CHEMISTRY COMMUNITY

samanthaywu

What is the electrochemical series? I saw this on our outline and I'm a little confused because when I googled it I think I just saw a table of reduction potential values?

samanthaywu

I understand that Wmax = G, but I'm a little confused on how those two became related. It makes sense somewhat but I don't completely see the connection. Is someone able to explain in more detail why this is true?

samanthaywu

When not mentioned, is it generally okay to assume that the reaction is taking place at 25 degrees C (so that you can use the simplified form of the Nernst equation)

samanthaywu

Do we need to understand biological examples for the final? What is there to know about kinetics in relation to biological processes?

samanthaywu

Which form of the Arrhenius equation is used more often / recommended for calculations: the one that solves for k or the one that solves for ln(k)?

samanthaywu

Is the differential rate law the one thats like:
-(1/a) * d[A]/dt = (1/b) * d[B]/dt for aA --> bB

or is it the one that's like:
k[A]^a (given that the reaction is an elementary reaction)

Or are these the same?

samanthaywu

Is the method of initial rates the one that gives us the differential rate law? (As opposed to the integrated rate law)

samanthaywu

When galcantic cells are written in shorthand, do we need to include the Platinum / other substance that helps the reaction proceed when were deriving the half reactions and over equation?

samanthaywu

Can someone explain this to me? Write the half-reactions and the balanced equation for the cell reaction for each of the following galvanic cells: (d) Pt(s) | O2(g) | H+(aq) || OH2(aq) | O2(g) | Pt(s) Here's the answer: (d) anode: 2 H2O(l) --> O2(g) + 4 H+(aq) + 4 e-; cathode: O2(g) + 2 H2O(l) + 4 e...

samanthaywu

Hello can someone help me with this: 6K.5 Balance each of the following skeletal equations by using oxidation and reduction half-reactions. All the reactions take place in basic solution. Identify the oxidizing agent and reducing agent in each reaction. (a) Reaction of ozone with bromide ions: O3(aq...

samanthaywu

I'm still confused how you got the reduction half reaction, like what is being reduced? And also if there are 2e- on both sides of the reduction half reaction, how does that add to the oxidation half reaction to cancel out the electrons? And where did the Cl- ions come from? 2 H2O + Cl2 --> 2 HOCl +...

samanthaywu

Can someone help me with this? I'm confused about what the reduction half reaction is because there is only one reactant. 6K.3 Balance each of the following skeletal equations by using oxidation and reduction half-reactions. All the reactions take place in acidic solution. Identify the oxidizing age...

samanthaywu

Is the final exam going to be on everything covered throughout all of winter quarter or just the stuff we didn't cover in midterm 1 and 2?

samanthaywu

On slide 1 of Lecture #225 (monday, week 10) there's a picture of reactants and products when K > 1 and K < 1 (image attached). The arrows labeled on the picture say "slow" and "fast," but I was confused because I thought the rate of the forward and reverse reactions were suppose...

samanthaywu

I know someone already said that you solve for Q by doing PH2 / [H+]^2 and that you can mix the atm unit with the concentration units, but I'm still confused as to why that's allowed?

samanthaywu

Last question that I think I need help with: 4J.15 Which of the following compounds become less stable with respect to the elements as the temperature is raised: (a) PCl5(g) (b) HCN(g) (c) NO(g) (d) SO2(g) Answer: (a) -234.2 J/K*mol - this one becomes less stable as temp increases (b) 34.90 J/K*mol ...

samanthaywu

Can someone explain why total entropy change is 0 for isothermal reversible expansions in this question: (I've included the answer for reference) Question: Initially an ideal gas at 323K occupies 1.67L at 4.95atm. The gas is allowed to expand to 7.33 L by two pathways: (a) isothermal, reversible exp...

samanthaywu

Hello can someone help me with this questions: Suppose that 50.0 g of water at 20.0 deg C is mixed with 65.0 g of water at 50.0 deg C at constant atmospheric pressure in a thermally insulated vessel. Calculate Delta S and Delta S tot for the process. I'm not really sure if I'm supposed to use delta ...

