CHEMISTRY COMMUNITY

Neha Mukund

When one observes the equation to the zero order rate law, A = -kt +A0, it can be seen that the slope is -k. Hope that helps.

Neha Mukund

I believe that a reaction can be controlled by both thermodynamic as well as kinetic controls.

Neha Mukund

Kinetics tell us the speed of a reaction, whereas thermodynamics tells us favorability and stability of a reaction. Depending on the task at hand, one can decide whether to implement kinetics or thermodynamics in solving a problem.

Neha Mukund

Catalysts decrease the activation energy for both the forward and reverse directions in a reaction.

Neha Mukund

I agree with what was said above. It was likely a calculation error!
I also got 2 x 10^-5 as a value.

Neha Mukund

In order to find the half life of a reaction, you use these equations:
First order is t=.693/k, 2nd order is t=1/k[o], and Zero order is t=A[o]/2k

Neha Mukund

The half-life for a zero order reaction is:
t1/2 = [A]0/2k

Neha Mukund

0 order reactions are less common because most reactions depend on the concentration of reactants, whereas 0 order reactions are independent of reaction concentration which is why they are less common.

Neha Mukund

In order to determine the half-life of a reaction, you can begin by using this equation:
t1/2 = [A]0/2k

Neha Mukund

0 order means that k, the equilibrium concentration, is constant and the rate is independent of the concentration of the reactants.

Neha Mukund

A zero order reaction is a reaction in which the rate is independent of the reactant's concentration.

Neha Mukund

Hi everyone! My name is Neha Mukundan and I am a coordinator/director in Alumni Scholars Club, and wanted to ask you all to consider voting for your favorite professor! Do you have a favorite professor? Maybe one that encouraged you to push your hardest or even made you pursue a minor or major in th...

Neha Mukund

Cv is the heat capacity/specific heat at a constant volume, whereas Cp is the heat capacity/specific heat at a constant pressure. Those are plugged into the proper equations, and multiplied by R, the gas constant.

Neha Mukund

Hi! Entropy can be simply defined as disorder. For example, when comparing a solid and a gas, one knows that a solid, more densely packed, occupies much less positions than a gas does. Since gas molecules are able to occupy so many more positions, you would say that gases are more disordered, theref...

Neha Mukund

In free expansion, no work is being done, and since w=0, we know q and deltaU both are equal to 0.

Neha Mukund

Hi,
Yes that equation would work for compression as well.

Neha Mukund

Hi,
Yes the total change in entropy for a reversible reaction is always roughly 0.

Neha Mukund

Yes, when deltaS>0, the reaction is spontaneous. deltaS can be zero, yes. It is possible.

Neha Mukund

Residual entropy is the amount of disorder at absolute zero (0K).

Neha Mukund

State functions are independent of the path taken, and instead depend on the current state. Entropy and Enthalpy do not depend on the paths taken, but rather the initial and final states.

Neha Mukund

A reaction is spontaneous when it is exergonic, meaning it releases energy and requires no input of energy to occur.

Neha Mukund

In a reaction, the oxidizing agent is what is reduced and causes the oxidization of another molecule. The reducing agent is what is oxidized and causes the reduction of another molecule. Oxidation is the loss of electrons, whereas reduction is the gain of electrons.

Neha Mukund

As temperature and volume increase, so does entropy since the substance will have more disorder. The entropy of a gas is greater than the entropy of a liquid, which is greater than the entropy of a solid.

Neha Mukund

A closed system can still exchange energy with its surroundings, however an isolated system cannot.

Neha Mukund

Entropy is disorder, therefore as temperature and volume increase, so does entropy. The entropy of a gas is higher than that of a liquid and the entropy of a liquid id higher than that of a solid.

Neha Mukund

A system is at equilibrium is when both the forward and reverse reactions occur at the same rate. The work done is the same in both directions.

Neha Mukund

A spontaneous reaction is exergonic/does not require energy to occur and releases energy.

Neha Mukund

It is best to use molarity in ICE tables, because a lot of times we are asked to find Kc which is concentrations, so molarity would need to be used.

Neha Mukund

It is negligible when it is less than 10^-3 I believe. Hope this helps.

Neha Mukund

Kc is for concentrations whereas Kp is for partial pressures.

Neha Mukund

ICE tables are used to determine concentrations, so for this, you need M (molarity) which is mol/L.

Neha Mukund

Hi!
When you calculate the final equilibrium concentration, if it is less than 5% of the initial concentration (divide it by the initial concentration) then that means that the x is negligible and ( - x ) can be excluded from the formula.

Neha Mukund

In a closed system, matter cannot enter or leave however its energy can change. In an isolated system, neither the energy or matter can change. Hope this helped.

Neha Mukund

An extensive property depends on the amount of particles, whereas an intensive property is independent of matter. Hope this helps.

Neha Mukund

When I see exothermic, I think of heat "ex" iting. When I see endothermic, I think of heat "en"tering. I hope this helps.

