CHEMISTRY COMMUNITY

Lauren Tanaka 1A

You find the k value by using the Nernst equation and plugging in numbers for all the other values in the equation. From there you can use algebraic manipulation to find the value of k.

Lauren Tanaka 1A

The electromotive force is the same as the cell potential of the cell.

Lauren Tanaka 1A

You don't need to convert but Dr. Lavelle said in lecture that the conversion can be useful in biological situations since it makes it easier to calculate pH.

Lauren Tanaka 1A

Termolecular means that the reaction used three reactants to form the product.

Lauren Tanaka 1A

The catalyst in the reaction will not be used up in the reaction. Therefore, it will be in the final overall reaction equation. Whereas an intermediate will be used up and won't show up in the overall reaction equation.

Lauren Tanaka 1A

The orders of each reactant will add up to the overall reaction order.

Lauren Tanaka 1A

Yes zero order is only dependent on the rate constant because it doesn't incorporate other factors like first-order and second-order reactions do.

Lauren Tanaka 1A

I think it will usually tell you which one is the slow step and the fast step when calculating. Another way to find out is by looking at the rate law and if there is a particular reactant in that law that is the same in one of the reactants of the steps then you can find out which is the slow step. ...

Lauren Tanaka 1A

You can tell it is exothermic when the activation energy is higher for reactants than it is for products. If the activation energy for products is higher than for reactants then the reaction is endothermic.

Lauren Tanaka 1A

Termolecular means that there are three molecules that must come together for a reaction to occur. This means you would have three reactants.

Lauren Tanaka 1A

This is because in a second-order reaction the initial concentrations don't cancel out like they do in a first-order reaction. Because of this it doesn't matter for a first-order reaction but does for a second-order reaction.

Lauren Tanaka 1A

Molecularity is the number of molecules that will come together to react. If there is one it is unimolecular, two is bimolecular, and three is termolecular.

Lauren Tanaka 1A

The strongest reducing agent will be the reactant that is oxidized. When comparing oxidized reactants the strongest reducing agent will be the one with the lowest reduction potential.

Lauren Tanaka 1A

It will always be the anode over the cathode since the equation for Q is products over reactants. The products of the equation will be the anode concentration and the cathode concentration will be the reactants.

Lauren Tanaka 1A

The Nernst equation can be derived using the equation for gibbs free energy. This equation is ∆G = ∆G˚ + RTlnQ. You can then set ∆G equal to -nFEcell and ∆G˚ to -nFE˚cell. Then you can divide both sides by -nF.

Lauren Tanaka 1A

A concentration cell occurs when the anode and the cathode both have the same electrodes but with different concentrations. This would mean that the voltage difference would be created by the different concentrations rather than different cathodes.

Lauren Tanaka 1A

Yes you can use partial pressures and molar concentrations in Q. This is because partial pressures can be used to calculate the Q value as well as the molar concentrations of the reactants and products.

Lauren Tanaka 1A

I don't think the order of those are particularly important but it is important to remember that the aqueous solution is always closest to the salt bridge and solids are always on the outside.

Lauren Tanaka 1A

I think it means that the Pt is needed because there is no solid that can be either oxidized or reduced. Because of this Pt would need to be added to that side of the reaction.

Lauren Tanaka 1A

You add Pt when there is no solids involved in the galvanic cell for either the reduction or oxidation reactions.

Lauren Tanaka 1A

It is true that the cathode will be the Ecell that is more positive. You can also to see which part of the reaction is oxidized and which part is reduced to figure out what will be the anode or cathode in the half reactions.

Lauren Tanaka 1A

I think the reduction potentials will always be given for calculating Ecell. However, I do think that it is possible for them to give the E of oxidation and then you would have to do Ecell = Ecathode + Eanode.

Lauren Tanaka 1A

In the notation the anode will be on the left side of the cell diagram and the cathode would be on the right side of the cell diagram.

Lauren Tanaka 1A

E is not a state function and because of this we can't apply the same rules as we did for enthalpy and gibbs free energy. It is an intensive property so the value would stay the same no matter how many times the reaction occurs.

Lauren Tanaka 1A

If it is at equilibrium you will have the naught symbol on the delta G and the E. If there is no not naught symbol, you can assume that the system is not at equilibrium.

Lauren Tanaka 1A

Since E is not a state function you can't apply the same concepts that we used in Hess's Law. E is an intensive property too so no matter how many times the reaction occurs the E will not change.

Lauren Tanaka 1A

Platinum is used in the problem because there is no conducting solid so platinum is used. Since it is resistant to oxidation it won't react easily in a redox reaction.

