CHEMISTRY COMMUNITY

Zenita Leang 2K

when is delta h equal to q?

Zenita Leang 2K

Can someone quickly summarize how to balance redox reactions in a basic solution?

Zenita Leang 2K

what is a triprotic acid?

Zenita Leang 2K

Yes, the Arrhenius Equation shows how a change in temperature affects rate of a reaction

Zenita Leang 2K

If activation energy increases, the reaction will be slower since more energy is needed in order for the reaction to occur and the reaction rate would be a larger value.

Zenita Leang 2K

It makes the reaction go faster by decreasing the activation energy.

Zenita Leang 2K

Where does the 0.0592 come from in the nernst equation?

E = E (standard) — (0.0592/n) log Q

Zenita Leang 2K

The experiments are necessary because they are the means by which we can compare concentrations and equilibrium constants in order to determine the rate law.

Zenita Leang 2K

If something is more negative, then it has more reducing power. To have more reducing power means it can gain more electrons. When E cell is more negative, this means that the reducing power is very high and and it can be easily oxidized.

Zenita Leang 2K

balance the moles of a reaction first and then on the side that is most positive, count to see how many electrons to balance the charge.

Zenita Leang 2K

what does gibbs free energy tells about a reaction?

Zenita Leang 2K

why is a salt bridge needed in a galvanic cell?

Zenita Leang 2K

You use 3/2R for Cv, when volume is constant in a reaction. This is seen in deltaS=nClnT2/T1. You use 5/2R for Cp when pressure is constant in a reaction, this could be used in the same equation.

Zenita Leang 2K

If you have a constant volume then you will use C_v which is equivalent to $\frac{3}{2}$ R. If it has a constant pressure, then you will use C_p which is equivalent to $\frac{5}{2}$ R. R is the constant on the constants and equations sheet.

Zenita Leang 2K

Cv is constant volume, which is $\frac{3}{2}$ times the constant R. You use this in deltaS=nCvln(t2/t1) instead of deltaS=nRln(V2/v1) when you have a monatomic ideal gas at constant volume to calculate for entropy.

Zenita Leang 2K

The derivations are helpful in understanding I think, but we should just know how to use them and under what conditions each one can be used for the midterm.

Zenita Leang 2K

An open system is where matter and energy of a system can interact with the surroundings, so for example, an open beaker. A closed system is where energy, but not matter, of a system can interact with the surroundings. In this case, this would be like a frozen bottle of water, where the matter stays...

Zenita Leang 2K

ΔHf^o is the enthalpy formation under standard conditions (so 1 atm, 1 mol, and and 278 K) whereas ΔHf just refers to enthalpy formation. ΔHf^o is otherwise known as standard reaction enthalpy for a substance.

Zenita Leang 2K

I still don't really have a clear understanding of what a state function is. Can someone define it and explain why work is not a state function?

Zenita Leang 2K

Otherwise, it is mostly usually given.

Zenita Leang 2K

Only CO and H2O is used since Carbon (C) in the equation is in a solid phase and the gaseous H₂ would have an enthalpy of 0 since it is a diatomic molecule.

Zenita Leang 2K

The textbook defines heat as the energy that is transferred as a result of temperature differences, whereas enthalpy refers to heat transfer. Energy itself is the capacity of a system to do work.

Zenita Leang 2K

I believe it is based off of the difference in heat of the enthalpy of the reactants subtracted from the enthalpy of the products at standard reaction enthalpy

Zenita Leang 2K

Is heat capacity the same thing as enthalpy? If not, what is the difference?

Zenita Leang 2K

In lecture, we were shown the three different ways to solve for enthalpy (Hess' Law, bond enthalpies, and standard enthalpy). Can these 3 methods be used interchangeably to solve or is one method preferable to the other?

Zenita Leang 2K

If percent ionization is more than 5% (and we were not able to approximate and determine the "x" in change in molarity as insignificant), what would we have to do to figure out K?

Zenita Leang 2K

How can you determine the conjugate acid of a strong base and the conjugate base of a strong acid in a reaction?

Zenita Leang 2K

What exactly is autoprotolysis? Does it refer to one specific reaction or does it describe a different type of reaction?

Zenita Leang 2K

Changing the concentration of reactants or products will change the reaction quotient, the Q, of a reaction. The K doesn't change because there is a specific equilibrium constant, K, for each reaction at given temperatures. When you change the concentration of a reaction or a product, the reaction w...

Zenita Leang 2K

You can look at the units that are given in the problem! If they give you mol/L (molarity) then you will use concentration to find K but if they give you torr, atmospheres (atm), or bar, then you will use partial pressure.

Zenita Leang 2K

You can use ICE tables for concentrations but you can also fill ICE tables with values of partial pressure.

Zenita Leang 2K

The limiting reagent is both. If a reactant runs out first, then the amount of product produced is limited to however much reactant there is, Therefore, the limiting reagent is the reactant that runs out first and would thus dictate how much product could be produced.

