CHEMISTRY COMMUNITY

Nuoya Jiang

Yes, if we only have (aq) or (g) at one side and no electrode told.

Nuoya Jiang

So what is the difference between oxidation number and the charge the atom carries?

Nuoya Jiang

The problem would probably tell you whether the solution is acidic or basic. But you always add H2O when balancing oxygen.

Nuoya Jiang

It is first formed as a product and then a reactant in the reaction.

Nuoya Jiang

So if a product forms when the temperature is high, it is controlled by thermodynamics; if another product forms when the temperature is low, it is controlled by kinetics since it has a relatively low activation ennergy.

Nuoya Jiang

Usually, graphs of k and t will be given for a reaction for us to find out its order.

Nuoya Jiang

When you only have a solution and gas at one side of the cell.

Nuoya Jiang

After you balance the redox reaction, the number of electrons in the overall reaction is n.

Nuoya Jiang

It is either given in the problem, or it matches the rate law.

Nuoya Jiang

Q is the reaction quotient. When we are using the Nernst Equation in a concentration cell, we should try to make lnQ negative.

Nuoya Jiang

It allows for a complete electric circuit by letting the ions and the charge that they carry to move.

Nuoya Jiang

Appendix 2B. I googled one table for Ecell values but calculations based on those were not the same as the solution manual.

Nuoya Jiang

You balance the oxygen first by adding water and then you balance H+ if it is an acidic environment.

Nuoya Jiang

Yes, it is. Because it is spontaneous, so delta G is negative for it.

Nuoya Jiang

A reducing agent is a reactant that gives electrons (increase its oxidation number) during the reaction, while an oxidizing agent is the reactant which gains electrons during the reaction.

Nuoya Jiang

It uses chemical energy in redox reactions to produce electricity.

Nuoya Jiang

No, but you can see it on the equation sheet.

Nuoya Jiang

The oxidation number of oxygen would probably always be 2.

Nuoya Jiang

Yes, because when it dissolves, the NH4+ ions in water can donate a proton, so it can lower the pH.

Nuoya Jiang

It has no effect because adding an inert gas would not change the concentration/partial pressure of the reactants and products.

Nuoya Jiang

Because in the ideal gas law, P and V are inversely proportionate to each other.

Nuoya Jiang

Yes, because when delta G is negative, it tends to release energy when proceeding to the products, and vice versa.

Nuoya Jiang

Usually, in an isothermally reversible gas expansion, the work done by the heat equals the heat it received.

Nuoya Jiang

delta H naught is 0 when the element is in its most stable form.

Nuoya Jiang

Most of the time J.

Nuoya Jiang

The pizza rolls review sheet can be super helpful.

Nuoya Jiang

Most of the time yes, because you have to cancel the units in the gas constant R. But when you are calculation the difference between temperatures, for example, in the equation involving heat capacity, you don't have to worry about that.

Nuoya Jiang

It depends on the sign of delta G. If delta G is negative, the forward reaction can occur spontaneously.

Nuoya Jiang

It is usually negative because heat is released during the combustion process.

Nuoya Jiang

Probably temperature, volume, and pressure since we can only change the "energy" part of the system.

Nuoya Jiang

No, but we have to hand in the homework. The practise questions in the discussion are usually helpful.

Nuoya Jiang

Yes, it is isolated in an ideal situation because we can neither exchange substance nor energy with the surrounding.

Nuoya Jiang

There is a review sheet and some sessions provided by the UAs, which is super useful for midterms and finals.

Nuoya Jiang

It requires energy to break a bond, so the change in energy should be positive. When a bond form, the system indeed goes more stable, with less energy, so it releases energy, and the enthalpy should be negative.

Nuoya Jiang

Yes, during phase change, the temperature remains constant, but latent heat is released or absorbed.

Nuoya Jiang

Enthalpy is the change of heat in a chemical reaction, while heat is a more general term.

Nuoya Jiang

Energy is required when we break a bond, so the sign should be positive. When bonds form, it releases energy, and so the sign should be negative.

Nuoya Jiang

It should be the final ionized acid/base divided by the initial concentration of the acid/base.

Nuoya Jiang

Yes, we can get partial credit.