samanthaywu

Could someone help me with this questions? I feel like I'm supposed to convert the change in pressure to a change in volume, but I don't know how:
Calculate the change in entropy when the pressure of 1.50mol Ne(g) is decreased isothermally from 15.0 atm to 0.500 atm. Assume ideal behavior.

samanthaywu

For this question we know that 765J of heat is being transferred therefore q=765J (and so does delta H like you said). With that in mind we can use the equation q=nCdeltaT to find the final temp. For constant pressure you would set it up as .820*5/2*R(T(final)-298K)=765. The 5/2*R is coming from th...

samanthaywu

Use the first law of thermodynamics: delta U=q+w. Use the ideal gas law pv=nrt to find-p*deltav (note that temperature is 298k and you would manipulate it so that -p*delta v=-delta n*r*t). Work is equal to -p*delta v and q is equal delta h at constant pressure. Wait one more questions, how do you k...

samanthaywu

The change in moles is delta n = 1 mol.
Using PV = nRT, you change it to P(deltaV) = (delta n)RT
Then use P(delta V) to get the work done by expansion.

Also thank you for the explanation, this makes much more sense now!

samanthaywu

What are some real life applications of this equilibrium relationship? Like what field of study or possible use in society might it have?

samanthaywu

I'm a little confused what the relationship between internal energy and enthalpy is. Other than delta U = q + w, what are the relationships we need to know and what conditions are those under (constant pressure, constant volume, etc.)

samanthaywu

I also need help with this textbook question, I'm just confused how to get to internal energy? Oxygen difluoride is a colorless, very poisonous gas that reacts rapidly and exothermically with water vapor to produce O2 and HF: OF2(g) + H2O(g) --> O2(g) + 2 HF(g), delta H = 2318 kJ What is the change ...

samanthaywu

Can someone help me with this:
Calculate the final temperature and the change in enthalpy when 765 J of energy is transferred as heat to 0.820 mol Kr(g) at 298 K and 1.00 atm (a) at constant pressure; (b) at constant volume. Treat the gas as ideal.

All I have is that a) delta H = +765J

samanthaywu

Of the three ways to solve for Gibbs Free Energy, the Hess approach, using standard free energy values, and using delta H - T(delta S), which one is most commonly used in real-life labs?

samanthaywu

Under constant volume I believe the equation for entropy was something like delta S = n Cv ln(T2/T1). Is this Cv value only different from the Cp value when there is a change in the number of moles of gas in the reaction?

samanthaywu

If its so rare for W = 1, then why do we need this observation that S approaches 0 as T approaches 0? What might be some useful application of this law?

samanthaywu

For this law, q is reversible. How do we calculate the change in entropy when q is irreversible?

samanthaywu

Does the change in internal energy equal zero for isolated systems only? Not for closed systems because closed systems can have energy transfer?

samanthaywu

What is the meaning of isobaric and what would we use this for?

samanthaywu

What do isochoric and isometric mean?

samanthaywu

Why do we study isolated systems if there is no energy transfer possible?

samanthaywu

Why is it useful to have the heat capacity for something like water when it's dependent on the amount of water you have? Why don't we just have specific heat capacities of everything?

samanthaywu

What happens to halogens when the temperature is increased?

samanthaywu

Do we need to know how to calculate integrals for 14B?

samanthaywu

Do we need to remember which elements are gases / liquids / solids at standard temperature and pressure? Like I know halogens are gases up to bromide and carbon is a solid (graphite) but I don't know exactly where the borders are, I just have a general idea.

samanthaywu

Do we need to be able to explain why H2O in the form of vapor would burn more than H2O in the form of water when they are both at the same temperature (100 degrees celsius)?

samanthaywu

Whenever the idea of bond enthalpies were invented, how were these values able to be measured in the lab?

samanthaywu

Will we need to have memorized any common bond enthalpies and standard enthalpies of formation or will we always be provided a table when this information is needed?

samanthaywu

Are there any heat capacity values we need to remember more specifically or just have an idea of which element blocks have higher / lower heat capacities?

