CHEMISTRY COMMUNITY

Letizia Ye 4F

This is also because the the third step of the reaction is not included in the overall rate expression. Thus a catalyst speeding up the third reaction doesn't actually affect the overall rate, as it would only lower the activation energy of the third reaction to make it faster, not the rest of the r...

Letizia Ye 4F

Would each reaction have a unique frequency factor? Does the forward and reverse reaction have the same frequency factor?

Letizia Ye 4F

In what circumstances would rate be dependent on the [H2O]?

Letizia Ye 4F

You can infer from either the units of the rate constant, or the experimental data will tell you.

Letizia Ye 4F

For a pseudo first order reaction, the overall reaction could be second order, but because we make one of the reactants be in excess, the concentration of that reactant doesn't really change. Thus we can regard it as a constant, resulting in only the other reactant changing concentration affecting t...

Letizia Ye 4F

The equilibrium constant K is equal to k/k'. Thus if K is greater than 1, it means that k' (the rate of the reverse reaction) is very small or slow. This makes sense since when K is greater than one, the products are favored in the reaction, and vice versa.

Letizia Ye 4F

Why is it that for some notations different species are separated with a comma (ex. Pt| Ti2+, Ti3+||Co2+|Co) while others are separated by a line (ex. Pt|H2|H+||Fe2+,Fe3+|Pt)?

Letizia Ye 4F

Why do we have to convert cell potentials to $\Delta G$ using $\Delta G = -nFE$ to find unknown cell potentials?

Letizia Ye 4F

Why is the Gibbs free energy of formation for elements always zero?

Letizia Ye 4F

Can someone explain how inert electrodes work and which ones we should use in our cell diagrams?

Letizia Ye 4F

I don't think it matters whether the final answer is in J or kJ, but make sure when you're plugging them in the equation they're in the same units.

Letizia Ye 4F

Yes, since the tables given are usually of the standard reduction potentials, to get the standard oxidation potential you simply have to flip the sign.

Letizia Ye 4F

The value of the heat capacity will change depending on how much of the substance there is, while the specific heat capacity will always remain constant regardless of how much stuff you have.

Letizia Ye 4F

If the reaction is isothermal, delta U=0.

Letizia Ye 4F

Q: What is Josaiah Willard Gibbs' favorite holiday?
A: ThanksGibbing

Letizia Ye 4F

If volume is constant, there can be no work done from expansion, thus the heat provided to the system is converted to work, which explains the lower Cv value.

Letizia Ye 4F

During lecture we mentioned bomb calorimeters and normal calorimeters, what is the difference between the two? What conditions and equations apply to each of them?

Letizia Ye 4F

During lecture we mentioned bomb calorimeters and normal calorimeters, what is the difference between the two? What conditions and equations apply to each of them?

Letizia Ye 4F

Irreversible processes have changes in pressure and volume that occur so drastically that the system does not have enough time to reach equilibrium, and thus the system and surroundings are not at equilibrium while work is being done. However, since reversible processes occur with an infinite amount...

Letizia Ye 4F

Not necessarily, SPC of a substance depends on properties such as intermolecular forces. SPC is just a measure of how many Joules it takes to raise 1 gram of a substance by 1 degree Celsius.

Letizia Ye 4F

Steam causes worse burns as when it contacts your skin, it's transferring both the energy from the phase change, as well as the additional energy it possesses as a vapor.

Letizia Ye 4F

This is similar to chemical equilibrium we covered last unit, where the energy transfer between the molecules don't stop, but rather there is no net energy movement between the system and the surroundings as the rate of energy transfer is the same.

Letizia Ye 4F

Hi!
How can we tell how strong an acid is by looking only at their Ka and pKa value? Does this rule work the same for bases? Thanks.

Letizia Ye 4F

A salt is composed of a cation and an anion. By examining the dissociated cation or anion you can tell how the pH will change. If the cation is able to give off an H+, it will lower the pH, if the anion is able to accept an H+, it will raise the pH.

Letizia Ye 4F

The ideal gas law can first be used to solve for an unknown property for a gas problem, or it can be rearranged to P=(n/V)RT to convert between concentration and partial pressure for gases.

Letizia Ye 4F

Catalysts will speed up both the forward and reverse reaction by lowering the activation energy. This means that equilibrium will be reached more quickly.

Letizia Ye 4F

Energy is required for bonds to break, and in the decomposition of halogens more energy is used to break the bond than released in the formation of the products. Thus the overall reaction is endothermic.

Letizia Ye 4F

Since the gas is inert, it won't react with anything else in the mixture and won't affect concentration levels.

Letizia Ye 4F

Catalysts only lower the activation energy for the reaction pathway, they do not change the value of K

Letizia Ye 4F

A spontaneous reaction is one that favors the formation of products since it is more energetically favorable

Letizia Ye 4F

it's on the constants and equations sheet provided on Dr. Lavelle's website!

Letizia Ye 4F

Polydentates have multiple "bites" which allows them to bind to multiple sites on the transition metal cation. Monodentates only have one "bite" so they are only able to bond to one site. You should also consider the structure of the ligand to see if they are able to be properly ...

