CHEMISTRY COMMUNITY

Katie Bart 1I

Can the order keep increasing? Or do they stop at two?

Katie Bart 1I

are the units for rate different for reactions of different orders?

Katie Bart 1I

The second order graph has a slope of k, and the zero order graph has a slope of -k. For the first order, sometimes the graph is exponential, but the slope is equal to k if ln(A) is on the y axis.

Katie Bart 1I

What is the easiest way to tell if something is thermodynamically stable?

Katie Bart 1I

Why are the units different in first, second, etc. ordered reactions?

Katie Bart 1I

Oxygen naturally occurs in its most stable form, O2. Because this is its stable form, its charge is zero.

Katie Bart 1I

Why would you not just write the half reaction how it is given?

Katie Bart 1I

I also think it's Cl- because we wouldn't be able to solve it using concepts we know if the Cl2 is on both sides.

Katie Bart 1I

In this problem, is the equation Cl2 + 2e- yields 2Cl- given to us?

Katie Bart 1I

Why do you add 2e- to the left side of the oxidation reaction? (how do you know how many e- to add?)

Katie Bart 1I

So are groups 1 and 2 metals considered to be conducting solids?

Katie Bart 1I

I am still a little confused after lecture today-what exactly do we need to know about electrolysis? I know it has to do with converting electrical energy to chemical energy, but how does it do this?

Katie Bart 1I

What would be a biological example of a salt bridge?

Katie Bart 1I

Could you use other metals? Or only Pt?

Katie Bart 1I

In a redox reaction, how do you know how many electrons to add to each part of the reaction? And how do you know which side of the equation to add them on?

Katie Bart 1I

Can we always assume that delta S naught is constant when using the Van't Hoff Equation?

Katie Bart 1I

It depends on what values/information are given, if the reaction is at equilibrium, and if it is in its standard state.

Katie Bart 1I

Does the system have to be at equilibrium in order to use this equation?

Katie Bart 1I

When do you use the Van't Hoff Equation? And how does it relate to Gibbs Free Energy?

Katie Bart 1I

It also helps me to think of the signs in terms of energy being absorbed and released.

Katie Bart 1I

In the solutions manual, it says that the equation we need to obtain is N2 + 5/2O2 yields N2O5. How do we know that this is the reaction we want?

Katie Bart 1I

When you find the standard reaction enthalpy for a reaction, is the value in units of kJ or kJ/mol? I've seen both used in the textbook.

Katie Bart 1I

In this problem, where do you obtain the information you need in order to write the three different balanced equations that are written in the solutions manual?

Katie Bart 1I

On the tests/midterm, should we put energy and work in units of J or KJ?

Katie Bart 1I

In the different heat capacity equations, how do you know whether to use grams or moles? Does it depend on the units that the given heat capacity is in?

Katie Bart 1I

When it says that pdeltav is insignificant when a reaction that involves solids and liquids is under constant pressure, what does that exactly mean? Is it similar to excluding the concentrations of solids in liquids in ICE tables in chemical equilibrium problems?

Katie Bart 1I

What are entropy's units?

Katie Bart 1I

When exactly do we use entropy?

Katie Bart 1I

What exactly is a microstate?

Katie Bart 1I

Also, a change in temperature is the only factor that will change the K value for a reaction.

Katie Bart 1I

Because elements exist in the form that requires the least amount of energy, so in their natural state, the standard enthalpy of formation would be zero.

Katie Bart 1I

Is calculating enthalpy from bond enthalpies more accurate?

Katie Bart 1I

When is delta H written in kj versus kj/mol?

Katie Bart 1I

What is the difference between the qp and qv equations besides the fact that the first occurs under a constant pressure and the second occurs under a constant volume?

Katie Bart 1I

It's all about the reaction rebalancing after a physical change occurs.

Katie Bart 1I

Do we need to know Van't Hoff's equation for this test?

Katie Bart 1I

Why does adding heat to an exothermic reaction favor the reactants?

Katie Bart 1I

The stronger the acid, the lower the pH. The weaker the acid, the closer to 7 it is.

Katie Bart 1I

Why does expanding the volume shift the reaction towards the side with more moles?

Katie Bart 1I

Why do conjugate bases/acids and group 1/2 cations not affect pH?

Katie Bart 1I

Why does changing the concentration of the reactants have no effect on the K value?

Katie Bart 1I

It's also important to remember that amphiprotic is different than amphoteric, which means that it reacts with both acids and bases.

Katie Bart 1I

So just to confirm, volume affects the products/reactants of a reaction, but it doesn't affect the value of K? And how does volume affect the reactants/products?

Katie Bart 1I

Does the quick way work every time? Or only in certain scenarios?

Katie Bart 1I

When does pressure affect the reactants/products of a reaction at equilibrium? Does it depend on the type of gas?

Katie Bart 1I

What is the difference between K and Q? Since the same process is used to find both values, how can they be equal to different numbers?

Katie Bart 1I

How do you know whether to use Kc/Kp versus simply K? What is the difference?

Katie Bart 1I

That should work because 1/3 is still a number that can be multiplied through and thus be used as the power of a constant.

Katie Bart 1I

Why are solids and liquids not included in calculating the equilibrium constant? Are only gases and aqueous solutions considered in the K value?

Katie Bart 1I

Why does the equilibrium constant not have units?

