CHEMISTRY COMMUNITY

Bela Patel 2B

The rate of reaction is determined by the slow step rather than the fast step because the reaction can not progress without the slow step so you must calculate the rate for that rather than the faster one.

Bela Patel 2B

ΔG=0 when the reaction is at equilibrium

Bela Patel 2B

If work is being done BY the system, then the work value will be negative and if work is being done ON the system, then the work value will be positive. This relates to pressure because of the equation: w=-P*deltaV

Bela Patel 2B

The variable Q represents the reaction quotient and you are able to solve for this by using the Nernst Equation: E=E-(RT/nF)lnQ

Bela Patel 2B

When more product is added to a reaction, then the equilibrium will shift towards the reactant and if more reactants are added to the reaction, then the equilibrium will shift towards the products.

Bela Patel 2B

Cp is 5R/2 and Cv is 3R/2, and as said, they are used for ideal monatomic gases.

Bela Patel 2B

In an acidic reaction, you balance the equation using H2O and put it on the opposite side, while for basic reactions you put H2O on one side and you place OH- on the other.

Bela Patel 2B

The 3 Nernst Equations come from the same equation, but differ in a way where they can be better applied to different problems and situations. For example one is under room temperature and another one is written with log base 10 instead of log base e, this can be helpful when given questions with di...

Bela Patel 2B

To find oxidation numbers in a reaction, you use the known oxidation numbers for elements such as oxygen, hydrogen, and chlorine to calculate the oxidation for the other elements in the reaction.

Bela Patel 2B

If Q is less than K, the reaction will favor the product side and if Q is greater than K, the reaction will favor the reactant side. If Q and K are equal, the reaction is at equilibrium.

Bela Patel 2B

Because inert gases can not change the concentration of the products or the reactants in the equation, then therefore the equilibrium won't be impacted.

Bela Patel 2B

In order to figure out which R value to use, 0.08205 or 8.31, you need to know the units involved and decide based on that.

Bela Patel 2B

Including water in a rate law equation has no effect on the rate of the reaction and the concentration of water can not be measured in an aqueous solution, so therefore we do not include water in rate law equations.

Bela Patel 2B

Degeneracy is the number of ways you can get a the same and given energy state (W).

Bela Patel 2B

The constant, n, is the number of electrons that are being transferred and it should be the same when writing the oxidation and reduction half reactions.

Bela Patel 2B

You are right, in the ideal gas law the conditions has to be ideal and it can be used whenever you don't have changes in temperature or volume and you know the values of the constants and most of the other values in the equation.

Bela Patel 2B

In a cell diagram, a double line shows that there is a salt bridge, while if there was a single line, that would show a porous disk instead

Bela Patel 2B

The oxidizing agent will be reduced and gain electrons while the reducing agent will be oxidized and loose electrons.

Bela Patel 2B

F is Faraday's constant, which is 96,485 Coulombs/Joules

Bela Patel 2B

If it is negative, then it is losing heat but if it is positive then it is gaining heat.

Bela Patel 2B

You can use the equation ∆U=q+w, and since you are calculating this under a constant volume there will be no work being done. Therefore, w will equal 0, leaving you with ∆U=q.

Bela Patel 2B

When work is positive, that means work is being done ON the system and if work is negative, that means work is being done BY the system.

Bela Patel 2B

An open system is a system where matter and energy can be exchanged in the environment and flow in and out of it.

Bela Patel 2B

In an exothermic reaction, heat will be released from the reaction and will be added into the surrounding area, while in an endothermic reaction, heat is added into the reaction and will be removed from the surrounding area.

Bela Patel 2B

The larger the K value, the more stable the product because there will be a larger amount of products during equilibrium, which makes it more stable.

Bela Patel 2B

You are correct, if the volume remains constant, there will be no work to be done, even if the pressure changes.

Bela Patel 2B

An adiabatic process is when there is a change in a system with the transfer of energy, except not in the form of heat, but in the form of work.

Bela Patel 2B

Enthalpy is the total energy or heat of a certain reaction, while heat is the energy that is moving in between objects in that reaction.

Bela Patel 2B

Since the calorimeter constant is the amount of energy needed to increase or decrease the temperature in a reaction, I think that the constant will change the overall heat released. This is because increasing or decreasing the temperature will impact which direction of the equation it will favor and...

Bela Patel 2B

I do not think we need to know the process/math behind deriving the work equation, but we do need to know the equation, w = -nRTln(V2/V1), when working with isothermic reversible expansions.

Bela Patel 2B

We should typically convert our answer to kJ units, unless told otherwise in the problem or directions.

Bela Patel 2B

For me I remember exothermic is releasing energy because the beginning of the word ex- is like the word exit. While, I remember endothermic is requiring energy because en- is like the word enter.