Neha Mukund

I also got [H30+] is not equal to [HA]. Hope this helps.

Neha Mukund

Exothermic reactions release heat whereas endothermic reactions absorb heat. This means that the deltaH for an exothermic reaction is negative, whereas the deltaH for an endothermic reaction is positive. I hope this helps.

Neha Mukund

Hi, heat capacity is the amount of energy required to raise the temperature of an object by 1 degree Celsius. The specific heat capacity is the amount of energy required to raise the temperature of 1 gram of a certain substance by 1 degree celsius.

Neha Mukund

Hi, in an isolated system there is no way of changing the energy. Hope this helps.

Neha Mukund

A closed system is a system in which energy can exchange with its surroundings. An isolated system is a system in which nothing exchanges with its surroundings.

Neha Mukund

An open system is a system in which matter and energy can exchange with its surroundings. Hope this helps.

Neha Mukund

An isolated system is a system in which nothing exchanges with its surroundings. Hope this helps.

Neha Mukund

Melting is endothermic because heat is drawn in from the surroundings (in order to melt, an input of energy is needed to break the bonds).

Neha Mukund

Condensation is exothermic because heat is being released.

Neha Mukund

With respect to thermodynamics, work is the quantity of energy transferred from one system to another.

Neha Mukund

Enthalpy is the measure of the total heat moving in and out of the system whereas heat is energy that transfers to or from a thermodynamic system.

Neha Mukund

The heat goes towards breaking and creating the bonds/intermolecular forces, therefore the temperature of the sample does not change.

Neha Mukund

If Q < K, then the reaction goes towards the products. If Q > K, then the reaction goes toward the reactants. Hope this helps!

Neha Mukund

When comparing Q (which tells you the concentrations of the molecules at any given time) and K(the equilibrium constant), this test will help you figure out if the reaction is at equilibrium or not. If Q=K, the reaction is at equilibrium. Hope this helps!

Neha Mukund

If K<1 * 10^-4, we can assume that x is insignificant enough that it would not make a difference for the changes in concentration. Hope this helps.

Neha Mukund

K, in general, is used to refer to the equilibrium constant. Ka is used for acidity constants, Kb for basicity constants, and Kp for partial pressure. Hope this helps.

Neha Mukund

Yes, when Q=K the reaction is at equilibrium.

Neha Mukund

Hi,
you would have to put [PCl3] = [Cl2] = X and [PCl5] = 0.08 - X into the Kp expression, then get the quadratic equation, then solve for X. Then you would find the equilibrium pressures for each, then add them all up to find the total pressure. Hope this helped.

Neha Mukund

K is a constant of a reaction at equilibrium, and Q is the reaction quotient at any given stage of a reaction. Hope this helped!

Neha Mukund

First, you would go from moles to molar concentrations: Divide the mol of SO3 by the given L amount. Then you would do the same for the O2. The initial values in the box should be SO3's initial molar concentration (Divide the mol of SO3 by the given L amount) , 0, and 0. The change values should be ...

Neha Mukund

I think it was just a matter of rounding, and we are also not graded on significant figures so I wouldn't worry about it!

Neha Mukund

Hi! What has helped me before was if a number was larger than any of the concentrations then you will end up with a negative final concentration, which is not possible. So, if there is a much smaller number, it likely will be that number that is X. You could always plug them in and assess by trial a...

Neha Mukund

When determining molecular shape, both the number of bonds to the central atom as well as the number of lone pairs are necessary.

Neha Mukund

Trigonal planar molecules can be non-polar because the dipoles can go in symmetrically opposite directions, which will cause in the dipoles cancelling out.

Neha Mukund

One indication that a molecule has the shape "bent" is that the central atom has two bonds to it and one lone pair. This lone pair pushes down the other bonds and causes shape to be bent.

Neha Mukund

Hard water has a large amount of minerals dissolved in it, whereas soft water obtains only sodium ions.

Neha Mukund

An amphoteric substance is defined as a substance that has the capability to both accept and donate a proton. Between the answer choices given, you need to observe which of the molecules have both a hydrogen and a negative charge (to account for the donation and accepting of a proton). This tells us...

Neha Mukund

I believe an anion is stabilized when regions of electron density around the atom are delocalized.

Neha Mukund

Strong bases are especially ones that easily dissociate in water, so this means that hydroxide bases can completely ionize in water.

Neha Mukund

As Jessica said, noble gases are not classified as acids nor bases. This is because they have a full octet, and do not have a need to gain or donate any electrons, so they are unreactive.

Neha Mukund

The way to determine the strength of a base is by determining its ability to accept an H+ or how strongly it can bond to a H.

Neha Mukund

I believe that since Be and Mg have shorter and smaller bond lengths, they are weak bases because weak bases do not dissociate completely. This means that the hydroxide ion will not dissociate from Be or Mg.

