean Tran 2K

Since we’re on the topic of writing hybridization, does it matter if we write d hybridization before s and p? Or can we out it after.

Sean Tran 2K

Sigma bonds exist in single, double, and triple bonds.

Sean Tran 2K

Acids give H+ ions (protons). Bases receive H+ ions.

Sean Tran 2K

Yes, the transition metals in the d-block all can form coordination compounds.

Sean Tran 2K

You will have the arrow pointing to the more electronegative atom, as well as the slightly negative and positive symbols on the respective atoms.

Sean Tran 2K

Organic molecules are covered in future Chem courses, being 14C and 14D.

Sean Tran 2K

I'm not too sure what exactly, so you may want to go over the examples we covered in lectures and ask your TA/Lavelle for more information.

Sean Tran 2K

In addition to the s and p orbitals, the d orbitals can be used in hybridization as well.

Sean Tran 2K

Typically, atoms in the third period or further down are exceptions to the Octet Rule, as they can use the d-orbitals for extra valence electrons.

Sean Tran 2K

The least electronegative atom is placed in the center of the electron structures, with the exception of Hydrogen, which will never be in the center.

Sean Tran 2K

Atoms within the third period or past that can have expanded valence shells for electrons, since they have the d-orbitals.

Sean Tran 2K

The atomic radius of an atom increases as you go down the periodic table and towards the left.

Sean Tran 2K

The double and triple covalent bonds are stronger than the single bonds, as more electrons are shared. As a result, these bonds are shorter.

Sean Tran 2K

If we were required to know bond lengths, I think the values would be given to us to use in whatever calculations are required.

Sean Tran 2K

We are saying that there are exceptions to the octet rule, as formal charges of zero take priority, but these exceptions will still mean that the atom breaking the octet rule would have more than 8 atoms or no?

Sean Tran 2K

Central atoms in the 3rd period or further down are able to accommodate more than 8 electrons due to having the d-orbitals available, as d-orbitals start becoming available at n=3.

Sean Tran 2K

I thought that resonance structures were "ideal" when the formal charges of the atoms were equal to 0? Or close to that value in some cases.

Sean Tran 2K

Indeed, and covalent bonds are different than ionic bonds because electrons are shared between the non-metals.

Sean Tran 2K

The trend for electron affinity and electronegativity is the same, but what are the differences between the two? Or rather, how similar or they?

Sean Tran 2K

A quick tip for trends is that atomic radius increases as you go down and left, while ionization energy and electronegativity increase as you go up and to the right. In addition to these, I believe another trend is that elements as you go down and to the left on the periodic table tend to have more...

Sean Tran 2K

So in lecture, I remember there was a briefing discussion regarding the exceptions of the configurations of electrons in the groups with Chromium and Copper, taking one electron from the s orbitals to half fill their d-orbital. Is there a specific reason regarding the energy of these and why the def...

Sean Tran 2K

Orbital diagrams are used to display the electrons within an atom. According to Hund's Rule, an each orbital in a subshell will have one electron in each at the ground state, and these unpaired electrons will generally be spinning up initially. When all the orbitals are filled, electrons will begin ...

Sean Tran 2K

The first ionization energy of an electron is the energy required to remove the first electron from a ground state atom. The trend for this is seen on the periodic table as you go to the right and up.

Sean Tran 2K

I think that most questions, at least on the tests, would ask for a specific unit for the final answer to be in.

Sean Tran 2K

When I use the periodic table for math on problems, I take the entire number shown on it, then round off my final answer to the required number of sig figs, in hopes of retaining accuracy.

Sean Tran 2K

I believe that Planck's Constant (h) is also able to be used when determining the energy level of an electron.
E_n = -hR/n²

Sean Tran 2K

Can someone explain what Angstroms are? I was confused on the test on this question. Angstroms are a unit of length equivalent to 10^(-10) m. I was taken aback by this question on the test as I do not ever remember being told we had to memorize the quant. value of Angstroms. Did I miss that in clas...

Sean Tran 2K

I don't think sig figs were looked at too carefully for this test.

Also, I believe questions heading in the direction are given partial credit, and the grader will read through your work.

Sean Tran 2K

As Ami mentioned, .9 would be okay to round up for figuring out empirical formulas, but what if it is .8?

Sean Tran 2K

I believe a CASIO scientific calculator is permitted, as it meets the criteria listed on the syllabus. I will personally be using a TI-36X scientific calculator which (hopefully) should work.

Sean Tran 2K

On the class website, there is a link that will lead you to a PDF for assistance regarding sig figs. It has examples included, so it doesn't contain strictly definitions.

Sean Tran 2K

In addition to resources already listed, the class website for 14A has something that will help with sig figs. It provides a link to a document covering how to use sig figs.

Sean Tran 2K

Based on what I've read on other posts on this regarding the usage of sig figs, I think sig figs are required for the first test. Even if they aren't required for the first test, I'm sure that learning them now in preparation for future tests won't hurt you.

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