Bela Patel 2B

When work is done BY the system, it is losing energy and the value will therefore be negative. When the work is being done ON the system, it is gaining energy and the value therefore will be positive.

Bela Patel 2B

When work is done ON the system, the volume of the system will expand and it will gain energy, while when work being done BY the system the volume will decrease and energy will be lost.

Bela Patel 2B

A state property is a quantity that is independent from how it was prepared. Some examples of this are pressure, volume, altitude, and temperature.

Bela Patel 2B

I'm pretty sure that the phase change diagrams show the temperature of the system and the amount of energy where the phase changes.

Bela Patel 2B

Condensation is exothermic because in order to form hydrogen bonds, it is releasing heat so the vapor turns into liquid and forms bonds. Since it is losing heat, then that means it is an exothermic reaction.

Bela Patel 2B

Melting is endothermic because heat is absorbed during the melting process to break apart the forces between the hydrogen bonds. Since it requires heat and absorbs it, it is constituted as an endothermic reaction.

Bela Patel 2B

Hess' law is significant in that it can be used to determine if the energy change in an overall chemical reaction is equal to the sum of the energy changes in the individual reactions within it.

Bela Patel 2B

As said, it fully depends on what you are given in the question. If you are talking about bases you use, Kb, pKb, and pOH, but if you talking about acids you use, Ka, pKa, and pH. However, if you are given acid units and are asked to find the base then you would need to convert the values.

Bela Patel 2B

Inert gases can not react with chemical reactions so it has no affect on the equilibrium, however, as said above it does have an affect on the pressure of the reaction.

Bela Patel 2B

The equilibrium constant, K, is used for chemical reactions that are at equilibrium and when acids and bases are involved in the reaction then Ka is used for the acid constant, and Kb is used for the base constant.

Bela Patel 2B

Those are the right steps, but I also think you switched the first two steps. You would use Ka to determine x, and then find the concentration of [H3O+].

Bela Patel 2B

The ratio between atm and bar is the same so you do not need to choose which one to use. Instead, just use the units provided in the question.

Bela Patel 2B

You use an ice box when you are trying to calculate a change in concentration of either the reactant or products side of a reaction to find the new equilibrium point. In order to do this, you will be given Kc, or you will find Kc by determining the initial conditions before change.

Bela Patel 2B

The equilibrium constant is the ratio of reactant and product concentrations when at equilibrium, while the rate constant is the rate of the reaction, which can be found by multiplying K by the reactant concentration.

Bela Patel 2B

So if it is an endothermic reaction, it requires heat so it will favor the product side. However, it will favor the reactant side if it is an exothermic reaction meaning it gives off heat. The constants will change based on if the reactions require or give off heat.

Bela Patel 2B

If you remove NH3 from the reaction, then it will reduce the concentration of the product, so then in order to return to equilibrium, it will create more product.

Bela Patel 2B

K has no units and instead a ratio of concentrations between reactants and products.

Bela Patel 2B

Endothermic reactions require heat, so it will favor the products side, while since exothermic reactions give off heat, it will favor the reactants side. No matter what, if there is a change in temperature, then the chemical equilibrium will change and favor one side over the other.

Bela Patel 2B

I am also unsure of why oxygen has a lower ionization energy than Nitrogen, however, Fluorine has a larger ionization energy because it almost has a full outer shell and the attraction between the electrons and nucleus is stronger, making it harder to remove an electron.

Bela Patel 2B

You would have to use the diameter instead of the radius because the radius only represents half the length, rather than the diameters that shows the entire length it would have to travel.

Bela Patel 2B

You can determine the number of electrons in an element by looking at the atomic number. The atomic number represents the number of protons in the element but since there are the same number of electrons as protons, you can use that number.

Bela Patel 2B

To go from pH to [H+], you would do 1*10^-pH and to go from [H+] to pH, you would do -log([H+]).

Bela Patel 2B

In order to determine the [OH-] from [H+], you would need to divide [H+] by 1*10^-14.

Bela Patel 2B

I am also pretty sure that Lavelle used HClO3 as an example in one of his lectures, but it is a strong acid. The other common strong acids used as examples are HCl, HBr, HI, HNO3, HClO4 and H2SO4.

Bela Patel 2B

You can figure out if an acid or base is strong/weak by determining how much the acid dissociates in water. The more it dissociates in water, the stronger that acid will be. Examples of strong acids can include any molecule with an H+ attached to it.

Bela Patel 2B

The acid dissociation constant measures the strength of an acid in a solution and the purpose of calculating it is to be able to see the strength of the acid.

Bela Patel 2B

The bond strength correlates with the bond length, with the shorter the bond, the stronger it is and the longer the bond the weaker it is. Single bonds are longer and are weaker, while triple bonds are shorter and are stronger.

Bela Patel 2B

Coordination numbers is the number of atoms or molecules surrounding the central atom in a complex or coordination compound, while the steric number is the number of atoms bonded to the central atom plus the number of lone pairs attached to the central atom. The steric number helps determine the mol...