Katie Bart 1I

Why is H-F the only anion in the halogen species that makes the conjugate base of a weak acid alkaline?

Katie Bart 1I

Why doesn't the conjugate base of a strong acid affect pH?

Katie Bart 1I

Is it necessary for us to memorize any weak acids/bases for the final? I know we should know some of the common strong acids/bases but am unsure about the weak ones.

Katie Bart 1I

How can you tell if water is acting as an acid or a base?

Katie Bart 1I

Will a cation ever be within the coordination sphere of a coordination compound?

Katie Bart 1I

In our class notes, it says that Cr assists insulin in the control of blood sugar. Is this referring to the element Cr, or is it referring to Cr in the context of a coordination compound?

Katie Bart 1I

How does the solutions manual know that en is bidentate and edta is hexadentate?

Katie Bart 1I

How do you know if a molecule is going to be chelating based off of its lewis structure?

Katie Bart 1I

Do we need to memorize the equation to determine the oxidation number of a coordination compound? And are we going to learn this equation in class?

Katie Bart 1I

How do you know whether the name of a compound has, for example, cobalt versus cobaltate at the end of it?

Katie Bart 1I

When d orbitals hybridize, what new orbital(s) do they form?

Katie Bart 1I

How do you know when hybridization will occur? Does it only occur when an atom forms more bonds than the number of unpaired electrons it has?

Katie Bart 1I

So do bond angles change when an atom is hybridized? Or does it just depend on the atom?

Katie Bart 1I

When determining the coordination number of a molecule/compound, does a double bond count as two bonds or just one?

Katie Bart 1I

Is the coordination number the number of bonds to the central atom or the total number of bonds in a molecule?

Katie Bart 1I

How do radicals exist? Isn't it extremely unstable for an atom to have an unpaired electron?

Katie Bart 1I

Can someone define exactly what a dipole moment is? I understand the concept, but is there a specific definition we need to have for it?

Katie Bart 1I

What is the difference between molecular shape and molecular geometry when using VSEPR?

Katie Bart 1I

Also, ion-dipole interactions are stronger than dipole-dipole interactions.

Katie Bart 1I

You might also here London forces referred to as induced-dipole-induced-dipole interactions.

Katie Bart 1I

Going off of the initial question, can interactions between molecules affect each molecule's shape?

Katie Bart 1I

In VSEPR molecules that have varying bond angles between atoms, how do we know which angle degrees are where in the molecule?

Katie Bart 1I

Before electrons begin to fill the shells, the 4s orbital is lower in energy than the 3d orbital. However, once the 4s orbital is full and there is at least one electron in the 3d orbital, it becomes lower in energy than 4s, so you write 3d before 4s in the configuration.

Katie Bart 1I

Ionization energy and electron affinity do follow the same trends on the periodic table (even though they are two separate concepts).

Katie Bart 1I

When do we use electron affinity? I feel like we use ionization energy a lot but rarely electron affinity.

Katie Bart 1I

Can a bond have both covalent and ionic properties?

Katie Bart 1I

Will the same molecule always have the same dipole moment or can the value change?

Katie Bart 1I

What is a delocalized bond? (A delocalized double bond in particular)

Katie Bart 1I

I do that as well.

Katie Bart 1I

Are double bonds always shorter than single bonds? Are there any exceptions?

Katie Bart 1I

I'm not sure, but I bet he will address it in class on Wednesday.

Katie Bart 1I

When an ion's valence electron configuration is 4d10 5s2 or any variation of that, and the ion is positively charged, how do you know which subshell you remove the electrons from?

Katie Bart 1I

What is this unit? KeV

Katie Bart 1I

Since p=mv, if you are given either mass or velocity (or both), use the DeBroglie Equation.

Katie Bart 1I

The energy of an electron does increase when it moves up an energy level.

Katie Bart 1I

A subshell is determined by the l value, and an orbital is determined by the ml value.

Katie Bart 1I

In this problem why do we only use 5m/s as the velocity and disregard the uncertainty of + or - 5?

Katie Bart 1I

Since it only shows through the f sub-shell, where on the periodic table is there evidence that l can be greater than 3?

Katie Bart 1I

And when velocity changes, so does momentum since velocity is a component of momentum.

Katie Bart 1I

So does the number of photons have an effect on frequency? Or only intensity?

Katie Bart 1I

My TA said that as the tests get harder, the equations sheet will become more extensive so we don't have to memorize all of the new equations we learn.
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Katie Bart 1I

If you're dealing with momentum, you will use the third equation.

Katie Bart 1I

What are the units for Planck's constant again?

Katie Bart 1I

Is this also what "quantum theory" means? Like it refers to the discrete states in which electrons exist?

Katie Bart 1I

So light intensity is determined by both amplitude and the number of photons? Do they play an equal part in determining frequency, or does one overpower the other?

Katie Bart 1I

How big is a photon in comparison to an electron?

Katie Bart 1I

Does an electron lose energy when it moves up an energy level? Or does it just decrease?

Katie Bart 1I

Does the speed of light constant only apply to a vacuum?

Katie Bart 1I

It would, but we have to make sure we account for significant figures. Also, we lose precision every time we round so this isn't significantly worse than other problems we have done.

Katie Bart 1I

In these situations, the input of energy is implied, so we don't have to write it. However, as the reactions get more complicated, we may have to indicate the input of energy.

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