Lauren Tanaka 1A

The delta S for an irreversible expansion means that the surroundings change in entropy is 0. In an adiabatic system the total heat would be 0. This doesn't necessarily mean the same for irreversible expansion.

Lauren Tanaka 1A

At equilibrium the delta G is 0 but delta H and delta S could still be nonzero numbers.

Lauren Tanaka 1A

You use this equation when you want to see the change in gibbs free energy relative to when the K value changes in the equation (products and reactants ratio).

Lauren Tanaka 1A

I think you can look at the elements within a compound where you know the oxidation numbers and based on the total net charge of the molecule you can figure out the number for those elements you don't know.

Lauren Tanaka 1A

The naught sign means that the conditions are under STP or standard temperature and pressure. If the delta G has the naught symbol then so does the delta S and H.

Lauren Tanaka 1A

Increasing the temperature would increase the entropy because if you are increasing the temperature, there would be more states in the system. More states in a system means there is more entropy for the system.

Lauren Tanaka 1A

Negative entropy is possible and just means that there is an overall decrease in entropy for the given system.

Lauren Tanaka 1A

Since U is the internal energy it is a state property because it does not matter the final or initial conditions/the path the system took to get to these results.

Lauren Tanaka 1A

It would be a closed system because matter can't be exchanged with the surroundings since it is sealed but heat could be.

Lauren Tanaka 1A

The internal energy or ∆U is the energy found in the system or the total energy of a closed system. This can be found using the equation ∆U = q + w where q is heat and w is the amount of work.

Lauren Tanaka 1A

∆U is the change in the internal energy of the system. Mathematically it equals work + q.

Lauren Tanaka 1A

A calorimeter is a device that is used to measure the specific heat of a reaction.

Lauren Tanaka 1A

The difference between q and ∆H is that q is the amount of energy transferred in or out of the system and ∆H is the total change in enthalpy of the system.

Lauren Tanaka 1A

Enthalpy is a state function since it depends on both the final and initial conditions of the system. Heat would not be a state function because heat is a measurement of change in energy and does not depend on the final and initial conditions of the system.

Lauren Tanaka 1A

Heat is a transfer of energy due to a specific temperature whereas enthalpy is the change in the amount of heat in a system at constant pressure.

Lauren Tanaka 1A

Yes Q is just the value of equilibrium at any given point and K is the equilibrium constant. When Q and K are equal, that would show you that the reaction is at equilibrium.

Lauren Tanaka 1A

In chemical equilibrium, most of the reactions will be reversible. A strong acid or base is able to completely dissociate in a solution and so the reaction is not reversible. However, a weak acid or base does not completely dissociate in a solution making the reaction reversible.

Lauren Tanaka 1A

If the ∆H is given a negative value means that the reaction is exothermic and a positive value means that the reaction is endothermic.

Lauren Tanaka 1A

An endothermic reaction means that there will be heat as a reactant since the reaction requires heat. Increasing the heat will therefore result in the formation of products since adding more heat will lead to more product formation.

Lauren Tanaka 1A

Adding a catalyst to a chemical equilibrium reaction will not affect the K value since a catalyst will only speed up the reaction so a reaction can occur quicker. It has no effect on the K value.

Lauren Tanaka 1A

It depends on the number of products or reactants that are present initially. If there is an initial amount, that number will decrease and those that start at 0 will increase.

Lauren Tanaka 1A

The partial pressure represents the it is the pressure of each individual gas of the chemical reaction. The total pressure would be the combined value of each individual gas in the reaction.

Lauren Tanaka 1A

A change in volume will not affect the equilibrium constant value. It will shift the reaction to favor one side more but will not change K because the temperature is the only factor that is able to change the value of K.

Lauren Tanaka 1A

We ignore liquids and solids since their concentrations do not change. We can then leave them out of the equations when we are solving for the K value.

Lauren Tanaka 1A

Yes I think it does since when they talk about expansion they are referring to the volume of the container. Since volume affects the reaction at equilibrium, so will expansion.

Lauren Tanaka 1A

Whatever the units are given in the problem are the units you should probably use unless you are asked to convert it into another unit.

Lauren Tanaka 1A

Yes I think so since Kp and Kc are generally the same thing except one is used for reactions with aqueous solutions and the other is used for reactions with gases.

Lauren Tanaka 1A

Le Chatelier's Principle describes what happens to a reaction and what direction it will go in when the concentration of Q is greater than K (reverse reaction favored, more reactants) and when the concentration of Q is less than K (forward reaction favored, more products).

Lauren Tanaka 1A

The reverse reaction will occur when Q is greater than K. When this happens the products are more abundant than the reactants in the reaction.