Neha Mukund

We do have to memorize bond angles ) atleast the basic ones such as Tetrahedral = 109.5, Trigonal Planar = 120, Linear = 180, etc. When dealing with a lone pair that pushes down the atoms in a molecule however, you can also just say the bond angle will be less than the bond angle for whatever the el...

Neha Mukund

VSEPR stands for Valence Shell Electron Pair Repulsion theory. It determines molecular geometry and bond angles based on the placement of atoms and electron densities in a molecule.

Neha Mukund

Axial atoms are the atoms on the bottom or top (vertically placed), equatorial atoms are horizontally placed.

Neha Mukund

Xenon can have an expanded octet, which is why it is able to have an extra lone pair.

Neha Mukund

Electron geometry considers lone pairs (regions of electron density) as well as bonds to name the structure. Molecular geometry just considers the arrangement of atoms.

Neha Mukund

At least for the midterm, I do not think second ionization energies will be asked about.

Neha Mukund

I don't believe there is a way to find the exact value by looking at the periodic table.

Neha Mukund

Electronegativity and Electron affinity have the same periodic trends. They increase moving left to right and decrease moving down the periodic table. Hope that helps.

Neha Mukund

Electronegativity increases left to right because the closer an atom gets to having a full octet, the more electronegative it will be. It decreases going down because the more shielding it has from more shells, the less electronegative it becomes. Hope this helps.

Neha Mukund

Ionization energy increases going up and from left to right. This is the same as the electronegativity trend. Hope that helps.

Neha Mukund

VSEPR stands for Valence Shell Electron Pair Repulsion. It determines the geometry of molecules.

Neha Mukund

Each oxygen has a charge of 2- (4 Oxygen's would make the overall charge 8-), However, Perchlorate has an overall charge of -1, so Cl's oxidation number would have to be +7 to fit this. Hope that helped.

Neha Mukund

I believe that a H2O molecule is "bent" because of the 2 lone pairs of electrons on the Oxygen. They push the bonds down. Hope that helps.

Neha Mukund

I believe "experimentally observed" structures are actually seen in labs, rather than people theorizing shapes using their conceptual knowledge. Hope that helps!

Neha Mukund

I agree, I think knowing all of the general molecular shapes and bond angles is what truly matters, and in lecture on friday I remember Dr. Lavelle doing H2O as an example (2 lone pairs and 2 bonding pairs e-) and I am fairly certain he mentioned not needing to know the exact bond angle but just tha...

Neha Mukund

I think that you read 2A-D and 2A.4 is probably one of the embedded problems within the chapter.

Neha Mukund

I think midterm 2 will just cover weeks 4-7. The final however will be cumulative I believe.

Neha Mukund

I always see what week we are on and divide the total number of posts I have by 5 to make sure I have done 5 per week. I hope that helps.

Neha Mukund

I think the midterm will not be cumulative and only include material after the midterm and the monday before the midterm or the friday before the midterm.

Neha Mukund

Yes, I believe taking summer classes is a good idea so you do not overwhelm yourself with too many classes during the school year.

Neha Mukund

Yes, when going from moles to atoms you need to use Avogadro's number.

Neha Mukund

Hi Emily,
I would use the same amount of sig figs as the number given in the problem with the lowest amount of sig figs. I would not round however, until the very end of the problem. Hope that helped.

Neha Mukund

I would just use the lowest number of sig figs from the numbers given in the problem, hope that helps.

Neha Mukund

I usually never round until the very end of the problem, and in this case I would round it to 3 sig figs. Hope that helps.

Neha Mukund

When doing operations like multiplying and dividing, you should round your final answer to the lowest number of sig figs given in the problem. Hope that helps.

Neha Mukund

I believe 0.023 has two sig figs; This is because leading zeros (zeros in front of non-zero numbers) are insignificant.
Hope that helps.

Neha Mukund

I ask myself the same question a lot, and I always use method two just to make sure I am not making any mistakes.

Neha Mukund

It should be in the textbook; There is a section called "Odd-numbered exercises" In the back matter part of the textbook. Hope that helped.

Neha Mukund

The ratio would be 1:3 for PCl3: 3 HCl. To find the amount of moles of a reactant, you would divide the given grams by the molar mass. Hope this helped!

Neha Mukund

I believe they multiplied the entire equation by 2 because the question stated that 12 moles of ClO2 were used, and 6 (the original amount of moles in the equation) goes into 12 2 times, so to make the entire reaction proportional to its original mole-to-mole ratios, they scaled the entire reaction ...

Neha Mukund

Whenever given an equation and asked to state the Limiting Reactant, I always look at the mole-to-mole ratios of the reactants and determine which has less, which would then give one the limiting reactant.

Neha Mukund

Wavelength and frequency have an inverse relationship, which means that when one increases, the other decreases. Hope this helps!

Neha Mukund

I wouldn't round any numbers in between steps. I would only round at the very end of the problem when matching it to the proper amount of sig figs. This is would result in the most precise answer. Hope this helps!

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