Bela Patel 2B

London dispersion forces can be applied to every polar and non polar molecule. The larger the surface area of the molecule is, the stronger the LDF forces will be.

Bela Patel 2B

A ligand is an ion or molecule that binds to central atoms and they usually bond with metals by being donated through bases.

Bela Patel 2B

As the others said, yes, you can combine the two equations to make it E=hc/lambda by substituting the v in the E equation with the V equation.

Bela Patel 2B

The strength can be determined by finding out the pH, acids go from 0-7, 0 being the strongest acid and bases go from 7-14, with 14 being the strongest base.

Bela Patel 2B

The coordination number is the number of ligands connected to the metal center while the oxidation number is the central atoms charge if all the ligands and electrons were to be removed.

Bela Patel 2B

Some elements that have an expanding octet are sulfur, phosphorus, and chlorine. Any element in period 3 and below in the p orbital because then it'll expanded to the d orbital.

Bela Patel 2B

Intermolecular forces are forces that are between molecules, while intramolecular forces are forces that are within a molecule.

Bela Patel 2B

The bond angle is just a very close estimate for that actual molecular model, but it is not an exact number. When answering a question that is asking for the bond angle, I typically say approximately ___ degrees.

Bela Patel 2B

If you look at the formal charges of all of the elements in each Lewis structure, then the Lewis structure who has the most neutral charge would be the more favorable Lewis structure.

Bela Patel 2B

Yes, for AXE notation, we can find the shape of the molecule based on the central atom.

Bela Patel 2B

Ionization energy is the energy required to remove electrons from an atom. If an atom has a higher ionization energy that means it requires more energy to lose the electron, so you are right, the higher the ionization energy, the harder it is for the atom to lose an electron and gain a positive char...

Bela Patel 2B

A coordinate covalent bond is a covalent bond where the two electrons come from the same atom. This can be seen in the bonding of metal ions to ligands. Other examples would include CO, NH4+, and H3O-.

Bela Patel 2B

Formal charge is used to determine which resonance structure is the most stable Lewis structure for a compound. Ideally, all atoms would have a formal charge of zero, but since that can't be the case all the time, the closer the formal charge is to zero for each atom, the better. However, I am unsur...

Bela Patel 2B

The least electronegative atom goes in the middle of the lewis structure because it requires the most amount of electrons to fill its outer shell, and therefore needs the most amount of bonds to complete its octet. When it's in the middle, it is in a better position to bond with other atoms and more...

Bela Patel 2B

Lewis bases donate electrons, while the lewis acid accepts the electron. For example a lewis acid would be H+ and a lewis base would be OH-

Bela Patel 2B

Any element in period 3 and below in the p orbital because then it'll expanded to the d orbital. For example, sulfur, phosphorus, and chlorine

Bela Patel 2B

In lewis structures, every dot is counted as one electron, every single bond is counted as two electrons, every double bond is four electrons, and every triple bond is 6 electrons.

Bela Patel 2B

Ionization energy is the energy needed to remove electrons from an atom. You can determine it by looking at trend on the periodic table, ionization energy increases when going across a period and decreases when going down a group. For example, He has the highest ionization energy because it is in th...

Bela Patel 2B

Fluorine is the most electronegative element and has one of the highest electron affinities, so it will always reacts with metals and becomes an anion because it only needs 1 electron to complete its valence octet. Elements want to gain or lose electrons to fill their valence shell, so Fluorine will...

Bela Patel 2B

Formal charge is the charge assigned to an atom when all electrons are shared equally, while partial charge is the assigning of a partial negative or positive charge to an atom based on the unequal sharing of electrons.

Bela Patel 2B

I have no tricks to remember the period but, to remember which one is the group, I think of the columns of the Noble Gases, Halogens, etc. and I think of them as “groups” of elements.

Bela Patel 2B

Electron affinity is the amount of energy released when an atom gains a negative ion or electron. Having a low electron affinity means that when it gains an electron then it releases energy and for low electron affinity it needs to absorb energy in order to gain electrons. Therefore, release of ener...

Bela Patel 2B

There is a conversion factor of 1eV = 1.602*10^-19 J. You can also find this on the Equations sheet on Lavelle's class website.

Bela Patel 2B

The electron configuration for Br is [Ar] 4s²3d¹⁰4p⁵. The d orbital is filled before the the 4p orbital because 3d orbital has less energy than 4p and the electrons fill up in order based on the orbital's energy level.

Bela Patel 2B

Ionic bonds form between oppositely charged ions, while covalent bonds are formed from shared electrons between nuclei. Covalent bonds are stronger because there is a stronger Coulombic attraction between the nuclei and since there is a stronger attraction compared to ionic bonds, it'll take more en...

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