Lauren Tanaka 1A

The difference between K and Q is that K is only used when the reaction is at equilibrium and you know it is at equilibrium. Q, on the other hand, is when you are unsure whether the reaction is in equilibrium and you have to compare that value of Q to the K value that you will be given.

Lauren Tanaka 1A

An amphoteric compound is one that has both acidic and basic characters. Because of this they resemble more metalloids that react with water which is why the diagonal band of amphoteric compounds is similar to the diagonal band of metalloids on the periodic table.

Lauren Tanaka 1A

I think the 2 is just indicating the energy level of the hybridized orbitals.

Lauren Tanaka 1A

Polydentate is when a ligand can have multiple bonding sites to the transition metal. An example of this would be ethylenediamine (en) or diethylenetriamine (dien). Polydentates form chelates where the ligand forms a ring of atoms including the transition metal cations. These cations are bound tight...

Lauren Tanaka 1A

Vitamin B12 is in relation to cobalt as a coordination compound. I think you just have to know that cobalt is a transition metal and this is one of its biological functions.

Lauren Tanaka 1A

The term ferrate is used when naming a coordination compound that has iron in it. More specifically, this coordination compound must have an anion.

Lauren Tanaka 1A

The conjugate base is what is formed when an acid loses a hydrogen atom in a chemical equation. It is a base because it is a proton acceptor that receives an H atom from the proton donor or acid.

Lauren Tanaka 1A

A Lewis acid is a proton acceptor and a Lewis Base is a proton donor. Notice that this is different from the definition of bases and acids from the Bronsted-Lowry.

Lauren Tanaka 1A

HCl is a stronger acid than HF because Cl has a larger atomic radius than F therefore the bond between the H and Cl would be longer than in HF. This makes the bond weaker since it is longer making it easier to break the bond between HCl compared to HF. The bond will dissociate more in HCl than in HF...

Lauren Tanaka 1A

Since the Bronsted acids are proton donors, you can usually identify them with an H at the beginning of the molecule. The Bronsted bases are proton acceptors and usually consist of a hydroxide group

Lauren Tanaka 1A

I think you just need to understand the differences between a bronsted acid/base and a lewis acid/base. Bronsted acids are those that are proton donors and bronsted bases are proton acceptors. However, Lewis acids are proton acceptors and Lewis bases are proton donors.

Lauren Tanaka 1A

NO would have a linear shape since there are only 2 regions of electron density. It would also be polar since there's a difference in electronegativity between the N and O atoms. This would lead to a partial negative charge for the O leading to the molecule being polar.

Lauren Tanaka 1A

I think writing only X or E is fine when there is only one.

Lauren Tanaka 1A

Bent and angular have the same shape but the bond angles might be different for both. Bent usually has two lone pairs whereas angular has one so the bond angles would be less in bent than in angular.

Lauren Tanaka 1A

NaCl would have a higher boiling point than HCl since it has ion-ion intermolecular forces compared to the dipole-dipole forces of HCl. These ion-ion forces makes the molecule an ionic molecule whereas HCl would be covalent. Therefore, since ionic bonds are stronger specifically ion-ion forces, the ...

Lauren Tanaka 1A

Yes since the number of bonds in a molecule whether that be single, double, or triple all equal a single electron density region resonance structure won't matter.

Lauren Tanaka 1A

A stronger intermolecular force will have a greater boiling or melting point. This is because since the bonds are stronger, they are harder to break apart. Increasing the polarizability of a molecule will create a stronger interaction leading to a higher boiling and melting point.

Lauren Tanaka 1A

The boiling point of AsF3 will be higher than AsF5 since based on the Lewis structures you can determine that AsF3 is polar and AsF5 is nonpolar based on a net partial negative charge. Thus the dipole-dipole interactions for AsF3 will be stronger than AsF5 causing the boiling point to be higher.

Lauren Tanaka 1A

It might be helpful to draw the Lewis Structures of each molecule. From there you can see which molecules have a hydrogen bonded to N, O, or F atoms. This indicates that there is a hydrogen bond in that particular molecule.

Lauren Tanaka 1A

By drawing the Lewis Structure of each molecule you are then able to determine the type of intermolecular forces in each molecule. The molecules with stronger intermolecular interactions will then have a higher melting point than those molecules that are weaker.

Lauren Tanaka 1A

NaCl will have a higher melting point than HCl since NaCl is an ionic bond and HCl is a covalent bond. Ionic bonds are generally stronger than a covalent bond so it takes more to break apart these bonds than those in covalent molecules.