Nuoya Jiang

When the steam hits your art, it releases its latent heat because it is changing its phase from a gas to a liquid.

Nuoya Jiang

When the equilibrium constant is 10^-3 or greater, we should use the quadratic equation.

Nuoya Jiang

Is it the same reason that we do not include it when we are calculating the equilibrium constant?

Nuoya Jiang

Yes, it is. The product side is favoured.

Nuoya Jiang

The stronger an acid, the smaller the pka.

Nuoya Jiang

k is a constant and is used as a standard that we can compare with. Q is what we can calculate based on the data we've got.

Nuoya Jiang

K is a constant and if anything of the environment changes, such as the temperature, the system adjusts to the changes, resulting in the constant k.

Nuoya Jiang

We can use the Kc in this table if the question asks us to solve for concentrations of gases in the reaction, such as question 5.39.

Nuoya Jiang

Probably outline1 and ouline2.

Nuoya Jiang

In fact, you can use both. Table 5G.2 shows an example of how Kc works for gas reactions.

Nuoya Jiang

We can see the exothermic reaction as a reaction with "heat" as a product. Thus if we increase temperature of the system, we are indeed increasing the "concentration" of heat (product), so the reaction goes to the left. It works the same as in an endothermic reaction. We simply s...

Nuoya Jiang

Yes, because the electrons in all the molecules have a chance to move to a place where a dipole appears.

Nuoya Jiang

No, chelates can form at least BIdentate.

Nuoya Jiang

We need to know the basic calculation of the concentration of titration for a strong acid and a strong base, plus the situation of the equivalence point involving a weak base and a strong acid, or a strong base and a weak acid.

Nuoya Jiang

A few examples of biological importance we covered in class are necessary to know, at least.

Nuoya Jiang

polyprotic means an acid can give more than one proton and its conjugate base can accept more than one proton.

Nuoya Jiang

Are we going to get them on week 10?

Nuoya Jiang

Will we be curved based on the performance of the whole class?

Nuoya Jiang

Single bond: sigma bond
Double bond: one sigma bond+one pi bond
Triple bond: one sigma bond+two pi bonds

Nuoya Jiang

Is it true that a relatively weak acid has a stronger conjugate base and a relatively weak base has a stronger acid?

Nuoya Jiang

The order you put your ligand doesn't. The order seems only easier to name, instead.

Nuoya Jiang

More questions cover topics from the beginning of this quarter, with a focus after the midterm, on the molecular shape, bonding, acids and base.

Nuoya Jiang

one or two, which also decide the bond angle.

Nuoya Jiang

The bond strength of a double bond is talking about "INTRA" molecular force, while the melting point is related to "INTER" molecular force.

Nuoya Jiang

I think on a test, we would be asked to identify which transition metal is bound to which ligand at least, and describe why this is important for all living things?

Nuoya Jiang

Professor Lavelle has posted some outlines/learning outcomes on his class website. Read through them and find some videos online to catch up. Those videos online are good learning materials because they are more focused and test problem oriented. Good luck.

Nuoya Jiang

That would be a bent shape. I believe we'll talk about this in a few days.

Nuoya Jiang

Yes, they are always popular test materials.

Nuoya Jiang

For this midterm, I don't think he would curve, either.

Nuoya Jiang

Only with O, F and N because they have the highest electronegativity.

Nuoya Jiang

Question2 tests your knowledge of the photoelectric effect, which indicates that light can be viewed as particles. The first thing you need to do is to convert 492 KJ for a mole of light particles to the work function of a single light particle.

Nuoya Jiang

Their n=3, which indicates that they are able to have 3d orbitals.

Nuoya Jiang

After checking the formal charge, we also prefer structures that have -1 on the more electronegative atoms.

Nuoya Jiang

Yes, always include all the electrons in the structure.

Nuoya Jiang

Like Test1 which is also graded by the TAs, it should take one week.

Nuoya Jiang

A symmetric molecule usually does not have a dipole moment, but if it is asymmetric, check the difference in electronegativity, so you can find out its dipole moment.

Nuoya Jiang

Polarizing power describes the power of a cation to distort an anion, and polarisability is the property of how easy an anion is distorted.