samanthaywu

Will we learn how to use calorimeters in lab later on? If so what class would we learn this?

samanthaywu

Other than dry ice, does anyone know other examples of substances that undergo sublimation?

samanthaywu

If Q > K but we accidentally found Q < K and do our ICE table calculations accordingly, what would happen with our answers? Would we still get concentrations that fit K? I think I did this on my homework and I somehow still got an answer for x.

samanthaywu

When it asks for an equilibrium constant for a reaction between gases, is it wrong to write the Kc (equilibrium constant using concentrations) instead of Kp?

samanthaywu

Will we be learning about Gibbs Free Energy later on and how it's used in calculations?

samanthaywu

Is there a way to calculate the change in K from a change in temperature? Or do we usually use a table to find K for a given temperature.

samanthaywu

When will we have to start adjusting our activity calculations because of non-ideal gases? Because right now we assume concentration and partial pressure are representative of activity.

samanthaywu

When will we start using non-ideal gases? Like which course in the Chemistry series? Or is it another series?

samanthaywu

Do we need to remember which person discovered which part of PV = nRT? Or is it enough to just know what their findings were, but not necessarily remember the person.

samanthaywu

Which metal oxides and metal hydroxides form bases? Do all the group 1 and group 2 elements work? Are there any transition metal bases that we should know?

samanthaywu

Are organic acids just acids containing a Carbon and the rest can be assumed to be inorganic?

samanthaywu

Just wondering what section of Chemistry this topic will be covered in? Will it be part of the General Chem series or part of a more specified series of UCLA Chem classes?

samanthaywu

If the predicted pH range is included within the range of multiple indicators, how do we decide which indicator to use?

samanthaywu

I would like to learn how to calculate titrations for weak acid / base reactions. Is this something that will be covered in 14B? I have only taken 14 A so far.

samanthaywu

Are there any other common acid rain complexes besides carbonic acid and sulfuric acid that form regularly?

samanthaywu

If a salt containing the anion of a strong acid or the cation of a strong base is dissociated in water, is it safe to assume that the ions will remain dissociated and the solution pH change is negligible?

samanthaywu

When solving for the equilibrium concentrations of polyprotic acids and bases, do we always have to break them into individual protonations of one H+ ion released / gained for each reaction and use the Ka1, Ka1, etc.?

samanthaywu

Can someone explain this idea of the conjugate seesaw? I don't really remember learning this before, but I'm curious what it is because it sounds interesting!

samanthaywu

I know the conjugates of weak acids and bases are important because they'll create acidic or basic solutions in solution when they revert to their lower energy form, but since salts containing strong acid or strong base ions remain largely dissociated in water, will their conjugates ever be signific...

samanthaywu

Are lewis acids actually acidic in the sense where they'll turn up acidic through pH tests? Are any of our everyday substances such as detergents or foods Lewis acids or Lewis bases but not Bronsted Acids and bases?

samanthaywu

Do amphoteric compounds have a tendency to exhibit acidic behaviors over basic behaviors depending on the compound? Or vice versa? Does this involve the equilibrium constants K1 and K2?

samanthaywu

Is it easier to think of acids using the Lewis acid definition, the Bronsted acid definition, or the conjugate acid definition?
(Same for bases)

samanthaywu

Do we need to understand this concept completely for the final exam?

samanthaywu

If I come across a compound I don't know how to name, where can I find more detailed instructions / steps?

samanthaywu

Do we need to be able to thoroughly explain specific biological examples? I'm confused to what extent we need to know the information on this from lectures.

samanthaywu

Where do I find industrial examples of coordination compounds? Do I need to know these off the top of my head for the final?

samanthaywu

How do we know the coordination number for a coordination compound with polydentate ligands? How do we know how many of the lone pairs are actually bonded to the metal?

samanthaywu

Will we have to memorize names for all ligands and anionic ligands for the final?

samanthaywu

I know this is called the Einstein equation, but I always thought Einstein was know for E = mc^2. What is the relationship between these two equations?