Lauren Tanaka 1A

The electrons would not be equally shared since one of the atoms in the molecules is more electronegative than the other. Thus that particular atom will pull electrons more strongly than the other atom and would lead to an unequal distribution of charges leading the molecule to be polar covalent.

Lauren Tanaka 1A

Polarizing power is usually associated with cations. The usual trend for this is similar to atomic radius in the sense that polarizing power increases as the size of the atom increases. Therefore, down a group the polarizing power increases and decreases as you go across a period.

Lauren Tanaka 1A

Noble gases like Xe can bond with other atoms since it has an expanded valence shell and thus have an empty d-orbital. This allows the atom to add more electrons into that d-orbital.

Lauren Tanaka 1A

All the bond lengths are the same because in resonance structures the bond lengths are an average of every single bond leading them to all be the same length.

Lauren Tanaka 1A

I think if you are looking for the most stable form of the molecule then you should put the radical on the oxygen since it is more electronegative. For most resonance structures we always used electronegativities to determine if the particular arrangement would be the most stable form.

Lauren Tanaka 1A

Electronegativity is the ability of atoms to attract electrons and it increases across the period and decreases down a group. Electron affinity is the energy released when electrons are added to a gaseous atom it also has the same trend as electronegativity on the periodic table.

Lauren Tanaka 1A

You should calculate the formal charge of the structures to find which structure would be the most stable. The formal charge will then tell you if the structure is stable if the number is closest to 0.

Lauren Tanaka 1A

The electronegativity is the ability of atoms to attract electrons whereas ionization energy is how well the atom holds valence electrons. The ionization energy is the energy required to remove electrons from a gaseous atoms.

Lauren Tanaka 1A

For the most part the ionic radius does follow the same trend as the atomic radius. Both the atomic radius and the ionic radius decrease across periods and increase as you go down the group. This is because across the period increased protons leads to an increased positive charge which pulls electro...

Lauren Tanaka 1A

The 2nd ionization energy is greater than the first since successive ionizations are bigger. This is because removing a 2nd electron is harder than removing the first electrons since there's less electron repulsion.

Lauren Tanaka 1A

Typically you would represent that it's an anion by adding a negative sign in the top right hand corner after the brackets.

Lauren Tanaka 1A

The element with the lowest ionization energy will be the central atom for the Lewis Structure.

Lauren Tanaka 1A

I'm not completely sure whether we have to know how to calculate it but I think you do need to know the different bond lengths of bond types. A triple bond would be the shortest and double would be the next shortest and then a single bond would be the longest.

Lauren Tanaka 1A

The energy of an electron increases when it moves up an energy level. This is because the electron goes to a higher energy state and are excited by an external energy source which allows them to move up the energy level.

Lauren Tanaka 1A

That is the symbol psi and represents the height of the wave and the state of the wave-particle.

Lauren Tanaka 1A

The photoelectric effect is the correct answer because in that experiment they were able to find that there would be more electrons ejected from a piece of metal if the frequency of the light is increased. They tried to increase the intensity of the particular light source and the same amount or no ...

Lauren Tanaka 1A

The Heisenberg Indeterminacy Equation is used to figure out where the location of an electron could be in an atom. The calculation compares the change in momentum and position of the electron and compares that number to the speed of light.

Lauren Tanaka 1A

I went to one of the UA sessions and they gave us a constants and equations sheet for practice problems. On that sheet was the masses of protons, neutrons, and electrons so I'm assuming that we don't need to know these values.

Lauren Tanaka 1A

Light is a form of energy. However, light is made up of photons which are light particles that form light. Both light and photons consist of energy.

Lauren Tanaka 1A

The photoelectric effect is defined as E(Photon) - threshold E = Kinetic energy of the electron. In order for an electron to be ejected and have KE, the E(Photon) has to be greater than the threshold energy of the metal. If the E(Photon) and threshold energy are equal an electron will be removed but...

Lauren Tanaka 1A

If the light source's energy does not pass the energy threshold the electrons won't be ejected since E(Photon) is less than the threshold energy. If the E(Photon) and the threshold energy are equal then the electron will be released but will have no kinetic energy.

Lauren Tanaka 1A

Amplitude does not have an effect on the intensity of the wave. Frequency, however, does have an effect on the intensity of the wave and is more important for the photoelectric effect. Frequency relates to the number of photons and the energy within each of these photons. An increased frequency can ...

Lauren Tanaka 1A

To find the concentration of the individual ions you take the moles of each compound and multiply it by the mole ratio of the ions in that compound. This will leave you with the number of moles of the particular ion. From there you are able to use the molarity equation c = n/v (where n is the calcul...

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