Zenita Leang 2K

From least strongest to strongest, the order goes:
1. induced dipole-induced dipole (LDF/vanderwaals)
2. induced dipole-dipole
3. dipole-dipole
4. H-bonds

Zenita Leang 2K

Lone pairs don't affect in this orientation so it would be non polar.

Zenita Leang 2K

Take the mass of the element you are looking for divided by the mass of the total molecule times a hundred and this is how you get the mass percentage.

Zenita Leang 2K

Yes but we don't need to know how to do that

Zenita Leang 2K

Coordination number is how many bonds there are on a transition metal. Transition metals don't have more than a single bond attached.

Zenita Leang 2K

I believe equilibrium is for chem 14b so calculating equilibrium shouldn't be on the final!

Zenita Leang 2K

The strong acids are HCl, HI, HBr, HNO₃, HClO₄, H₂SO₄, HClO₃. The strong bases we should know are the Group 1 hydroxides (NaOH, LiOH, KOH), alkali earth metal hydroxides, and Group 1 and 2 oxides.

Zenita Leang 2K

To be considered "polar," you don't necessarily have to look at the strength of the dipole. Determining polarity can also be determined on direction/orientation and whether the dipole moments cancel each other out or not.

Zenita Leang 2K

Br does not contribute to the production of OH^- or H₂O so that is why it is not included in the equation. NH₄ on the other hand can donate its H⁺ so it acts as an acid.

Zenita Leang 2K

Amphiprotic is a compound that can both donate or accept a hydrogen ion (aka a proton). Amphoteric means a compound can act as either an acid or a base. Amphiprotic refers specifically to its ability to accept and donate protons whereas amphoteric refers to whether a compound can or cannot react wit...

Zenita Leang 2K

A chelate compound's structure would depend on how many ligands there are

Zenita Leang 2K

I think your theory is correct, also since Fluorine is more electronegative and so it repels the Hydrogen and would alter the bond angles.

Zenita Leang 2K

I think the formula would be [Cr(NH₃)₃(H₂O)₃)]Cl₃

Zenita Leang 2K

Why is HOCl a stronger acid than HOI?

Zenita Leang 2K

This is called trichlorooxalatochromate.

Zenita Leang 2K

You use bis-tris-tetrakis for polydentate complexes. This is in comparison to bi- tri- and tetra- which is used for monodentate.

Zenita Leang 2K

The name of this compound is potassium tetracyanonickelate (II)!

Zenita Leang 2K

Can someone explain why chlorine is labeled as "chloro" in this compound? [Co(NH₂CH₂CH₂NH₂)₂(CN)(Cl)]Cl
Also why is ethylenediamine labeled as "bis"?

Zenita Leang 2K

Hello.

Why is cisplatin used in chemotherapy?

Many thanks.

:)

Zenita Leang 2K

A coordinate covalent bond has bonds with a complex ion whereas a covalent bond is just simple ions being bonded.

Zenita Leang 2K

Electronegativity is how strongly electrons are attracted to an atom. Ionization energy is the energy required to remove an electron from an atom.

Zenita Leang 2K

The molecule with an AX₃E shape have a trigonal pyramidal shape.

Zenita Leang 2K

A ligand is a molecule that can bind to another molecule. The ligand donates since it is an acid donor.

Zenita Leang 2K

For metals and nonmetals (in Group 1, Group 2, and Groups 13-18), you can determine an ion's charge by looking at the valence electrons in the s and p group. Calcium for example would be a +2 charge. Sulfur would have a -2 charge because it has 6 valence electrons and needs two more to complete its ...

Zenita Leang 2K

Its molecular shape is trigonal pyramidal since it has a lone pair! Lone pairs will throw the electron shape off a little and thus SO₃^2- has a bond angle of 109.5.

Zenita Leang 2K

Why does BrF³ have a hybridization of sp₃d?

Zenita Leang 2K

What is a dipole and how are they determined?

Zenita Leang 2K

We can use the VESPR theory to predict shapes by looking at the amount of electrons of an atom and understanding how the electrons will arrange themselves in a geometric shape since electrons will repel each other. Different amounts of electrons and bond angles will have different shapes.

Zenita Leang 2K

Sigma bonds allow bound atoms to rotate, meaning the electron density has cylindrical symmetry around the axis. Pi bonds do not allow bound atoms to rotate and thus the electron density is on each side of the internuclear axis. Sigma bonds also interact from one bond to the other while pi bonds over...

Zenita Leang 2K

Intermolecular forces are easier to break since they are weaker.

Zenita Leang 2K

A lone pair in the central atom

Zenita Leang 2K

Yes, to double check you can look for any lone pairs in the model and see if there is any repulsion with any of the other bond angles.

Zenita Leang 2K

Tetrahedral shaped atoms have bonds at a 109.5 degree angle because of its 3 dimensional shape! If each bond was 90 degrees away from each other, it would be more similar to having a flat shape but to maximize the space that the atom has (and because of the negatively charged electron's repulsion fr...

Zenita Leang 2K

what is the electron configuration of Niobium?

Zenita Leang 2K

Yeah, he said not to use the Rydberg equation but we can use the E= -hr/n^2 instead! :)

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