Nuoya Jiang

It should cover materials started from "bond strength" and "molecular shape", just after the midterm.

Nuoya Jiang

Lewis Acids are electron acceptors and Lewis Bases are electron donors.

Nuoya Jiang

A positive sign means taking energy into the system or the system needs energy to so some certain activity. The negative sign means the system releases energy or loses energy during activity.

Nuoya Jiang

I think it would cover the Quantum World all the way to the start of molecular shape, for we still have one week before the midterm.

Nuoya Jiang

Yes, it is a Lewis structure and P is able to extend the octet because it is in the d-block.

Nuoya Jiang

Hi, what are some examples of exceptions in the periodic trends, such as the radii of oxygen and nitrogen do not fit the trend?

Nuoya Jiang

Elements that have d-orbitals are able to fit more than 8 valence electrons, so they can expand the Octet.

Nuoya Jiang

n=2, (principle quantum number, shell); l=1, (subshell is p); x describes the axis of the orbital.

Nuoya Jiang

So for Cr, 5 electrons in 5 3d orbitals and 1 electron in 4s has lower energy than 4 electrons in 3d, and 2 electron in 4s.

Nuoya Jiang

I think we only need to understand the relationship between Schrodinger's equation and quantum numbers. After all, the emphasis of Focus 1 (Quantum World) is still on the model of electrons and properties of light.

Nuoya Jiang

Do every homework question and read concepts on the text bool as well. Tne syllabus says 1/8 of the homework questions are likely to be on the exams as well, so we should definitely pay attention to those questions.

Nuoya Jiang

I think the midterm is in the evening, lasting for 2 hours, so it is unlikely on a discussion session. For the final, it won't be in the lecture or the discussion.

Nuoya Jiang

Increasing the number of photons means increasing the intensity of light, counterintuitively. Only when the energy of each photon is sufficient, can it remove a electron. One photon is responsible for removing an electron, so it is the energy (frequency) counts, not the number of photons.

Nuoya Jiang

For this question, first calculate the total energy the lamp produced in 2 seconds. Then use E=hc/\lambda[/tex] to calculate the energy of a single violet photon. Divide the first result (total energy) with your result in the second step (energy of a single photon), should give to the answer to the ...

Nuoya Jiang

For this question, try to think of the the lower energy level of these groups of lines. For example, for the Lyman series, these lines show the lower energy level of the transition of an electron from different energy levels is n=1, while for Balmer, it is n=2.

Nuoya Jiang

Considering the DeBroglie equation, which needs you to calculate the momentum=mv, the light does not have a mass, so you can't use this equation for light.

Nuoya Jiang

Hi, why is the UV light a typical experiment tool to conduct atomic spectroscopy? I know it has great energy and can probably excite electrons, but why do we usually use this wavelength of light to conduct related experiments? Thank you.

Nuoya Jiang

After you finish balancing the chemical equations, always remember to convert fractions into integrals because fractions should never appear in chemical equations to the definition of stoichiometric coefficients.

Nuoya Jiang

It would be easier and clearer to do all the converting after you solve the question and do the correct the calculations, and if you can cancel the units and cut it to a reasonable/desired unit, the answer would probably be right.

Nuoya Jiang

Hi, so in a classical mechanics, we see things and explain the reasons behind them in a macro scale, and as a result, our measurement is continuous. In a quantum mechanics, or a situation for micro things, everything is so small that we can only use discrete numbers to describe a transition. Try to ...

Nuoya Jiang

Thank you for the replying. I saw the textbook said that when we rounded numbers with stuff like 0.75, we should round it to the nearest even number, so 0.8(+0.5), but for 0.65, it should be rounded to 0.6(-0.5). Is this right?

Nuoya Jiang

Hi, I have a question about rounding numbers to its nearest integral, tenth, or hundredth, etc, and how the significant figure can effect that. For example, how to round 5.454545 and 5.55555 and make them each have 1,2,3 or 4 significant figures? Thank you.

Nuoya Jiang

Hi Baoying, calculating the limiting reactant can be a tough task because the evidence we use to prove which reactant is limited is indeed the balanced chemical equations with their stoichiometric coefficients. Therefore, you either calculate the moles of each reactant to find the limiting one as th...

Search found 99 matches