samanthaywu

Since both light and electrons can be considered a wave and a particle, are there any other major difference between the two other than the fact that electrons have mass and a negative charge?

samanthaywu

How important is it to know the exact experimental setup for this experiment? Do we need to know anything aside from the fact that photons were shot at a metal surface and the kinetic energies of the ejected electrons measured?

samanthaywu

What is the difference in use between the DeBroglie wavelength equation and the E = hv equation in terms of applications?

samanthaywu

Aside from knowing bond angles that are greater or less than 109.5 degrees, etc. will we have to know the relative magnitude of how much less two different bond angles are? For two molecules with bond angles less than 109.5, do we need to know between those two which one has a smaller bond angle?

samanthaywu

Are there hybridizations beyond sp3d2? If so when will we start having to use these? (Like what level chemistry)

samanthaywu

What is diamagnetism and paramagnetism? Are there any recommended resources for better understanding these concepts?

samanthaywu

Does anyone have effective strategies for memorizing the prefixes for units? (like mega- kilo- deca- milli-, etc.)

samanthaywu

When is molarity used besides in solutions? Is it ever used for solids or gases?

samanthaywu

When adding do you round answer to the number with the least specific decimal places?
Like 12.5 + 9 = 22?
And when multiplying you round to the same number of sig figs as the number with the least number of significant figures?
Like 8.0 * 2.51 = 20 (1 sig fig)

samanthaywu

40. is 2 sig figs and 40 is 1 sig fig right?

samanthaywu

How do you know when to assume the remaining reactant is O2? O2 is usually not the limiting reactant but sometimes it's not explicitly mentioned.

samanthaywu

How is vapor pressure impacted by the strength of intermolecular forces? Do compounds of all of the above types of forces have a vapor pressure or do some compounds exert near negligible vapor pressure?

samanthaywu

What is an ionic liquid? Is it like an ionic compound in liquid state? If so does this mean the compound has to be at a very high temperature because ionic bonds are so strong?

samanthaywu

What are liquid crystals? Aren't crystals solid?

samanthaywu

Is the viscosity or surface tension of a liquid directly proportional to the strength of the intermolecular forces?

samanthaywu

How do we know whether the London forces between two atoms are stronger or the dipole induced dipole forces if they are both about 2kJ / mol?

samanthaywu

How do you use oxidation numbers to predict resonance structures? I remember this was mentioned on the Sapling homework at some point.

samanthaywu

Do all expanded octets contain hybridized orbitals?

samanthaywu

Is there a way to remember the electronegativities of elements with just a periodic table? I have trouble comparing some values for tests sometimes because I don't know the exact values?

samanthaywu

Does octet expansion apply to atoms with 3s valence electrons? I'm wondering if 3s energy is high enough for electrons to expand and occupy the 3d orbital.

samanthaywu

Are there ever instances where we need the polarizing power of anions even though usually they are the ones being polarized? Or the polarizability of cations even though they are usually the ones polarizing anions?

samanthaywu

I remember lecture covered how electronegativity is a value calculated from ionization energy and electron affinity. Can anyone give a slightly more detailed explanation as to how it was calculated?

samanthaywu

If there are two resonance structure options with the same total formal charge from different atoms, which atom would we want to put more negative charges on and which atom would we want more positive charges?

samanthaywu

Is anyone able to give an example of a wave function equation in the form f(x, y, z) to explain the abstract idea of functions representing orbitals?

samanthaywu

Why do we need to know the minimum uncertainty in position or velocity? Wouldn't it be more important to know the maximum?

samanthaywu

Does ionic radius increase or decrease as the charge gets more positive? How can this be explained in terms of nuclear attraction and shielding?

samanthaywu

Does anyone have a good way to remember the VSEPR acronym? I can't seem to get the letters to stick in my head.

samanthaywu

Can anyone define bond order comprehensively?

samanthaywu

Is anyone able to give a clear written connection from how the Schrodinger equation is representative of atomic orbitals like the s, p, d, or f? I know it represents a function in some way but the idea is a little too abstract for me to understand.

Search found 103 matches