Letizia Ye 4F

Another thing to note is that the conjugate bases of strong acids do not affect the pH of the water, for instance Cl- ion doesn't raise the pH despite it being a conjugate base.

Letizia Ye 4F

Acids with an -COOH group are organic acids (carboxylic acids). They create hydronium ions by donating the hydrogen at the end of the molecule to the water molecules.

Letizia Ye 4F

A conjugate base results when the original acid donates one of its protons. For example, H2CO3 is the acid, and HCO3- is its conjugate base.

Letizia Ye 4F

Since weak acids do not dissociate 100%, they will produce less H3O+. The concentration of H3O+ will be lower, and results in a higher pH value.

Letizia Ye 4F

They dissociate completely in water to form hydronium ions. Examples would be HCl, HBr, HNO3 etc.

Letizia Ye 4F

These are so helpful, thank you!

Letizia Ye 4F

I think hybridized orbitals can be thought of as electrons existing in between the energy levels of both s and p orbitals.

Letizia Ye 4F

Regions of electron density around central atom is equal to the number of hybrid orbitals. For instance, if there are 6 regions of electron density, the structure would be six sp3d2 hybridized bonds.

Letizia Ye 4F

Pi-bonds are always present in double and triple bonds, which makes those shorter and stronger than single bonds, which only consists of only a sigma bond, making it the weaker and longer bond.

Letizia Ye 4F

A single bond consists of a sigma bond, a double bond consists of a sigma and pi bond, while a triple bond consists of a sigma and two pi bonds. Sigma bonds are formed in 3 conditions: 2 s-orbitals overlap, 1 s-orbital and 1 lobe of a p-orbital overlap, and when one lobe of each p-orbital overlaps w...

Letizia Ye 4F

Polarizability can be thought of as the ability for a molecule's electrons to be distorted/affected by other charges. Atoms with more electrons typically have a higher polarizability since they are less attracted to the positive nucleus due to shielding of electrons.

Letizia Ye 4F

Since the dipoles are equal in magnitude but opposite in direction, they will add to zero, meaning there is no overall dipole for the molecule.

Letizia Ye 4F

Since expanded octets apply to all elements Period 3 and on, they have access to their d-orbitals to form more bonds.

Letizia Ye 4F

Any calculator that doesn't have programming capabilities is acceptable i think, you should be fine.

Letizia Ye 4F

There are more electrons involved with double and triple bonds, which pulls the atoms closer together and contributes to bond strength.

Letizia Ye 4F

The overall charge of the sulfate ion is 2-, but the central atom sulfur has a formal charge of 0 based on the FC = V - (L +S/2) formula.

Letizia Ye 4F

I think benzene is a special case where you add the ring in the middle of the diagram to represent the delocalized electrons. For other resonant structures, you use double arrows to show that each of the structures "shift" between each other.

Letizia Ye 4F

Since sulfur is a p-block element, it's able to have an expanded octet, since it has more room in its energy level to form other bonds.

Letizia Ye 4F

Taking a look at the Roman numerals, the copper cation can either have +1 or +2 charge.

Letizia Ye 4F

The first ionization energy is the energy required to remove one mole of electrons from a neutral atom, while the second ionization energy is the energy required to remove another mole of electrons from the ion at its already positively charged state.

Letizia Ye 4F

Light is subject to the wave-particle duality! It exhibits both properties of light, which means you can use applicable wave equations to determine frequency and wavelength etc., while also using equations that show that it's a particle, like the work function equation.

Letizia Ye 4F

Higher intensity of light will not affect the amount of energy the ejected electrons will have. No matter how intense the light is, if it still does not have enough energy to surpass the threshold energy (work function), no electrons will be ejected. Frequency does affect the amount of energy of eje...

Letizia Ye 4F

Each metal has a different work function, or the minimum energy that the incidental photons required to eject electrons from the surface. The excess energy is then converted to kinetic energy for the electron in EK = hf - work function

Letizia Ye 4F

ψ^2 is a wave function that describes the probability of finding an electron in a certain area, our TA said for the next quiz there wouldn't be too much about it, but you should know the definition.

Letizia Ye 4F

As long as your final answer is in the correct units the problem asks for, and you're able to cancel out the extra ones properly you should be fine!

Letizia Ye 4F

You can also check the websites for more info on their Step-Up program! I heard it's really helpful and thorough with their explanations.

Letizia Ye 4F

The actual yield is like the experimental yield of the reaction, something you would get if you performed the reaction in real life. The theoretical yield is the value you get when you do your stoichiometry calculations!

Letizia Ye 4F

Hello!

I'm still a little confused between the differences for systematic and random error in labs, could someone please clarify using some examples? Thanks!

Letizia Ye 4F

Hello!

Are there any necessary data booklets (ones that include the periodic table, relevant formulas, etc.) that we should have? Thanks!

Letizia Ye 4F

Hello!

I'm a student from Canada and we've always referred to the molarity of a solution as the concentration (C) of a solution. They're still in the same units (mol/L), and have the same formula (C=n/V), I was just wondering if there is a conventional preference? Thank you!

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